Posted for "Steve Richard" <steve@oasissolutions.com>:

I believe the 'bitching betty' (annunciator) indicates 'stall' about 5 knots
above Vs1(clean stall {flaps up?}, gross weight). The listed Vso and Vs
(Vs1 at 0g?) for my Lancair ES are 61 and 74 knots. That means that around
79 knots the annunciator starts talking (seems like it is usually higher!) .
That's a little high for me when I am on final with full flaps trying to
maintain 1.3xVso(79 knots). I have found no way to adjust it accept to
lower the Vs in the limits.txt file (i.e.. 'fool it') which I don't like to
do.

The person sitting next to me doesn't like to hear 'stall' while on final.

The AOA is easily calibrated to the 'speed' that you want it to start
talking to you. It works well (I have about 90 hours total) and has kept me
from doing something really embarrassing while testing the autopilot.

My Chelton configuration can't tell if I am landing (flaps down) or just
falling out of the sky during cruise. The AOA can.

Does anyone know if the Chelton can be wired for a flap up/down switch?

Steve
The attached .pdf's are excerpts from the Chelton manual. Hopefully these
files are not too big.

[Steve, you must remember that the AOA is telling you about stall angle of attack, and that angle remains the same (for a given flight regime, ie, clean vs dirty) regardless of the amount of fuel on board, number of passengers you're carrying, how much baggage is in its compartment, angle of bank, time of day, or whether you're hungry or sated.  If you're still trying to fly approach SPEEDs you're missing the whole point of the AOA.  If it's calibrated properly (I'm assuming, here, that you're talking about the (originally PSS) Advanced Flight Systems AOA) you should be flying the approach with the line piercing the donut in the middle of the display (AOA Pro) or with half the display lit up (2-greens, 2-yellows) with the AOA Sport.  That will give you 1.3 X Vs whether you're clean or dirty. If bitching betty is yelling at you it means that your AOA is too high and she's telling you "angle, angle, push" to get the nose down.  She couldn't care less what your airspeed is, because that's going to vary all over the place dependent on that list of things I mentioned earlier that have no effect whatever on the AOA.  If, when you're lightly loaded (flying alone, 1/4 fuel each wing, no baggage) your actual Vsf might only be that 61 knots you mentioned.  Betty is going start bitching at you around 1.15 x Vs, or about 70 knots.  You'll find youself flying the approach that day at 79 (1.3 X Vs) and  betty will remain silent until you flare and pass through 70 kts on the way to touchdown.  OTOH, load that baby up with 3 other people, fill the tanks and stick a piano in the back and take off.... then decide right after takeoff that you left the lights on in the car and re-enter the pattern to land.  Due to the vastly increased wing loading your Vsf has probably moved up to 75 or 80 knots.... try to fly the same pattern from yesterday when the airplane was just about empty (and the approach speed (1.3 x Vs) was 79) and bitching betty's going to be screaming at you while you're slowing down on downwind, forget base and final.  Oh yeah, when you took off heavily loaded, had you used the AOA it would have shown you your Vy because that's the same as L/D max... you'd have had advanced warning that things are happening at higher speeds today due to the increase in wing loading.  Anyway, lets say that the Vsf (loaded) is actually 75... that means that  B.B. is going to start screaming at you around 86-87 knots (1.15 X 75) and in order to fly the approach at 1.3 x Vsf with the AOA displaying properly, your approach speed is going to be 97.5 knots....  now I hope you see why flying V speeds in the approach is such an impossible task.  They vary all over the place, and unless you see where the actual stall is that day based upon your actual wing loading, you really have no idea what your stall speed is.   Unless, of course, you have an AOA..  Then you can work it out based on its indications, as it will always show you your stall angle of attack.  Period.  I hope this helps.    <Marv>             ]