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NAR Competition Question Thread
#21
Hi Bill,

It's pretty rare in competition for people to deliberately put in spin, because all the energy consumed in spinning up the model is derived from the motor, and directly reduces performance. The best ways to limit weathercocking are to control the stability margin, and to get higher velocity at end of launch guidance (piston + longish tower is good for superroc) which reduces the apparent angle of attack when launching with a crosswind. Towers add drag but using a bare piston on superroc is a bit dodgy IMO.

As far as fins for very small models, I usually go with airfoiled 1/16 balsa, or 1/32 plywood. In last year's NARAM cycle I built a set of models with thin FG fins and a set with 1/32 ply and found that the FG was much more flexible (too flexible) and yet still quite a bit heavier (a gram or two in the fin set for small PD models, which is a lot). Balsa is even lighter than the ply but the difference is less than going to FG.
Dave Cook 
NAR 21953 L2    TRA 1108
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