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Building Angle of Attack Indicator

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Aesquire

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Good article on AOA indicator for a Moyes Dragonfly.

Really fun little airplane. Lots of power, excellent control at low speed with oversize rudder etc.

Yarn. Pink or orange. Worked for me. Even indicates stalls. If it points straight down you've stopped.... straight up you're falling. Easy.

Of course you have to spend more to get voice feedback through your headset.
 

Aesquire

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I don't mean to be too evangelical on AOA indicators.

They strike me as a tool for instantaneous analysis, like a Variometer. In some cases rate of change is the desired information, not numerical.

In other cases you are attempting to maintain certain numbers. In other's you want relative states most.

Which really leads to my question.

Which are the minimum instruments you'd want?
Which are the desired ones?

Here's a minimum VFR list. Required VFR Day and Night Instruments for Aircraft | MzeroA.com

For purposes of argument, we will consider minimum/desired engine gauges one category, and Flight gauges another.
 

SVSUSteve

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Aug 20, 2007
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Evansville, Indiana
3. Why doesn't everyone have an Angle of Attack Indicator?
1. People are cheap.
2. A lot of pilots have a belief they are too good or proficient to need one even though most of us being Bob Hoover-esque is not supported by the crash rates.
3. A few people are truly stupid or reckless (hence VFR into IMC, ignoring obvious maintenance issues, most cases of flying into convective weather, etc)
4. Occasionally you have someone who is all of the above and is a statistic waiting to happen.

2. What are the top 2/3 features you want (Easy install, LED Display, etc.)
1. Reliable
2. Low maintenance
3. Icing resistant (if we're able to ask for anything our heart desires; obviously not needed for your average GA aircraft).
4. Two lighting intensities to allow for use in bright sunlight and at night without messing with your night vision.
5. Voice callouts

Also, I'd like to see education that AoA isn't an excuse for complacency nor an insult to your flying ability. It's a simple tool that gives you a bit of information that might prevent you from doing something tragic in a moment of inattention or distraction.
 

Ahhh_Eng

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May 1, 2015
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Cokato, MN USA
It appears to me that Angle of Attack indicators are useful and even necessary.

If the price was $10, would people still prefer to use their but?
 

Aerowerx

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Marion, Ohio
Also, I'd like to see education that AoA isn't an excuse for complacency nor an insult to your flying ability. It's a simple tool that gives you a bit of information that might prevent you from doing something tragic in a moment of inattention or distraction.
Do you mean just like the airspeed indicator, altimeter, tach, oil pressure gauge, oil temperature gauge, fuel gauge, variometer, compass....? Aren't they all "crutches"?

I was just reading the other day that on the Wright's early experiments all they had was a slip indicator (piece of yarn). Later on they added a stop watch so they could time their flights.

IIRC, there is a place in Wisconsin where you can spend two weeks and learn to fly a J-3. For the final exam, they cover up all the instruments and have you go flying.
 

cluttonfred

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Sometimes electronics are overkill. It should not be hard to come up with a simple vane-type AOA probe connected to a light push-pull cable, maybe a racing bicycle shift cable? Connected to a simple indicator and green-yellow-red scale in the pilot's field of view, it would let you experiment with the utility of an AOA indicator for a small investment.
 

cluttonfred

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Actually, now that I think of it, this might be a perfect use for a little Arduino processor running off a battery, a rotary potentiometer turned by the vane and a small LED indicator, maybe a bar graph or an LED circle or arc. The inexpensive electronics approach might actually be easier and produce a lighter and cheaper installation than a mechanical one.
 

radfordc

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Feb 5, 2008
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When I was a student pilot about 45 years ago, I was taught to do short field approachs to a spot landing with a sheet over all the instrument panel. No airspeed or anything. Over and over until I was pooped.
Good that it took you hours of instruction to master that skill. But, a new solo pilot with an AoA equipped plane can consistently land as well or better.
 

N91CZ

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Nov 19, 2013
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Location
Woodland, CA
Interesting thread.
Here is an AoA probe I used for Stability and Control flight testing.
0.02 deg resolution.

DSC_0046sm.jpg

I didn't see any discussion of resolution and sensitivity.
AoA unit are great near stall in terms of knots per degree. At approach speeds not so good unless your approach speed is 140 KIAS. As a results, for GA you can be more precise with the ASI.
Military AoA displays for approach only show a 2 degree band. Approach AoA through stall is a pretty big spread to show on any display with enough resolution to be very useful. Transport category only uses AoA for various forms of stall warning: Stick shaker, PLI (pitch limit inidicator) etc. They use ASI for flying.
The ASTM spec for GA AoA units is rather interesting. No requirements for resolution or sensitivity - only that the display be 'intuitive'.
After looking at hours of recorded AoA data, I concluded that ASI was much more stable and precise for the speed range of my aircraft - a Lancair. AoA can be made more stable through damping, but then you introduce lag. You can easily define AS limits that assure wide margins to stall once you understand relationships of weight, speed, load factor etc.
 
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