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Old Jun 21, 2014, 12:23 PM
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AoA hardware and indicator

So I am going to be getting into fpv here soon and have been brainstorming about having an angle of attack indicator. I think this would be really valuable info to have as well as being a fun project.

I have been thinking about a setup for my EDF F-16 to control leading edge flaps using a potentiometer attached to small weather vane and an Arduino to control the servos. I also wanted airspeed information to control a variable exhaust cone at the rear.

For the FPV setup I was thinking about something much simpler. A small weather vane would rotate against a conductive strip connected to a small strip of LED's that are placed in camera view. Power would be a small button battery. There would be something like three green three yellow and two red ones that would light up in progression based on the AOA. Flying fast would be three green as you slow the yellows light up in progression, then red.

There would be some setup required of course. I was thinking about some strings on the wing in front of a box fan to get an idea for the angles. This could be further refined after some flight testing.

From all the videos I have watched it looks like people do fine without it but I think it would be a great tool to make much better approaches and landings.

I have come across many different potentiometers online and the one thing I cannot figure out is how much resistance the knob has to torque. It would need to be fairly loose so that it could rotate freely in the airstream. Obviously this is not important for the simple version but I still have plans for the Arduino version.

Anyway there are my thoughts. Any ideas?
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Old Jun 21, 2014, 04:29 PM
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OK, those are some great ideas! LOL
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Old Jun 22, 2014, 09:33 AM
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Really? No one has thought about AoA?
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Old Jun 22, 2014, 09:40 AM
resU deretsigeR
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My osd has AOA on it, or atleast the artificial horizon.....and that gives you the same info.
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Old Jun 22, 2014, 10:09 AM
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Originally Posted by LDGILLS View Post
My osd has AOA on it, or atleast the artificial horizon.....and that gives you the same info.
Yes, I have seen ODS's with an attitude indicator. That's not the same as AoA but it is certainly very useful.
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Old Jun 23, 2014, 08:22 AM
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Really? No interest in AoA?
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Old Jun 23, 2014, 12:27 PM
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Would need to be something pretty simple to build tho... Something like the below, on the fuse? Not sure if the smaller reynold numbers would play a role in how accurate it would be... Maybe someone smarter than me could chime in on that..

http://www.aircraftmech.com/pics/aoa.jpg

I'm current building a airspeed sensor with a pitot tube and I'd love to have a AoA indicator as well, got plenty of free ADC pins left on the atmel328.

So yeah, I'm interested!
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Old Jun 23, 2014, 01:27 PM
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Of course the idea is very interesting
I can see a bit of trouble converting the aoa vane position to electrical signalling?
Perhaps a piece of very light wire suspended small amount away from fuselage but in fpv camera wiew can provide the same information?
Something like this?
Hero with a wing (6 min 55 sec)

oops! video credits to ommadawn
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Last edited by sweflyer; Jun 24, 2014 at 01:03 PM. Reason: not my video!
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Old Jun 23, 2014, 01:39 PM
KD0EMB
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I've thought about it too. would be cool if you could do it in a compact way.
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Old Jun 23, 2014, 02:21 PM
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Originally Posted by sweflyer View Post
Of course the idea is very interesting
I can see a bit of trouble converting the aoa vane position to electrical signalling?
Perhaps a piece of very light wire suspended small amount away from fuselage but in fpv camera wiew can provide the same information?
Something like this?
Nice! I think you could get some crude AoA info off of a string like that. I was actually thinking of something similar with some sort of backing, like a flat piece of plastic, to get a closer idea of the angle. Mark the plastic with a line perpendicular to the zero AoA chord of the wing. Index some other marks and then fly it to see where the stall angle is. The string would follow the wind and be attached to the leading edge of the plastic and move up and down against the indexed marks.

Another way is to attach the AoA vane to a rotary potentiometer. Potentiometer output is voltage that varies based on the position. A simple program could read the voltage and drive servos or light up lights or possibly generate a display on an OSD
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Old Jun 23, 2014, 02:51 PM
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Quote:
Originally Posted by Bazed View Post
Would need to be something pretty simple to build tho... Something like the below, on the fuse? Not sure if the smaller reynold numbers would play a role in how accurate it would be... Maybe someone smarter than me could chime in on that..

http://www.aircraftmech.com/pics/aoa.jpg

I'm current building a airspeed sensor with a pitot tube and I'd love to have a AoA indicator as well, got plenty of free ADC pins left on the atmel328.

So yeah, I'm interested!
Yes exactly! Make a similar weather vane and attach that to a potentiometer. Send that output to the pin and write a program to do what you want with it. That is way over my skill level at this point though. I know what I want to do but writing the code and finding a proper potentiometer are the biggest challenges right now.
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Old Jun 23, 2014, 02:57 PM
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Quote:
Originally Posted by Bazed View Post
Would need to be something pretty simple to build tho... Something like the below, on the fuse? Not sure if the smaller reynold numbers would play a role in how accurate it would be... Maybe someone smarter than me could chime in on that..
I don't think the small r number would be a problem. As long as it is sticking out the side if the fuselage a bit it should be fine.
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Old Jun 23, 2014, 03:03 PM
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I was thinking of a small flat piece of balsa triangularly shaped and attached to the potentiometer about 25% from the leading edge like all flying elevators. A small weight at the back will help bias it to "fly" without flipping the other way.
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Last edited by Sherlock; Jun 23, 2014 at 03:10 PM.
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Old Jun 23, 2014, 03:35 PM
KD0EMB
United States, KS, Wichita
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I like the rotary potentiometer with measured voltage output. Could do a red, green, yellow LED indexer that's visible to the camera if you didn't want to work it into existing OSDs.
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Old Jun 23, 2014, 04:59 PM
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Yeah, I like this idea too. Any idea how to set up a circuit like that?
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