Angle Of Attack.

What is AOA , angle of attack?
Angle between the relative wind and the chord of the airfoil

Is this a New technology?
Hell NO !! The Wright brothers, were using it ! Just a piece of yarn will do.

You need more technical info on the subject ?
See How It Flies (short) (long-version)
See some military use the AOA
Some Nasa technical info
Experiment with airfoils and lots of it's variables.

The Angle of Attack displays are commercially available.

P/N 10-00011 $123.950
funny ACS is cheaper than the designer
Bacon Saver AOA Indicator $125.00 plus $5 S&H and insurance

Conclusion: KISS principle, working perfect(nothing can go wrong !!)
Looks like shit !

Consists of: a vane, a potentiometer (pot), an electronic module.
Each light represents a little more than 2 degrees angle of attack.
$ 179.95 , plans can be bought for $ 79.95.

Conclusion: 2deg. resolution on your AOA is not what you expect.
Electronics looks like shit, nice vane


P/N 10-00025 $595.000 (ACS)
If you like this buy it direct from the designer for $395.00
The instrument is designed by a former McDonnell flight test engineer. So he used
a non-contact optical encoder as a sensing element in the probe. It doesn't use a potentiometer as the riteangle does.
These optical encoders are extreme expensive, I didn't find a expectable one below the $230,-. (please send a mail if you found one !!)
order direct

Conclusion: Resolution is still a problem even if the optical encoder is perfect.
You need more leds to show the resolution.
Maybe the redzone can be calibrated with a nice resolution.

Commercial and military stuff $$$$$$

Nice thing to know is that the resolution of these multi $ stuff is 0,25 deg.

Conclusion: perfect stuff, but not in everyone's reach.
You can steel it from a parked Boeing are airbus. (No.. it's not worth the trouble)

As you should know by now, the above types are of the
pivoted vane-principle.

There is another principle around in the AOA indicators.
The differential pressure tube.

Take a look at

P/N 10-00018 $695.000 P/N 10-00019 $785.000 (ACS)
Conclusion: Looks nice, can easily be homebuild.
Why buy if you can build it your self.
The sport version The Pro version goto the page

P/N 10-00017 $875.000 P/N 10-00016 $1481.000 (ACS)
This version doesn't use a probe but has pressure ports in the wing surface.
Conclusion: Looks nice, can easily be homebuild.
Why buy if you can build it your self. More electronics stuff needed.


LRI homebuild tips

The gauge used is a “DWYER MINIHELIC II” pressure gauge.
Part number 2-5002. This gauge reads 0-2” of water column.
easy ordered online for $45,- order example
3 separate zones: You have to do this your self !
The first zone is the “red zone” which is from 0 to .5” of water.
The second zone(white or yellow) goes from .5” to 1.0” of water.
The third zone is from 1.0” to 2.0” of water column
see a larger picture
Now you need a probe: Material is not critical, you can use wood, fiberglass, aluminum
It's your plane ! The dimensions are found here Download-probe_dimensions

If you need more help to build it see :

OK you don't like the probe because you are building an all composite plane.

The theory the pressure differential depends on:
probe shape, (fixed and is taken care off in the calibration)
angular position of the orifices (size, angle all is fixed and influence the sensitivity)
Mach number
Reynolds number.

The wider the angle of the orifices the sensitivity increases.(page19, naca-tn-4351)
The smaller the diameter the sensitivity increases. .(page18/19, naca-tn-4351)

For the historians among us: take a look in sport aviation 43 maybe your grandfather has one !! or download it here SA_AOA_43

On the vaiEze it works fine in front of the canard.
Guess what we are going to do on our Cozy MKIV !!

We are building 2 tubes on each side of the fuselage, so we can correct slip.

The differential pressure is measured by the smallest sensor of the MXP2010DP
sold for $14.43 at

Testing and calibration will be done