> Jeremy Davey wrote: I'm at the stage of deciding whether to fit a simple
> stall warner or to go for a more sophisticated angle-of-attack indicator. Has
> anyone out there got an angle-of-attack indicators on their Europa and
> can offer some thoughts on their experiences. I'm looking for any positives
> and negatives I can get. Thanks and regards,Jeremy
Hi Jeremy,
I have been very interested to read all the input on stall warning, angle of
attack and stall behaviour. My experience and comments are as follows :-
* I have a mono XS and in an extravagant moment when I was specifying my panel,
I chose a very fancy PSS (Proprietary Software Systems), 4 colour LED
Professional AOA system. This unit is driven by static pressure pick ups in
the wing upper and lower surface, the normal pitot static signals and a
micro-processor. (see www.angle-of-attack.com/ ).
* I have not fitted stall strips as I had heard of a negative effect on take
off roll.
* I chose to power up and calibrate the AOA system only after completing my 40
hour FAA test programme. The unit is calibrated in the flaps up and flaps down
configuration and a microswitch on the flap linkage provides the appropriate
signal for status.
* Stalls at min and max weight, with passenger and baggage ballast, flaps up
and flaps down, during the test phase were not alarming at all but did have a
left wing drop quickly corrected with stick forward and top rudder.
Fortunately, my experience is much more benign than Tony Ks inverted in a
spin entry experience with ZK-NWM; 400 feet for recovery sounds ugly to me.
* I find that from habit, on the approach, I still refer to my air speed
indicator first, and AOA second. I think the US Navy protocol calls for AOA
first.
* I believe that the value of any AOA/stall warning device comes to the fore
when one is in an unusual situation, perhaps with distractions. Classic (pun
not intended) scenarios might be (i) engine power loss during take off or (ii)
at a fly-in at an unfamiliar field with busy traffic, slow planes, planes not
listening to ATC, cross wind affecting base leg timing, etc, etc. Any and all
of these can contribute to turning too low, too slow, too tight, you name it -
next thing is that you may be in trouble. It can happen, I have been there and
I have the tee shirt.
* My AOA alarm has a very nice ladys voice recording which comes into my
headset at 1.15 x Vs1 or 1.15 x Vs0 and says Angle, Angle, Push. Normally,
the only time I hear this alarm is during the take-off roll just before lift
off and just as I flare for touch down. I try and keep it that way.
* Curiously, my planes stall behaviour seems to have improved since the test
phase. During a recent biannual FAA check ride, my examiner asked for a demo of
clean and dirty stalls. Both were straight ahead with a small degree of
buffet. My only explanation was that I may have had more bug splats on the
leading edge compared to the test phase. On reflection, this should encourage
me to think about experimenting with some small stall strips.
My final comments are :
* Any AOA/stall warning device is probably a bacon saver and a good
investment.
* If you are buying a PSS system, the less expensive Sport version is probably
very good value for money. It has a smaller display and may be more easily
placed at the top of the panel near the line-of-sight.
* Although the PSS manual did not specify this, the calibration should be done
at max gross weight. I found that if I calibrated the unit at low weight, it
gave a premature warning when I was at a higher gross.
Cheers, John
N262WF, mono XS, 912S
Mooresville, North Carolina
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