The Alpha Systems procedure is here, page 39 (of the PDF) onwards.
The mechanical vanes only require geometric alignment relative to the chord line of the wing which can be done on the ground
You should get the AoA angle out of that, without calibration, but will you get the correct colour indications? Only if you know the type of aerofoil and know the data for it.
Had a quick look at that document. If you follow the procedure according chapter 5.7 you will calibrate your AoA indicator using the combined errors you made in you mass &balance calculation, interpolation of values from the airplane manual and misreading of your ASI due to various factors.
I think it would probably be OK if you always fly the plane in a similar configuration, e.g. a 2-seater flown mostly solo, or mostly 2-up.
But then you may as well just look at the ASI 
Reading between the lines, I suspect the device is good for low levels only. There doesn’t appear to be an altitude based procedure.
The critical angle of attack is independent of weight, why would ‘configuration’ apply? If you mean different loading configurations.
Flaps will reduce the critical angle of attack, slats increase it – so this change in configuration would need to be reflected, hence the PA-44, and 34, etc having a different stall vane depending if flaps are extended or not.
Higher TAS, once compressibility comes into play, will influence critical alpha, so altitude will be an influence indirectly – but assuming incompressible flows, critical angle should be independent of altitude?
Fedex have AoA on their Enhanced Vision Head Up Displays – have not managed to find an article that describes their latest EVS/HUD, but it is lurking somewhere on the web. Partly safety motivated, but also appears to be used for dispatch reliability allowing lower minima while operating to CAT 1.
Most aerobatic aircraft ‘speak’ to you, ideally through the ‘burble’ you feel as you approach an accelerated stall condition – AofA in aerobatics may be the province of fly by wire advanced fighters where this ‘feel’ can’t be replicated by either Q-feel or stick shakers?
Maybe I misunderstand how these devices are meant to be used, but while the critical AoA is independent of the wing loading, won’t the aircraft stall more easily at a higher wing loading?
For example, if one needs to make a tight base to final turn, and has height to play with, unloading the wings during the turn provides an increased stall margin during the turn.
Yes – by “configuration” I mean the loading envelope.
Peter correct with respect to speed, not critical alpha. The square root of Load Factor times Vs1g (clean stall at 1 g), gives you the new stall speed.
Hence in a stall turn you approach zero g, and can pivot over without spinning, as the square root of close to nothing, results in a Vs close to zero.
I maintain that my digital AOA display on my EFIS played a MAJOR part in me having a safe outcome from an EFATO at 500ft.
A completely black AOA (meaning no lift at all) and a nice lady shouting in my ear, “angle, angle, push!” certainly helped maintain my focus on flying the aeroplane.
A completely black AOA (meaning no lift at all) and a nice lady shouting in my ear, “angle, angle, push!” certainly helped maintain my focus on flying the aeroplane.
Which is basically the same, a usual stall warning does. (For the record: if you had zero lift, your AOA was probably too low, your wings off or your airspeed gone.)
Aspen’s fake AoA
http://www.avweb.com/videos/Video-Aspen-Angle-of-Attack-for-Evolution-EFIS-Demo-Flight-223831-1.html
What do you think? Can this actually provide useful information? How does it “detect” aircraft weight? To me it looks like complete BS.
It doesn’t need to detect weight, simply calculate the AoA which it has all the information for.
I’ll be installing as soon as it has EASA approvals.
