This topic has come up on the Socata TB scene many times…
Reports indicate a big improvement in low speed handling on the TB9 and TB10 but negligible on the TB20 and TB21. I don’t understand that… but really very few have tried it and this is only from the Socata owners’ group where only very few are actively posting these days.
Are these seals routinely used on other types?
The Cirrus has plastic stripes that cover the aileron gaps. They do improve cruise performance and low speed handling.
Peter wrote:
Are these seals routinely used on other types?
Yep, lot’s of planes either incorporate them in their design, like Mooney and some Cessna models or have STC’d kits avail like Pipers and Cessna 172s and 182s .
There effectiveness all depends on the wing design and the gap that they’re filling.
Flyer59 wrote:
They do improve cruise performance and low speed handling.
Cruise speed I can understand, but low speed handling? in what way?
LeSving wrote:
Cruise speed I can understand, but low speed handling? in what way?
I am not an aerodynamics engineer, but I believe the aileron & flap seals enhance the effectiveness of the ailerons & flaps by blocking “leakage” over the ailerons & flaps, hence better low speed control .
Yes, that is the common opinion at COPA too, the seal makes the ailerons more effective in slow flight.
Peter,
Experience with my Maule, possibly not applicable to a normal aeroplane:
MX-7 has a large elevator gap, and factory option/STC for gap seal and vortex generators.
Before fitting either, full-flap power-off stall could be progressed to the point of a graceful departure from controlled flight (pitch down). After fitting VGs, there was no longer sufficient elevator authority to achieve such uncontrolled pitch down, even with the trim tab at neutral. After sealing the elevator gap the original behaviour was restored, albeit at lower speed/greater AoA. One thing leads to another, so to take advantage of the new AoA stalled in ground effect, we now need extended main gear legs and 29" tires…
Conclusion: if you perceive a lack of elevator authority when using stall warning horn as a lift reserve indicator, gap seals may help, perhaps as much as an extra few hundred prop rpm, but if you don’t often fly below the bottom of the white arc, there’s probably not much point.
YMMV, Peter.
Michael wrote:
I am not an aerodynamics engineer, but I believe the aileron & flap seals enhance the effectiveness of the ailerons & flaps by blocking “leakage” over the ailerons & flaps, hence better low speed control .
That’s still rather counter intuitive. With “leak” they will act as slotted flaps, which works better than “plain” flaps at low speed. Same with ailerons.
Flap gap seals seem to be very effective in the Cessna 182, giving a bit more cruise speed and reducing the stall speed.
However, they also significantly decrease flap effectiveness. This is the reason I never considered installing them as flap effectiveness is one of the nicest things about the C182, allowing it to land pretty much everywhere. I would not want to sacrifice that.
Peter
The seals are STCed to all Comanches. Owners report better performance mainly at slow speed. I have never fitted them so have no first hand experience.
http://www.knots2u.net/flap-aileron-gap-seal-kit-piper-comanche-pa-24-models-24gs/
