3D printed AOA vane prototype

punkin · #1 08-22-2017, 08:11 PM

Inspired by my kids' aforementioned aquisition of a 3D printer, a few commercial aoa vanes like belite, two days of watching YouTube videos on how to use Fusion 360, and a lot of stubbornness, I created this:

I bought a couple little Hall effect sensors and magnets (which I have not successfully used yet) and a couple tiny little rotary encoder doohickeys.

This version will use the rotary encoder.

I'm not sure when I'll get to play with it more, but I'm hoping to eventually couple to an OnSpeed tone system like the super smart guys on here have been developing and working on.

I was pretty excited with how it turned out visually, we will see where it goes.

punkin · #2 08-22-2017, 09:06 PM

I got mad when I let some of the smoke out of the very simple circuit I built for a differential pressure setup. My -6 even has the piper blade style pitot which I think will be really easy to modify for such a setup.

In the mean time, I needed something to practice with Fusion 360, and this became it. I was kinda proud of that part -- I've got about 4 hours experience with Fusion 360, and a little over two of it was hacking this thing out from scratch to real life built parts! 20 years ago this would have seemed like voodoo magic to me.

I had a private message from one of you super smart types and figured I might have more coming

Weasel · #3 08-23-2017, 05:50 AM

That is real nice.

sblack · #4 08-23-2017, 09:25 AM

I deal with AOA vane calibration on transport airplanes. They don't read true AOA because they are affected by flow around the fuselage. But, the vane reading always has the same relationship with the true AOA, so as long as you don't worry about the actual numbers, but calibrate the vane so that the display shows red when you stall, and yellow when you are 5% speed above stall, it should work well, assuming you put it where there is clean flow (which can be difficult on a prop plane). So the vane AOA could also be a function of power, since the local flow could be affected by prop swirl. It could also change with flap. The stall angle changes with Mach, but I don't think even an RV is fast enough to worry about that

We calibrate them to +/_ 0.25 deg. It is a real pain. You don't need nearly that accuracy. Should be an interesting project.

rjtjrt · #5 08-23-2017, 04:32 PM

This is intriguing and 3D printers are fascinating.

It strikes me if you are going to rely on AoA indicator, especially during critical phases of flight, it has to be totally reliable/fail safe.
You want the pivot point/mechanism to be totally unable to jam or bind or get stiff or notchy.

sblack · #6 08-23-2017, 05:51 PM

Quote:

Originally Posted by rjtjrt

This is intriguing and 3D printers are fascinating.

It strikes me if you are going to rely on AoA indicator, especially during critical phases of flight, it has to be totally reliable/fail safe.
You want the pivot point/mechanism to be totally unable to jam or bind or get stiff or notchy.

You should NOT be relying on an aoa indicator. It is there as a backup in case you get distracted. Your first defense against stalling has to be airmanship and proficiency.

catmandu · #7 08-23-2017, 05:55 PM

Quote:

Originally Posted by sblack

You should NOT be relying on an aoa indicator. It is there as a backup in case you get distracted. Your first defense against stalling has to be airmanship and proficiency.

Explain this, please. I guess the key verb is 'rely', but interested in your reasoning.

Bcone1381 · #8 08-23-2017, 05:59 PM

Quote:

Originally Posted by sblack

You should NOT be relying on an aoa indicator. It is there as a backup in case you get distracted. Your first defense against stalling has to be airmanship and proficiency.

Seems like the same could be said about an airspeed indicator.

Also, try telling a Naval Aviator the an AOA cannot be relied upon, or the FedEx MD-11 crew that struck their tail while landing using there airspeed indicator because they figured there Gross Landing weight at 100,000 pounds light. AOA would have saved them. One who Flies AOA during approaches has wisdom beyond the average aviator.

And if one is distracted what good is the AOA or an Airspeed indicator? By definition of being distracted your looking at the moose in the field, or the kids in the sandbox. Seems like that audible generated AOA indication might be pretty handy about that time.

rjtjrt · #9 08-24-2017, 05:43 AM

Quote:

Originally Posted by sblack

You should NOT be relying on an aoa indicator. It is there as a backup in case you get distracted. Your first defense against stalling has to be airmanship and proficiency.

I'm not gonna bite!
Scott, have a nice day.

sblack · #10 08-24-2017, 10:34 AM

There is an amusing video on youtube of an old and grumpy Chuck Yeager, trying to get his 93yr old body into an F-15 (his legs are not cooperative). He points to the AOA indicator and he says "that's a stupid instrument - if you don't know what your AOA is you shouldn't be flying".

Yeager is known for being grumpy, and I don't think most of us can expect to have his level of situational awareness. But if you can't fly a light airplane safely without an airspeed indicator, or an AOA indicator, then you need better training or perhaps you should take up golf.