Hi all,
The gap seal thread reminds me the incident I had about ten years ago with
my former plane, a Robin DR380. This airplane had very simple flaps hinged
at the bottom. In order to reduce drag, I had sealed the flap gap using ad
hesive tape. Although the speed increase was not mesurable, I was happy wit
h that mod until a few years later, I noticed the tape becoming unsticked i
n some places under the right wing. As a temporary fix until I was back hom
e, I decided to remove the whole tape on that side. The next landing was in
teresting: when I lower the flaps, the airplane quickly rolled to the right
and I had to apply half aileron to the left to compensate.
Conclusion: sealing the gap of that rudimentary flap design does not signi
ficantly reduce drag at cruise but clearly increase lift with the flaps dow
n.
On the Europa fowler flaps, a seal certainly reduce drag at cruise, as note
d by Jeff on Baby Blue, but the effect on lift and drag with flaps down is
uncertain and will be very dependant on the design of the seal. In any case
, be prepared for a strong rolling and possibly yawing effect, should the s
ealing tape fail during flight.
Instead of using tape, why not design an aluminium seal similar to those wh
ich are STC=99ed on Cessnas and Cherokees ?
Regards
Remi Guerner
F-PGKL, XS S/N395 monowheel, 912S, Airmaster, 467 hours
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