AOA indicators

AdamZ

AdamZ

Touchdown! Greaser!
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Adam Zucker
I was reading an article in Plane and Pilot today about angle of attack indicators. I'm wondering why these units have not replaced the stall alarm. I do see them on some LSAs and would not be surprised if they were on a Cirrus, but don't see them on most of the GA fleet including new production. I'd think they would be a whole lot more useful than a stall alarm and give more accurate information.
 
Saw one freshly installed going up for a test flight when I dropped my plane off for a CDI problem..... It was in a glass panel cessna 150.
 
AdamZ said:
I was reading an article in Plane and Pilot today about angle of attack indicators. I'm wondering why these units have not replaced the stall alarm. I do see them on some LSAs and would not be surprised if they were on a Cirrus, but don't see them on most of the GA fleet including new production. I'd think they would be a whole lot more useful than a stall alarm and give more accurate information.
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AFAIK no AOA has been TSO's for our aircraft. There are some that have been installed on production/certificated/whatever aircraft (our old stuff) but only with 337s and depending on your local FAA office, a lot or very little aggravation.

They're standard on the Remos and other LSAs and really great to have. One of the C182s on the field (FTG) is investigating and will let us know what the level of effort is dealing with the FAA. If it's not a lot of agony, there's a number of us planning on doing the same thing.
 
I'm going to pick my plane up in the morning, the avionics shop just intalled one in a Cessna 150, I'll ask what is needed to install it.
 
Some certified aircraft have AOA indicators. The Piper Cheyenne II comes to mind as one that needed it because it had enough power that people were getting into power-on stalls without realizing they were getting close to it.

But it costs more. They've probably figured out how to make it cheaper these days for the experimental world, but still expensive for certified.
 
Go here for all AoA information: http://www.ballyshannon.com/aoa.html
including a letter from the FAA stating that it's considered a minor alteration for most GA certified aircraft.

Not terribly expensive, and a damn good idea. If I didn't fly a stall-proof airplane I'd have one.
 
Ted DuPuis said:
Some certified aircraft have AOA indicators. The Piper Cheyenne II comes to mind as one that needed it because it had enough power that people were getting into power-on stalls without realizing they were getting close to it.

But it costs more. They've probably figured out how to make it cheaper these days for the experimental world, but still expensive for certified.
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Alpha Systems AoA isn't "certified" (e.g. STCd) to replace the OEM stall warning but the FAA has stated that it's acceptable in a certified airplane.
 
pericynthion said:
Go here for all AoA information: http://www.ballyshannon.com/aoa.html
including a letter from the FAA stating that it's considered a minor alteration for most GA certified aircraft.

Not terribly expensive, and a damn good idea. If I didn't fly a stall-proof airplane I'd have one.
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A "stall proof airplane?" Wouldn't that sort of be like the "unsinkable Titanic?"
 
gismo said:
Alpha Systems AoA isn't "certified" (e.g. STCd) to replace the OEM stall warning but the FAA has stated that it's acceptable in a certified airplane.
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I was thinking you had an AoA indicator in your plane.

But unless there's a good demand or a certification requirement, if it costs more, I can't see the OEMs putting it in. I could also see wanting both a stall horn and an AoA (or an AoA that has a horn), simply because the times when I'd need the audible warning are probably times when enough is going on that I wouldn't have the AoA in my scan as much as I should.
 
MBDiagMan said:
A "stall proof airplane?" Wouldn't that sort of be like the "unsinkable Titanic?"
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The Rutan canards actually don't stall in the traditional sense. But with the stick all the way back, you'll still have plenty of descent rate to hurt you.
 
RoscoeT said:
The Rutan canards actually don't stall in the traditional sense. But with the stick all the way back, you'll still have plenty of descent rate to hurt you.
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Indeed. Also, AoA indicator is most useful where attitude against the relative wind is difficult to judge visually: e.g. in turns. And as N555JD crash shows, you can easily spin an otherwise unstallable LonEZ to your death.

P.S. I fly Remos with factory AoA. Its ticker seems like a more convenient system than 3-LED indicator. Of course if you lose PFD in Remos, you lose AoA too.
 
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That's true - an AoA is useful for more than stall prevention. It can be used to get the most performance out of any aircraft, even a canard, in certain maneuvering situations.

The nice thing about the LED versions is that they put the indicator in a spot that's within your field of view while you are squarely looking out the window not down at the panel.

As an aside, I don't think Denver spun in the traditional sense, AIUI it was just a case of not maintaining altitude in an steep bank condition caused by inadvertently leaning on the stick while looking behind his shoulder.
 
Ted DuPuis said:
... I could also see wanting both a stall horn and an AoA (or an AoA that has a horn), simply because the times when I'd need the audible warning are probably times when enough is going on that I wouldn't have the AoA in my scan as much as I should.
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Yup pretty much my thoughts.
 
Audible is integrated in Remos and CTLS. Dynon sounds alarm through intercom on them. So does Garmin (for ground proximity). Both alarms are annoyingly loud: I almost peed myself when it said "FIVE HUNDRED" - and it says it on every base-to-final turn. Dynon also alarms on low fuel and any other engine parameters out of whack. This kind of integrated solution may be good, but I have no idea if cheaper certificated airplanes carry something like that. Or it may be not good, as I hear complaints about Eclipse overloading pilots with alarms. The good old stall warning light on Cherokee at least has its own fuse.
 
Ted DuPuis said:
I was thinking you had an AoA indicator in your plane.

But unless there's a good demand or a certification requirement, if it costs more, I can't see the OEMs putting it in. I could also see wanting both a stall horn and an AoA (or an AoA that has a horn), simply because the times when I'd need the audible warning are probably times when enough is going on that I wouldn't have the AoA in my scan as much as I should.
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You can have an audible option on the Alpha AOA's. I was just looking at some installations at Beech get together. I sat in a King Air with a Legacy model - actually two of them and in two bonanzas with the horizontal LED versions. The legacy version to me seems the most intuitive and it looks nicer than the ones with the row of LED's.

Other than the screams of my passenger, my plane doesn't have a stall warning so I've been thinking about an AOA indicator. I've got to find a spot on my limited panel for the indicator and a spot under the wings outboard of the prop for the sensor.

PS - there's an excellent thread on beechtalk.com about AOA indicators.
 
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AOA's can be too expensive to put on regular GA planes.
 
They retail for under $1000. Not sure of installation costs but it's not complicated.
 
RoscoeT said:
The Rutan canards actually don't stall in the traditional sense. But with the stick all the way back, you'll still have plenty of descent rate to hurt you.
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True. But if don't stall you CAN'T spin. Which is one of the original points.
 
> wondering why these units have not replaced the stall alarm.

Cost of the components & FAA certification (which itself, is a significant cost).
 
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