Stalls??

On Feb 16, 4:26 pm, WingFlaps wrote:

I think a still warning device is very useful for a pilot who is
preoccupied with other tasks. A question, will a typical air pressure
stall warning always sound off at the same AOA regardless of speed
you are flying at? (I know really fast planes use a vane device to
measure it directly).

The stall warning device on a lightplane is an indirect AOA
detection device. AOA is directly related to the stagnation point, and
as AOA increases the stagnation point moves farther back under the
leading edge. When it gets just under the vane, or just under the
suction slot, the warning will sound. Airspeed doesn't figure into it.
Try slow flight someday (at altitude) when the air is rough from
thermal activity, and listen to it beep intemittently due to updrafts
even though the airspeed is constant.

Dan

On Feb 18, 8:17*am, wrote:
On Feb 16, 4:26 pm, WingFlaps wrote:

I think a still warning device is very useful for a pilot who is
preoccupied with other tasks. A question, will a typical air pressure
stall warning *always sound off at the same AOA regardless of speed
you are flying at? (I know really fast planes use a vane device to
measure it directly).

* * * *The stall warning device on a lightplane is an indirect AOA
detection device. AOA is directly related to the stagnation point, and
as AOA increases the stagnation point moves farther back under the
leading edge. When it gets just under the vane, or just under the
suction slot, the warning will sound. Airspeed doesn't figure into it.
Try slow flight someday (at altitude) when the air is rough from
thermal activity, and listen to it beep intemittently due to updrafts
even though the airspeed is constant.


Thanks,

I know how it works, but I was unsure if the stagnation point is
always in the same position at all airspeeds for a given AOA. You seem
to be saying it is -right? Your thermal test doesn't answer the
question because the AOA is not constant.

Cheers