Filling in the gaps on control surfaces

I was told recently that I should be putting covering material across any gaps in the hinge areas of my aircraft control surfaces. That seemed very superficial to me, so I put off making these changes for several weeks. However, after flying the Extra 260 today with these modifications I am a believer… at least for this type of plane and flying.

It seems that by putting covering material over all gaps between the wing and ailerons at the hinge line, and eliminating all air gaps from this area, the control inputs and flight characteristics of the Extra are much crisper and happen more quickly than before. I performed the same modifications on the elevators and horizontal stabilizers as well, and again the control inputs seem to be much more noticeable than they were previously. Only the rudder and vertical stabilizer went untouched.

The covering job for this area certainly wasn’t of the highest quality, but the end result speaks for itself. Where the Extra 260 once was docile and slow on low control rates with a gap between the surfaces, now control inputs are fast, crisp and very predictable. I wouldn’t have said that a 1/8th or 1/16th gap between surfaces would mean that much to overall flight performance but I saw and felt today that on aerobatic aircraft, every gap does indeed matter.