Build Your Personal Jet

BEARHAWK, FINALLY! THE FOREVERHAWK IS DONE K ITPLANES November 2019 SubSonex Jet • FabricSubSonex Wings Canopy Landing • Leak-Down • Dead-Stick Bond • Bearhawk LSA • Sikaflex Test • Wheels and Brakes • Buzzing Accidents • Aircraft Hoses 2019 November ITPLANES

® SubSonex! Build Your Personal Jet

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NOVEMBER 2019

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19-MCJT19630 G3X ENJOY_THE_VIEW Ad-7.875x10.5-Kitplanes.indd 1 3/12/19 8:45 AM NovemberCONTENTS 2019 | Volume 36, Number 11 Builder Spotlight 6 TURBINE TEMPTATION: Making the decision. By Paul Dye. 14 BUILDING THE BEARHAWK LSA: It’s finally finished! By Ken Scott. 18 AVIONICS AT AIRVENTURE 2019: A bit of innovation and some surprises. By Larry Anglisano. 22 FABRIC COVERING 101: Lessons learned applying fabric to a Murphy Maverick. By Dan Kerr. 28 SIKAFLEX CANOPY BOND: Tips for making The Big Cut and bonding a canopy. By Larry Larson. 14 36 ALTERNATOR MODS WITHOUT MAJOR SURGERY: Another way to modify a Nippondenso alternator for use with an external voltage regulator. By Graeme Coates. 40 HOMEBUILT ACCIDENTS—BUZZKILL: Crashes while maneuvering at low altitude have a high mortality rate. By Ron Wanttaja. 44 GROW A THIRD HAND: When you need an extra hand, make a jig. By Omar Filipovic.

Shop Talk 46 MAINTENANCE MATTERS: Tires, brakes and wheel bearings. By Dave Prizio. 55 UNAIRWORTHY: Fuel leak and cracked flare. By Vic Syracuse. 58 BEST PRACTICES: Aircraft plumbing—flexible lines. By Dave Prizio. 64 HOME SHOP MACHINIST: RV quick stick. By Bob Hadley. 75 AERO ’LECTRICS: Tall transmission tales (antennas, chapter 3). By Jim Weir.

Designer’s Notebook 72 WIND TUNNEL: Design process—landing gear, part 3. By Barnaby Wainfan.

Exploring 2 EDITOR’S LOG: Notes from the heartland. By Marc Cook. 6 52 CHECKPOINTS: The 2-mile decision. By Vic Syracuse. 56 BUILDING TIME: Taxes and shipping additional. By Kerry Fores. 78 REAR COCKPIT: The big scare. By Tom Wilson.

Kit Bits 4 LETTERS 67 LIST OF ADVERTISERS 68 BUILDERS’ MARKETPLACE 80 KIT STUFF: Drawing on experience. By cartoonist Robrucha.

On the cover: Paul Dye flies his SubSonex personal jet over Lake Tahoe in the 28 Sierra Nevada. Photographed by Richard VanderMeulen. For subscription information, contact KITPLANES® at 800/622-1065 or visit www.kitplanes.com/cs. KITPLANES November 2019 1 EDITOR’S LOG Notes From the Heartland No surprise that my first trip back to Long-EZ in a magazine must have been TruTrak can help BendixKing gain some Oshkosh in years was a funny combina- truly invigorating. I have mad respect for traction among Experimentals. tion of beginner’s excitement and jaded Rutan as well as the builders who made Finally this: MOSAIC. There isn’t an journalist’s déjà vu. So much was basi- his imaginings into real aircraft, and you aviation journalist in the land who isn’t cally the same—and remember that I’ve can sense in his public talks a bit of frus- tired of reporting on or watching the been coming to the event off and on tration that today’s homebuilts are so craziness that’s stemmed from the since 1988—but there was enough that mature, so safe in their design choices. Boeing 737 MAX debacle. But the reper- was new to make this one of the best Moving on. Later in this issue, you’ll find cussions go further than inconveniences shows I’ve experienced in a long time. Larry Anglisano’s avionics report from in the summer air travel, with Southwest That said, the volume of raw news from AirVenture, which follows the theme of and American canceling flights as they this year’s AirVenture was more a trickle there being no seismic news. I am curi- worked without dozens of aircraft. than torrent. We’re in the phase of this ous about the acquisition of TruTrak by That’s not our concern. Ours is: The sport where the industry is mature and Honeywell to put it into the BendixKing FAA has been criticized for allowing there is one dominant design, the Van’s product family. I have seen small, agile Boeing to control too much of the cer- RV, at least in terms of pure volume. As companies purchased by mega-glom- tification process. The expectation is for the design of homebuilts have shifted erates with the idea of borrowing some the FAA to halt or even reverse any pro- from wild-eyed inventors truly trying on of that free-spirited, we-can-do-it inven- gram that might be seen as loosening its “something new” to well-established tiveness for the good of the whole. It’s hold on safety. I wouldn’t want to be the companies creating kits that just about not uncommon for the small company to FAA staffer standing up in a meeting say- anyone with a budget and persistence simply get subsumed into the larger cor- ing the agency should give the industry can complete, the sense of blunt innova- porate culture, but here’s to hoping that more rope. tion seems to have left us. This is much less an indictment of where Experimentals have landed than an observation of the homebuilding life cycle. Nowhere was this more evident to me than standing around Boeing Square. This year featured Burt Rutan speaking several times during the show and his designs featured prominently in the main display area. I’ve done enough fiberglass work—mainly on the Pulsar that I built in the 1990s but also, later, on my Sports- man—to fully appreciate the challenge of “inside-out” moldless construction. Rutan’s ability to imagine, design, build, and document wild forms set imagina- tions alight in the 1970s. If you were sitting in a smoke-filled FBO in the ‘70s, Huge props for those intrepid builders who created some of the earliest, most demanding- looking out at dowdy Cessnas and Pipers to-build Experimentals. Burt Rutan’s willingness to bust open orthodoxy helped fuel the on the ramp, the image of a VariEZE or movement, that’s for sure.

Marc Cook is back as KITPLANES’ Editor in Chief after a hiatus playing with motorcycles and learning about e-commerce. A veteran special-interest journalist, Marc has built two airplanes, an Aero Designs Pulsar XP and a Glasair Aviation Sportsman. Both are on to new owners as he flies a shared Grumman Traveler in southern Rhode Island and considers what the next aircraft build Marc Cook will be. Marc has 4500 hours spread over 200-plus types and three decades of flying.

2 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes And yet that seems to be happening. At AirVenture outgoing FAA administrator Dan Elwell (and currently deputy admin under Steve Dickson) discussed MOSAIC in terms that surprised me. Specifically, that it wasn’t dead on arrival. In fact, the program is moving forward in meaning- ful if not specifically revealed ways. MOSAIC is a broad program to recast certification and approvals for non- commercial aircraft. It came as part of a plan to recast all of FAA Part 23 certification to be simpler (thus cheaper) and more reliable. Among the proposals in MOSAIC were an adjustment of the Light Sport Aircraft weight limit and a bump to four seats, to which I say, “Yay.” I was in this chair when LSA was announced, and it was clear the weight limit was both arbitrary and far too restrictive. I won’t suggest that the failure of the category to bring some 6000 new airframes into the world every year hinges on that, but the LSA limitations surely didn’t make life easy for the airframers. Any intelligent relaxation of those limits is a great thing. Other parts of MOSAIC include per- mitting non-builder owners of Experi- mental/Amateur-Built aircraft to take a course to allow them to conduct the annual condition inspection. And, according to the EAA, MOSAIC would look into ways to formalize a program to allow “custom building” of aircraft that are ostensibly E/A-B designs. I don’t doubt there will be a burble of anger from those following the current rules to the letter, but the reality is that the customer looking to have an airplane built is not the same customer deciding whether to get a slow-built or quickbuild version of a new RV. Other parts of MOSAIC include the possibility of installing non-certified components (mostly avionics) into production-line aircraft not used in commercial operations. I know most of you have heard all this before. Promises of big change, then the years go by. But the fact is that the FAA, even pushed along by EAA and AOPA, is not an agency that can move quickly. The fact that it hasn’t completely shut down MOSAIC in light of the 737 MAX traumas is good news for general aviation and our thriving part of it. J

Photo: Marc Cook KITPLANES November 2019 3 LETTERS

EDITORIAL Editor in Chief Marc Cook Winner’s Circle my KITPLANES® subscription through [email protected] What’s this I hear about Paul Dye the new interface way more than ever. Editor at Large Paul Dye already winning some kind of award for Keep it up. Tell the whole team that we Executive Editor Mark Schrimmer his SubSonex? When will we see more appreciate it. Art Direction Dan Maher on this airplane? ROBERT CONNELLY Contributing Editors LeRoy Cook, Jon Croke, RALPH MCKIMMY Kerry Fores, Robert Hadley, Thanks, Robert. Praise should go to our Dan Horton, Louise Hose, Amy Laboda, Dave Martin, We’ll answer the second question first. You in-house web-development team generally Sid Mayeux, Myron Nelson, can see it now since it’s on this month’s and to GlaStar builder Omar Filipovic David Paule, Dave Prizio, Ken cover. Check inside for the first installment specifically. While our dev people did a Scott, Dick Starks, Eric Stewart, Vic Syracuse, Barnaby Wainfan, of his build series, which will run over the lot of the groundwork on the WordPress Jim Weir, Tom Wilson. next 8-10 issues. Paul did, indeed, win platform, Omar took on the task of reor- Web Editor Omar Filipovic an Outstanding Workmanship award at ganizing years and years of old material, Cartoonist Robrucha AirVenture this year, which, he says, took recategorizing for ease of use, and gener- Editorial Director, Larry Anglisano him almost totally by surprise. We’ll crow ally just whipping things into shape, which Aviation Division a bit for him; the airplane looks amazing is no small feat when you consider how old ADVERTISING in person. But that’s not all the praise the our platform was and how many itera- Advertising Director Tom Bliss staff and close family of KITPLANES® tions of the content were banging around. Belvoir Aviation Group [email protected] 602/625-6815 can be proud of. Our very own Dave Prizio We’re just as happy with the new platform Advertising Representative Ivy Ericksen was awarded the coveted Tony Bingelis and look forward to making the most of it [email protected] award from EAA, which recognizes EAA in the months and years to come. 612/743-8512 Technical Counselors for their “dedicated CIRCULATION service and/or significant contributions to Show Us Your Stuff Circulation Manager Laura McMann homebuilding.” We think Dave falls into Have you recently finished a homebuilt? BUSINESS OFFICE both of those categories. So hats off to Paul Or maybe you completed your project Belvoir Media Group, LLC and Dave for their duly recognized efforts. a while ago, but finally got around to 535 Connecticut Avenue, Norwalk, CT 06854-1713 painting it? If your plane hasn’t previ- EDITORIAL OFFICE ously appeared in KITPLANES®, send 535 Connecticut Avenue, Norwalk, CT 06854-1713 [email protected] a brief description (250 words maximum) about the project and the finished SUBSCRIPTION DEPARTMENT aircraft. Also include a digital image of 800/622-1065 www.kitplanes.com/cs the plane (painted or unpainted). Mini- P.O. Box 8535, Big Sandy, TX 75755-8535 mum digital image size is 1500 pixels REPRINTS FOR PUBLICATION wide x 900 pixels high. Other builders AND WEB POSTING AVAILABLE may want to contact you by email, but Minimum Order: 500 let us know if you prefer not to have your Contact Jennifer Jimolka, 203/857-3144 email address published. Your aircraft CHANGE OF ADDRESS? will appear in the printed magazine and MISSING ISSUE? also on our new website. Send text and SUBSCRIPTION QUESTION? photos via email to: editorial@kitplanes. Visit www.kitplanes.com/cs. Or call 800/622-1065 Praise For the Website com. Be sure to put “Completions” in from the U.S. and Canada I wanted to pass along kudos to the web the subject line. Additional informa- Foreign 903/636-1112 or team for a great job on the redesign. I tion can be found at www.kitplanes.com/ fax 203/857-3100 love it, and I have enjoyed content from category/newsline/completions. J

WEBSITE INFORMATION: General homebuilt aircraft information, back issue availability, online directories ordering info, plus a KITPLANES® article index and selected articles can be found at www.kitplanes.com. Unsolicited manuscripts: Are welcome on an exclusive basis, but none can be acknowledged or returned unless accompanied by a stamped, self-addressed envelope. No responsibility is assumed for loss or damage to unsolicited material. KITPLANES® (ISSN 0891-1851) is published monthly by Aviation Publishing Group, LLC, an affiliate of Belvoir Publications, 535 Connecticut Avenue, Norwalk, CT 06854-1713, Robert Englander, Chairman and CEO; Timothy H. Cole, Exec. Vice Pres./ Editorial Director; Philip L. Penny, COO; Greg King, Exec. Vice Pres./Marketing Dir.; Ron Goldberg, CFO; Tom Canfield, Vice Pres., Circulation. Periodicals postage paid at Norwalk, CT, and at additional mailing offices. Copyright ©2019 Aviation Publishing Group, LLC. All rights reserved. Reproduction in whole or in part is strictly prohibited. Printed in USA. Revenue Canada GST Account #128044658. Canada Publishing Agreement #40016479. Subscriptions: One year (12 issues) is $29.95 U.S. $41.95 in U.S. funds in Canada, includes GST. $41.95 in U.S. funds for Foreign Surface Mail or $57.95 in U.S. funds for Foreign Air Mail. Single copy price $4.99 U.S., $5.99 Canadian. POSTMASTER: Please send address changes and subscription inquiries to: KITPLANES®, P.O. Box 8535, Big Sandy, TX 75755-8535, or Canada Post: Return undeliverables to P.O. Box 2601, 6915 Dixie Rd, Mississauga, ON L4T 0A9 or call 800/622-1065. KITPLANES® is a registered trademark of Aviation Publishing Group, LLC.

4 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes

BUILDER SPOTLIGHT: R SPOT E TheL MakingI of LD G I H

U T

B Paul Dye’s SubSonex Part 1 Turbine Temptation

6 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes Turbine Temptation

Making the decision. BY PAUL DYE

I’m going to be upfront with you right from the start—no one a personal, Editor’s Note: Yes, we’re working back- needs single seat jet. Deciding to build—or buy—such an aircraft is hard to justify finan- ward just a bit. As you can see from the cially, so I am not even going to try. Sure, you can come up with a plan to make it cover and elsewhere, Paul Dye has finished worthwhile by selling advertising or going on the airshow circuit—but once you look and is flying his SubSonex. In fact, as this is into the income you could receive from such endeavors, you’ll realize that the best written, he’s just returned from a success- way to make a small fortune in aviation is to start with a big one. No one gets rich ful AirVenture appearance. But the story flying airshows—many performers don’t even make a living at it. But still they do it of the build is a fascinating one that will because they have a passion for all things aviation. unfold here and on KITPLANES.COM over the next few months. So now, as they say, Drawing You In let’s begin at the beginning. My decision to build the jet wasn’t made overnight. I first got to fly the factory prototype SubSonex in order to do a review of the new kit for this magazine. In order

Photos: Richard VanderMeulen, Louise Hose and Paul Dye KITPLANES November 2019 7 to fly the jet myself, I had to first train in the BonusJet sailplane, an aircraft that shares little in common with the Sub- Sonex save for the powerplant. A few hours in the BonusJet took me to a check ride for the “Experimental Aircraft Authorization”—a type rating in all but name because there is no Type Certifi- cate for an Experimental aircraft. After receiving this, I was given a Letter of Authorization to fly the little jet for the purpose of preparing for the check ride to obtain the permanent authorization for that aircraft. Following an unusual (solo) check ride, I had a new line item Training to fly a micro-jet by first flying a sailplane might not make sense to most on my plastic license—SUBSNX. pilots—but it does to the FAA, and they hold all of the cards. So that’s what we did! So there I was—authorized to fly the jet (the authorization never expires), The SubSonex, I knew from the needs a pilot in the cockpit to make it but I had no jet to fly. With four other previous pilot report, is a blast to fly— a nose-dragger. So plan accordingly and homebuilts in our family hangar, it was smooth, powerful and unique. But with practice getting in and out without help hard to see why another was needed. At a no-reserve range of about 300 nautical before you commit to going “remote.” a price of about $130,000, it was difficult miles and a dry-tank endurance of two Frankly, the jet wasn’t designed to be to justify a machine that has some signif- hours, cross-countries are always going flown cross-country—it was designed to icant limitations on how it is used. Our to be a challenge. If you’re going to fly be trailered if you were going to go more RVs, for instance, are fun for local sight- a multi-leg cross-country, you need to than a tank of gas away from home— seeing, aerobatics, hundred dollar ham- make sure that when you get to your but so were all of the early airplanes burger runs—or loading up and flying destination there will be enough run- and they were used well outside their all the way across the country for a vaca- way to get on and off, plus an assurance original operational areas. It’s all in the tion or major fly-in. Our big, lumbering that there will be fuel. You also have to planning and practice to make sure you Tundra can be loaded with two people, remember that you’re not going to be can handle the vagaries of being on the three dogs, camping gear for the lot and able to carry fuel funnels or anything road—and on your own. flown off to backcountry strips where all else to make refueling easier. Oh, and From my base in western Nevada, a you hear is the drone of mosquitos and remember that when you get out of the trip to AirVenture would require at least the burbling of the nearby stream. jet, it is going to settle on its tail—it seven fuel stops—probably one more, very close to Oshkosh to fill up before arriving, just to be ready for anything like a go-around or diversion. That trailer option looks pretty good when you think of it, and it’s not that expensive—so long as you already have a tow vehicle! So how do you justify buying the jet? Many suspect self-delusion is involved, and it probably is. Start out by admit- ting that it is a luxury, something that you want to do because you want to do it. Cost-wise, it is not out of order with what many spend on a two-seat RV— although, admittedly, the RV would be equipped with full IFR avionics for that price! But if you look at that two-seater, ask yourself this: How often do you fly without a passenger? And how often do you really file IFR? Most people The author got last-minute instruction from high-time SubSonex pilot Bob Carlton wait for reasonable VFR weather to go before his first flight in the tiny jet. on trips and rarely file IFR to do local

8 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes Sonex prepares quickbuild kits in batches of five in its Oshkosh facility. Miss the “window” and you might be waiting a bit for your kit. flying—what fun is it to fly to the local tell other pilots, draw a 220 nautical Experimental/Exhibition. There is some hamburger stop if no one else shows up? mile circle around your home base. Now baggage that comes with that category, Bragging rights, sure, but there’s no one put a dot on every hamburger stop or including an annual letter to the FAA to which you can brag! pancake breakfast airport in that circle. describing the events it is going to be Even though our family has two pilots And on any given Saturday, you’re the used at, the locations, and other fly- and four airplanes, we rarely fly with more person that shows up in the jet…how ing activities you plan to do. That has than one of us in an airplane and often are much is that worth? turned out to be a fairly painless letter going just 500 miles or less if cross-coun- to write, with deviations allowed by the try. Local flying is more common—a way Buying Options FAA in most cases. But there is no guar- to unwind during the day, or in my case, For those familiar with normal kit air- antee that they won’t get strict in their local flying of acro and various maneuvers craft—even quickbuilds, the SubSonex interpretation in the future, so some to stay sharp and precise for test-flying is going to be a bit different. Originally, thought should go in to this decision. jobs. The jet can do that! Sure, it’s going to the jet was offered as a “super Quick After the first 10 kits were sold, burn a lot more fuel, but Jet-A is cheaper Build” only—that meant that more Sonex sharpened their pencils with the per gallon and…oh yeah, there I go, trying than 51% of the work was done by the NKET list (used to determine if the kit to actually justify it again. factory, so the airplane did not qualify satisfies the 51% rule or not) and made If you can afford it and you want it, for Experimental/Amateur-Built cer- a few changes here and there to slip the why not indulge yourself? As I frequently tification. It had to be licensed as an airplane’s quickbuild kit in just under

The SubSonex kit is so complete (left) that it even includes the main batteries. The skeleton of the stabilizer (right) takes shape quickly since all of the parts are pre-punched and match perfectly. Ah, the joys of modern kit manufacturing!

KITPLANES November 2019 9 The first step in any build is, of course, a careful inventory (left), which is a task best accomplished with an understanding spouse. The SubSonex’s control surfaces use lots of piano hinge (right), so you’ll be drilling lots of mounting holes. the wire for amateur-built certifica- is deducted from the overall kit price most reciprocating powerplant airplanes tion. Some parts (very few) have to be when you commit to the rest of the these days. The jet is more like 50% for fabricated. More structure has to be project, so there is no real cost impact the powerplant, 40% for the airframe, built. You’ll have more systems work to for going for the tail first. The biggest and 10% percent for the avionics. Most do. But compared to most other kits— expense you’re going to run in to is are unlikely to go with IFR avionics, so even quickbuilds—this thing is pretty going to be the engine package any- a VFR panel is more than enough—and simple to assemble. And assemble it you way—the airframe looks downright far less than what you’d spend for that will. This is not construction, it is put- reasonable by comparison. dual-screen panel with an IFR navigator ting together well-fitted parts to create in an RV or Sportsman. a finished aircraft. Costs and Decisions The SubSonex doesn’t, in fact, require You can now buy the tail kit for the With most kit aircraft, we generally tell a lot of decisions in the buying depart- SubSonex—this allows you to put a toe people to use the “rule of thirds” when ment. The airframe has just a few in the water of building before com- it comes to cost. Allow one third of options—BRS ballistic parachute, oxy- mitting to the entire project. It will the cost for the airframe, one third for gen, lights and interior are about it. The help you decide if you really want to go powerplant, and one third for avionics engine has no real options—you buy ahead with the entire kit or not, with a and finishing. That works out well for the complete package from PBS, the modest financial investment up front. For a few thousand dollars, you build the same tail surfaces that you would build if you bought the complete kit up front—and learn fabrication as you go. The thing is, once you finish the tail, the fabrication is mostly finished—the rest of the jet is so far along in assembly that there are few tasks that relate to building the tail. Sure, you have to build flaps and ailerons, but they go together just like the ruddervators. After they are done, you can pretty much put away the drills, Clecoes and riveting tools until you get very near the end of the project, when you have to close up the belly skin. Still—getting that tail kit into your workshop does mean that you are building a jet! It is the first step down the road to addiction that many are A standard homebuilt project requires lots of reference material and catalogs. The looking to follow. The tail-kit price SubSonex kit is much more complete, and you’ll find you hit the books less frequently.

10 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes

SONEX SUBSONEX

Kit Price ...... $44,000 Estimated completed price ...... $120,000 Estimated build time (experienced builder) . 500 hours Number flying (at press time) ...... 10 Powerplant . . . PBS TJ-100, 258 pounds static thrust Propeller ...... None! Powerplant options ...... None

AIRFRAME Wingspan ...... 18 ft 0 in Wing loading ...... 16.67 lb/sq ft Fuel capacity ...... 40 gal Maximum gross weight ...... 1000 lb Typical empty weight ...... 550 lb The fuselage comes with a pre-fitted canopy so you can sit and make airplane noises Typical useful load ...... 450 lb right from the start. Full-fuel payload ...... 185 lb importer, and it includes everything that finding places for remote mounted Seating capacity ...... 1 you need to make jet noise. boxes, relocating the engine monitoring Cabin width ...... 24 in About the only place you will do panel and a few other things. All of this Baggage capacity . . . . Whatever fits in your pockets some window-shopping involves avion- is doable for a homebuilder with a mod- ics. Jets have flown with MGL, Garmin, icum of experience, but as anyone who PERFORMANCE GRT and Dynon equipment so far. The has built before knows, modifications Cruise speed ...... 190 kt panel itself was designed around the always take about five times longer than Maximum rate of climb ...... 1500 fpm MGL screen, which fills the available you anticipate up front. Little changes Stall speed (landing configuration) ...... 52 kt space and ends up looking much big- have far-reaching consequences, so know Stall speed (clean) ...... 60 kt Takeoff distance (to 50 ft agl) ...... 2300 ft ger than it is because the panel is so that before you start! Landing distance (from 50 ft agl) ...... 2100 ft small. There really isn’t a lot of room for In my case, I did a lot of soul search- options! Necessary switches fill up the ing, and decided that since I already Specifications and pricing provided by the builder. remaining panel space, and if you want had airplanes with Garmin, GRT and to use something that takes more real Dynon packages, I’d go ahead and use is that they have already done some soft- estate, you’re going to be in for some the factory-preferred MGL EFIS and ware integration for the jet, so configura- real homebuilding! accessories. It would lead to a faster build tions are a bit easier. Another advantage At least one jet is using a full-sized and give me an opportunity to fly with a is that the remote-mounted boxes (radio, Garmin G3X Touch, and it looks very new EFIS—one that I have little experi- transponder, ADS-B and engine data nice. However, that meant modifying ence with but which has a good reputa- box ) are pretty compact, which is an the panel to be deeper on the bottom, tion. One advantage of the MGL system important consideration in the jet.

The author’s jet was sitting on its gear (left) and had its tail on after less than a month of work. Although you don’t need a mill and lathe to build the jet (right), some advanced tools make doing precision work quick and easy.

KITPLANES November 2019 11 Some have designed their jets to be IFR capable, but I found that trying to shoehorn an actual IFR GPS in was just going to be too much trouble— plus the fact that the engine’s generator doesn’t really put out enough amperage to make the power budget work. Yes, you can fly IFR with a single com and a single VHF nav for VOR navigation and ILS approaches. But today’s IFR system isn’t very friendly if you don’t have a GPS, and the required reserves make this a very marginal IFR airplane anyway. The old joke with the T-38 Talon was that you took off in afterburner and declared a fuel emergency as soon as you were done with your initial climb. The SubSonex isn’t much better. If you consider that it has two hours’ endurance, lop off 45 minutes for IFR reserves, plus something to divert to an alternate, it’s clear your leg lengths are going to be less than an The author used the factory-standard MGL EFIS and avionics, which fired up (without hour. On the bright side, you can easily emitting any magic smoke) after a small amount of wiring work. More about the MGL avionics platform and the installation process later in this series. hand fly that length of mission, which is good, because you don’t have the the components for the required sys- any aircraft kit. The thing about the Sub- weight or power budget for an autopi- tems—fuel pumps, fuel fittings, air Sonex is that you need to choose mods lot anyway…. pumps,landing gear actuators, etc. You carefully, for it is a very tiny aircraft, and The SubSonex kit—whether you buy need to buy your own pilot harness, but there isn’t a lot of room to make addi- it all at once or pick up a tail kit first—is aside from that everything is included in tions without impacting something that remarkably complete by today’s stan- the box (except the avionics). I decided is already trying to occupy the space. dards. All of the hardware is included to add the O2 system, BRS and lighting (although I occasionally dipped in to options—and those are very complete as Going for It! my reserves of hardware for a slightly well. If you want to make modifications, Once you have decided that you want the longer or shorter bolt), as are most of you’re pretty much on your own, as with jet, it is hard to get it out of your mind— eventually, you’re going to succumb. Sonex builds the jets in batches—in Media Benefits the summer of 2018, they were doing It turns out that there are benefits to being in the aviation media beyond free breakfast at five at a time. You can get your name on the AirVenture media center during the show. Getting to fly the Sonex yellow jet was one of one then follow it along with a deposit. them. While I have described the transition training process of starting out in the BonusJet Mine took about three months to be sailplane, and then moving on to the SubSonex once your letter of authorization (LOA) has ready to ship. Engine lead time was been obtained, it turns out that due to insurance requirements—and the fact that the about 10 weeks and I did my best to get factory only has the single prototype jet that is used for development and airshows—the everything else in house about the same average pilot doesn’t get to fly that machine in his training flow. time so that I wasn’t slowed down for I was able to fly it when it was new for the purpose of evaluation and reporting, but most lack of parts. new SubSonex pilots will have to wait until their own jet is complete. BonusJet training can If you know you want one, about all be completed any time, but there is no way for them to fly an actual SubSonex until they I can say is to remember a line from have finished their jet. So far, a number of owners have used experienced SubSonex pilots to an old maker of ski movies, Warren do their first flights while others have done the test flights based on their years of military Miller. He used to say that “you need to jet time. Or, in my case, the transition training and checkout process. go and ski (whatever mountain) today, What does this mean to a more typical GA pilot considering buying a SubSonex kit? Well because if you don’t, you’ll just be one you’ll have to take it on faith that you will enjoy the way it flies since there is really no way year older when you finally do!” The to try one before you can buy one. jet’s a lot like that. Don’t try to justify —P.D. it—just do it!

12 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes So What’s It Like? While we’re going to make you wait for a full report on the flying pounds in my flight gear, I am just 5 pounds under max gross if the Sub- qualities when we get to the end of the series, it would be wrong not Sonex is full of fuel. Roll is heavier than pitch, just because you don’t have to tempt you just a little at this point with what the airplane is like to much leverage on the little side stick. But it is perfectly adequate. Roll fly. After all, explaining the irrational desire to fly one of these things gets noticeably heavier with speed, so plan ahead before going into that is what this installment is all about! red-line dive. Yaw is stable, but there is a little Dutch roll if you disturb it. First off, the jet does not require the skills of a guy named Hoover Aerobatics are fun, of course, but because the airplane picks up to fly. It has a forgiving Hershey bar wing that stalls nicely at about 52 speed very quickly with the nose down, I stay away from anything that knots (flaps out), and the speeds are actually in line with a high-perfor- puts me vertical for very long. Yes, it will loop and split-S, but be careful. mance piston single. In fact, it lines up well with your run of the mill You can roll it all day long, however, there are no negative G systems, so Rocket, and would easily get run over by a late-model Lancair. We flight keep it a little positive. Stalls are straightforward, steep turns are fun, plan for about 190 knots, and block times are always going to be less as you’d expect, and wingovers even more so. I like to do military 8’s than two hours, because at that point, you’re out of fuel, and gliding. with a roll on top of each one, just for style. Plan on about one and a half hours of flight time, which will give you I try to get the landing gear out before I enter the pattern because if a comfortable 30-minute reserve—and in that hour and a half, if you’re you get on downwind and aren’t below the 108-knot gear/flap speed, going cross-country, you can plan about 220 miles in a straight line. On you’re going to have to pull the nose up and balloon to slow down, my recent trip to AirVenture 2019, I averaged 200-mile legs, and those which is not very elegant. Once the wheels are down, drop the flaps, took about an hour and 20 minutes from engine start to engine stop. add power and fly downwind about 90-100 KIAS, slow a little on base Don’t let yourself get stuck behind a student/instructor in a 172 at the and I try to fly final about 80-85. The engine takes several seconds to hold-short line, however; you don’t have fuel to waste. spool up from idle, so if you hit some sink and fall below the glideslope, Takeoff requires a higher rotation speed than you’d expect because it can feel like an eternity before thrust resumes. A little extra energy the high-mounted engine pushes the nose down. While the wing will is your friend in those seconds. That means you will cross the threshold fly at 52 knots, the tail doesn’t have enough authority to rotate until fast, and you’ll float, float, float until touchdown. With practice, it all about 75. At that point you can lift off, but be careful not to over-rotate works out better, but until you master it, I’d recommend 5,000-foot and skip. You get used to it after one or two tries. The gear sucks up runways. You will easily float 2,000 feet from an 80-knot approach. All quickly, and you can accelerate over the runway to a best climb speed of this is easily learned, and when you fly it you’ll be impressed by the of about 120 KTAS. Hold that 120 all the way to whatever altitude you smooth, vibration-free nature of the little machine. J like—the IAS will, of course, drop as you go up. —P.D. The airplane is fairly sensitive in pitch because, if you build it stock and weigh an average amount, you’ll probably be in the back of the CG envelope. You also won’t have much margin to add nose ballast. At 180

KITPLANES November 2019 13 Building the Bearhawk LSA

It’s finally finished! BY KEN SCOTT

A week after Valentine’s Day, we the weather was cold and clear, and the airplane doing the same thing. I finally had the confluence of circum- winds were light. wanted to be able to put my hands and stance we’d been awaiting, and the For- We’d been inspecting the airplane feet exactly where I wanted whenever everHawk, our six-year and two-week for a couple days, writing and rewrit- I needed. I wanted to know what the Bearhawk LSA project, was ready to fly. ing checklists, and reviewing the new pitch attitude looked like in the three- The scales said the empty weight was EAA test flight manual. I spent several point stance. I wanted to be sure I could 836 pounds, including oil and three sessions alone, sitting in a plastic chair get full control movement. quarts of unusable fuel. The CG, with in my hangar (the warm part of my While I was doing that, Rion Bour- the pilot seated, was close to the front hangar!), trying to visualize my way geois, Philip Groelz, and Greg Hughes edge of the envelope. We’d been signed through the first flight. Then I spent were installing GoPro cameras on the off by the DAR, insurance was in place, the better part of two hours sitting in wing struts and cabin ceiling. Rather

14 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes After six years, two weeks, and two days, the ForeverHawk was finally completed.

than try to record instrument readings line up with the spinner, and pushed I wanted, and as I eased it back down, on a kneepad, I’d just monitor them the throttle to the forward stop. the main wheels left the ground. A and let the camera do the recording. Nothing much happened. Most of quick glance at the tach showed about Finally at 1 p.m., I started the engine my last 2500 hours have been in RVs 2100 rpm. No wonder it seemed so lei- and, after warming up the little O-200 with constant-speed props—airplanes surely! But, finally, here we were with for a few minutes, taxied out to Runway that make a loud noise, give you a firm the shadow falling away and the trees 34. With 2500 feet of grass in front of shove between the shoulder blades, and sliding underneath the nose. A quick me, I lined on the right side of the run- throw themselves into the air. Not this grab at the trim and a few deep breaths, way—just in case there was more swing airplane. It trundled slowly forward, and we’d reached 600 feet. Another than I was ready for—focused on the taking its own sweet time to acceler- couple minutes of climbing, and it was tip of a faraway tree that happened to ate. The tail came up a little higher than time to try a few gentle turns. That was

Photos: Ken Scott KITPLANES November 2019 15 humbling…the tail went swinging one way and the nose the other. Well, that’s why those pedals are on the floor! A few more tries got things better organized, and I circled the strip for 15 minutes or so. The engine sounded good, even though it wasn’t turning many revs. The left wing was very slightly heavy, and if I held the wings level and took my feet off the rudder pedals, the nose would yaw slowly but steadily to the left. I spent the next 15 minutes determin- ing that the airplane was controllable and handled normally. That and an engine reading were all that was on our first test card, so it was time to land. With some effort I got the speed down to 60 knots Ken Scott fastens the five-point Crow harness before making the first flight. on an upwind leg and had to work harder to get down to 55 on the downwind. As 1400-foot mark, I turned around and only get about 2350 rpm and about I turned base I was still high, and even at taxied home. My wife was there, along 104 knots indicated. We’d like to see idle and 55 knots, the slippery little beast with a few neighbors and my partners, about 2750 rpm and hope that gives just wasn’t coming down. On short final, Rion and Philip. To varying degrees, they us about 115 knots. Crashing static on unwilling to try a hard slip until I knew all looked relieved. FoPaw, the poodle, the radio was annoying. The carb heat the airplane better, I gave it up and went seemed unimpressed. You’re back? OK. cable stop needed reinforcing. On the around. On the next try, I flew the pat- Throw the ball. third flight, a fine mist of oil started tern 200 feet lower and 5 knots slower. A few minutes later, Rion was in the stippling the windshield. The approach angle was much better, but air on his first flight. Philip flew it the Two weeks later, we’d fixed the radio the threshold went by and the first run- next day and was the first to land it with- and carb heat cable. Replacing the front way light went by and the second runway out going around at least once. crank seal solved the oil leak. Reworking light went by—obviously I was still too The next day the weather had turned the prop allowed the engine to turn up fast! Eventually the main wheels stroked back to winter crud and was forecast faster, but we’re still not getting redline the grass. I pinned them on with a touch to stay that way for a week, so we went rpm. Right now, 24 inches of manifold of forward stick and let the airplane roll. to work on the squawk list. The prop pressure at 3000 feet density altitude Finally the tail came down, and we rolled was quite overpitched—even at 27 gives us an indicated airspeed of 100 out without using the brakes. At the inches MAP and 2000 feet, we could knots at 2475 rpm. Full throttle results in something around 115 knots. When spring finally arrived, we really started to learn our new toy. It had been a long time coming. Summing Up the Project Partnership: We’re all still friends. In fact, although we had some minor dif- ferences along the way, I can’t remember a serious disagreement. We made a lot of decisions, and most of them were better for having been decided jointly. I’ve built four airplanes, two from kits and two from scratch. The kits I built by myself, but the scratch-builts were done with partners. A good partnership, with clearly spelled out expectations and financial arrangements, is a good way to build an airplane. I doubt if I would, or Empty weight came in at 836 pounds with oil and about three quarts of unusable fuel. could, have completed the scratch-builts

16 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes The official logo of the Pudding River Bearhawk LSA. It flies! The Bearhawk LSA on takeoff. without the partnerships. There’s a lot invested about 5000 hours over three much unaccounted for—and we ended to be said for knowing that even if you years. He worked by himself in an un- up spending just south of $50,000. can’t work on the airplane, others are air-conditioned shop—in Arizona. Our Well, if you buy a $1000 exhaust sys- still making progress. hats are off to that man! More than tem, an $800 alternator, a $700 GPS, and Time: When we first spread the plans ever I am convinced that the thing that hire a professional welder at (a bargain!) around on my living room floor and makes homebuilt airplanes doable for $25.00 per hour for 160 hours, it all adds agreed to build the airplane, we figured most mortals is the kit. If you think a up. This is another place the partnership it would take about three years. When Bearhawk LSA is the airplane that fits benefited us. We could make some expen- we set down the tools, looked at one your needs, by all means build one. But sive—but quality—choices that individu- another, and declared it finished, we’d do it from the kit! ally none of us could have afforded but been working on it for six years, two Money: I originally figured on around could tolerate when split three ways. weeks, and two days. We have no idea $25,000 to complete the airplane. That So, in the end, we took twice as long how many man-hours went into it. might be possible, but that’s not how ours and spent twice as much as we origi- Another scratch-built Bearhawk ended up. We formed an LLC and ran all nally estimated. LSA was completed by a builder who the purchases through that, so there’s not Sounds about right… J

Rion Bourgeois, Greg Hughes, Rob Hickman and Philip Groelz, with Ken Scott in the plane.

KITPLANES November 2019 17 AVIONICS at AirVenture 2019

TruTrak autopilots now wear the BendixKing nametag after its parent company, Honeywell, announced a surprise merger of the two.

A bit of innovation and some surprises. BY LARRY ANGLISANO

Avionics systems and accessories usu- with an IFR-approach-capable GPS and the GNC 300XL. This was a TSO ally attract attention at the big show, Mode-S/ADS-B transponder and the lat- C129(A1) IFR approach GPS navigator, and while there weren’t any real show- ter just the GPS. While we thought the and as a bonus, it had a utilitarian mov- stoppers this year, there were a few major units offer decent utility and are smartly ing map and a built-in VHF com radio. announcements that caught our eye, even designed to save space in the radio stack— It had no VHF nav—strictly GPS. The if we had to go looking for them. making them perfect for older Experi- GNC series was a clever idea and almost mentals needing an upgrade—we wished the perfect solution for backing up a tra- More From Garmin there was a version that had a com radio. ditional nav/com, or for more basic pan- Garmin kicked it off with yet another new We didn’t have to wish for long because els, it worked as the primary rig because GPS navigator: The $6995 GNC 355. In that’s just what Garmin delivers with the of the built-in com. We’re glad to see the August 2019 issue of KITPLANES® GNC 355 GPS/com. this concept back as an option for both we looked at Garmin’s new GTX 375 and It was around 1996 or thereabouts new and existing kits. Like the other GPS 175 budget navigators—the former when Garmin started cranking out two budget units, the idea with the

18 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes Need a com radio with GPS? Garmin’s new space-saving GNC 355 has it. Built on the bones of the GPS 175 and the GTR 375, the 355 can do IFR approaches as well as communicate. GNC 355 is to replace aging navigators the savior is the wireless interface for without having to do much if any stack tablets running the Garmin Pilot or rework. Maybe there’s an old Apollo ForeFlight apps. Allow the GNC itself GX60, King KLN89B or even a King to be the data input and use the tablet KX155. The GNC should easily fit in for higher-resolution mapping, weather, looks to require diversity systems, or without restacking. and traffic information. those with dual antennas. The new series has Garmin’s Connext The effort to install that second wireless interface for traffic, weather uAvionix Gears Up For antenna could easily blow a “budget” and flight plan streaming to and from Canadian ADS-B Spec upgrade for kits that are already com- a tablet. Like the GPS 175 and GTR The uAvionix booths at AirVenture pleted. So with a clever but obvious tech 375, the new com-equipped GNC 355 were packed layers deep with last-min- redesign, uAvionix is testing a second has a 2-inch-high bezel, which helps ute ADS-B buyers as the 2020 mandate blade antenna on the current single- differentiate itself from the larger GTN was 23 weeks away—January 1, 2020. antenna style skyBeacon design. 650 navigator, nor does it have a VHF But high on the list of ADS-B equi- Like the original skyBeacon, the nav receiver. While this might be a deal page concerns is the developing ADS-B skyBeacon X is an LED position light breaker for those not willing give to up space-based Aireon tech in Canada (and replacement, but has an integrated on ILS approaches and having to rely the US aircraft that will fly there), which 1090ES transponder (and WAAS GPS), on WAAS approach guidance alone, we think this simplifies the installation. Who wants more antennas? Garmin used its noodle and made the GNC 355 compatible with a wide variety of nav indicators—everything from Gamin’s own GI 106A/B to the King KI209 and KI525A HSI—even old Narco and Collins indicators. With a digital databus, the unit works with Garmin’s own G5 EFIS, G500 TXi display and the G3X Touch integrated suite, plus ones from Dynon, Advanced Flight Systems, and others. The point here is that if you’re upgrading from an older nav/com or maybe found a “veteran” indicator on the shelf, the new Garmin GPS will accommodate it. Of course, there’s some downside to the compact platform, especially compared to the larger GTN 650. At 4.8 inches diagonally, the GNC 355 display is comparatively small, but uAvionix is testing a version of its skyBeacon ADS-B Out device for Canadian ops.

Photos: Larry Anglisano KITPLANES November 2019 19 plus a baro altimeter. The company says it might be ready in 2021 and it hasn’t mentioned pricing, but uAvionix Presi- dent Christian Ramsey hinted it will be budget-based. “We specifically designed the skyBeacon and tailBeacon to target a low cost of installation, and we are doing it again with the skyBeacon X,” he said in a news release. If you haven’t been following along, back in January 2019 Nav Canada announced it will be implementing ADS-B airspace performance requirements in three phases. Phase 3, to be implemented no sooner than 2023, is the biggest impact on GA operations and will require ADS-B Out systems with two antennas—one on the top and the other on the bottom—of the aircraft. Don’t overthink the tech: Since Aireon is satellite based, an antenna on the bottom of the aircraft won’t do much for performance, or specifically, the aircraft’s ADS-B Out data update rate. The skyBeacon X testing, so far, If we saw anything that surprised us at AirVenture it’s that BendixKing appears to be shows that the new design can work well making a real push to become the general-aviation force it once was. out on the wingtip for both ground and satellite signals. We’ll be following and Check that against the $499 full-size If there is more than one iPad con- reporting on this product and others Sentry (introduced at last year’s show), nected, each iPad will be synced to moving forward. which measures 3.25 by 2.25 by 1.25— have the same data replayed. Fore- still compact. Flight will also animate ADS-B radar, Another Portable ADS-B Unit The main reason for the Mini’s looping up to 30 minutes of radar from ForeFlight slightly smaller footprint is it doesn’t while in flight. If there’s a rub with The market is saturated with stick-it- have an onboard battery. You’ll need the Sentry Mini, it’s that it only works on-the-window ADS-B receivers, but to plug it in to any 5-volt USB power with the ForeFlight tablet app. ForeFlight brought its new Sentry source using the supplied cable. Mini to the show. Priced at $299 and The Sentry Mini is slightly scaled back BendixKing and TruTrak Merge made by uAvionix, the product’s name on features compared to the full-sized One of the biggest surprises on the avi- suits it well—the device is 3.3 by 2.3 Sentry. It doesn’t have built-in AHRS onics front was BendixKing’s announce- by 0.6 inches and weighs 0.1 pounds. or the CO detector. It does have a built- ment that parent company Honeywell in GPS receiver for providing position purchased autopilot maker TruTrak. to iPads that aren’t so equipped. If you The acquisition of TruTrak gives Ben- plan to use ForeFlight for backup flight dixKing access to a wide range of prod- instruments, the Mini probably isn’t the ucts for experimental aircraft and will device for you because it doesn’t have the likely form a gateway to new product AHRS sensor to feed the app. It does, applications in the certified world, too. however, support the full range of FIS-B TruTrak’s current boss, Andrew Barker, weather and ADS-B traffic data. will continue in his role under the new We like that the Mini has onboard ownership, and BendixKing will absorb memory to support ForeFlight’s Weather at least some of TruTrak’s engineering Replay, which provides automatic staff. “Honeywell and BendixKing’s storage of up to 30 minutes of FIS-B data. capabilities in the aerospace industry will That means you can sleep the iPad and accelerate the continued development of ForeFlight makes the Sentry smaller by then receive a burst of updates when the products TruTrak has built from the losing the battery the iPad wakes. ground up,” said Barker.

20 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes No more guessing how much O2 is in the tank with Aithre’s Altus smart monitor (left), which is physically connected to your onboard oxygen tank. It works on the company’s app or on EFIS displays (right) to show tank pressure and carbon monoxide levels. What we don’t know going forward the company President Jim Ruttler’s plus there are audible Siri notifications is what impact this acquisition will have struggle with seeing the behind-the-seat that work with Bluetooth headsets. We on prices, availability or future develop- oxygen tank gauge in his Van’s RV-10, think these are products with legs. ments of Experimental-class products. and running out of oxygen when he At its booth Aithre was showing It’s fair to say that right now the out- needed it the most. both the $350 Altus O2 monitor and look for autopilot applications is bright, The monitor is a simple upgrade to the $250 Shield eX avionics-integrated with all the major EFIS makers offering any tank and basically converts a por- carbon monoxide detector displaying add-on servos that make up a complete table oxygen tank into a smart device, on an Advanced Flight Systems dis- flight-control system, in addition to stal- with wireless (Bluetooth, of course) play. Using Bluetooth, the company wart Trio. Where TruTrak was once the real-time monitoring of oxygen pres- said the sensors will also work with go-to autopilot source for Experimen- sure, flow rate, pressure altitude and Garmin’s experimental version of the tals, the rise of add-on systems has cut oxygen levels. It’s a smart system, trig- G3X Touch and Dynon’s SkyView. We into its market share. gering oxygen use reminders, low-level like what we saw. alerts and shutoff reminders on landing. Innovative Biometric Devices Installation takes less than 15 minutes Wrap Up We like wandering the AirVenture and consists of connecting a high-pres- As we said at the outset, there were no Innovations Showcase building at sure tee fitting between the tank and legitimately eye-widening new prod- Oshkosh because there’s always inter- existing pressure gauge and strapping ucts at AirVenture this year, reflecting esting stuff to see, even if some of it is the housing on using Velcro. the maturity of the industry as a whole never to be seen again. That won’t be The device runs on four AA batteries, and the avionics offerings therein. But the case with the utilitarian and smartly detects pressure changes within a 10-psi that doesn’t signal entropy. Avionics designed products on display from resolution, samples pressure every six shops catering to Experimentals report Idaho-based Aithre. seconds with a built-in pressure altim- strong sales and continued demand Two products from the company that eter and throws a low-oxygen warning for high-end, complete systems, and caught our eye were the Altus portable when it drops below 500 psi. The system it’s possible that Garmin’s new retro- oxygen tank monitor and an avionics is designed to work with Apple smart- fit-friendly offerings will get owners display-compatible carbon monoxide phones and iPads, and there’s an Aithre of older machines into more modern sensor. The O2 monitor is the result of Connect app for monitoring trend data, boxes soon. J

KITPLANES November 2019 21 Fabric Covering 101

Lessons learned applying fabric to a Murphy Maverick. BY DAN KERR

The advertisement for my Murphy the Poly-Fiber System, sat down with fees. Seems that someone figured prod- Maverick said metal fuselage with a pot of coffee, and read it more than ucts such as methyl ethyl ketone (MEK) metal and fabric wings. Can’t be too once. It seemed fairly simple. You just could do damage to the watershed if it hard, I thought… had to follow the steps, one at a time. wound up there. Starting with the small After 15 years, the metal fabrication control surfaces and not knowing how was finished, and I was ready to tackle The Products fast I was going to use these products or the fabric. It turned out to be a whole Chemicals the length of their shelf life, I ordered new experience. The first shock was acquiring the chemi- small quantities to begin with. Getting some direction for this is rec- cals to do the job. Ordering from Air- Poly-Tack is the first product you’ll ommended. Take a course, take advice craft Spruce Canada is as good as it gets, use. It’s used to stick down the perime- from an old aircraft maintenance engi- as those folks are very knowledgeable ter fabric and goes a long way, so a quart neer (AME) or A&P, or find someone and provide excellent service. At this was the perfect initial size. who knows an old AME or A&P and point, I almost feel like a shareholder Poly-Brush is next, which is used to also knows what they are doing. Other- in the company. Up here in Broken seal the fabric after it’s been shrunk. wise, do as I did: Because of my remote Toe, Ontario, everything is shipped, You will use a lot of this stuff, especially location, I acquired a book from Air- and these products arrived by Purola- when it’s brushed on, or not so much craft Spruce & Specialty Company on tor Courier with extra environmental when you have to spray it on.

22 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes Poly-Spray is a UV light sealer that is matter before the microwave does. Proper punching or cutting them. Melting the sprayed on and also goes a long way. fit is to place the respirator on your face, holes for rivets will sear the circumfer- Poly-Tone is the final finished coat cover the filter holes with your hands, ence, preventing any fraying. These do that I don’t know much about. I liked and breathe in. If the mask sucks down not need to be calibrated, just hot. the color of the Poly-Spray and left it as to your face, you’re good to go. It’s time to Pencils: Number 2 soft is the pre- the final coat. This is not recommended replace the filters when you can smell the ferred type. They should be soft enough by the folks at Poly-Fiber, and I was told product you’re trying to filter out. to write easily on the fabric and are the it can scratch as a final coat. Sprayer: High-volume low-pressure only thing recommended for doing so. Methyl Ethyl Ketone is a product (HVLP) is recommended. Along with No ink or felt pens are allowed as they used to undue what you have done that the sprayer, you’ll need an air compres- will bleed through the fabric onto the you don’t like. Instructions in the book sor, regulator, and moisture filter. An finished surface. say that you can simply apply MEK, and exhaust fan is also a good idea. You’ll Tape Measure: Time to go buy a new it will dissolve what you want out of the need a space inside that is large enough one and designate it “airplane use only.” fabric. Yes it will, but by the time it has, to spray paint on the largest piece, and The one you used for the roofing job will the fingers in your latex gloves have also you must have clean air lines. By clean, I not do for the same reason as felt pens. dissolved. A quart of this will go a long mean don’t use the ones that you use for This virgin white fabric stains like noth- way if you are careful while you work. your air tools; if you run an auto-oiler, ing I’ve ever seen. R65-75 Reducer (thinner) is needed the oil in the lines will ruin the entire Vapor Barrier: Buy a roll of light to thin down both the Poly-Brush and process. If you start with some new tools, vapor barrier from the hardware store. Poly-Spray, 1:3 and 1:4 respectively, so it you’ll save money to spend on shipping. When you roll out your fabric to start too goes a long way. Gloves: Latex is the type. The cheap- a covering, roll out a piece of vapor bar- RR-8500 Reducer is another prod- est place to buy is Walmart, and you’ll rier to cover it, marking the outside as uct I found I didn’t really need while liv- need several boxes. “dirty.” When your day is over, cover the ing up here in igloo country, as it slows Scissors: You’ll need good, sharp job. If you miss a day or two, you will be down the drying process in tempera- ones, including pinking sheers. surprised how much unwanted dirt will tures above 85° F. Thermometer: It should be capable accumulate, including flies. of reaching 350° F. Before use, start by Other Items making a cup of tea. While the water The Procedure Brushes: Your call here, but I ordered is at a rolling boil, check for accuracy. As I mentioned, reading the book, mak- these by the boxful. At $15 for 20, they’re If it’s way off, return it. If it’s a little off, ing notes, and highlighting tempera- cheap, but this price is augmented by $17 mark the dial at 212° F and calculate/ tures, etc. will ease the anxiety of this for shipping. It’s either this or you clean mark 225°, 250°, and 350° as these are task. The procedure goes like this: the brush with MEK after each use. This the numbers required. • Starting with the bottom, cover becomes rather expensive, and then you Irons: Two are required for the job, any sharp objects with anti-chafe have to environmentally dispose of the one large and one hobby size. Good tape, then lay out the fabric you used MEK at the hazardous disposal luck with this one. The first hobby size I need to cover the piece, includ- site, which in my case is not open all ordered from a box store was so far out, ing a little extra, and cut it. year, so you get to store this potentially it might as well have had a toggle switch. • Using Poly-Tack, glue down explosive product until then. The store sent me a replacement, which the perimeter. Fabric: Some fabric came with the was significantly more accurate. • Heat-tighten the fabric. kit, but it can also be ordered from Air- As for the large one, we have a used • Brush on Poly-Brush. craft Spruce. It ships with a surcharge products store here in my small town, • Stick down reinforcing tape. because it comes in a long tube. and after explaining to the owner that • Install fabric rivets (necessary in my case). Tapes: You’ll need four kinds: anti- I had to “calibrate” an iron for a specific • Apply finishing tapes, inspection chafe, reinforcing, straight, and bias job, he allowed me to take all 10 from the rings, and doilies. (pinked edges). They come in various store and return what I did not want to • Add drain holes. lengths and widths and are used for pro- purchase. I returned eight, all with tape • Smooth out the rough points and tecting, adding strength, and covering on them listing the low/high ratings of paint with Poly-Spray, then Poly-Tone. attachment points and seams. each. He was pleased. The entire procedure sounds easy Respirator: This is a mandatory tool. Temperature is very important. The enough, but let’s take a look at the details. Order with organic filters and extra fil- key here is to use the same extension ters for replacement time. Note that it cord and calibrate the irons prior to each Fabric Preparation has to fit properly. If you have a beard, use. In addition, a small, pointed wood Start with a small piece such as an aile- it won’t, but again, it’s your call. Reduce burner is a good idea. I found that melt- ron, which is straight, has no compound the beard to a goatee or cook more gray ing holes is much more positive than bends, and is manageable. Run your fingers

Photos: Dan Kerr KITPLANES November 2019 23 (Left) Put anti-chafe tape over anything rough or sharp. (Right) Size up the fabric leaving plenty of overlap. over the structure, feeling for sharp pro- making an army bed then sitting on it. and pressed it down with the unloaded trusions and edges. Smooth these by fil- If it’s too tight, you can create structural brush. You don’t want to brush Poly-Tack ing or cover them with anti-chafe tape to issues, especially in light aircraft. Prop- on top of the fabric, or you’ll overload the prevent them from cutting the fabric. erly applied, this is one strong product seam, which can create drying issues and When you’re satisfied with that, get that significantly pulls when heated. possibly unsuccessful adhesion. out your roll of fabric and spool off a When you’re satisfied with your dimen- Once set, rotate the aileron and iron piece, leaving overhang all around— sions, cut the fabric with a sharp pair of the fabric around the trailing frame onto especially on the ends. You definitely straight scissors, not pinking shears. the top surface. When it takes shape, want to cover the ends/root of the piece. Different pieces are covered differ- Poly-Tack it into place, and when dry, I left enough so that the fabric went from ently. I did the ailerons and horizontal flip it back upside down. the top surface to just past the bottom stabilizer with a single wrap. The seam surface, and then I clamped it. on the ailerons was at the trailing edge, Tighten the Fabric Don’t be afraid to mark the fabric and the seam for the horizontal stabi- Wrap the fabric around the aileron with a #2 soft dull pencil. Anything you lizer was the leading edge (the wrap is on loose, and Poly-Tack the top trailing write on will be covered by the solutions. the straight edge). edge to the wrapped-around bottom I marked dimensions, temperatures, and piece, which will give you the fabric-to- number of coats of solution, all without Apply Poly-Tack fabric seam on a structural piece and any problems. The long sides don’t need With the aileron, I started by applying meet the supplemental type certificate as much overhang as the ends, and the Poly-Tack on the bottom trailing edge. (STC) compliance. The ends are now wingtip will be trimmed after Poly-Tack When applying Poly-Tack, I folded the folded down and attached with Poly- is applied and heat-treated. fabric on a 45-degree angle and painted Tack. The extra material allows for the The fabric should be loose, not tight. about 6 inches of Poly-Tack at a time. Then minimum 1-inch overlap and again STC Not baggy loose, just loose—sort of like I folded the fabric into the wet Poly-Tack compliance. Once dry, break out the

(Left) Start on the bottom of the aileron and glue the trailing edge down. Then rotate the aileron, snug up the fabric, and glue the overlapping trailing edge down. Finally, glue the ends. (Right) After calibrating your iron, do three heat treatments to shrink the fabric.

24 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes (Left) Protrusions, such as this filler tube for the fuel cell on the wing, require reinforcement. Melt a circle (slot or square) just smaller than needed, and it will form around the protrusion. (Right) Lay down the self-adhesive reinforcing tape over the holes, leaving ½ inch at each end. iron, calibrate it and have some fun: two you can because, from here on, every- should be drawn on the fabric to guide levels of temperatures are used for the thing you do shows. you. Keep these very straight and cen- two steps of heat shrinking. tered. Again, I used one piece of tape, An important note here: Do not use Install Fabric Rivets starting at the trailing edge and wrap- an iron unless you calibrate it before use, Using a flashlight placed face down ping all the way around the aileron and every time. on the fabric, the fabric rivet holes (if back to the trailing edge. Now that the fabric is tight as a drum, needed) are easily located, marked with These tapes are applied with Poly- take the finishing iron and smooth out the pencil, and then melted with a wood Brush. Pre-coating the reinforcing tape the rough spots on the seams. I found burner. Note that when melting the two times and the finishing tape one that using parchment paper between holes, twist the wood burner so the fab- time will prevent the tape from stealing the iron and the fabric prevented residue ric doesn’t stick to the tip. Poly-Brush from the fabric and unsuc- build-up on the iron. Applying the fabric rivets is a no cessful adhesion. brainer; just be careful not to let the For rounded pieces, such as the hori- Apply Poly-Brush and stems that break off puncture the fabric. zontal stabilizer leading edge, the tape Reinforcing Tape Once complete, again run your fingers used is a bias tape. This is a cross-weave When satisfied that the fabric is tight over the tops of the rivets, ensuring no cut material that is sewn together about and smooth, the first coat of Poly-Brush sharp edges remain. If so, cover with a every 85 inches, and the seam cannot be is applied to the entire wing. small piece of anti-chafe tape. used. To begin, you have to apply Poly- With that complete, the application Brush to about 3 to 4 inches of the bias of self-adhesive reinforcing tape is next. Apply Finishing Tape tape on a straight part of the leading Leaving about 1 inch past the last holes, Start with the ribs and then the leading edge. Once it’s dry, apply Poly-Brush measure, cut, and apply as straight as or trailing edge if there is a seam. Marks to the curve and pull the end of the

(Left) Use a flashlight to locate the holes, then melt them out with a wood burner. (Right) Add the fabric rivets. Be careful not to allow the broken stem to fall onto the fabric and puncture it.

KITPLANES November 2019 25 bias tape, allowing it to conform to the shape without ridges. All of this pulling, painting, and clamping can be simpli- fied with a little welcomed help.

Add Drain Holes At some point during the process, water drain holes have to either be attached or melted through the bottom surface. The easiest way is to simply melt them, and to comply with the STC, this has to be done where there are at least three layers of fabric. If you need to add a small patch so you have three layers, now is the time to do it. In my case, the trailing edges are pre-formed “V”-shaped aluminum, which allowed me to melt holes in the ends. After a pre-coat, recoat and lay down the finishing tape.

More Brushing and Spraying coat. Because I really like the color, I of it, which is the glue line for the top With the drain holes complete, brush ended the fabric painting with Poly- and bottom pieces. This results in the on another coat of Poly-Brush. This isn’t Spray and didn’t apply Poly-Tone. This 2-inch overlap required by the STC. too bad with the small pieces, but the is definitely not recommended by the The other difference is the installa- wing seemed to take forever. Soaking people at Poly-Fiber, and I was warned tion of inspection rings, which is done the fabric is the point here; if it’s loaded, that Poly-Spray can easily scratch with- prior to spraying the Poly-Brush. Using you won’t get any bubbles. Take your out a Poly-Tone top coat. We’ll see how Poly-Tack, stick down the plastic inspec- time and really soak it to the point that my decision works out once the Maver- tion rings at every location you think it almost runs through. When done, go ick is flying. you will ever need to access. These are over the wing and look for pinked ears then covered with fabric doilies, which that are sticking up. Again using parch- Covering the Wings you make and are stuck down with ment paper and the finishing iron, stick The wings are covered using the same Poly-Brush. Using clean cardboard in them back down. basic procedure as the ailerons except between, I stapled the fabric onto the Spraying two coats of Poly-Brush is you use one piece of fabric for the top table, then using the large iron, shrunk next, then multiple coats of Poly-Spray, and one for the bottom, starting with it. Using a 1-gallon paint can as a tem- applying just enough to prevent light the bottom. With the wing, it is essen- plate, the circles were drawn with a pen- from penetrating. Last, but not least, tial to mark the center of the wing with cil and cut out using pinking shears. I use Poly-Tone for the final finished a chalk line. Next, mark 1 inch each side painted Poly-Brush on the wing where

(Left) Bias tape needs to be pre-stuck for about 3 to 4 inches on a straight plane. Lay the tape around the curve and paint on the Poly-Brush, then pull the tape around the bend, clamping it at the end. (Right) For smoothing out, I found using parchment paper under the iron worked perfectly to prevent any accumulation of product on the iron.

26 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes When you start your day, plug in the iron and lay it on the thermometer at the setting you marked and leave it for a while. Mine goes way over temperature, then under and finally stables out right on the mark. the doily was going and set it into place. Note here: Do not melt out these holes unless you absolutely need to; you may never need to remove some of them.

Be Patient The last item you need is patience. This is something you’ll need a lot of. You have to be patient and vigilant for this job. At some point, you will want to just walk away. But at other times, you’ll see that you have learned a new skill, and the end results really don’t look too bad. There’s always someone better, but this one is mine, and I built it. J

The top hole is melted, and the bottom is punched. Note the melted fabric is singed closed and will not unravel.

KITPLANES November 2019 27 Sikaflex Canopy Bond Tips for making The Big Cut and bonding a canopy. BY LARRY LARSON

For the typical RV builder one modified as methods change. of the first questions is: Build Specifically, Sikaflex bonding a slider or tip-up? Then, some- canopy to frame. It’s fairly new where much further into the to the Experimental world. So, build comes the question a bit how do we do it? more difficult to answer: How The first step is research how do I complete the canopy with- others have done it. I did the out messing it up? (For non-RV same. However, in my case, they builders out there, understand were saved as PDF files for ref- that part of the process is to sep- erence, and the computer wore arate the provided canopy glass out reading them over and over. into sections and bond them to In the end, I still craved a step frames. This is known inside the by step how-to but the job had RV community as The Big Cut. of the world; actually, you should fear an to be done, so I jumped into the abyss. Those three words are sure to drive a infarction much more. In the process, I documented as much as builder’s blood pressure to hypertensive So where to begin? The manual is possible, hoping to save the next builder levels. Not to worry. Neither is the end the first step, but manuals may not be from making my mistakes and maybe,

28 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes Tools and supplies (clockwise from left): Nitrile gloves, 3/8-inch variable speed drill, oscillating multi-tool, various tape rolls, spring clamps, angle grinder, paper towels, caulk gun, Sikaflex 295UV, Sikaflex Aktivator 205, Sikaflex Primer 209D, various sandpaper, tongue depressors, acid brushes, 3M fine line masking tape #218, maroon Scotch-Brite pad, sanding block, Plexiglas drill bits, various reamers, Unibit.

just maybe, impart a tiny fragment of Which Product? To cut the Plexiglas, Van’s recom- wisdom that might help keep their There are three products typically used mends a cut-off wheel on a die grinder. blood pressure under control. to glue our canopies. Sikaflex Aktivator They even provide the disk in the fin- #205. The previous part number was ishing kit. Feel free to use it, but there’s The Details #226. The 250ml bottle is plenty. Sikaf- a new tool on the market. The Dremel My build is a Van’s RV-7A slider. Clearly lex Primer #209D. The 250ml bottle is Saw-Max Model SM-20 kit comes with the process is unique to the model, but plenty. There’s some discussion regard- a SM500 Wood/Plastic blade and SM some methods should apply to other ing which primer to use where, but the 510 Metal blade. It’s available at most aircraft with similar build require- consensus seems to be #209D is fine for big-box home-improvement stores for ments. After all, most airplanes have a both the Plexiglas and the steel frame about $100. This tool with the SM500 windshield, right? with or without powder coat. There blade cuts through Plexiglas like the Many steps in the manual instruc- is also some discussion as to the pow- proverbial hot knife through butter. tions for my slider were altered to der coat, but once again, the consensus Once the Plexiglas has been cut, that accommodate the process of gluing the seems to point to leaving it in place. cut must be sanded and polished or canopy to the frame. I also added the Sikaflex is pretty tenacious stuff. Most you’ll risk a crack. I found that an oscil- Flyboy Accessories Supertrack Canopy likely the powder coat would break lating multi-tool has so many uses. My Tracks Extension modification. I docu- loose before the adhesive. preference is for the Ryobi 18V ONE+ mented the changes and encourage you Finally, Sikaflex #295UV Black is JobPlus with Multi-Tool Attachment. to review my blog (see link below) for the actual adhesive. Most canopies (Yeah, that’s a long title for a tool.) This details. So, let’s start. and windshield assemblies will require tool will also cut Plexiglas well, but it Sikaflex is the same bonding agent two tubes. They also make Sikaflex really shines at sanding an edge with the the automotive window replacement #208 Remover and Sikaflex Handclean pad attachment. company uses to glue your windshield Wipes. Feel free to try them. I used lots After The Big Cut, use 60- or 80-grit in place. It’s a different Sikaflex prod- of nitrile gloves. sandpaper to take out tooling marks, uct, but from the same company and Van’s canopies are molded from a then switch to 220 grit to smooth the the process is very similar. It’s also used sheet of Plexiglas. One huge canopy edge. This is adequate to protect the edge, extensively in the marine industry to front and back, tipper or slider. The first but for the final cut and prep for assem- glue windows in place, so we are not in step is The Big Cut. Sounds scary, sure, bly, you want to polish the edge with a uncharted territory. I actually had an but don’t worry. Let’s start with some sanding pad and 400-grit wet sand. auto windshield replaced not long ago common tools. Safety is first. So grab The final few trims are usually very and tortured the technician with ques- those safety glasses, dust mask, ear muffs small amounts. The Saw-Max would tions. Poor guy. He even gave me a cou- and a respirator. The chemicals emit work for most cuts, but if you’re taking ple of the special tips for the Sikaflex. vapors and you want to protect yourself. down 1/8-inch or less, it’s not the best.

Photos: Larry Larson KITPLANES November 2019 29 For that, I used a 60-grit flap disk on the Ryobi 4.5-inch cut-off tool/grinder. You probably have at least one drill, but I recommend a variable speed drill with a clutch. Most cordless drills have this feature for driving screws. Turn the clutch all the way down. This may save your canopy when drilling a hole. If a bit catches, the drill clutch will slip much faster than you can release the trigger. Yes, it adds time dealing with the clutch slipping, but just might save a nice crack. There are a few miscellaneous items that will also come in handy. A variety of spring clamps are useful, but be wary of the sharp clamping edge. I recommend using a strip of wood from a stir- FIne Line Tape is the bees’ knees and the only tape that will withstand the chemicals ring stick or chunk of hose to pad the used in this process. Homemade black electrical fine line tape is great for protecting clamp against the canopy. Find some- other areas. Remember to mask pretty much everything you don’t want Sikaflex on. thing to use as spacers. I used clear plastic tubing, but some builders repurpose the fillets. Marking the canopy is tricky. and spills. Remember the nitrile gloves the garden hose. Bet the wife loves that! I tried a Sharpie but found it difficult to and paper towels. Treat Sikaflex just like A dozen pieces 1/8-and 1/16-inch thick and write on the protective plastic. A simple Proseal. It will end up everywhere, so be about 1-inch wide is adequate. grease pencil worked beautifully. It’s easy ready and dress appropriately. The Sikaflex comes in a tube, so you to sharpen just by rubbing on paper like a Depending on model, you may need need a caulk gun. The Aktivator and crayon. Make all your marks on the out- drill bits and/or a Unibit. I experi- Primer are very thin, viscous fluids. I side clear protective film. Tape is critical. mented with scrap and found reamers found disposable acid brushes worked The Aktivator and Primer are very thin made the best holes and left a nicely pol- best. They hold very little fluid and pose and will release pretty much any tape. Buy ished edge. Plexiglas bits worked well, less of a danger with excess running or some 3M Fine Line Tape #218. It’s pricey, but I needed a 5/8-inch hole for the latch. dripping everywhere. You can also use but resists solvents really well. Any other The Unibit is recommended by Van’s. It foam brushes, but do so at your own peril. tape will release and leave a nice mess works, but not as well as reamers. You They hold a lot of liquid and release it where these chemicals seep under the can also take a bit and drill a few times at the most inopportune moment. The tape. Black electrical tape will work just into concrete to dull it. I didn’t try it. Primer is quite tenacious and very dif- fine as a secondary line of defense. Blue or The canopy needs to be stable while ficult to remove. Tongue depressors or green masking tape may be used to mask working on it. Upright, the canopy Popsicle sticks work great for making off large areas to protect against drips needs to rest on edge flat on the bench so all the weight is distributed evenly. Upside down, it needs support to minimize stress of the weight trying to spread it apart. Figure out what works best for your shop and canopy. I used my EAA Benches placed about 2’ apart then spread an old blanket over them and clamped the blanket in place forming a sort of hammock. A couple of pool noodles come in handy to support the canopy with no stress. See photo. We’ll talk about the edge later. Let’s Get to It Now that we have our tools ready, it’s time to cut some Plexiglas. First, let’s turn up the heat—the shop heat. I live Drawing a line equally spaced from the bench using a washer and black grease pencil. in the mountains, so it’s tough to heat

30 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes Get some help and flip the canopy over on its back on the blanket. Support it with pool noodles such that it’s stable. Plug in the Saw-Max and put on your dust mask and eye protection. (I suggest a hoodie. Yes, it’s hot, but Plexiglas dust is going to go everywhere. Pull the hood over your head, zip it all the way up and tie the string. Put the ear muffs on over the hoodie. You’ll thank me later.) The Saw-Max cut line is easier to see looking at the left side where the blade and cut notch are visible. That means cutting left to right. Support the Saw- Max with your right hand so the saw foot is firmly against the Plexiglas. Notice the notch. Fire that puppy up One hole in the canopy for the latch. Start with Plexi bits then enlarge with reamers or a Unibit. Go slowly, carefully. and gently guide it while supporting the foot against the Plexiglas. Go slow and my shop to recommended tempera- The first cuts should be practice. straight. It will bind and kick back just ture, but I try and get above 75 degrees. Van’s recommends the first practice cuts like a circular saw, leaving a gouge—so The hotter you can stand it, the better. should be removal of the forming flanges if it feels like it’s binding, stop, slowly I must confess, none of my work was on either side bottom edge. The manual back up and go again. Release the trig- done above 68 degrees. suggests cutting at the bottom of the ger and stop if needed. The blade will We need to know where to cut and canopy frame. Better to leave too much cut really fast so be careful. make some marks, so follow the manual than cut off too much. There’s plenty The object here is to make a practice cut and find the location of The Big Cut. of opportunity to remove more later. following just outside the line. The piece Mark it with short tick lines on the inside I recommend cutting off just enough may try to fall away and pinch the blade as protective film. What? You peeled it off? to make the canopy edges lay perfectly you get close to the end, so stop about half NO! Leave it till the last moment. If you flat on the bench. While the canopy is way and use one of those spring clamps to peeled it off, use blue masking tape to tem- upright on the bench, use a big washer hold the start of the cut and keep the piece porarily locate the line on the inside. Get to draw a line along the bottom edge by stable. Ideally, you want to see the line some help and rotate the canopy upright rolling it with the grease pencil against when you’re finished right at the edge of and mark the centerline. Find center in the canopy. The idea is to practice yet the cut. Your first cut done with success! several places by measuring across the preserve as much as possible. This cut Let’s clean up that edge. width and make tick marks. Connect the will allow the canopy to rest on the Use the multi-tool with 80 grit pad dots and you have a centerline. bench perfectly flat with minimal stress. and smooth off the tooling marks. If you

This canopy is ready for The Big Cut. The plywood braces are not in this photo (see text), but they’re vital for stability.

KITPLANES November 2019 31 can’t see them, grab a light and shine it at the edge. They pop right out. Every one of them is a potential stress crack so we need to remove them. Use a damp paper towel to wipe off the dust and you can really see them clearly. Get rid of them. While you’re at it, hold it at 4 degrees and chamfer the inside and outside edges. The 80 grit removes material fast, so don’t dwell in an area. Use 220 grit to final sand the edge and the inner and outer chamfered edge. Lather, rinse, repeat for the other edge. Now the canopy will sit flat with no localized stresses. This is important when it’s time to make The Big Cut. Slide a section of pipe insulation or pool noodle over the edge. Get some help and flip the canopy Cutting with the Saw-Max. The foot is offset. It’s much easier to cut left to right. Support back over right side up. the rear end of the foot while using fingers touching the canopy to guide the saw.

Time for The Big Cut! these will keep the canopy halves from Now We Bond Now that you have some confidence, sagging in the middle. Follow the manual to fit the canopy to The Big Cut is no problem. Position Make a dry run as practice. If you’re the frame, but consider how it will fit the canopy so the cut line is between height challenged like me, make another with Sikaflex. Sikaflex recommends 1/8- the two benches with room for you to dry run with a step ladder. You want to inch gap for the adhesive to allow for maneuver the saw. Cut the pipe insula- practice without a live tool till you feel thermal expansion and contraction. tion and leave a gap where the cut will confident you can make the cut at least Remember those spacers before making be made. Find two sections of plywood to the middle without losing balance. the final trim adjustments. This gap will about 8 inches wide and tall enough Now do it for real. Be really careful as affect the final dimension in relation to to touch the inside of the canopy plus you get to the end of the cut. A helper is the frame. Mark and start making fit- enough to clamp to the bench. Place a recommended to stabilize both halves as ment cuts. Always cut outside the line. piece of pipe insulation on the top edge the cut is finished. Remember to dress Final adjustments are easy to make with of each. Clamp the plywood so the those edges. Success! Take some pho- the angle grinder and 80-grit flap disk. canopy is resting on it but not lifted off tos and show your pride. This is a big Mark the canopy for final trimming the bench. When the cut is complete, moment. Go have a few adult beverages. each time. Don’t guess and try for a

Dressing stages of Plexiglas edge. L-R, Dremel Saw-Max with SM500 blade, oscillating multi-tool with 80 grit pad, oscillating multi-tool with 240 grit pad, Sanding block with 400 grit wet sand. Notice the imperfection between the last two sections. It is very important these be thoroughly dressed out to prevent stress fractures from occurring.

32 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes This RV canopy is fully taped and ready for Sikaflex. Time to take a breath and calm the mind. ballpark trim. Clamp a section of sac- down well, especially at the glue edge. black electrical tape mask to the frame rificial aluminum so the trim line is Apply a layer of black electrical tape as well. The fillet won’t be deeper than even with the aluminum. Use the angle right over the 3M to the same mask half the thickness of the tubing, so grinder to sand away the material to the edge. Rub it down well. Don’t put that shoot for that level with the masking. line. If you go too far, the aluminum is 3M tape away just yet. Apply a strip on Scuff the areas well with maroon there to stop the grinder. Remember to the actual edge of the canopy. This tape Scotch-Brite. Wipe the areas clean dress that edge every time. Once you mask will keep chemicals from leaching with a damp microfiber cloth. Time to have the canopy fit perfect, it’s time to around the edge onto the outer surface glue a canopy. glue it. But we need to polish the fin- of the canopy. Rub that tape layer really ished edge first. good onto the edge. Apply blue or green Are You Still Breathing? Use the sanding pad with 400 grit painter’s tape and paper to mask off the Remember that respirator! Start a or finer wet sand paper. Wet the paper rest of the open areas. Trust me, you timer or make note of the time. Apply and polish by hand. Use a damp paper don’t want these chemicals anywhere the Sikaflex Aktivator #205 using an towel to wipe the edge and examine it other than the masked area. Apply a acid brush. Apply to both the canopy with a light. You want it polished like the edge of a piece of glass. Remember those chamfered edges. The edge of polished Plexiglas is just as sharp as glass and will cut just as easily. Finished? Okay, we are ready. Assuming you know exactly where the frame is to be located, remove the protective plastic film. Unless, of course, you already did. It’s time to mask. Place the canopy upside down on the blanket hammock with noodles so it’s nice and stable. Last thing you want here is the canopy moving when you’re working with the Sikaflex. A 1-inch-wide mask line is best, but you could use less depending on the frame. It’s up to you, but remember the fillets need some area. Whatever you decide, start by masking the edge with the 3M Fine Line tape. Do not pull tension on it as you mask. Rub it

KITPLANES November 2019 33 Here’s the canopy after the Aktivator and primer have been applied. It’s just waiting for Sika and final assembly. and frame. It’s extremely thin, so be black electrical tape line at the edge of will rub right off beyond the tape line. careful. Wait 10 minutes. Start the the 3M just as before. The reason for You have 30 minutes to 2 hours before timer again. Apply the Sikaflex Primer this is the Sikaflex #295UV will not the Sikaflex must be applied, so watch #209D. This stuff is a bit thicker, but stick in the absence of Sikaflex Primer the clock. it dries really fast so spread it quickly. #209D. This is your savior. Use it to Remember the spacers? I only used Apply to both the canopy and the frame your advantage. If you get the Sikaflex them to position the canopy and make contact areas. Watch that tape line. It #295UV where you don’t want it, leave a uniform gap. Once the gap was uni- is really difficult to remove the Sikaf- it till it dries. It rubs right off like that form and the sides clamped, I removed lex Primer #209D, so be careful where booger-looking adhesive they use on the clamps on the bows and removed the you apply it. Wait 30 minutes. Peel the credit cards when they send them in spacers. The idea here is to glue the can- first layer of black electrical tape off the the mail. The replacement electrical opy in a uniform curve with no localized canopy and the frame. Check the 3M tape mask will make it much easier to stresses. The spacers and clamps create tape line and fix it if necessary. Feel make a nice fillet when the time comes. stresses at each clamp. Once the Sikaflex free to peel the 3M tape off the edge at Feel free to reapply the electrical tape sets, it locks those stresses in place. I may this point. Any Sikaflex will not stick to the frame as well, but it really isn’t be way off base, but it made sense at the where primer is missing. Apply a fresh necessary. The excess Sikaflex #295UV time. Let’s glue a canopy.

Applying a bead of Sika to the side frame. Notice the intense concentration!

34 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes Canopy clamped for curing. Notice the clamps at the forward and aft bows have been removed. Walk away for a day or two.

Get some help. You have up to two bead down of Sikaflex #295UV where Primer #209D and Sikaflex #295UV hours from application of Sikaflex the canopy frame will contact first. I allowing the new application to adhere Primer #209D, but time flies when chose the spine since the other areas properly. Apply Sikaflex #295UV and you’re having fun, so let’s work. Some were not touching till the canopy was dress the fillets. Pull the black electrical builders cut the Sikaflex applicator tip clamped. Get some help and place the tape mask then pull the 3M tape mask. off square to the end then cut in a “V” frame right on the center of the bead. It should be a nice beautiful line. Walk to produce a triangle shaped bead. I Locate the position for the remaining away for another 24 hours or more. I chose not to, but feel free. There are a application and apply a bead or dol- recommend leaving it clamped as long few different methods to choose. One lops. Clamp the canopy and massage as you can stand it. After 48 hours, it’s is to place dollops of Sikaflex #295UV it into final position. If you need to pretty stable, but after 2 weeks it’s solid. along the contact areas and allow it remove or address any excess, use the Now you can say you’ve made The Big to set then return to apply the fillets. tongue depressors. Walk away for at Cut and bonded your canopy—and Another option is to apply it every- least 24 hours. survived it all! J where except where the spacers are Apply a fresh coat of Sikaflex Aktiva- positioned, allow it to set and return to tor #205 before applying more Sikaf- You can read more about Larry Larson’s apply the fillets. I chose the latter. Lay a lex #295UV. It will soften the Sikaflex RV-7A build at wirejockrv7a.blogspot.com.

The finished canopy and frame ready for the next steps. The Big Cut is over so just a few more steps to go!

KITPLANES November 2019 35 Alternator Mods without Major Surgery

Another way to modify a Nippondenso alternator for use with an external voltage regulator. BY GRAEME COATES After seeing Ted Miller’s article, “How minor modification, enlarging a brush- and regulator. Next, remove two screws to Rewire a Nippondenso Alternator for holder mounting hole, but this does to release the brush holder, then remove External Regulation,” in the March 2019 not prevent the alternator from being three screws to release the regulator. The issue of KITPLANES®, I decided there returned to its standard configuration. two long screws will be reused, but the had to be a simpler way to modify an Starting with the standard alterna- third screw is not used again. ND alternator. This alternate method tor, remove the terminal shroud and The only (tiny) modification to the requires no major surgery. There’s one end cover to expose the brush holder alternator is to ream out the left-hand

36 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes Remove the terminal shroud (left) to expose the brush holder and internal regulator.

(Left) The brush holder is held in place with two screws. (Right) The alternator after removing the brush holder.

mounting hole of the brush holder to 5 mm. As mentioned earlier, this will not prevent the alternator from being restored to standard. This minor mod is necessary as the wire to this terminal on the brush holder must not contact the frame or output terminal of the alternator, or the magic smoke will escape! The new components are two M4x10-mm screws; two fiber washers with 4-mm holes; one small piece of nylon tube (or equivalent), OD 5 mm, ID 4 mm, and a length of 1.5 mm; and two 18-gauge terminated wires. A mounting block (phenolic, canvas Bakelite, etc.) replaces the regulator with three holes: two for the original mounting screws and one with a captive nut to become the right-hand mounting point for the brush holder. This block is 1/4-inch thick and precisely replaces the regulator after being cut to

To release the regulator, remove three screws.

Photos: Graeme Coates KITPLANES November 2019 37 (Left) Brush holder and new components: two M4x10-mm screws, two fiber washers with 4-mm holes, one small piece of nylon tube (OD 5 mm, ID 4 mm, 1.5 mm long), and two terminated 18-gauge wires. (Right) The regulator is replaced by a mounting block with three holes: two for the original mounting screws and one with a captive nut that aligns with the hole in the regulator pointed to by the pen. This becomes the right-hand mounting point for the brush holder. shape. I used two 1/8-inch thick pieces 5-mm hole, and fit the screw into the frame or the output terminal. These epoxied together and holding the nut. now 5-mm hole in the brush holder. two wires go to the external regulator; Alternatively, use a 1/4-inch block, drill Mount the brush holder on the alter- one will get grounded or connected to a 3.3-mm hole, and tap for M4. Mount nator with the right-hand new wire 12 volts depending on regulator type, this on the alternator, and put one fiber under the brush-holder lug. This keeps but do this at the regulator. I used a washer where the left-hand brush holder the brush holder precisely level and B&C LR3C-14 regulator, and thus terminal was attached. only a tiny fraction higher than the one wire is connected to ground at Assemble one fiber washer and the original position. the regulator. nylon tube on an M4x10-mm screw, Conduct a test to ensure that neither Fit a rubber grommet to the opening then add a new wire terminal with a wire is in contact with the alternator on the alternator rear cover, thread the

(Left) The mounting block is 1/4-inch thick and replaces the regulator after being cut to shape. It’s made from two 1/8-inch thick pieces of canvas Bakelite, epoxied together and holding the nut. (Right) The mounting block attached to the alternator. Put one fiber washer where the left-hand brush-holder terminal was attached.

38 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes wires through, and refit the screws and terminal shroud that were previously removed. Be sure to protect and ter- minate the two wires as necessary. An alternative to having wires coming out of the cover is to mount a Molex-style terminal in the cover, and attach it with two pop-rivets. Done! And remember that the alternator can be returned to the standard configuration at any time.J

Graeme Coates is an Australian electrical engineer who is building a tri-gear Assemble one fiber washer and the nylon tube on an M4x10-mm screw (left), then add a new Europa (slowly!). wire terminal with a 5-mm hole, and fit the screw into the now 5-mm hole in the brush holder.

(Left) The brush holder mounted on the alternator with the right-hand new wire under the brush-holder lug. This keeps the brush holder precisely level and only a tiny fraction higher than the original position. (Right) Alternator with terminal shroud reinstalled and wires threaded through a rubber grommet fitted to the rear cover.

An alternative to having wires coming out of the cover is to mount a Molex-style terminal to the cover and attach it with two pop-rivets.

KITPLANES November 2019 39 Homebuilt Accidents: BuzzKill

The pilot of this Great Lakes was waving to friends on the ground when the plane struck the trees. (Photo: FAA via NTSB)

Crashes while maneuvering at low altitude have a high mortality rate. BY RON WANTTAJA

Most pilots love aviation movies. Our passes, and perform aerobatics close to of low-level aerobatics. Also counted are favorite parts usually involve buzz jobs the ground. runway passes that end in stalls after steep flown at insanely low altitudes. From And each year, such maneuvers in pull-ups or low-level turns, scud running, Moggy Cattermole flying his Spitfire homebuilts kill an average of nine people. and flying into box canyons. under the bridge in Piece of Cake to If you do pull it off, fine—but if you crash, For this analysis, I use the term “aero- James Bond flying a BD-5 through a there’s a greater than two-thirds chance batics” in the sense of definitive aero- hangar in Octopussy to Maverick buzz- it’ll be fatal to you or any passengers. batic maneuvers such as loops and rolls. ing the tower in Top Gun, the high-speed Other than not ignoring the siren An abrupt pull-up after a low pass might low-altitude buzz job and victory roll are call of the buzz job, what are pilots meet the criteria of 14CFR 91.303, but staples of aviation adventure. doing wrong? my analysis doesn’t count these with the Such behavior is often viewed as the “aerobatic” cases. I also exclude cases sign of a “hot pilot,” which makes such Defining the Event where maneuvers were started at a legal behavior irresistible to a subset of the In my homebuilt database, I have an acci- altitude, and the pilot, for some reason, aviation population. Despite discour- dent category called “Maneuvering at failed to recover in time. agement by many and enforcement Low Altitude” (MLA). The category cov- For those unfamiliar with the term, actions by the FAA, pilots still buzz ers a fairly wide set of circumstances. Buzz “scud running” refers to attempting to houses, pull up steeply after low runway jobs are included, of course, as are cases fly under lowering clouds. It differs from

40 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes continued VFR into IFR conditions in that the aircraft stays under control of the pilot; he or she is forced into the terrain while trying to maintain visual contact with the ground. Basic Statistics There are 194 accidents meeting the MLA criteria in my 20-year Experi- mental/Amateur-Built (E/A-B) accident database. That’s about 4.6% of the total. The percentages of MLA accidents for individual homebuilt types vary widely. Many types have no accidents of this kind, but for several aircraft, over 10% of their accidents were MLA. The worst I found was 16.7%…one out of six accidents of that homebuilt type’s accidents was due to unnecessary low flying. Figure 1: Percentage of accidents involving maneuvering at low altitude (MLA). However, this sort of comparison can be deceptive. A single buzzing accident list is low-altitude aerobatics, followed In Figure 2, exhibitionism is split involving a relatively rare homebuilt closely by stalling during a low pass or into two categories, “away from air- type can disproportionately raise its rate. buzz job. Hitting wires is number three. port” and “airport environment.” We can avoid this by looking only at An accident can show in more than One of the scarier aspects? In about a the more-common homebuilt types; a one category in Figure 2, and “exhibi- quarter of the away-from-airport cases, larger fleet tends to even out the varia- tionism” is a prime example. These are people on the ground report the occu- tion in accidents. Figure 1 shows the accidents where MLA activity was at pants of the plane waving at them prior MLA accident rate for homebuilts with least partially motivated by a need to to the accident. 60 or more accidents from 1998 through “show off” to people on the ground. MLA events around the airport tend 2017. Above the 4.6% overall fleet aver- This is admittedly a judgment call on to be less flagrant, probably due to the age is a hodgepodge of homebuilt types: my part. In most cases, we don’t know knowledge that illegal aerobatics are Pitts Specials, Kitfoxes, Glasairs, and a for sure whether the pilot was grand- more likely to be reported. Instead, these couple of RV models. standing for observers. But when the accidents generally stem from steep pull- accident occurs near the girlfriend’s ups and tight turns after low passes. Accident Circumstances house, or people in boats are diving There are a number of ways to become an into the water due to the proximity of Taking a Different Slant on Types MLA statistic, and Figure 2 summarizes the aircraft, one has to presume a bit of As mentioned earlier, one has to be how often each occurred. Leading the showboating was involved. cautious about computing an MLA

Over 16% of Skybolt accidents involve maneuvering at low altitude.

Photos and Illustrations: Ron Wanttaja KITPLANES November 2019 41 The pilot of this Kitfox remained clear of boats and structures The Glasair is one of the few non-biplanes with a relatively high rate while flying at 250 feet over a lake, thus remaining legal. However, of accidents involving low-altitude aerobatics. he stalled while looking for a submerged object. (Photo: NTSB) accident rate when the total number of planes on the list (Van’s RV-6 and -4, The fact that the Kitfox led the MLA accidents of a given type is low. Instead, and the Kitfox) had less than half. list was pretty surprising. Yes, there are let’s just look at the raw number of acci- Only two of the 12 RV-6 accidents and a lot of Kitfoxes on the FAA registry, dents each type has suffered, rather than one of the 14 Kitfox cases involved low- but there are twice as many RV-6s, and computing the percentage of the total. altitude aerobatics. they still suffered fewer low-altitude As mentioned earlier, there are 194 MLA accidents in the 20-year span of my accident database (1998 through 2017). Out of over 700 specific homebuilt types in my database, eight suffered five or more MLA accidents. These are summa- rized in Figure 3. This “five plus” list contains all the “above average” aircraft in Figure 1, and adds three more: the Christen Eagle, the Stolp Starduster, and the Steen Skybolt. With those additions, half the airplanes in the “five plus” list are small biplanes commonly used for sport aerobatics. For all four of these types, the majority of their MLA accidents involved low-altitude aerobatics. Figure 4 shows the breakdown of aerobatic vs. stall MLA accidents for each type. Figure 2: Major factors in low-altitude homebuilt accidents. While the Glasair, too, had a (slight) majority of aerobatic accidents (five out of nine accidents), the other three

The pilot of this Skybolt attempted a wingover after a low runway pass. (Photo: FAA via NTSB)

Figure 3: Homebuilt types with five or more MLA accidents.

42 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes Striking wires is fatal almost half the time, but it’s rare when the pilot is able to land normally afterwards. This Warrior did so and was repaired and returned to service. accidents. Almost half the Kitfox MLA cases involved stalling; otherwise, there just seems to be a lot of flying into things. There’s one thing we have to keep Figure 4: Low-level accidents involving aerobatics and stalls. in mind: There’s nothing aboutany of these aircraft forcing the pilots to take accidents” is still only six accidents out of We don’t know how often a buzz chances at low altitude. Some mod- 194. Not that significant over 20 years. job doesn’t end in tragedy or how els may appeal to those more prone to often a pilot flies home, flushed with take risks, while other types may have Wrap-Up excitement, after successfully per- a ragged corner of the performance Pilots who engage in dangerous activi- forming a low-level victory roll. What envelope that will bite in some circum- ties usually dismiss the safety issues. we do know is that if an accident does stances. But it isn’t the airplane’s fault They’ve “thought things out” and are occur, about 65% of the time the pilot it’s being flown so low. “managing the risks.” doesn’t survive. But there are graveyards full of pilots Get your low-level thrills vicariously “Hold My Beer?” who thought they had the risks man- from the Fokkers in The Blue Max One thing airplanes don’t do is drink aged. The pilots in every one of those or the B-17 in The Thousand Plane booze. How often is consumption of 194 cases in my database (an average of Raid. None of these movies include a alcohol involved in low-altitude fly- almost 10 per year) thought they had “don’t try this at home” disclaimer. But ing accidents? the danger controlled. They didn’t think remember, even the professional stunt In my main database, alcohol is listed what they were doing was hazardous, pilots who make these movies occasion- as a contributing cause in only 16 out and they felt their piloting skills were ally die during filming. of 4041 accidents, or about 0.35%. more than adequate to the challenge. Keep it high, folks. J But three-fifths of those cases (no pun intended) were MLA accidents. About 3% of all MLA accidents had alcohol The Legalities Down Low involved. That’s almost 10 times higher With all this discussion about buzzing and low altitude aerobatics, it’s important to than the overall rate! remember that low flying isn’t necessarily a violation of FAA regulations. 14CFR 91.119 However, keep in mind the relative states that, other than over congested areas, a pilot should not operate within 500 feet rarity of these events. That “3% of MLA of any person, vessel, vehicle, or structure. Over much of the country, and many water- ways, there are broad areas that allow low flight meeting these criteria. The regulations prohibit aerobatic flight below 1500 feet agl, but other than that, as long as you can keep While there are slightly more RV-8s than 500 feet away from man or man’s creations, you’re legal. RV-4s, the -8s were involved in low-altitude accidents less often. Safe? Well, that’s up to you. Play chicken with a ridgeline or pull up into a tight wingover, and the safety factor goes way down. It’s always hard to know if some hiker is standing beside the tree you just buzzed, but it would seem that one can ensure compliance with 91.119 by flying over water. There, boats can be easily seen and avoided. One small problem: The human race often runs power lines over rivers, and even over lakes. Only 7% of U.S. geography is water, but about 40% of homebuilt wire-strike cases occur over a body of water. Wires can be hard to spot from the air, and planes never come out the victor. —R.W.

KITPLANES November 2019 43 Grow a Third Hand

When you need an extra hand, make a jig. BY OMAR FILIPOVIC

44 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes What do you do when the construction manual says “for this task you will need a helper,” but there is no one around who can help for a couple of hours? You make a jig, of course. The GlaStar wing has a mix of ribs and hat sections—stiffeners so named because their profile looks like a hat—and they need to be placed and held tightly against the wing skin for drilling. The wing skin has to be in place for this, so there is no way to reach around and hold the stiffener in position on one side while drilling through the skin and the stiffener from the other. That’s where a jig comes in handy. Most jigs are specific to a task, but their purpose is to hold the workpiece in place or to guide a tool operating on it. The specific purpose of my jig is to press the stiffener against the wing skin freeing me to walk around the other side and drill holes and insert Clecoes, thus obvi- ating the need for a human helper. It is quick and easy to make, and it only needs to last for the duration of the assembly—then its parts can be repurposed for something else. The problem: GlaStar hat sections have to be drilled through from the outer wing skin To push against the flat part of the stiff- (left), but there’s no way to hold them in place on the inside of the skin. Here’s the final fixture (right) ready to be used. ener I made feet with rubber bumpers which are screwed into a small piece of plywood. The opposite side has a partly drilled 3/8-inch hole to receive one end of a 3/8-inch threaded rod. There is no need to capture the rod in the foot because wood fibers in the hole are sufficient to keep it attached, yet the hole is loose enough to allow rotation. The rod passes through a T-nut installed in the larger piece of plywood that I’ve cut to fit snuggly between the wing spars. The shape of the spars keeps the plywood in place, but it also dictates that the top and bottom rods be Here’s the basic hardware required to build this jig (left). Nothing fancy, nothing you at an angle to reach the correct spot on the won’t find at your local hardware store. Bumpers (right) hold the hat section in place stiffener, which sits below the edge of the without marring the surface. spar. I drilled the holes for the top and bottom T-nuts at an angle, and plywood is soft enough to allow them to be inserted like this. The T-nuts are inserted on the side facing the wing so that the applied force is pushing them into the plywood. If they were on the outside, they would likely pop out. The most expensive parts of the jig are the threaded knobs. They are held in place with a jam nut and make it easy and comfortable to turn the threaded rod. At the outer edges of the hat section (left), the “third-hand” jig rests inside the spar When the hat stiffeners are done, I’ll put channel. Note the angles needed to place the foot in the correct spot. At the mid- the jig away and probably find another use section (right), the jig presses the hat section. The length of the screw will, obviously, for the parts in a different jig.J be determined by the depth of the wing you’re working on.

Photos: Omar Filipovic KITPLANES November 2019 45 MAINTENANCE MATTERS Tires, Brakes & Wheel Bearings Like most people, I spend a lot more time worrying about and taking care of my airplane’s engine than its wheels, brakes, and tires. In fact, I really don’t like working on the rolling parts much at all because they require me to bend over, something that is harder to do than it used to be—and I always get dirty. That said, brake, wheel, and tire problems can send you into the weeds (or worse) if they aren’t properly maintained, so let’s look at what it takes to maintain them well. The easiest part of keeping them in good shape is to take a look at the tires and wheels during your preflight check. Be sure to watch the tires as you pull your airplane forward so you can see all the way around them. At this time, you should also be looking for any signs of leaking brake fluid. Any wear that goes When installing a new tire and tube, line the valve up with the red dot on the tire. If there below the grooves on a tire is cause for isn’t any red dot, don’t worry about it. Most tires will not cause you any trouble by being replacement, and any deep cuts or tire out of balance unless you have fairly high takeoff and landing speeds. If that applies to you, stick-on wheel weights you can get at an auto parts store can be used to statically cord showing calls for immediate atten- balance your tire and wheel assembly. tion. Visible brake fluid on the ground next to a wheel is likewise cause to park nose tire to last twice that. Tailwheels, aft of the bottom of the bolt. This creates the airplane and fix the problem before on the other hand, rarely enjoy such a a positive caster angle. the next flight. long life. Especially on trikes, it is easy Nosewheel shimmy is usually caused Wheel and bearing conditions are to get in the habit of simply ignoring by the tension on the retaining nut being harder to evaluate on an ongoing basis, the tires because of their relatively long set too low. It should take about 15-20 but they should be on your condition life expectancies. This is risky, because pounds of force to get the nosewheel inspection checklist or any time you one bad landing can ruin a good tire. to turn when it is unweighted. See your hear odd noises coming from the wheels Tailwheel or nosewheel shimmy can sim- assembly manual for specific recom- while taxiing. Let’s look at each part or ilarly wear out a tire before you know it. mendations for your aircraft. Another the rolling assembly in turn for mainte- If you have a shimmy problem, do not let thing that leads to nosewheel shimmy nance and repair tasks. it go. It is not something that cures itself. is landing with too much weight on the Tailwheel shimmy is usually caused nose. Always try to land on the mains Tires by the angle of the king bolt being set first with the nose in the air. Checking It is not unusual for the main tires to wrong. The angle of the bolt or pin the amount of force it takes to move last 3-400 hours on most planes and the should be such that the top of the bolt is your nosewheel should be on your

Dave Prizio has been plying the skies of the L.A. basin and beyond since 1973. Born into a family of builders, it was only natural that he would make his living as a contractor and spend his leisure time building airplanes. He has completed three—a GlaStar, a Glasair Sportsman, and a Texas Sport Cub—and is helping a friend build an RV-8. Dave shares his love of aviation with Dave Prizio others by flying Young Eagles or volunteering as an EAA Technical Counselor. He is also an A&P mechanic, Designated Airworthiness Representative (DAR), was a member of the EAA Homebuilt Aircraft Council for six years, and is the recipient of the Tony Bingelis award.

46 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes A sheet of plywood with a hole cut in it is just the ticket for breaking a tire bead loose These photos illustrate the correct king from the wheel. Do one side and flip it over to do the other side. Be sure to steady yourself bolt angle for a Scott or similar tailwheel. so you don’t fall. Positive camber should eliminate tailwheel shimmy. If you have negative camber, you brakes, running over objects, or less-than- tubeless tires. I know tubes are expen- may need to modify your tailwheel spring perfect wheel alignment may cause pre- sive, but old tubes and old tires need to or place a wedge between the tailwheel mature wear. Some planes like to wear out go together. Speaking of getting new casting and the spring. the outside edges of the main tires first. tires, don’t be afraid to take a hard look at condition inspection checklist. An inex- GlaStar owners see this often. To get some Desser recap tires. They are good tires pensive fish scale is the easiest way to extra life out of your tires you can simply at good prices. Many flight schools use do this. Severe nosewheel shimmy can flip the tires on the rims to put the fresh them, so they are well-proven. They also not only eat up your tire but can cause grooves that were once on the inside on have good deals on tubes. major damage to your nosewheel pant. the outside. Be sure to do this before the Breaking a tire loose from the wheel Don’t ask me how I know this. outer groove is completely gone. can be a chore, but I have a slick and inex- Main tires, in a perfect world, wear out When it comes time to replace a tire, pensive solution for you. Get a two-foot evenly after several years of reliable ser- you should also replace the tube, unless square piece of plywood at least ½-inch vice. However, in the real world locking up you have wheels that will allow for thick and cut a hole in the center that just Lift Safely! Before we start talking about removing wheels for tire and brake service, we should make a few points about safety. Before jacking up your airplane be sure the wheels are securely chocked so the plane can’t roll. Once it has been jacked up and a wheel removed, be sure to lower the aircraft onto blocks or a jack stand instead of leaving it on the jack. Jacks can leak down or tip over, sending your homebuilt who knows where—and possibly injuring you. When cleaning brake parts, nothing beats a spray can of automotive brake cleaner, but good ventilation and proper eye protection are a must, and it is very important to keep it away from any possible source of ignition. For wheel bearings I used to recommend Stoddard solvent as a somewhat safer substitute for gasoline, but it is no longer available in some states such as California and there are now safer alterna- tives such as Skykleen 1000, which is available from Aircraft Spruce. No matter what solvent you use, be sure to handle it in a safe manner, minimize the use of it, and dispose of it properly. When in doubt, read Be sure to lower the plane onto blocks after it is jacked up. It the MSDS for safe handling instructions. isn’t safe to leave it on the jack for an extended period of time, —D.P. especially while you are working on the plane.

Photos: Dave Prizio and Werner Schneider KITPLANES November 2019 47 clears the outer diameter of the wheel. Let all the air out of the tire by removing the valve stem, then place the wheel with the tire on it on the ground. Center the hole in the plywood over the wheel and then step on the plywood to break the tire bead loose. Steady yourself on something solid to be sure you don’t lose your balance. Turn the tire over and break the other side loose, then disassemble the wheel to remove the tire and tube. Don’t use tire irons to break the bead loose, because they can damage the wheel. Be sure the inside of the new tire is completely clean and free of debris, then sprinkle some tire talc into the inside. Next place the tube inside the tire with the valve lined up with the red dot on This wheel needs to be retired. It earned its keep by surviving a ground loop, so it doesn’t owe anyone anything. Any of the deep gouges in the rim could turn into a crack. the tire. Remove the valve stem from the new tube and inflate it to seat it into the different pressure. Don’t guess at the good condition. Watch out for cracks or tire. Next mount the tire onto the wheel number. Find out from a reliable source deep nicks on the rims, especially if you and secure and torque the bolts. Lastly, what to use on your plane. do a lot of off-airport work. A cut or nick insert the valve stem and inflate the tire can easily turn into a crack. A crack can to the proper pressure. Most people are Wheels cause a wheel failure, usually at a most running 40 to 45 psi in main and nose It is easy to take wheels for granted, inconvenient time—resulting in loss of tires, but your situation may call for a but a damaged wheel can be a real control of the airplane during landing hazard. Whenever working on tires and or some other mishap. A small effort brakes always give your wheels a good will keep your wheels in good shape for look. Wheels can corrode, so be sure to a very long time. Whenever your wheel keep them dry and ensure the paint’s in pants are off, it is a good time to give

This wheel bearing has signs of corrosion of the rollers and thus needs to be replaced. Check the accompanying race to see if it is damaged in any way.

48 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes wheel bearings at every yearly condition inspection. I will leave that to your judgment, but it should be noted that skipping it occasionally is not a great idea and skipping it all the time is a really bad idea. Moisture does find its way into wheel bearings, as do other contaminants, causing damage and eventual failure. Wear disposable gloves when you work on wheel bearings to protect your hands from solvents and to make cleanup easier. Bearings that show any signs of rust or any damage to the bearing rollers or the races should be replaced. When replacing races, take care to avoid damage to the wheels. A hydraulic press is Use an old bearing race turned upside down to tap the new race into place in the wheel. best for this work, but a punch can be Even with a hydraulic press this makes the job easier. Always use eye protection when hitting steel to steel. used, if you are careful, to extract an old race. Flip the old race over and tap on the wheels a quick check. If you don’t Of course, our favorite part of wheel it to drive in the new race if you don’t have wheel pants, that look should be maintenance is repacking the wheel have a press. part of your pre-flight inspection. Don’t bearings. If your airplane is only oper- Repack cleaned or new bearings with forget the tailwheel. It can be damaged ated in dry climate and is always han- an appropriate grease. The grease that by a rough landing or just taxiing over gared, you may be tempted, with comes with new bearings is a preser- rocky terrain. some justification, to not repack your vative and not for use in your airplane.

KITPLANES November 2019 49 (Left) Use a brake rivet tool to install new brake pad rivets. The right tool makes the job easy and properly secures the pad. (Right) Measure the thickness of the rotors whenever you service your brakes. Consult your wheel manufacturer for wear limits on all brake parts. Rotors should also be replaced if they have significant grooves or ridges or are warped.

Aeroshell 6 is a good choice for most you work on your brakes. Besides thick- for that minimum thickness. Putting light and medium duty applications. ness, the flatness of the rotor is a concern. new pads together with badly worn Aeroshell 22 synthetic grease is a better Rotors that are warped or have deep rotors is just a waste of money. choice for aircraft subject to harsh cli- scoring or ridges need to be replaced, When you replace pads, it is best to mates or hard use. as do rotors that have any point below use a brake rivet tool and not a rivet When you install a wheel after servic- the minimum required thickness. If you tool left over from building your plane. ing the bearings, tighten the axle nut have access to a lathe, you may be able These tools are inexpensive and readily until it is snug and then back it off just to clean up a worn rotor, but watch out available wherever airplane brake parts enough to let the wheel turn freely without any looseness as you try to move it back and forth with your hands. Then secure the nut with a new cotter pin.

Brakes Assuming there are no leaks or obvious failures of the brake system, our most common concern is brake pad wear. Unfortunately, the brake pads are usually hidden by the wheel pants. Because of this it is important to note the percent wear at each condition inspection and try to project when they are likely to wear out. Or a better strategy might be to replace any brake pads that are likely to wear out before the next condition inspection. As your plane accumulates more hours, you will need to be concerned with rotor wear, too. Consult your wheel and brake manufacturer for the mini- Use the depth gauge on a set of calipers to measure the thickness of the brake pad. In any mum rotor thickness, and check it with case the pad should not be worn down to the top of the rivet head that holds it in place. calipers or a micrometer when you do Most Grove and Cleveland brake pads should be at least 0.10-inch thick, but check with your condition inspection or whenever your brake manufacturer for its recommendation.

50 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes give the locating studs on the calipers a light coating of grease to allow them to move freely, but be careful not to get any excess grease on the pads or rotors. Lastly, don’t forget to safety wire the caliper bolts when you have put everything back together. If you had to disconnect the calipers from the brake lines while working on your brakes, be sure to bleed them from the bottom (caliper) up by pumping fluid into the bleeder fitting. Always use MIL-H-5606A aviation hydraulic fluid in your brake system. Of course, if you have already put in something else, you should stick with what you have and not mix brake fluids. All of this work is not something you want to do wearing nice clothes. It is Don’t forget the safety wire on the caliper bolts when you are finished. A good alternate unavoidably messy, but it is necessary at to safety wire is the Nord-lock lock washer assembly. These lock washers are available at Aircraft Spruce. least annually. If you are one of those rare people that gets to fly their plane are sold. Drill out the old rivets from the brake caliper. Then use the rivet tool to more than 100 hours per year, you tail end and take off just enough mate- squeeze new rivets into the new pads. should probably be looking at that 100- rial to allow a punch to push out the It is pretty easy if you have the right hour mark for brake inspection and ser- old rivet. Be careful not to drill into the tool. When you re-install the calipers, vice rather than the calendar. J

KITPLANES November 2019 51 CHECKPOINTS The 2-Mile Decision For those of you who read my column perhaps even fly over the Peach State that is two complete revolutions of the last month on keeping the fires lit, I find it Father’s Day event with a smoke pass. engine and ensures every cylinder is ironic that I find myself telling you about Summer morning flights in the Stear- pulled through a compression cycle. No another engine failure that happened man are really comfortable—the air harm being extra cautious with a very since then. Perhaps I shouldn’t write has not yet been superheated, the ride expensive engine, especially since it is about engine failures? But it did happen, is smooth, and the visibility is great. No the only one on the airplane! and my thoughts are to share the experi- doubt about it, the Stearman is like riding ence and decision-making with you. a motorcycle through the sky, and flying This failure was of the Jacobs radial solo once in a while is a great treat for me. engine in my Stearman. It’s my favorite Preflight was normal, including my airplane in which to share aviation, and routine of pulling the prop through 14 I’ve introduced many a person to fly- blades, which ensures there is no oil in ing in the Stearman. It was Father’s Day the lower cylinders capable of produc- weekend, and I had given three rides ing a hydraulic lock when the starter on Friday evening, two more on Satur- is engaged, the results of which could day, and lunch with Carol at Alexander be catastrophic. Pulling through seven Memorial Airport (formerly Peach State blades is really all that is required, as Aerodrome) on Saturday afternoon. On As seen on the GPS “Nearest” function Sunday morning, I decided I would just (recreated post flight), KHMP turned out go enjoy a short flight by myself and to be the closest—and best—decision.

The view out the left and right wings when the engine began to fail. South (left), toward Griffin (6A2), looked to have fewer fields and more populated areas. The view north (right) toward Henry County (KHMP) looked like it had more open fields and less population.

Vic is a Commercial Pilot, CFII with ASMEL/ASES ratings, an A&P/IA, DAR, and EAA Technical Advisor and Flight Counselor. Passionately involved in aviation for over 40 years, he has built 11 aircraft and logged over 9000 hours in 72 different kinds of aircraft. Vic volunteers as a Young Vic Syracuse Eagle pilot and Angel Flight pilot. He chairs the EAA Homebuilt Council and is a member of EAA’s Board of Directors. He also has his own sport aviation business called Base Leg Aviation.

52 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes (Left) After I fell off of the wing I noticed the entire left side of the airplane was covered in oil. (Right) Once I picked myself up and walked around to the front of the aircraft, I noticed the broken cylinder head on number 5 cylinder. Takeoff was normal, and I climbed to to turn back to there. However, there engine was making some power, so I 2500 feet msl, which put me 1700 feet were stores and electrical wires very concentrated on managing airspeed agl, my normal cruising altitude in the close to the final approach, making a and keeping the VSI at 400 fpm. I esti- Stearman. The temperature was com- short landing very dicey, so I stopped the mated the airport at 4 miles, and some fortable, and I leveled off and adjusted right turn with Henry County on the nose quick head math told me I should make the throttle and prop for 20 inches MAP and never waivered from that decision. it if the engine didn’t seize. I assure you and 1950 rpm, the recommended book The VSI was showing 400 fpm down, and the oil pressure was constantly in my cruising setting. From the downloaded I figured I could make it. scan until short final. JPI 830 engine data, that was about 4 I had at least 10 fields picked out in minutes after takeoff. I then started a Shakey Jake which to land between the initial mal- slight turn to the left and set a course for Now that I had a destination picked out, function and the actual touchdown, and Alexander Memorial. Three minutes later, it was time to manage the engine, which passing each one of them was quite tri- just as I was starting to enjoy the flight, by now was shaking quite a bit. I quickly umphant for me! Interestingly, Alexander the engine dropped power to about glanced at the fuel gauge, which is kind Memorial and Henry County were on the 1800 rpm and got a little rough. My initial of hard to miss in a Stearman as it is hang- same Unicom frequency, so I didn’t have thought was that it was acting as if it was ing right underneath the top wing. Yep, it to manage the radio. I did hear a Dia- out of fuel, yet I knew I had more than a showed more than half. Fuel valve was still mond aircraft announce final, and I soon half-full tank when I departed. on. I do know a carburetor with a stuck/ saw that it would get to the runway first, Air, fuel, spark, right? Aviate first! sunken float can make an engine run and since he announced a touch-n-go, Having just set a course to Alexander way too rich, and the proper action is to I counted on him being out of the way, Memorial, I knew exactly where I was, lean the mixture, which I did to no avail. or else I would land in the grass between and I wasn’t real excited about it. I was A quick cycle of the ignition switches had the runway and taxiway. pretty much equidistant from three air- no effect, and I only moved the prop and I ended up on a close-in left base for ports, one 90 degrees off the left, one throttle a small amount to see if there Runway 24. Once I saw I had the runway 90 degrees off the right, and home base would be any impact. There was none, so I made, I quit looking at the oil pressure right behind me. Griffin (6A2), off to the knew I had a serious engine problem. and pulled the throttle back to idle on left, was heavily populated with shop- The Stearman is a very high-drag air- short final. The engine was really making ping areas, a heavily traveled highway, plane. It has 15 more hp than my RV-10, some clanging noises now, which were and not many open fields between me weighs almost 800 pounds less at gross very loud—so loud in fact that I don’t and it. Henry County (KHMP), off to the weight, yet it flies about 65 knots slower. think I heard the exhaust at all. I made an right, had some open fields, including There is a joke about throwing a brick out uneventful wheel landing right on the one grass runway that had been plowed of the Stearman if you have an engine numbers, and my guess would be that, under. All of my tools were, of course, at failure to help locate your landing spot. unless anyone heard the clanging, it all home base, and it was a very strong urge I wasn’t quite in dire straits yet, as the probably looked normal. In fact, I had

Photos: Vic Syracuse KITPLANES November 2019 53 (Left) Even after all cylinder hold-down bolts were removed, we were not able to remove any of the 7 cylinders. Number 3 was finally able to be pulled out enough to allow cutting the cylinder skirt with a torch, which enabled us to see inside the engine. (Right) Look closely above the piston and you will see damage to the counterbalance weight from pieces of the connecting rod. enough power at idle to taxi off the run- on the ground could help me anyway, I left side of the fuselage and left wing were way onto the apron. A quick glance at the wasn’t in communication with ATC, and I covered in oil. In fact, the whole bottom JPI 830 showed two cylinders still firing, had the field made with no interference. of the airplane was dripping a substan- but just as I rolled into the parking spot, The next part probably looked hilarious tial amount of oil onto the ramp. I had a the engine came to an abrupt stop. to anyone watching, but not from my per- pretty good view of this from my prone spective. I secured all the engine controls position on the ground. Slip ’n Slide and electrical switches, stepped out onto I managed to get up and couldn’t find As I mentioned, it probably looked normal the wing, then promptly fell off of the anything broken on myself, and walked to anyone watching. I hadn’t bothered wing and onto the ramp! That really hurt. around to the front of the airplane. The with an emergency radio call as no one What I hadn’t noticed is that the entire first thing I noticed as I got to the wingtip was that the cylinder interconnect oil drain hoses on cylinder 5 were discon- nected, and oil was pouring out of them. No way, I thought! I had just replaced all of those hoses on Friday night, and I knew they were properly secured and tight. Actually, they are a real bear to get on and off, and I couldn’t imagine one coming off by itself. However, I am thinking this is my fault. It was then that I noticed the cylinder head on number 5 cylinder was actually in two pieces, separated from the cylinder barrel, and only attached by the ignition wires. Even the piston was clearly visible. I felt some relief that I hadn’t caused the failure by some shoddy workmanship. I tried turning the prop, but it would only turn a little bit in each direction, and I noticed that the piston did not (Left) Once a hole was drilled in the top of number 5 piston and it was removed by move at all, which meant the connect- inserting a bolt and using a slide hammer, the broken connecting rod was discovered. (Right) Although the connecting rod was mangled beyond belief, on one side it was ing rod probably wasn’t connected quite smooth, perhaps from rubbing the cylinder wall for a long time. Allegedly, Jacobs anymore. A quick check of the oil tank engines have been known to go to TBO with bent connecting rods. revealed nothing on the dipstick, so I

54 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes that teardown was a revelation! None of the cylinders could be removed, and finally one was cut off with a torch. The connecting rod for number 5 cylinder looked mangled beyond belief, and the internal damage to the engine from all of the pieces floundering around pretty much destroyed the engine. There is some speculation that in the past (I am the third owner) there was a hydraulic lock on cylinder 5. Jacobs engines have been known to go to TBO with bent connecting rods. I’m upset with myself for not having this engine on an oil analysis program, as it probably would have caught it. I’ve always had my RVs on oil analysis programs, but somehow hadn’t considered the Stear- man. You can bet the new engine will It was amazing with all of the pieces flailing around inside that there wasn’t any visible be on the program. damage to the gears. Lucky for me, that’s probably what kept the engine producing Yes, it’s taken a lot of fun out of prime enough power to get me to the runway. Stearman summer flying, and I am miss- assume I ran out of oil pressure some- Once I removed the engine, Carol ing the chance to fly with the Veterans where on short final. We all joke about and I drove it to Air Repair in Mississippi, and Blue Angels in Pensacola. I now a little bit of oil looking like a huge leak where the airplane and engine were find myself patiently waiting for a new when it gets on the airplane. Here I was built by Pete Jones and his team. Pete engine, which I get to install in the heat looking at about 4.5 gallons of oil all also holds the STC for the Jacobs engine of Atlanta’s summer. Patience isn’t one over my beautiful Stearman. A quick call and was just as curious as I was as to what of my virtues. But at least I am OK, the home and family was soon on the way precipitated the failure, and he even airplane is OK, and with a new engine, it to help clean it up, but I bet the airframe said I could watch the teardown. Boy should be fun again! J will leak oil for a very long time.

Aftermath We all train for emergencies and, of course, wonder how we will do when the real McCoy happens. This one Unairworthy worked out OK, with no scratches on the airplane or myself, except for the bruises Fuel Leak and from falling off the wing. That doesn’t stop the second guessing though. It is Cracked Flare very annoying now that the Stearman is A major fuel leak was dis- at an airport other than my home base, covered on this airplane not but at least it is hangared, courtesy of a long after the first flight. The good friend, Delta captain, and fellow majority of the fuel in the RV driver, Glen Fink. I realized later that tank leaked out overnight. night that staying the course to Henry The culprit was a cracked flare County once I made that decision was at the tank pickup, as well as probably one of the best decisions I’ve the use of an improper flaring made. It turns out home base was 2 tool. Standard AN fittings miles farther, and while 2 miles doesn’t require a 37-degree flare, look like much in the air, I landed on the not the typical 45-degree numbers at Henry County with not a lot flare used in the automotive of energy to spare. I never would have industry. Be careful when you made the extra 2 miles. I am thankful I purchase your flaring tool! J stuck with my original decision. —Vic Syracuse

KITPLANES November 2019 55 BUILDING TIME Taxes and Shipping Additional The technical writer in me likes brevity: 1. Pay to have your kit shipped. 2. Delay paying sales tax as long as possible. With that you could move on to another article, but perhaps you’ve grown curious—and I have a remaining budget of 959 words. Most homebuilders—and just I’m spit- balling here—have waited a long time to justify the cost of building an airplane. I base this assessment on the demograph- ics of the fly-ins I attend. (Hair color: flesh; eyes: trifocal; weight: increasing; height: decreasing; hearing: .) When we press pencil to paper to estimate the finished cost of an aircraft, we lie a bit to ourselves or our spouse. We round big numbers down. We treat little numbers, $400 A hidden expense in the decision to pick up a kit yourself is learning it isn’t insured during transport. seatbelts, $300 batteries, as incidentals and leave them out. We push and pull the idea of borrowing a trailer and pick- certainly more time consuming than hav- the pencil until the numbers fit our bud- ing up the kit themselves. That, however, ing the kit shipped. You’ll spend on fuel, get and the shape of the airplane we’ve triggers the addition of state sales tax, trailer rental, meals, hotels, tarps and tie- committed to building. Comfortable which can exceed the cost of shipping. downs. An often overlooked cost of pick- with the lies we’ve told ourselves, we Caught between these two expenses, ing up a kit is insurance coverage for the place the order. the decision can be difficult. precious cargo. Homeowner’s insurance Immediately, two costs we gloss over doesn’t cover an airplane project in your confront us; shipping and sales tax. An Ship or Pick-up? garage and your car insurance may not unfortunate few face both costs up front, I’ll cut to the chase. Most builders should cover the contents of the trailer. but for most builders the kit comes from have their kit shipped to them. When a a state other than the one in which they kit ships by common carrier, it is insured State Tax Considerations reside, so sales tax is not charged at the against loss or damage from the time it (I am not a tax professional. The follow- time of purchase. Shipping expenses leaves the manufacturer to the time it ing statements are intended to help you confront everyone. While the purchase arrives at your home, hangar, or the truck- explore the topic with your state’s tax- of seatbelts and a battery can be punted ing company’s local terminal. All you ing authority.) down the road a year or five, commenc- have to do is write a check and wait. If Taxes cannot be avoided, only posting a build is difficult if the kit never you decide to pick up the kit, you trigger poned. Shortly after you register the arrives. Convinced by the person who a cascading series of decisions and events finished aircraft, your state will send you took our order there is no way to reduce that, if you’re honest with yourself—more a tax bill. The bill, generally, is based on the shipping cost because the trucking honest than you were with your initial the total of your receipts less sales tax company set it, some builders entertain budgeting—will prove more costly and you have already paid on purchases.

Kerry Fores grew up jumping the airport fence in Oshkosh, Wisconsin. He wanted to build an airplane in 10th-grade woodshop but was asked to choose a smaller project. In 1998, unconstrained by teachers, Kerry scratch built a Sonex he polished and named Metal Illness. It was awarded Plans Kerry Fores Built Champion at AirVenture 2006. Kerry is on the web at www.thelifeofdanger.com.

56 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes (Keep your receipts in case you face the challenge of disputing what you owe.) There is a caveat, one that requires defeatist thinking. We all begin a project convinced we will finish it. That makes a tax bill inevitable. Statistics suggests otherwise. If you sell the project before it is registered, you won’t face the tax bill. For that reason, if you delay paying state sales tax on as many of your project- related purchases as possible you may never have to pay state sales tax. It’s a small reward for giving up. Your delivery decision impacts how the kit and, ultimately, the finished aircraft are taxed. If you pick the kit up at the factory, the sale becomes an in-state sale and the manufacturer must charge their state’s sales tax. If the kit is shipped to you from another state, you aren’t charged state sales tax at the time of purchase. Shipment must be accomplished by common carrier, however. You can’t dodge the sales tax by sending your friend or brother-in-law to pick the kit up for you. If the kit is manufactured in the same state in which you reside, you’ll pay state sales tax whether you pick it up or have it shipped. There is a silver lining to this; taxes paid at the time of purchase are deducted from the taxes due when you Print and Digital register your aircraft. States tax at different rates (3%, 4%, 6%), so you may owe additional tax on items you have already paid tax on. (Another reminder to keep your receipts.) To ease the pain of paying state sales tax to a kit manufacturer, think of it as an installment payment on your final tax bill. However, as I mentioned earlier, you have to finish and register your aircraft to trigger the final tax bill. I’m sorry to have sullied these pages of KITPLANES® with two topics we’d rather ignore, neither of which add value to your project. Paying to have your kit shipped by professionals doesn’t always save on the cost of getting it to your shop, but it does save the hassle. Paying taxes is unavoidable in the long run but can often be delayed for years. It is my sincere wish that all KITPLANES® readers get a tax bill for their homebuilt, as that is a state’s Either Format – Great Savings! awkward way of saying, “Congratulations Subscribe Now at www.kitplanes.com/subscribe on completing your airplane.” J

Photo: Kerry Fores KITPLANES November 2019 57 BEST PRACTICES Aircraft Plumbing: Flexible Lines There are several things to consider when it is time to decide what hose material to use in your airplane project: compatibility with common aviation chemicals, pressure rating, temperature rating, service life, and cost. Not every hose offered by an aviation parts supplier will satisfy all of these criteria for any particular application. Also, your search for suitable hoses and fittings need not be restricted to aviation vendors. The automotive world has products that are perfectly well-suited for Experimental airplane use and may offer more options and lower prices than traditional aviation sources. However, the use of automotive products does require a higher level of diligence on the part of the buyer. Your engine installation is going to use a variety of hose types, from low-pressure Chemical Compatibility pneumatic to fuel and oil. Choosing the right flexible hoses for the job is essential. Aircraft hoses need to be compatible literature on any automotive product AE246. Hydraulic landing gear systems with avgas and engine oil to be sure, you plan to use to make sure it is suit- would be best served with the higher but in some cases compatibility with able, and if you can’t clearly identify the rated hose. ethanol is also a concern. For example, product, don’t use it. Rotax engines prefer unleaded auto gas Temperature Ratings and allow for up to 10% ethanol. A fuel Pressure Ratings Aeroquip 303 and Stratoflex 111, which line that was not resistant to ethanol Common Aeroquip and Stratoflex hoses are easily identifiable by their black rub- would be a poor choice. This becomes a used in aviation have pressure ratings ber exteriors, have a temperature range greater risk when using hoses where the that far exceed those required for fuel of -65 to +250º F. This is adequate for material used is not readily identifiable. and oil lines where pressures rarely most aviation applications with non- Also, please note that the new unleaded exceed 100 psi. However, brake systems turbocharger engines. The upper limit aviation fuels on the horizon may pres- will see much higher pressures. The of 250º F does not leave a very comfort- ent compatibility problems with rubber best choices for flexible brake lines are able margin above a possible maximum parts that are not known at this time. the stainless steel covered Teflon hoses oil temperature of 240º F, but that tem- Chemical compatibility is something such as Aeroquip 666 or Stratoflex 124. perature should never be seen in normal that is of special concern when using In the small -3 size Aeroquip switches to operations. Oil lines near turbochargers automotive store hoses. Not all of them a part number of 240-3, rather than 666. could see higher temperatures than 250º are as chemical resistant as you might Aeroquip also makes a stainless/Teflon F, so these hose materials are not recom- think. Be sure to read the manufacturer’s hose rated at 3000 psi designated as mended for such applications.

58 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes The hose shop at Desser Tire tests every hose they make to twice the rated pressure of the Use plugs and caps to keep fluids from spill- hose. In other words, a typical hose rated for 1500 psi is tested to 3000 psi. It is very hard ing and to keep contaminants from getting for an amateur builder to duplicate that test procedure. in hoses when you disconnect them. These caps and plugs are available wherever they Aeroquip 601/701 and Stratoflex 156 seem fairly obvious. Fuel and oil lines sell hoses and fittings. hoses, the familiar stainless steel cov- must be in unquestionably sound con- ered rubber hoses so many builders like dition since so much depends on them. lot of heat and chemicals to stress hoses, to use, can handle higher temperatures If you are building a new project, you a five-year limit is considered standard, up to 300º F. This extra 50º can provide wouldn’t even consider using any hoses at least for commercial operators. some peace of mind in certain installa- that were not in like-new condition, or at Since it is a rare Experimental pilot tions where heat is a concern, plus this least you shouldn’t. who can log more than 100 hours in a hose looks so much better when you are The tougher part of service life, and year (usually it’s more like 30 or 40), it showing off your engine installation. a strong argument against using like- seems to make sense to be more gen- If high temperatures are a major con- new used hoses, is the factory recom- erous when it comes to service life. cern, you should look to Aeroquip 666 or mended age limit on all rubber hoses, However, it is hard to get past 10 years Stratoflex 124 hose with an upper tem- including stainless steel covered rub- no matter how generous you want to perature limit of 450º F. This would be ber hoses. These hoses have a shelf life, be. Technically, there is no legal limit to the best choice for an oil line to a turbo- whether placed in service or not, of 10 hose life in an Experimental/Amateur- charger, for example, or one that must be years. Certainly, once in use a 10-year Built airplane, but safety should be your run very close to an exhaust pipe. limit must be observed. However, in the first concern. It is tough to take a great engine compartment where there is a looking hose and toss it out because of Service Life When a hose has become damaged or brittle or when firesleeve gets soaked with oil or gasoline, it needs to be replaced. If a fitting shows any signs of leaking, it has to go. If there is abrasion on a stainless steel hose that breaks more than two strands of wire in one location, that is no longer acceptable. If the outer covering of a rubber hose (AE030) has been penetrated by chafing or there is a bubble, bulge, or crack in the hose anywhere, it should be replaced. Firesleeve that has been damaged or soaked needs to be replaced. The underlying hose may be savable if it isn’t the source of the soaking. Heat damage such as blistering or permanent Three types of aircraft hoses are shown here, all in -6 size (3/8-inch). At the bottom is Aeroquip discoloration of the outer hose material is 303, the middle is Aeroquip 601, and the top is Aeroquip 666 Teflon hose. Only the Teflon also cause for replacement. These things hose has no calendar life limit. There is no significance to the color of the fittings.

Photos: Dave Prizio KITPLANES November 2019 59 a date on the calendar, but that’s what prudence requires. The alternative to junking your hoses every so many years is to use Teflon (PTFE) hoses with a stainless steel covering. These hoses are more expensive initially but have no calendar life limit. Aeroquip 666 and Stratoflex 124 hoses fill this bill. Of course, they cost more, but using a non- aviation vendor can help soften the blow. I cannot find a recommended service life for firesleeve material. Certainly, it should be replaced when its condition has deteriorated. The most common problems are heat or abrasion damage and fuel or oil soaking. A calendar life In some places push-on hoses work best. Be sure the hose you use is rated for fuel and oil and that it will withstand the heat of the engine compartment. limit of 10 years seems reasonable for installation where usage is low such as Push-on Hoses clamps in conjunction with barbed fit- we typically see with E/A-B. Some hoses are the push-on type with no tings give the most security. Firesleeve isn’t just for protecting pressure requirement, or a very low one Can these types of hoses be used for hoses. It can be very useful to protect in the case of vacuum hoses. The crank- aircraft fuel and oil lines (pressure lines)? control cables or wires that are exposed case vent hose is a good example of this Yes, they can, but it is hard to consider to excessive heat. Especially with wires, type of hose. Vacuum hoses have now that the best practice, unless you have the first choice should always be routing become nearly obsolete, but older planes an engine that does not allow for stan- them in a way that avoids heat, but some- (like mine) do still have such hoses. Here dard AN fittings. Many Rotax and Jabiru times it is very difficult to do that. Control the main concerns are heat and fuel/oil engines will only accept push-on fittings cables to forward-facing fuel injection resistance. Rubber hoses with stainless where the fuel line connects to the car- servos always seem to be routed in such steel covering can be use in these cases buretor, so you really don’t have a choice. a way as to come between the engine if aesthetics is a major concern, but most However, given the option, screw-on AN and the exhaust system. Firesleeve over people are satisfied with rubber fuel line- hose fittings are preferred. these cables can be very helpful to pre- type hoses. These hoses work best with serve the proper function and extend what are called barbed fittings. These fit- Roll Your Own vs. the life of these controls. Even though tings allow the hose to slip on fairly eas- Factory Made firesleeve is considered “fireproof,” what ily but prevent it from coming off. In all If we are talking about best practices, that actually means is that it is rated to cases, some type of barb or bead should it is hard to avoid the question: Is it the handle up to 2200º F for five minutes and be incorporated to help prevent the hose best practice to make my own hoses 500º F continuously. joint from coming apart. Of course, hose from fittings and stock hose, or do I

All hoses should be measured for overall length including the Cut your hose off so it just reaches the beginning of the flare fittings, even hoses with 45 and 90 degree fittings. inside the fitting. Be sure to tape up the hose before cutting to minimize fraying.

60 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes You can pull a patch of cloth through your finished hose to There are two ways to make a 90-degree end on a hose. The top make sure it is absolutely clean before you install it. Shotgun method uses a separate male to female 90-degree fitting. The cleaning patches work well for this, or use a piece of cotton bottom uses a single fitting to make the turn. The lower method T-shirt material. is preferred because it provides better flow. really need to have a professional shop on this later). The downside is that an Few people will be equipped to test make them for me? Shop-made hoses incorrectly installed fitting could fail at their new hoses to twice the rated burst- have two distinct advantages. One, they a very bad time. Many years ago, in my ing pressure, although it is possible to are tested to twice the rated pressure off-road racing days, I had a hose fail get a pump that will achieve those pres- of the hose and fittings (test pressures and pump all of the oil out of my engine sures for around $150. If you decide to of 3-6000 psi). And two, they are avail- in what seemed no time at all. Luckily, I test your hoses, it is much safer to use a able with machine-swaged fittings that simply pulled off the course and waited hydraulic pump than a high-pressure air cannot be duplicated by most people for the tow truck. Since then I am much pump. In any case use extreme caution working in their home shop or hangar. more careful about how I assemble and be sure to enclose the hose being These are distinct advantages of pro- hoses, and I have never had another tested in a sturdy container of some fessionally made hoses. The downsides failure. The bottom line is that if you use sort. If a hose fails at 3000 psi, flying are that they are pretty expensive and new material and fittings and carefully debris can do some real damage. This any discrepancy in communicating the follow the manufacturer’s instructions, is one place where factory-made hoses desired length to the hose maker may there is no reason why you can’t put have a real advantage. result in an unusable hose. together a high-quality hose in your The final concern with hoses, factory Homemade hoses have the advan- own shop, but if you are careless in your made or otherwise, is making absolutely tages of being less expensive and easier assembly process, you can get yourself sure they are clean inside before install- to get made to the correct length (more into trouble. ing them. At the very least blow them

FLEXIBLE HOSE CHART DESIGNATION DESCRIPTION FITTINGS SIZES AVAILABLE PRESSURE-PSI TEMPERATURE Aeroquip 303 Reinforced rubber with cloth covering 491 -3 thru -32 3000/2000* -65˚ to 250˚ F Aeroquip 401 601 hose with integral firesleeve 816 -3 thru -20 1000 500˚ F cont/ 2200˚ F for 5 min. Aeroquip 601/701 Rubber with stainless steel covering 816 -4 thru -32 1000 -65˚ to 300˚ F Aeroquip 666 Teflon with stainless steel covering F66000 -4 thru -12 1500 -65˚ to 450˚ F Aeroquip 240 Teflon with stainless steel covering F66000 for -3 3000 -65˚ to 450˚ F Stratoflex 111 Reinforced rubber with cloth covering 300 -3 thru -48 3000/2000* -65˚ to 250˚ F Stratoflex 124 Teflon with stainless steel covering 524 -3 thru -24 1500 -65˚ to 400˚ F Stratoflex H/J 124 hose with integral firesleeve 524 -3 thru -24 1500 500˚ F cont/ 2200˚ F for 5 min. Stratoflex 156 Rubber with stainless steel covering 676 -3 thru -32 1500 -65˚ to 300˚ F

*3000 psi rating in -3 and -4 sizes. 2000 psi in larger sizes

KITPLANES November 2019 61 out with compressed air. Better yet, pull a cloth cleaning patch through each hose with a piece of safety wire.

Ordering Hoses If you decide to have a professional shop make your hoses, you will need to take accurate measurements to get the correct lengths. You would hate to pay $50 or more for a hose only to have it come up an inch short. The best approach is to first install the AN fittings at the points where the hose will attach, such as your fuel pump or oil cooler. An AN816 nip- ple or an AN822 elbow would be some of the more common fittings you might This builder has elected to use professionally made hoses with integral fire protection. use. Then take a length of inexpensive This makes for a very nice looking installation, but does come at an added cost. rubber hose of about the same diameter as the hose you plan to use and the far end of that fitting. To be sure lines. Oil lines do carry a flammable liq- run it from one connection point to the you should talk to the hose maker to uid, even if it is less so than avgas. Most other. Be sure to use the exact same verify your mutual understanding of the people do not protect oil lines, and that routing you will use for the final assem- length measurement for any hose with has been my personal practice. Is that bly. Hold the beginning end on the end an angle fitting on the end. the best practice? Arguably not, but that of the far end of the threads of the flare Another advantage of professionally is your choice. I would not question any- fitting, and run the hose to the end of made hoses is that you can get them one who chose to protect their oil lines the threads of the other flare fitting. You coated with silicone rubber in lieu of just as they did their fuel lines. If you can then easily measure the length from installing separate firesleeve. This coat- make your own hoses, it doesn’t cost the end to the mark. Please verify with ing gives similar fire protection and is very much more to protect your oil lines. your hose maker that this is how they much less vulnerable to oil or fuel soak- want you to determine your hose length ing. Be sure to specify this when you Installation Concerns before you submit your order. order your hoses. The best hoses can be rendered unsat- If you plan to install a 90º fitting on isfactory by poor installation. Be sure one end of the hose, you can get a very To Firesleeve or Not hoses that run from the airframe to the close approximation of the correct length There is little argument about using fire- engine have enough slack in them to by temporarily installing a 90º swivel sleeve on fuel lines, but there is much allow for engine movement. Think about female to male fitting. Then measure to debate about whether to use it on oil routing carefully and the excessive use

This shop-made fuel line has an outer covering of firesleeve with silicone tape and steel bands securing the ends of the firesleeve. It does not look as nice as the pro-made hose, but it will do the job for much less money.

62 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes This manifold-pressure hose has a clamp made of a zip tie and a piece of hose to keep it away from the ignition leads and from rubbing on the SCAT tube. of angle fittings. Fuel flow is reduced by lacks confidence in their ability to fab- tight bends and angle fittings. Be careful ricate their own. These hoses offer not to let hoses twist when you tighten advantages that cannot be duplicated them. You may need two wrenches for by most amateur builders—swaged fit- this. You never want to put unneces- tings, integral fire protection, and high sary stress on a hose during installation pressure testing. On the other hand, it or set up a potential chafing situation. is possible to make good quality hoses Your trusty copy of AC 43.13-1B has more in your own shop with bulk hose and on this. And lastly, avoid heat as much fittings that are readily available from as you can. Pick a route that keeps your many sources. hoses away from hot exhaust pipes as Whatever you decide to do remember much as possible, and protect all hoses these important points: Measure twice from heat if there is any doubt about and cut once; these hoses don’t stretch. proper clearance. Be sure you communicate clearly how you made your measurements if you Conclusion have someone else make your hoses. Professionally-made hoses are no And be sure your hoses are absolutely doubt the best option for anyone who clean before you install them. J

Use torque seal to mark your hose fittings after you have tightened them. This makes it easier to keep track of what you are doing when you are building your project or replacing a hose later.

KITPLANES November 2019 63 HOME SHOP MACHINIST RV Quick Stick I live in a pretty cool neighborhood, which happens to include a couple of locals who are building airplane projects in their garages. In the April 2016 issue of KITPLANES®, I introduced Phil Hooper. The subject of that column was a custom drill guide for Phil’s Velocity RG. This month’s subject is a quick-release system for the copilot’s control stick on Mark Beattie’s RV-6. While the two airplanes couldn’t be more different—the Velocity is a retractable-gear, canard-wing, composite pusher, and the RV-6 is a fixed-gear, aluminum, low-wing monoplane—both Phil and Mark have the same detail- oriented mindset when it comes to the plans and instructions. Mark Beattie at work in his garage on the RV-6. When Phil was ready to set the angle of incidence for the canard, for example, he checked, rechecked, and re-rechecked the procedure for leveling the fuselage. Then, for good measure, he allowed it to settle for a couple days and checked it again before finally setting the canard in place. The old saying, “measure twice, cut once” is his guiding principle. If you’re an airplane builder, you can probably relate to that type of fussiness. Mark’s particular affliction for detail is he sometimes wakes up at night with “builder thoughts” in his head. Such was the other night when he was fret- ting about running wires through the wings for strobes. Then he remem- bered: No problem! When he assembled the wings, he put in nylon cords so he could fish the wires through when the time came. Both Phil and Mark started their proj- Using a parallel gently pinched between the tube and the drill bit is a quick and accurate ects before CAD, match-drilling, or way to center a tube for drilling. When the parallel is square to the drill, the tube is centered. quickbuild options became the norm. (See “Parallels, Stops, and Travel Limiters” [KITPLANES® July 2017] for more information.)

Bob Hadley is the R&D manager for a California-based consumer products company. He holds a Bob Hadley Sport Pilot license and a Light Sport Repairman-Airplane (LSRM-A) certificate.

64 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes (Left) To assure perfect alignment, the control stick and socket are assembled, aligned, and drilled together. A 17/64-inch drill provides the perfect clearance hole for the 6.5-mm (0.255-inch) spring button. (Right) Deburring is always important, especially when tubes telescope. But always deburr, regardless.

(Left) Installing the spring button is as simple as lining up the button with the hole and inserting it into the stick. (Center) Note the double bend at the end of the spring. It eliminates exposure to the sharp end and prevents button overtravel. (Right) Red arrows painted where the stick and sleeve align provide visual confirmation that the spring button is properly engaged.

“Vintage” kits, while quite good, often builder. Some bolt it together, others use are familiar with typical carry-on roller- leave many less-than-critical aspects of a cotter or a cross pin with a ring grip. bags with telescoping handles, which the assembly up to the builder. That’s Mark wanted a solution that, above all, usually have spring buttons made from part of the fun: It not only gives the would be safe and reliable, and, if pos- stamped steel, or the ubiquitous Razor builder a chance to learn and be inven- sible, provide quick release with no loose kick scooter, which has solid brass or tive, it helps personalize the project. parts that might get dropped under the steel buttons to engage the handlebars. Which brings us to the copilot’s control floorboard or misplaced. It turns out that scooter handlebars are stick on Mark’s RV-6. Unlike the pilot-side What we came up with is simple and the same diameter (0.875 inch) as the stick, which is non-detachable, the copi- easy to install: a spring-loaded “button Van’s control stick, so we repurposed a lot’s stick slides into a coupling sleeve at pin” or “spring button.” Spring buttons spring button from a Razor and made it the base of the control mechanism. How have been around for decades to engage the key component of the quick-release to fix the stick to the coupling is up to the telescoping mechanisms. Most people system for the copilot stick.

Photos: Bob Hadley KITPLANES November 2019 65 Spring Button Guard Option The goal of any quick-release mechanism is that it should never inadvertently release. The solid steel buttons used on scooters, as long as they are engaged correctly, will not inadver- Using a parallel to find the tube center. A stub-length drill or spotting drill is more accurate tently or accidently disengage. One of than a twist bit, which can flex and distort the accuracy. the reasons for this is the head of the button is protected from inadvertent contact by being recessed in a counter- sunk pocket in the handle. If necessary, this type of protection from inadvertent or accidental contact should be included in the design. The option to not have a guard depends on the location of the spring (Left) Using a 0.187-inch drill to make a pilot hole in a length of 11/8 x 0.065 tube. (Right) Core button. In the case of Mark’s RV control out the pilot hole from the tube with a 7/8-inch hole saw. stick, we pondered the situation and agreed that three things added up to assure a safe installation without a guard. One, because the button was located below the floor, no person could inadvertently bump it. Two, the placement and angle of the button on the stick was such that if some object were to be accidentally left in, or somehow worked its way toward the mechanism, it could never get pinched (Left) Deburring is essential to create a flush fit of the guard to the sleeve. Be careful! Small parts are hard to hold and can get hot. (Right) Position the guard over the sleeve and tack or jammed into the button, regardless weld as shown. Three or four good tacks secure the guard in place. of the position or movement of the stick. Last, in order to prevent access to the release button and the control mechanism in general, a stick-boot cover will be installed. Taken together, the spring button is effectively guarded“ by position.” So while there’s no direct mechanical guard around the button, its remote position and concealed access prevent (Left) With the 7/8-inch telescoping tube lined up inside the 1-inch sleeve, drill through the inadvertent or accidental contact. The guard and both tubes. (Right) Use a countersink bit to taper the opening of the guard. Make guarded-by-position concept is easy the depth of the counterbore no more than the thickness of the guard. to understand, but when considering applicability, it’s important to study every possible scenario, including abuse and potential user error. This sequence shows how to make a spring button guard to fit a 1-inch x 0.65-inch sleeve for a 7/8-inch diameter telescoping tube with a spring button. The guard was made from a 11/8 x (Left) A quick trip to the deburring wheel is all that’s needed to polish the guard to a 0.065 tube. J smooth finish. (Right) With a guard in place, it takes a deliberate effort to disengage the —B.H. spring button from the sleeve.

66 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes BACK ISSUES LIST OF ADVERTISERS Please tell them you saw their ad in KITPLANES® Magazine. O O NEW eBOOK KITPLANES® interactive makes it quick and easy for you to receive instant eBook download is exactly the information about products or services directly from our advertisers’ websites. same magazine as on the newsstand. ➥ Go to: www.kitplanes.com/links for a virtual shopping tour via links to their The difference is: websites. ➥ Call the phone numbers listed below and be sure to tell them you saw their ad you get it now! in KITPLANES® Magazine. & no shipping costs for Advertiser page # telephone Advertiser page # telephone e-books! Advanced Flight Systems 15 503-263-0037 Better Half VW 68 281-383-0113 (a big savings for our international customers) Aircraft Spruce & Specialty CV4 877-4SPRUCE Carlson Aircraft 69 330-426-3934 eBooks download as a single, full-size, full-color .pdf document that you can view Avemco Insurance Company CV3 888-241-7890 Crow Enterprises 68 714-879-5970 on your desktop, laptop, or tablet computer. Avemco Insurance Company 57 800-752-4208 Flight Data Systems 68 831-325-3131 PDF eMagazine issues are fully searchable and are compatible with all Adobe Acrobat Better Aircraft Fabric 33 907-229-6792 Flight Grip 69 800-204-7625 functions such as highlighting, page notes, and spoken word audio. California Power Systems 48 800-AIRWOLF Glen-L 68 888-700-5007

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KITPLANES November 2019 71 WIND TUNNEL Design Process: Landing Gear, Part 3 Last month we took a look at the basic We will start by looking at the case The moments generated by the wheels characteristics of the two most common where the airplane is stationary on must also sum to zero. The farther a wheel landing gear configurations: tricycle and the ground. is from the CG, the more moment it gen- taildragger. We will now turn our atten- erates per unit load. This means that a tion to some critical factors in the proper Equilibrium relatively lightly loaded wheel far from integration of the gear into the overall When the airplane is on the ground, it the CG (like a nosewheel or tailwheel) airplane configuration. is supported by the landing gear. The will produce enough moment to offset The configuration of the landing weight of the airplane is reacted by con- the moment created by a higher loaded gear and its placement affect the static, tact between the wheels and the ground. wheel mounted closer to the CG. ground handling, takeoff, and landing All of the force supporting the airplane The closer a wheel is to the CG, the characteristics of the airplane. The com- against the pull of gravity acts through greater the percentage of the total bination of all of these considerations the contact patch of the tires. weight of the airplane it carries. A wheel drives the landing gear to be placed The load is distributed between the placed directly beneath the CG of the air- quite specifically on the configuration. three wheels. How much load each plane will carry its entire weight. This leaves the designer with remarkably wheel carries statically is determined by little freedom as to where the landing the horizontal relationship between the Static Stability gear must contact the ground and where wheels and the CG of the airplane. The contact points of the three wheels it attaches to the airframe. It is important Equilibrium demands that the sum of of the landing gear form the vertices of a to understand this early in the devel- all of the forces and moments acting on triangle. This is called the “triangle of sup- opment of the design so that the gear the airplane must be zero. Accordingly, port.” In order for the airplane to sit stably can be successfully integrated without the sum of the loads on all of the tires in on its gear, the center of gravity, viewed requiring wholesale changes late in the contact with the ground must equal the from above, must fall inside this triangle. design process. weight of the airplane. When this is the case, the reaction loads

The contact points of the three wheels of the landing gear form the vertices of the “triangle of support.” In order for the airplane to sit stably on its gear, the center of gravity, viewed from above, must fall inside this triangle. (Photo: Kevin Wing)

Barnaby is a Technical Fellow for Northrop Grumman’s Advanced Design organization. A private pilot with single-engine and glider ratings, Barnaby has been involved in the design of unconventional airplanes including canards, joined wings, flying wings, and Barnaby Wainfan some too strange to fall into any known category.

72 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes The aft body of the VariEze and similar designs is so short that there isn’t a place to put a tail stand or tail bumper. Burt Rutan solved this problem by retracting the nose gear when parking the airplane. Tipping the airplane nose down moves the CG forward relative to the main wheels. (Photo: Arpingstone) on all of the wheels produce moments Suppose the CG moves aft to the This situation is relatively common about the CG that tend to rotate the air- point where it is behind the main land- for pusher configurations. As we saw in plane into the triangle. The moments then ing gear. The moments generated by our discussions of CG, the heavy weight balance each other out. gear reactions now look like this: of the engine, which is aft of the most For an airplane with tricycle gear, aft allowable flight CG, is counterbal- where the main gear is aft of the CG and Pitching Rolling anced by the weight of the pilot, who Gear Leg Moment Moment the nose gear is ahead of the CG, the sits well forward of the CG. Depend- moments produced by the wheel reac- Nosewheel Nose Up Zero ing on the details of the configuration, tion loads look like this: Left Main Nose Up Right Wing Down adding passengers may also move the Right Main Nose Up Left Wing Down CG forward. Pitching Rolling When the airplane is parked and the Gear Leg Moment Moment In this case, the rolling moments are pilot and, possibly, the passengers get Nosewheel Nose Up Zero still balanced, but all of the pitching out, the CG moves aft significantly. For Left Main Nose Down Right Wing Down moments are nose up. The airplane is not some airplanes, it moves far enough to Right Main Nose Down Left Wing Down stable and will tip over backwards until end up aft of the main landing gear. If some part of the aft fuselage contacts this happens, the airplane must have Looking at how these moments inter- the ground and produces a nose-down some provisions to keep it from tipping act, we can see that the nose-up moment moment to counteract the nose-up over backwards. created by the nose gear balances out moment being produced by the mains. It’s tempting to the designer to simply the nose-down moment created by the move the main gear aft of the empty CG two main gear legs. Loading so the airplane does not tip over back- On the roll axis, the right-wing-down As we have seen previously, the CG of wards when unloaded. This can some- moment caused by the left main is bal- an airplane moves as its loading condi- times work, but as we will see later, if the anced by the left-wing-down moment tion changes. This can be a significant gear is too far aft, it causes problems on created by the right main. issue for landing gear placement if takeoff. The main gear may be so far aft of Accordingly, all of the moments sum there is a significant distance between the flight CG that the main gear reaction to zero, and the airplane sits stably on the empty CG of the airplane and its forces produce too much nose-down its gear. loaded CG. It can be particularly prob- pitching moment. It will become difficult Now let’s consider a case where the CG lematic if the flight CG is significantly or impossible to raise the nose gear off moves outside the triangle of support: forward of the empty CG. the runway. This can make the takeoff

KITPLANES November 2019 73 run very long because the airplane can- use bumpers on the tip of a ventral tail aboard the airplane for every flight to not rotate until well above normal liftoff surface to guard against prop strikes on be able to park at any airport where the speed, and it may also cause controllabil- takeoff and also to protect against tip- airplane lands. ity problems on takeoff rotation. ping backwards when on the ground. Sometimes the aft body of the air- On configurations where the main Some configurations might require a plane is so short that there isn’t a place gear is placed in its proper location to retractable or removable tail stand to to put a tail stand or tail bumper. The the flight CG and the airplane will tip prevent tip-back. This approach should Rutan canards and their descendants backwards when empty, there are two only be used as a last resort in my opin- (VariEze, Long-EZ, Velocity, Cozy, etc.) solutions that have been used success- ion. A retractable tail stand is heavy have this issue. The solution created fully to keep the airplane in equilibrium and complex, and will prevent the air- by Burt Rutan for the original VariEze, on the ground. plane from rotating for takeoff if it is left which carried forward to all of the fol- The first approach is to use some deployed. This can lead to a hazardous low-on airplanes of similar configura- form of tail bumper to keep the airplane situation, so checking that the tail stand tion, was to retract or “kneel” the nose from rotating too far nose up. Airplanes is retracted will become a safety-critical landing gear when parking the air- using this approach will sit with the nose preflight checklist item, similar to ensur- plane. Tipping the airplane nose down gear off the ground and the tail bum- ing that all control locks are removed. moves the CG forward relative to the per grounded. The tail bumper can be A removable tail stand must be man- main wheels. In the kneeled attitude, relatively simple, like a skid or a small ually placed when parking the airplane the airplane sits stably when empty. tailwheel, provided the aft fuselage is and manually removed to go flying. This Most airplanes of this class have actua- long enough that the airplane will not tip can be troublesome since the operator tors that can extend the nose gear and back too far, and the aft fuselage will pro- must find a way to get the stand in place rotate the airplane to level on the gear tect the prop from hitting the ground in without letting the airplane tip back, after it is loaded and the engine started. the parked attitude. and it has the reverse problem when Next month we will continue our study A few tail-pusher airplanes like Ed the stand is removed before taxiing. It of landing gear with a look at what hap- Lesher’s Teal and the Taylor Mini-IMP will also be necessary to put the stand pens once the airplane is in motion. J Kitplanes subscriber alert! several of our Kitplanes subscribers have received what appear to be “renewal notices” or “automatic renewal notices” from a company known as preMier subscriptiOn serVice, 5star subscriptiOns, rapiD MaGaZine cOllectiOn, MaGaZine billinG serVices, publisHer’s billinG serVices, circulatiOn billinG center or other similar names. Addresses for these firms include Dallas, tX; lincoln, ne; Omaha, ne; san luis Obispo, ca; salt lake city, ut; White city, Or and prescott, Fl. These firms have nOt been authorized by us to sell subscriptions or renewals for Kitplanes and we cannOt Guarantee that any order or payment sent to them will be forwarded to us. Kitplanes does nOt offer a subscription term of more than 2 years, nor do we retain your bank account information. if you see an offer for 3 or more years or if you receive a notice that references your subscription anD your banking information, it is nOt an authorized offer. We urge you to report these notices to us, as well as to your state’s attorney General and better business bureau. any offer you receive that does not bear our company logo or corporate/customer service address or 800 numbers should not be considered approved by us. the only autHOriZeD inFOrMatiOn for Kitplanes is: toll free via telephone 1-800-622-1065, Dial america renewal telemarketing, or www.kitplanes.com/cs Our texas customer service center: 1-800-622-1065, pO box 8535, big sandy tX 75755 Or our corporate offices at: belvoir Media Group, llc. aviation publishing Group 535 connecticut ave norwalk ct 06854 should you have any questions at all about mail that you receive, please contact us at our website: www.kitplanes.com/cs or call us toll free to speak to customer service.

74 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes AERO ’LECTRICS Tall Transmission Tales (Antennas, Chapter 3) So far we’ve talked about polarization, copper tape, dipoles, ground planes, and the like. Now we come to those parts that pipe your signal to and from the antenna to the radio. We call them transmission lines. All transmission lines have what is called a “characteristic impedance,” and unfortunately for us to comprehend, this impedance is measured in ohms. A B D At first, you might think that you could just take your trusty Harbor Freight mul- timeter, put it on the ohms scale, and measure the impedance of your transmission line. Nope, doesn’t work that way. Impedance (in ohms) and resistance C (in ohms) are two totally different ani- mals. Strange to say that the only real way we have of measuring a transmission line is to put a signal in one end and see how much is left at the other end. There are a couple of dozen ways of (A) 10-picofarad capacitor with 1/2-inch leads for glideslope. (B) 100-ohm 1/4-watt resistor. making transmission lines, but the main (C) Coiling the coax up has absolutely no effect on the operation of the splitter. (D) Both coax cables need to have their shields grounded at both ends. one for aircraft use is coaxial cable, commonly referred to as coax, and over- coax wire, this will always be a negative You can get the exact number for your whelmingly we use 50-ohm cable. As number. For example, if I put in a watt of installation by multiplying by the num- I said in a prior article [“Three to Get power and only have half a watt at the ber of feet in your cable run. Using RG-58 Ready,” September 2018], 70-ohm coax other end of the line, we say we have a and the calculator at https://tinyurl.com/ has minimum loss while 30-ohm cable -3 dB loss. To put it in math format, dB coax-calculator, we find that at the end has maximum power capability. 50 ohms = 10 log P1/P2. P1 is the power at the of that foot of coax, you will have lost is a compromise between these two output end, and P2 is the power at the 0.05 dB, or about 1% of your signal. If and was chosen in the first place during transmit end. Try using that completely instead you choose to use the little WW-II as what could be made out of Brit- virgin “log” button on your calculator, tiny RG-174, you will increase the loss ish standard copper plumbing pipe. and prove to yourself that half power is to 0.1 dB and about 2% of your power. Those of you who have the shivering -3 dB (actually 3.010 if you carry it out for A 6-foot run of coax? Just multiply the timbers when remembering Algebra 3 decimal places). numbers above by 6. II in high school can skip the next two But what does all that mean in the real How about at the transponder fre- paragraphs. We are going to be talking world? Let’s compare two coax types and quency of about 1050 MHz? Those per- about decibels (dB). Any transmission see. How about we use the middle of the foot losses for RG-58 jump up to 0.17 dB cable you use is going to have a certain VHF nav/com band (it won’t vary much and 4%, while RG-174 loses 0.35 dB and loss, and we measure that loss in dB. from one end to the other) at about 120 8% of signal. However, now a secondary Since we can’t gain power in a simple MHz. And let’s do it for a one-foot length. matter rears its head: RG-58 can handle

Jim is the chief avioniker at RST Engineering. He answers avionics questions in the Maintenance Bay section of www.pilotsofamerica.com. His technical advisor, Cyndi Weir, got her master’s degree in English and journalism and keeps Jim on the straight and narrow. Check out their Jim Weir website at www.rstengineering.com/kitplanes for previous articles and supplements.

Photos: Jim and Cyndi Weir KITPLANES November 2019 75 VOR/LOC splitter with glideslope output. Total parts cost at any well-stocked electronic supplier (Mouser, DigiKey, et al.) is a little over $10. Same exact function in any well-stocked aviation supplier is a little under $150.

200-watt peak pulses of power, but Conclusion: For powers less than 50 For polyethylene, the signal will go at RG-174 will not handle more than about watts, my cable of choice (if loss is desired 66% of the speed that it goes through air: 50 watts. My coax of choice for the tran- or not a factor) is good old RG-174. But 186,282 miles per second in air is 122,946 sponder is and always has been RG-58. when it comes to powers greater than miles per second in polyethylene. Let’s jump up a bit to the GPS fre- this, I’ll go with RG-58. RG-400 isn’t even Why is this important? Because we are quency of 1525 MHz. RG-58 loses in the picture. going to go back to that thing we learned 0.25 dB per foot, which translates to a One more little item and we can get last month about calculating how long a 5% signal loss while RG-174 tops out on to a couple of neat things to do with quarter-wavelength is. For our first trick, at half a dB (0.50 dB) and 10% loss of coax other than just running from radio let’s do the calculation for the middle of power. But wait a minute—some of the to antenna. But to do that, we need to dis- the VOR/LOC band at 113 MHz: 122,946 GPS/ADS-B machines require a loss of cuss that polyethylene “dielectric” insula- mps divided by 113 million cycles per sec- around 5 dB, which you can get with tor between the center conductor and ond gives us a wavelength of 0.0010880 a 10-foot run of RG-174 that weighs the shield. Running signals through that miles times 5280 gives us 5.74 feet times about 4 ounces. Using the recom- dielectric has the same effect on the sig- 12 gives us 68.9 inches for wavelength. mended RG-400, you will need roughly nals that you experience running through Divided by 4 gives us 17.25 inches for a 30 feet of cable that weighs about 2 deep water. Neither you or the signal can quarter-wave in coax with polyethylene pounds. Not to mention finding space go as fast in thick water or polyethylene dielectric (which is used for both RG-58 to coil up all that excess cable. as you can in thin air. How much slower? and RG-174).

I built this one in a 2x3-inch aluminum box. If you get much smaller, Don’t forget to label the “goesintas” and “goesoutas” because it’s tough to bend the coax around to fit. when you bolt it together, it is absolutely symmetric.

76 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes Power Splitter/Combiner A pretty smart fellow named Wilkinson designed a power splitter/combiner using Now Cleared quarter-wave sections of coax and a single resistor. I’ve shown how to use it with BNC connectors. You can use it with connectors of your own desire. One thing that may not be too obvious is how the for Takeoff glideslope is coupled off. It turns out that a round, straight wire has a self-induc- Introducing the tance of about 24 nanohenries per inch, and it doesn’t vary too much across a relatively wide range of wire sizes. A series circuit made from a 1-inch piece of wire New .com and a 10-picofarad (pF) capacitor makes a series resonant circuit in the middle of the glideslope band and couples the glideslope signal off of the antenna. You may ask yourself how you can get a glideslope signal (at 330 MHz or so) from an antenna cut for the VOR/ LOC band down at around 110 MHz. I didn’t tell you the whole truth, so here it is: I said that a quarter-wave antenna is resonant, but it is also true that a three- quarter-wave antenna is also resonant, as is every odd multiple of a quarter- wave. Guess what? A quarter wave at 110 MHz is also resonant at three times that frequency or 330 MHz (and 550 MHz, and 770 MHz, and so on). You may also ask yourself about that comment on the schematic about using 70-ohm coax when I told you never to use 70-ohm coax. Again, I didn’t tell you the whole truth. For very special things KITPLANES® is rolling out a new website that is like this, we can bend the rule because it now quicker and easier to use. KITPLANES.com just works better this way. is YOUR guide to the most comprehensive Two caveats and we’ll wind up this month: One is that you can use this for homebuilt information available. combining two signals into a single antenna, but you cannot couple two KITPLANES.com Features: transmitters this way. And, that little 100Ω resistor is a tiny little thing with • Responsive website—looks great • Access to Back Issues as short leads; I generally use a quarter-watt on mobile devices, too! an easy-to-use, tablet-friendly, carbon film resistor with good results. downloadable PDF • Easy navigation with better search Next month might be my Oshkosh • Curated sections • Free Classified Ads Section for special column for all the new stuff I deals on aircraft and accessories saw this year, or if that doesn’t get done • Daily updates • Builders’ Marketplace in time (my deadline is the week I get • Revamped Aircraft Buyer’s home from Oshkosh), I may go into some Guide for quicker and better • More video! really neat ways of using your newfound search results • Weekly email news updates knowledge about transmission lines, quarter-wave, and all that stuff. In any case, until then…Stay tuned… J Check it Out Today! KITPLANES November 2019 77 REAR COCKPIT The Big Scare We pretty much all know the drill. You’re starting yet another condition inspection and the hangar is a mess. The wheel pants are stuffed under the table in the corner, and because there’s no room to lay it flat, the cowling squats on edge on the floor, looking like it might topple over the next time the breeze decides to give a big puff around the open hangar door. What looks like a Craftsman starter kit of wrenches and ratchets lies like tin- sel on the wings, which themselves are protected by the old beach towels you and that gal you married used to lay on up at the lake. Inspection hole covers and old tuna cans full of screws fill Here’s a leak-down tester reading no one wants to see, but don’t panic. Often such readings in between the tools while all that junk are temporary due to lightly stuck rings or crud on a valve seat. Run the engine and try again before breaking out the offset cylinder wrenches. that lives in the cockpit, the old charts, clipboard, checklists, flashlights, and to a determined placement of the feet For an instant your thoughts and a soli- the never used in 30 years barf bags are and a wrestling hold on the prop. tary word go blue. piled on the table the wheel pants are “Ready?” “Back it up a bit and see what you get.” hiding under. An unopened case of oil “Ready.” Your buddy pulls back on the prop with sits a little too cleanly, un-smudged and And with that, your right hand moves the sort of seriousness you hadn’t seen suspiciously prominent on the floor in to the little lever that lets air into the tes- since your days on the explosive ord- front of the engine. ter. It’s a sticky little thing that doesn’t nance detail. The needles drop on the And there you stand facing the valve endear you to the tool, but you do your tester, then zoom upwards as the prop covers, the leak-down tester cradled in best to slowly rotate the handle 90 moves forward. As the prop stops where your left hand while your right thumb sits degrees. Halfway there, the instrument’s your buddy senses top center, the nee- over the adapter in the cylinder’s spark needles jump as air madly hisses then dles find a slightly different resting spot. plug hole. Your buddy flips the prop two sighs into the cylinder; in the distant You tweak the tester’s adjustment knob times, and the piston starts pushing air background you hear the muffled yet and get a little rise out of the low reading, out of the adapter, lifting your thumb still vaguely metallic thunk of the piston but nothing like you’d like to see. Oh no. and with more assertiveness than seems tilting against the far wall of its cylinder You try again with no luck. So you polite, just like it always does. You’ve prison. Your buddy remains steadfastly try again, and the needles play with a done this how many times, and still the wrapped around the prop, waiting. slightly higher reading but then slide whooshing force behind the air off a ris- You look down at the instruments, and back a notch. Forty-nine over 80 is the ing piston is enough to get your notice. instantly energy drains down your body best you can get. Disgustedly, you dis- The whooshing slows, and your as if bomb bay doors on the soles of connect the air hose. buddy backs off his prop turning until your feet had opened and the concrete By now, half of you is ready to accept he creeps up on the impulse coupling. floor were a sponge. The first needle is defeat. Thoughts of offset wrenches and Clack! You’re pretty close to top center, pointing nearly at 80, just as you knew it cylinder base nuts cross your mind. All and your helper shifts his casual stance would, but the other is barely in the 40s. that baffling that needs to be removed…

Pumping avgas and waxing flight school airplanes got Tom into general aviation in 1973, but the lure of racing cars and motorcycles sent him down a motor journalism career heavy on Tom Wilson engines and racing. Today he still writes for peanuts and flies for fun.

78 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes at least it’s an end cylinder so the piston these steam-punk-sized cylinders and testing regimes that essentially sum up pin can slide out with little interference. pistons close to normal running clear- to “Run it and test it again until you get a Ugh, pulling a jug. ances, but because the air-cooled cylin- reading you like.” If you really have a prob- But the other half of you knows bet- ders expand and contract so much with lem, you’ll eventually get all the signs such ter. At least it thinks it knows better. The heat, their at-rest or cold clearances are, as rapacious oil consumption, wet spark engine runs too well, the spark plugs on um, generous. plugs, high EGTs, and so on. If you don’t that cylinder look normal, that expensive It’s also a big reason why airplane oil have a problem, then retesting will typi- engine monitor you stare at on cross- turns so foul and dark in 50 hours com- cally show a dramatic improvement. countries hasn’t shown any changes, oil pared to the stuff draining out of your The 49/80 cylinder noted above tested consumption has been stable. But 49/80? car’s sump after 10,000 miles, but that’s as 75/80 after a 7-minute ground running Well, the engine was stone cold during another story. session. Like tucking in your shirt and the test, and you know you’re supposed So, when we come along and try to combing your hair after a long flight, that to test them warm. But can that really pump the cylinder full of air, the cylinder engine just needed to re-adjust its piston make such a difference? Oh yeah, it can. can be far from normal running condi- rings. No doubt they had been lightly The major characteristic affecting tions. There’s no better illustration of this glued to the piston groove by cold oil. leak-down testing of our traditional than when we “rock the piston” by mov- In short, while leak-down testing can aircraft engines is their big-as-Texas ing the propeller around top center. The certainly pinpoint problems, it’s also a piston-to-cylinder wall clearance. “You piston is so loose in the cylinder, it literally tool that requires considered thought could pitch a dead cat through that” is flops around the piston pin. This changes when interpreting the readings. Like the how one of my more colorful (Texan) the piston ring to cylinder wall mating good advice to watch trends and not just associates put it, and he wasn’t far off. and often results in a big improvement in one sample in oil analysis, it sometimes Because they’re air-cooled and over five leak-down readings. takes a couple of goes with that sticky- inches in diameter, the typical 360–540 Because of this, it turns out leak-down valved tester to get the full picture of Lycoming and big-bore Continental testing of aircraft cylinders is rather more what’s going on in those big cylinders. cylinders require very large piston-to- ambiguous than we might think. Both But that doesn’t mean they can’t scare cylinder clearances. When warmed up, Continental and Lycoming offer various the stuffing out of you occasionally.J

Photo: Tom Wilson KITPLANES November 2019 79 KIT STUFF BY ROBRUCHA

80 KITPLANES November 2019 www.kitplanes.com & www.facebook.com/kitplanes Avemco Insurance Company is a member of the Tokio Marine HCC group of companies. ADS0165 (01/18)