Landing Critique

"Peter Clark" wrote in message
...
On Fri, 9 Sep 2005 23:51:54 -0400, "Icebound"
wrote:


wrote in message
groups.com...


stall warning horn does not "get louder" it either sounds or
it doesn't.

Did you mean that generically for all aircraft? ... or in this particular
case only?

Perhaps it's to do with the way the horn is activated. I seem to
remember the 172's horn getting louder the closer to stall you got
(pneumatically activated), but don't recall that phenomenon with the
182's horn (electric switch)?

Well, the 172's horn seems to be basically the same principle as blowing
across the mouth of an open beer bottle. If you blow lightly, it makes a
gentle hum and if you blow hard, it gets loud.

I don't know how other stall horns were designed, but it was my impression
that a stall horn is supposed to be designed to go off a little before the
true stall.

For the 172, this means that at a certain AOA, there is *some* air going by
across the opening, producing *some* sound, while you still fly not fully
stalled. It is not until a full stall that the maximum amount of air is
flowing across the opening, producing the loudest sound. Now the 172 has a
pretty thick leading edge, which may contribute to the way this seems to
work.


Since that is all that I am familiar with....

....does that mean that for most other aircraft, I would have to be aware
that the stall horn will go off suddenly and completely?

"Icebound" wrote

Well, the 172's horn seems to be basically the same principle as
blowing across the mouth of an open beer bottle.

Not all C-172s...some have the electric vane. The one that I fly does.

I don't know how other stall horns were designed, but it was my
impression that a stall horn is supposed to be designed to go off a
little before the true stall.

(c) During the stall tests required by §23.201(b) and §23.203(a)(1), the
stall warning must begin at a speed exceeding the stalling speed by a
margin of not less than 5 knots and must continue until the stall occurs.


...does that mean that for most other aircraft, I would have to be
aware that the stall horn will go off suddenly and completely?

Yes, but at least 5 knots above the actual stall per Part 23.

Bob Moore
ATP CFI