Wing Extensions

In article
, BRUCE
FRANK wrote:

Since there seems to be a thought that we all need an AOA indicator, I have
missed something. Are there planes that give no indication of an impending
stall? Isn't a large part of flight training concentrated on recognizing
that impending stall? The people with whom I have flown who regularly fly
the ragged edge of the bottom end of the airspeed ignore the stall warning
horn and just fly the plane. That isn't flying by the seat of one's pants,
its understanding the what the normally present indicators are telling you.
I will have to agree that no one survives all those years crop dusting by
looking at some kind of gauge. It is flying skill and knowledge. On a much
smaller scale it's like getting to the point as a student when you realize
you are flying approach and discovering you're not having to watch the
airspeed indicator gauge...and you're squeaking it on.

Bruce A. Frank


Type certificated aircraft are required to have some sort of stall
warning that occurs far enough before the stall so the pilot can
respond to the stall warning and avoid the stall (the regs don't use
exactly these words, but that is the intent). Ideally, the stall
warning would be aerodynamic buffet, but some aircraft either don't
have enough buffet, or it occurs too close to the stall, so system is
added to provide stall warning.

The original version of FAR 23 allowed the stall warning to be some
visual device in the cockpit, but FAR 23 amendment 7 in 1969 added
words "However, a visual stall warning device that requires the
attention of the crew within the cockpit is not acceptable by itself. "

I can't find an online copy of CAR 3, which predated FAR 23, and is the
design standard that many popular light aircraft were held to. I
assume it was similar to the first edition of FAR 23.

So, for type certificated aircraft, it is a mixed bag - a visual stall
warning device would be acceptable from a regulatory point of view on
some models, but not others, depending on when it was designed. From a
safety point of view, it is crazy to have a stall warning that is only
effective if you are looking at it. If you have enough situational
awareness to be actively watching the stall warning indicator, you are
probably not in danger of stalling. The dangerous stalls are the ones
that bite you when your head is buried up your a** as you are not
paying attention to the airspeed, or how hard you are pulling at low
speed.

If I was crop dusting, I would sure want an aircraft that "talked" to
you aerodynamically as you approached the stall. Two of the funnest
aircraft I've ever flown had nice progressively increasing buffet as
you approached the stall. You could manoeuvre hard just by feel and
really work the wing.

Homebuilts don't have to meet any stall warning requirements. For
example, the RVs that I have flown have very little aerodynamic stall
warning. Yes, there is a small amount of buffet a couple of mph before
the stall, and it can be noticed if you are looking for it. But if you
were distracted you could easily miss it and inadvertently stall the
aircraft, if you abused it bad enough.

--
Kevin Horton - RV-8
Ottawa, Canada
http://go.phpwebhosting.com/~khorton/rv8/