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Radi C Ntr Lleddigest July 2007 Vol SoaringRadi C ntr lledDigest July 2007 Vol. 24, No. 7 July 2007 Vol. 24, No. 7 Front cover: Loren Steel prepares to launch his "new" Super AVA on its first flight.This one was assembled by Rick Diaz of Austin Texas who Loren says did a superb job. It floats, and penetration will be improved once the ballast is in place. Photo by Bill Kuhlman. Konica-Minolta 7D, ISO 100, 1/400 sec., f8, 500 mm CONTENTS WeaselFest Israel 38 Event coverage by Rene Wallage with photos by Ariel Erenfrid Sneek Peek 43 Preliminary renditions of Daryl Perkins' Schizo. From a web page by Sergi Valls Batalla. 3 RC Soaring Digest Editorial Converting a Car Starter Motor 4 q! A physical, intuitive description for Reversible Operation 44 of dynamic soaring A conversion aimed at "roboteers," but applicable The first of three installments. By Philip Randolph to Simon Nelson's retriever system described in the May 2007 issue. Web-based instructions by Paul Hills E-Flite Ascent ARF 21 FAI F6D The Ascent spans 54 inches and is designed to be a 51 Rules for the RC-HLG event to be held in conjunction small field electric-assist sailplane. with the World Air Games in 2009, Turin Italy. A review by Jerry Slates 27 Wei Wu Wei Adding a Launch Blade to an Alula 53 Converting a SAL glider to a DLG. A brief history of WeaselFest The story of WeaselFest, an organic, self-organizing By Bill Kuhlman and Jerry Slates "happening" spurred on by interested parties and facilitated by modern technology. By Steve Lange Back cover: The RC Soaring Digest back issue archives <http://www.rcsoaringdigest.com/pdfs/> in graphical form. Accurate as of 20 June 2007. 2 R/C Soaring Digest R/C Soaring Digest Managing Editors, Publishers B2 Kuhlman In the Air Contributors Sergi Valls Batalla Chris Boultinghouse Jay Decker imon Nelson described his unique retriever system in the Dave Garwood May issue, and it seems to have generated quite a bit Paul Hills S Steve Lange of interest. While Simon was able to find a reversible motor Tom Nagel in the form of a winch for off-road vehicle use, this may not Mark Nankivil Simon Nelson be an option for some who wish to tackle this project. With Philip Randolph this in mind, we decided to follow up on Simon's suggestion Jerry Slates Rene Wallage and publish Paul Hills' web-based instructions for modifying a standard starter motor for reversible operation. We've Photographers Dave Garwood Ariel Erenfid included Paul's description of a basic speed control for the Gregory Luck modified motor in the hopes that some enterprising person Mark Nankivil will be able to utilize the information within some other Kevin Newton Michael Shellim concept. We do not have an electrical diagram for Simon's set-up, but it is essentially two separate circuits which are Contact [email protected] Web: http://www.rcsoaringdigest.com similar to that used on our winch systems. We would be Yahoo! group: RCSoaringDigest grateful if someone could draw up an applicable circuit AIM screen name: RCSDigest Microsoft Messenger: rcsdigest diagram. ———————————————————— Daryl Perkins, several time F3B World Champion, has been building his own web site, http://www.darylperkins.com, as R/C Soaring Digest (RCSD) is a reader-written monthly publication for the R/C sailplane enthusiast and has been published since January well as a new sailplane, Psycho. The web site is still under 1984. It is dedicated to sharing technical and educational information. construction and currently consists of the home page only. All material contributed must be exclusive and original and not infringe We're not sure of the current state of the development of upon the copyrights of others. It is the policy of RCSD to provide accurate information. Please let us know of any error that significantly affects the the Psycho, but we did find some digital renditions on Sergi meaning of a story. Because we encourage new ideas, the content of each Valls' web site. See page 43 of this issue. article is the opinion of the author and may not necessarily reflect those of RCSD. We encourage anyone who wishes to obtain additional information Yes, we're still working on our Redwing XC! The forward to contact the author. fuselage is finished, and we're now working on the vertical Copyright © 2007 R/C Soaring Digest fin and rudder. Hopefully we'll have it flying by the August Published by B2Streamlines <http://www.b2streamlines.com> issue deadline. All rights reserved Time to build another sailplane! July 2007 3 A Physical, Intuitive Description of Dynamic Soaring qBy Philip! Randolph, [email protected] Graphics by Alex Hart and Philip Randolph 4 R/C Soaring Digest How the opposing velocities of a a model glider gains double the speed couple of air currents can add so of the oncoming wind in each half-orbit! illustrates some basic physics. A glider’s much velocity to a model or full- less velocity losses to drag and trig turning-rebound from oncoming air is effects. scale glider or bird. a highly elastic collision, similar to the Part Four is “DS forces!” elastic collision of a ball with a paddle. A physical understanding of dynamic Part Five, “Trig effects,” is a wheelbarrow model glider gets batted back and forth, A soaring will allow model and of extras, including effects of the angle faster and faster, between opposing full-scale glider pilots to better take of entry to the oncoming wind, q, the airflows exactly! like a ping-pong ball advantage of a greater variety of DSable italicized, lower case Greek letter theta. gets batted faster and faster between airscapes, and should help observers of opponents’ paddles. bird flight to know what to look for. I picked q because it looks like a DS cycle. The Ancient Greeks put in a Installment 3 Where to horizontal bar so I could use it to Part Seven, “More ways to DS more A “Not-very-many-grownups-left- represent the shear layer between airscapes,” shows a few more ways to behind” article in eight parts, airflows.1 However, with severe lack of DS different terrains and wind patterns, three installments. foresight, they did tip q as if the wind including dust devils and shears around Installment 1 were coming from the right, contrary to vertical formations. The most easily Part One, “Introductory basics,” includes aerodynamic diagramming convention.2 flown, even by less-than-expert model flyers (such as your author) and by full- web links to great videos of DS; history Part Six, “DS and ping-pong elastic scale gliders, is a horizontal pattern in the of DS theory (starting with Lord Rayleigh collisions,” is a simple physics mini “convergence zone” where warm air in 1883!); how birds and fish do it; comparison of DS with ping-pong. It’s flows up both sides of a ridge to collide and the airflows in which DS works. A partly to give aerodynamic neophytes and turn upwards. fundamental is “rotors” in “shear driven one more way to “get it.” But it also cavities.” Part Eight, “Dynamic soaring dynamic 1 From the Non-Organization for Part Two is “DS History, from pteranodon seascapes,” raises the question of Adoption of the Italicized Lower-Case Greek petrels and northern fulmars DSing to Lord Rayleigh, 1883, current theorists, Letter Theta as the International Interspecies models, full-scale gliders, and flying fish.” waves, rather than just the horizontal, Symbol for Dynamic Soaring, better known shear-layer velocity gradient of wind Installment 2 by its acronym, NOAILCGLTIISDS. above water. It’s partly from a model Part Three, “Wild speed gains, DS 2 Republicans also claim wind comes glider competitor’s observations, and Arithmetic,” reviews in more detail how from the left. Therefore the Ancient Greeks partly conjecture. were Democrats. Nobody but intrepid slope explorer Chris Erikson would try to DS this rock pile. The bar in the theta represents the shear layer between opposing airflows. Photo by Allisson Woods. Graphics by Alex Hart. July 2007 5 feeding “how it works” to hopefully Several DS videos, including a clip of A lack of physical “most ’satiable curiosities.”3 Physical the above record, are downloadable at understandings understandings should also help readers slopeaddiction.com find, and more effectively use, a widened Too often, aerodynamic concepts aren’t A clip from the PBS “Nature” show variety of DS conditions on actual slopes. also stated in readily understandable, ‘Raptor Force’ is at http://homepage. physical terms. Even when the target mac.com/pnaton/iMovieTheater28.html audience is laypersons, where one would It shows Paulson DSing at 229 mph. The expect a good, physical explanation, one q! Part 1 record is now 302 mph. However, don’t often gets mysteries. be intimidated. These are just speed Introductory basics records by experts. DS isn’t the same as For example, in an otherwise excellent speed. presentation, recently aired on PBS, For jacklegs, abecedarians, and the of raptors and model gliders dynamic newly bitten on the nose by the crocodile Basics soaring, the explanations were obscure. of slope addiction. Dynamic soaring is a means of getting Maybe it’s because concepts a director velocity or altitude energy from shearing doesn’t understand end up on the cutting We’ll start with some links, so readers unfamiliar with DS can observe videos. airflows. Intermediate pilots can find DS room floor, or because aerodynamic conditions at lower speeds. Your author thinking is predominantly in the language We’ll follow that with a bit of history, and a note on where DS works.
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