rounding fuse corners?

[Bob Chiang]

Hi all,

I'm building a speed 400 powered pylon racer. The fuselage is built of sheet balsa with longeron/doublers in the corners.

Does rounding the corners of a fuselage help significantly? Is the benefit from reduced skin friction? turbulence at a square edge? reduced weight? ???

-Bob Chiang
Ithaca, NY USA
(Home of the Ithaca parade that includes a Volvo Ballet, and he-man chainsaw band http://www.ithacafestival.org/about/parade.htm )

[Ollie]

The benefits are small but they are cumulative. The reduced drag of the fuselage is very small. Reduced weight results in a lower coefficient of lift. Induced drag is proportional to the square of the lift coefficient and the benefit is bigger. Reduced weight allows tighter turns which is another lap time saver.

Don't discount appearance benefits. Planes that look good tend to be flown with greater care.

[Terry S]

The rounded corners help most when the fuse is not pointing directly into the airstream.

Terry
UK