Advanced Construction Techniques for Competition by Bob Kaplow, [email protected] Presented at NARCON 2006

How to reduce weight and increase strength of competition models by proper materials selection and using carbon fiber, , and tissue. Using a razor plane and T sander to airfoil wings. Warping helicopter rotors. Balsa cone egglofters. Hinges and torque rods.

Build light. Build Light. BUILD LIGHT. Add strength where necessary. Reduce drag. If your model survives the next power class, it's too heavy! Controlling weight - Paul McReady Gossamer Condor strengthen what breaks, lighten what doesn't. Take notes & record weights while building, learn to predict finished weight Balsa selection - grain and density - SIG article postal scale, triple beam balance buy good wood whenever you find it! Sig and others will custom select wood for a premium price Use of a razor plane best is David Combi from Sig taper wings and fuselage, airfoil T sanders final shaping T sander and jig to bevel dihedral breaks for perfect fit industrial sandpaper from sandingcatalog.com Glue FAQ - Titebond and Amberoid ideal for wood double glue joints - pin prick surfaces first Amberoid can be disolved and repositioned - good for test allignment NO CA or from a home store, hardware store, or drug store hobby shop ok, best from /boat building - NOT 50:50 for composites use thin laminating resins - syrup consistency if necessary thi with laquer thinner Wear Nitril gloves when working with epoxy Carbon fibre and kevlar tow - reinforce balsa Carbon spars - reinforce dihedral joints and fuselage stress points Kevlar thread - reinforce leading edges Dope and tissue - reinforce balsa - use Nitrate from SIG, Jap tisue from Sig or Peck BG design - Neutral point NEVER cut boom - creates weak point & breaks Reverse piece X, cut from pod, attach hook to fuselage Make goiders and pods interchangable Warping parts - HD rotors HD - rotacrock - milled nose cone for hinges Hinges and torque rods Balsa egglofter cones - A grain gores rolled into cone

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Balsa density chart and other personal goodies http://eisner.encompasserve.org/~kaplow_r/balsa.txt http://eisner.encompasserve.org/~kaplow_r/glider.faq http://eisner.encompasserve.org/~kaplow_r/astron_workshop.faq http://eisner.encompasserve.org/~kaplow_r/body_tube_diameter_ratios.txt http://eisner.encompasserve.org/~kaplow_r/bobs_rocket_faq.faq http://www.NIRA-Rocketry.org/LeadingEdge/MarApr03.pdf (Rotacrock 20) http://members.shaw.ca/whortens/ Palm software including NP

Reference list - handy URLs http://www.7cornershdwe.com/ tools http://www.acp-composites.com/ epoxy, carbon fibre, kevlar 4 homebuilt http://www.aircraft-spruce.com/ epoxy, carbon fibre, kevlar 4 homebuilt aircraft http://www.berlandtools.com/ Chicago area tool store http://www.depronusa.com/ black foam http://www.foredom.com/index.html professional rotary tool http://www.go-cl.se/balsa.html article that should be on SIGs web site! http://www.gothicarchgreenhouses.com/aluminet_thermal_screen.htm http://www.green-tek.com/alum.html aluminet mfgr http://www.jensentools.com/ tools http://www.mentornet.org/balsa3.htm another copy of SIG balsa article http://www.micromark.com/ ) has lots of small tools, but http://www.modelresearchlabs.com/ carbon fibre and more http://www.peck-polymers.com/ black jap tissue http://www.raka.com/ good laminating epoxy http://www.sandingcatalog.com/ industrial sandpaper http://www.scalesnow.com/handscales.htm (the one I have is the 4th one down) http://www.sciplus.com/ neat surplus http://www.sigmfg.com/ balsa, tissue, razor plane, and more http://www.skykingrcproducts.com/accessories/david/david_razor_plane.html http://www.systemthree.com/ epoxy sample kit http://www.techni-tool.com/ tools http://www.thetoolman.com/ tools http://www.westsystem.com/ another good epoxy

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