April 8th 18, 05:44 AM
Dick Johnson experimented extensively with sealing the gap between the flaperon and fuselage on one of the very early '3s after he found the polar curve to be erratic in the 70-80kt region. Fitting some rough seals apparently removed a 'notch' in the curve at about 75kts and smoothed the polar straight away - with improved performance.
I flew my LS3 without them once and was surprised how noisy it was. Anything above 80kts and the wing-fuse junction got louder and louder until it was really screaming above 100kts. Swift changes in angle of attack presumably sent the airflow shooting up through the gap, where it mixed with the turbulent flow off the wing top surface and hit the tail causing the pilot to feel a buffet through the stick. Fitting mylar seals as people have mentioned fixed everything.
When they get old they sometimes don't seal as well and can buzz at high speed. What annoys me more though is the increased stick loads when driving the flaperon which has four mylar seals constantly rubbing against the fuse. I flew a different LS3 once which had a fairing built up on the fuesalage to make the gap maybe 2-3mm, and then felt to fill the gap. I think that is the best solution (best of both worlds) but its a lot of work.
I flew my LS3 without them once and was surprised how noisy it was. Anything above 80kts and the wing-fuse junction got louder and louder until it was really screaming above 100kts. Swift changes in angle of attack presumably sent the airflow shooting up through the gap, where it mixed with the turbulent flow off the wing top surface and hit the tail causing the pilot to feel a buffet through the stick. Fitting mylar seals as people have mentioned fixed everything.
When they get old they sometimes don't seal as well and can buzz at high speed. What annoys me more though is the increased stick loads when driving the flaperon which has four mylar seals constantly rubbing against the fuse. I flew a different LS3 once which had a fairing built up on the fuesalage to make the gap maybe 2-3mm, and then felt to fill the gap. I think that is the best solution (best of both worlds) but its a lot of work.