I’m looking at my plane and theoretical drag reduction due to protusions such as antennas and exhaust pipes. I always assumed that reducing protrusions on the fuselage (within the propeller arc) would provide greater benefit than on the wings (outside the prop arc) such as pitot tube, landing light lenses etc. because the airspeed in this area is faster than at the wings. But then I got to thinking there’s not much thrust produced within first 1/2 of the prop’s radius anyway and therefore possibly not much difference in drag reduction by reducing any protusions along most of the fuselage compared to most of the outer wing. There would be a more critical area of the wing (within the outer 1/3 of the prop radius) that would benefit the most for attention to protusion detail. But RVs typically don’t have any protusions in this area anyway. Thanks Van!
In other words, if one must mount a hard point for some external load, avoid putting it under the wing near the outer arc of the prop. Tight to the fuselage or under the outer part of the wing would be better and possibly no significant different between the two.
Recently I’ve been experimenting with an ash dispensing tube I built for scattering ashes. It’s 4” in diameter aluminum tube with flat front and back doors, draggy. The main attach point is the existing tiedown hardpoint so out of the propeller arc. I expected some yaw (only one tube is mounted under the right wing) but can’t seem to notice any yaw at all. Since there is so little, if any yaw (drag) from a 4” blunt tube under one wing mid span, there must be very little drag but why? And if so, why would I be concerned about a bit of drag from something protruding from the fuselage like a skinny antenna, exhaust pipe etc.?
I’m thinking these protusions produce less drag than first thought.
Bevan