The display unit of the Alpha sensor looks remarkably cheap and ugly.
Have you seen it for real? I guess the case is plastic.
What attracts me to this product is the sensor, which is easy to mount and uses no moving parts. I am not interested in cutting a hole in the leading edge of the wing, for example.
I will probably mount it next to the pitot tube i.e. where shown here
The pitot tube is in the middle of that inspection cover (on the other wing).
However I have just realised that making use of the FAA Minor Mod concession does require mounting in an inspection cover. So that appears to rule out the use of a heated AOA probe on a TB20 – unless one can experimentally verify that there is no magnetic interference, by running two wires along the wing, with a 7.5A load at the end… I would be amazed if that worked OK because that unused inspection cover is very close to the fluxgate (which is at the top of the wing).
Garmin AOA indicator
Here is another one
It’s not clear how much of a complete system you get there, because the G3X is mentioned as a compatible device.
But the one issue which this product raises is that it appears to use the IAS and altitude as inputs to the AOA indication, which the other products don’t do. It’s also apparent, from reading about it, that the AOA indication needs to take into account the flap setting. That obviously complicates the matter substantially and immediately makes it a Major mod (N-reg, and prob99 even more so EASA-reg) which means a Field Approval which is almost infeasible to do in Europe, due to non-cooperative FSDOs.
So I am a bit confused as to what the other products do that is actually useful. Maybe they work only in the landing config (sea level assumed) and seek to prevent a stall on the base to final turn.
I believe the Pitot tube may consist of both a dynamic pressure chamber, a static pressure chamber and an offset pressure chamber. The offset pressure is provided by a hole that projects forward into the air at a different angle to the traditional dynamic pressure hole (usually downwards). The ADC measures the ‘difference’ in pressure between the dynamic and offset holes, and is calibrated to read provide a AoA reading. The offset pressure is likely what the third pressure transducer port is for on the air data computer is for.
p.s. Garmin have just found a clever way to get the G3X ADC installed into certified airplanes. Now if we could just bluetooth the data :)
Do you think the ADC is like the old ADC200 i.e. it outputs RS232 data for TAS etc which can be fed into a traditional IFR GPS, to get the wind vector etc? That would be a bonus, because an ADC200 requires the pitot and static connections anyway and costs more than the entire Garmin AOA package.
My understanding is that protocol is CAN bus, not sure whether its CANaerospace compliant or proprietary. It might be interesting to plug the D-sub connector into a CAN bus reader and see if anything useful is output. If the data were available on BT for say an iPad, the pilot would need to enter a manual magnetic heading (as no magnetometer) for a static wind vector. The app would need world magnetic grid to correct the heading to heading true first, but unlike aircraft systems, the grid etc could be kept upto date easily on over the web updates. The possibility of getting some pitot-static data onto an bluetooth is very exciting – it would be another major advancement in GA avionics. it would open up post flight analysis applications that would greatly advance safety. As an example, check out:
https://itunes.apple.com/us/app/aeroviepilot/id885996777?mt=8
Imagine being able to replay your flights, analysis the accuracy of your speeds, climbs etc and work on improving your performance. As the saying goes, you can’t improve what you can’t measure…
“New or existing G3X systems can easily add a second ADAHRS and AOA support by adding the GSU 25. When the GSU 25 is installed as a second ADAHRS, the GSU 25 may share the magnetometer and outside air temperature probe already connected to the first GSU 73 or GSU 25 ADAHRS (via data on the CAN bus), or support is provided for optional installation of a redundant magnetometer and OAT probe if preferred.”
CAN bus means different things to different people. It’s a bit like Modbus (I get stuck into that at work quite a lot) where you have standard registers, but the meaning of the bits can be anything whatsoever. I have a CAN programming thingy for messing around with the config on my Scirocco (turn off the DRLs, change the door locking, etc – sadly the ECU can’t be reprogrammed anymore otherwise I would have it doing 250HP 
) and many of the bit functions have been reverse engineered (in the VAG-COM software) but most of it remains a mystery. So, yeah, you have the CAN physical interface and you have the protocol, but all bets are off from that point on. Just plugging a vehicle CAN cable into it is likely to reveal nothing of use. No data comes out – it’s a master/slave protocol and you have to know how to drive the slave device.
Anyway, clearly these AOA sensors have more to them than meets the eye initially – if you want it to indicate correctly both at low levels and at the aircraft ceiling.
Does anyone understand what
“Unlike systems that rely on lift reserve indication, the GI 260 uses what’s known as normalized AOA, which provides the most accurate readout possible in all phases of flight.”
means? What is a “normalized” AOA? The Garmin site has a link to the manual, but the manual is missing. Does anyone has a working link to the manual?
A year later….there appears to be continuing, but lukewarm, interest in AoA indicators. Those who express support seem firmly convinced of the safety role this kind of device could, and should, play in GA.
“AoA is a direct measurement of approach to stall, not an approximation, like airspeed. With modern technology, we now have the ability to bring that system into small aircraft. I think AoA is a game-changer in any airplane. It’s long overdue.”
I was going to install one of these (posted about it here fairly extensively at the time) but gave up on it when the manufacturer stopped answering my questions about whether it works at high altitudes which was the main reason I wanted it.
It also became obvious that a non-heated version would be a waste of time, and the heated version drew so much power that it would damage the mounting surface (the wing underside) if left on by accident on the ground – unless modified with a temperature switch (an unapproved mod).
