Dear Carl,
The fitting of stall strips was originally devised as a means of complying with
the requirement that it is necessary to provide a stall warning of at least
5kts.
The wing alone provided only 2 -3 3 kts. The stall strips were also found
useful in enabling the 'tuning out' any adverse behaviour at the stall, as
some Classic wing owners do find, however if fitted or adjusted incorrectly you
could also adversely affect the take off and landing performace. Correctly
fitted, they will not do so. The template provides a good starting position
for the stall strips which should not make much affect at all, except perhaps
increase pre stall buffet. Only subsequent flight tests will enable the fine
tuning for eliminating any wing drop at the stall.
You probably know all this anyway as it's all described in Chapter 9 of the
Owners
Handbook, but your question to the Forum indicated that you may have thought
that it may no longer be valid with the introduction of the audible stall
warner.
My philosophy now is to suggest the fitting of the audible stall warner
for stall warning and only fit stall strips to tune out bad behaviour at the
stall.
One thing to check before you go to far is to check the flap extension angles.
As the wing drop only occurs in the landing configuration, is perhaps one flap
extending slightly further than the other? A more extended flap will enable
the wing to stall at a slightly higher CL.
Also to confirm is that the aircfaft is in fact in balance at the stall rather
than the 'ball' being in the middle. I have seen Turn Coordinators set so they
are level with the panel but the panel itself is not quite level with the
aircraft.
I hope that this is of some help.
Best Regards
Andy Draper
Technical Director
e-mail andy@europa-aircraft.com
>>> "Carl & Dot" <carl_p@ntlworld.com> 10/12/03 23:35:03 >>>
Does anyone that is flying have any views regarding the fitment of stall
strips. We were initially advised that these were a bad idea and that an
electric stall warner was a better option. From what I remember, stall
strips are supposed to have an adverse effect on the landing characteristics
of the aircraft.
We just recently completed our annual test flight and were a little
concerned that the aircraft has a habit of stalling left-wing down. With
the flaps up this is fairly benign, but with the flaps down is fairly
dramatic. The wing drops are easily recovered using standard techniques but
it would be nicer if we could eliminate this problem somehow. I discussed
this with several people last year and they were of the opinion that the
wing drop could be caused by the aircraft being out of balance prior to the
stall, however we tried repeated stalls with everything in balance and there
is still a significant drop to the left.
Has anyone attempted to eliminate a dropped wing by playing around with the
positioning of the stall strips and if so how successful was this. For the
time being we are relying on an electric stall warner which is excellent and
we are very happy with it but it would still be nice if we could get the
wings to stall in a more symmetrical manner, not that we intend to make
habit of stalling the aircraft.
Also what effect do stall strips have on landing/ takeoff performance.
Carl Pattinson
G-LABS
PS: If you fitted stall strips, how close to the factory reccomendations did
you end up. The book says about 12ins outboard of the fuselage and slightly
below the centreline of the leading edge (as per the template).
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