Posted for Don Ryan <dryan@gt.rr.com>:

 Marv:
 Is there a danger that the left wing (without the AOA)  will stall and no
warning will be given? I have long admired that instrument and if I ever get
my kit done will install one.
 Don Ryan
 

[Reply.... Don, that question has been asked many times and the answer is no. I am no aerodynamicist, but as I understand it, the only condition under which one wing is stalled and the other unstalled is in a spin.  Since both wings have the same angle of incidence they are both going to approach the stall at the same rate.   Even when in a slip or skid and given the moderate dyhedral on the Lancairs, the difference in AOA from one wing to the other is less than a degree.  The typical stall AOA is around 15 degrees and the stall warning occurs at about 2/3 of that, or right around 10 degrees, so as you can see, even in uncoordinated flight you still have a 4 degree cushion of warning before the critical angle is reached.  There is no way that I can think of under normal flying conditions that you are going to experience a stall on one wing without stalling the other and not have a critical AOA warning blaring in your headset during that final approach to the stall.  Any maneuver that forces that condition would be outside the realm of normal smoothly controlled flight and would be entering the realm of aerobatics (ie, abrupt maneuvers). Typical spin entry is usually forced (or blundered into) just as the stall occurs by application of full rudder in the direction you want to spin, thereby unstalling the outboard wing... and as I said, by that time you have been given plenty of warning about the impending stall in the first place.

There is typically no reason to install ports on both wings, and they perform just the same regardless of which wing they are installed on.  You could even install the upper port on the left wing and the lower port on the right (or vice versa), and as long as you have positioned them at the same relative chord locations at identical butt line stations the isntrument will still function as intended.

I've heard of only one installation that uses ports on both wings... it is a dual sport setup in a Christen Eagle (if memory serves... could be a Pitts). One sport display is mounted conventionally and is driven by one of the pairs of ports during normal flight, the other is mounted upside down, is driven by the opposite set of ports and is independently calibrated for inverted flight. A single instrument calibrated for normal upright flight will not give accurate indications when inverted... the relative pressures are completely reversed.  I think it was Scott that mentioned something about using his AOA when inverted, and I just thought I'd include here that it doesn't work that way.

I hope this answers your question.  If you have any more feel free to ask. I'm always glad to help out whenever I can.

  <Marv>           ]