On Tuesday, May 19, 2020 at 3:00:05 PM UTC-5, Luc Job wrote:
Hi!

I have developed last year a solid-state AOA indicator, based on a
differential pressure measurement (total pressure/pressure at angle)

Undoubtedly, this is a primary flight instrument to me:

-It shows where you are aerodynamically speaking, independently of
all the variable parameters: Load, flaps position, airbrakes...etc, and
does not need a calculation or interpretation to check if you are
flying right or not... And if the display is well done you will have a
clear indication of the ongoing tendency towards a safe or dangerous
situation.

-It give me an accurate indication to adapt the flaps position to stay
at the best glide angle through the whole speed range.

-It is a good indication of the optimal attitude during winch launch
and can prevent a high speed stall at high load factor.

Some pictures of my development are available he
https://bit.ly/aoaindicator
On the video the blinking effect is induced by the camera, the leds
simply fade in or out gradually, only the red one blinks at stall angle
or if the AOA rate of increase will induce a stall within 2 seconds...
you can see that the instrument works as good as its free
alternative...

The present system includes:

-A 5 leds indicator, red-amber-green-white-blue. The corresponding
AOA for each led is programmed in flight with a push-button.

-An audio input and output: Instead of adding a warning while flying
at higher AOA than the maximum Cz (minimum sink rate), the
instrument hashes the audio output of the vario gradually, cutting
the sound at stall. This is an excellent indication that something is
wrong without adding noise... You can continue to watch outside
while climbing at the best speed, and avoid to enter a spin in the
middle of others.

-A serial i/o for software upgrade and continuous transmission of the
data to another instrument.

-An optional light sensor to adapt the luminosity to the ambient light
level... But the indirect illumination and a better reflector (in
development) has proved that it is probably unnecessary.

The only hardware modification is the installation of an angled
pressure port at a suitable place: angle is not critical, but flow must
be as undisturbed as possible. On the DG I've put mine under the
nose, about 170 mm from the tip, where I had access to the outer
hull from the inside. I drilled a 2 mm hole and glued a small
pressure chamber inside to plug a 4 mm hose. That's all.

Power drain is lower than 20 mA @ 12V, less on ground as no led is
switched on... So no switch, but an internal polyfuse to avoid any
dangerous current drain... So it is simply added to the (fused)
instruments circuit.

Now as the system proves to be functional and efficient it's time to
do something with it.

Many options are possible:

1) I can order and sell PCB's only, with a BOM and the software...
This is obviously the cheapest way... But components are mostly
SMD... So you need an oven or a lot of patience and skill... Up to
you to make a box adapted to your needs. Price should be about $10
including shipping.

2) I can sell a complete kit with all the components, PCB, software,
connectors and box... Components are not expensive except the 2
pressure sensors ($35 each)... So I should be able to make this for
about $150...

3) If you prefer a complete instrument, ready to plug-in (except the
pressure port installation) the price should be in the 300-400$
range.

All this depends obviously on quantity... So if I have 1'000 orders it
might be significantly cheaper.

At first I need to know how many people might be interested... And
what is the best option for you.

At least we can fly again in Switzerland and France... So it might
take some time for me to build a website for this product...

Luc JOB
DG-800B

Luc I'm confused by some of your statements.

I am a professional, semi-retired, applied aerodynamicist who had done design and performance analysis work for most of the US General Aviation companies.
Aircraft angle of attack (AoA) is defined using a reference line fixed to the fuselage. For a zero-flap configuration, there will be s specific AoA at stall. For a landing-flap deflection, the the maximum lift coefficient will be higher, however, it will occur at an AoA that is several degrees lower. All lift curves for aircraft design at factories worldwide use this convention.

I also have extensive experience with using 5-hole probes in the wind tunnel and in flight (even a rakes of 21 probes behind several locations on the Beech Starship). These are excellent for providing AoA, angle of sideslip (or yaw), and can be calibrated to provide a good measurement of static pressure and total pressure. I have calibrated probes myself in a wind tunnel with calibration curves out well beyond stall angles.

I have seen simple probes systems proposed and developed Garmin and others, however, these do not fully generate a true AoA. I would be interested in seeing how your single probe can generate a true AoA, and particularly for multiple flap angles. I'm skeptical at this point. I look forward to seeing more information.

...... Neal
Wichita, KS
Consulting Engineer