While the FrankenHawk is getting its STOL Kit and new windshield installed, I'm thinking of putting an Alpha Systems AOA-5070K (http://alphasystemsaoa.com/mech.html) Angle of Attack Guage on the new glare shield.

Anyone have experience with these things?

Don

I thought about one of those when I built my RV8,
I have talked to several folks that have bought them that said they wouldn't do it again.

General consensus seems to be feeling is just as good.

I have only talked to one person that thought the sun and moon rotated around an AOA

He was an ex Navy pilot that was so hard I don't think he could feel the seat of his pants.

AoA gives you better information about your wing than anything else on the panel - but then, I'm Navy trained. Obviously you can max perform a light aircraft very well through scan and feel, but if you want to remove all doubt an AoA gauge is the ticket. It really only pays off in maneuvering flight so understandably most folks here couldn't justify the cost. I fly my Stinson just fine without one and have no desire to install one, but every landing in that doesn't depend on my ability to gnats ass l/d max.

Maybe if scout's hands were standard issue in flight school the Navy could save a few bucks in instrumentation.

Don,

We installed one of these things in a (government owned) Cessna 185, and let several pilots fly it. Nobody was impressed at all with the thing. There are several issues with these things:

1) they are not tso'd or pma'd, so if you're thinking of installing in a certificated airplane, you'd best check with your Friendly Flying Administration first, cause you'll have to get a field approval (Sparky Imeson's argument notwithstanding, this is NOT a minor installation). My guess is you couldn't get these things field approved in most offices.

2) they don't really give you any more information than your pitot system does.

3) This is NOT a true AOA indicator. A true AOA will measure actual angle of attack, and generally at more than one point on the airframe, then average the readings. This, just like your pitot tube, measures the angle at only one spot, and that out on one wing. What happens if you are slipping, and/or skidding? Bad data.

I flew that 185 a fair bit, and got to the point where I didn't even look at the thing. To me, it was worse than useless.

MTV

Don,
When I purchased my Skywagon, the AOA came with it. The previous owner had purchased, but never installed it. I am pulling all extra instrumentation OUT of the plane, so will not be installing this. If you are still interested, I have a new, complete kit with the analog gauge for a better price.
I agree with the previous posts that the seat of the pants feel does just as well for me, although if one is not flying a couple times a week, it seems that is one of the first things to go (maybe just a numb butt from sitting at a desk all week?). In principle though, the benefit of an AOA over pitot airspeed is that performance (stall speed, best rate/angle of climb, etc) at a given AOA remains constant regardless of weight whereas your target airspeed will change. Yeah, I know, who's looking at airspeed - well, if you're just a little rusty, that's the gauge you should be stealing glances at coming into a short strip or climbing out over an obstacle - unless you have AOA!

Vick wrote:
Maybe if scout's hands were standard issue in flight school the Navy could save a few bucks in instrumentation.

Ease up Vick, I wasn't nor would I even try to take anything away from the best trained pilots in the world other than,

As you know, there is a whole different feel to landing a Cub or Maule etc. than slamming one on the deck.

Seems you like that little gauge too

Sorry Scout, should've added a in there, didn't mean to come off harsh. I do like the little gauge in the heavy stuff that someone else pays for. I do agree with MTV that the GA systems I've seen available - certification issues aside - don't look to be the same caliber equipment that we use at work.

A real AoA system does tell you something that you can't get off of straight pitot static instruments, namely it corrects for varying weights and configurations - one speed is on speed. Stall speed varies with weight. In a light aircraft one approach speed may work for all weights, but as the weight envelope increases the utility of an AoA gauge quickly becomes apparent. It's importance in in-flight maneuvering (aircraft handling and air-to-air work) is another matter entirely.

Like I said before though, I don't have or want one in my 40's vintage tail dragger. Just not relevant to that kind of flying. If I built an experimental though I might throw one in just for geek factor

mr scout wrote:As you know, there is a whole different feel to landing a Cub or Maule etc. than slamming one on the deck.

Hey... I've slammed a few Cubs on the deck. I'm still picking up the parts I knocked off.

Gump

I think one reason is the difference in useful load as a percentage of aircraft gross weight. The military aircraft usually aren't power or structure limited and carry a huge useful load, and would therefore I assume have a huge variance in stall speed. The larger the difference in stall speed between empty and loaded, the greater the utility of an AOA system? The difference in stall speed actually isn't really that much in any GA aircraft that I have flown, plus I assume that the control "feel" is better in a slow GA aircraft than it is in a much faster hydraulic actuated fly by wire system.
I'm an old military fling wing kind of guy, so I'm assuming here.

Here's a releated question for you guys with AOA experience: does it jump around in turbulence or gusty wind? It seems like it would be subject to that. And if so, how are there any rules of thumb for it. For example with your airspeed indicator, the rule of thumb is to fly a bit faster by 1/2 the gusts on final.
thanks,
tom

Angle of attack allows you to fly at your slowest approach speed and varies your speed depending on your weight.

In a tight canyon turn around AOA allows you your tightest turn.
With increased g loading, your stall speed can increase dramatically. You cannot tell that increased stall airspeed on the airspeed indicator nor in your seat of the pants. AOA always shows you how close you are to a stall. It is the same as a stall warning except it gives you more information.

People that have not used AOA much seem to know the most. At least that is what they think.

I think AOA could have saved many lives. It is difficult to get some people to really try new things.

If you have flown many hours in your plane, you probably do not need any help.

flyer

flyer

Flyer,

You are absolutely correct on most counts, and especially that a TRUE AOA system would be wonderful, and probably could save some lives.

The point is that the device being discussed here is NOT a true angle of attack indicator, and to suggest it will give you all the information you need is incorrect. The problem with this device is that its sensor is mounted at one point on one wing. AOA varies over the span of the wings, particularly during maneuvering flight. THAT is what often gets people into stall/spin trouble, and that won't be improved with one of these devices, though it COULD be with a TRUE AOA sensor system.

Problem with true AOA systems is that they are complex, they are VERY expensive, and they probably are heavier than we'd want to install on our airplanes.

The device being discussed here is a very simplistic semi AOA device. It decidedly DOES NOT give you ALL the information you need to operate safely. Fly just a bit uncoordinated, and the information that device provides may or may not be accurate.

As to canyon turns, these need to be PRACTICED, not done simply by staring at some gauge on the instrument panel. If you don't practice them, you won't be able to extract maximum turning capability from your airplane in any case, and the device on the instrument panel isn't going to help much.

You CAN detect the onset of stall in most light aircraft via the feel of the aircraft, except in certain rare stalls, but unfortunately, for the reasons noted above, this device doesn't provide any more warning in those cases than does your butt.

And, yes, I have gone out and experimented with one of these devices, and spent some time working it. Unfortunately, if you use this thing as a stall avoidance device, it will keep you from stalling, but it will also have you flying faster in many instances than if you just worked the airplane.

MTV

The AoA systems I have flown had their probes mounted on the side of the nose - this keeps them in relatively undisturbed air but doesn't tell you anything about the variance in AoA along the wing. The obvious difference in application on GA aircraft is the prop on the front - AoA on the nose woulnd't help you much, so they move the probe out onto the wing to find undisturbed air. Just like any system you have to understand its limitations to make it work for you.

Vick,

Precisely correct. However, the problem when you move one of these things out onto the wing is that you have now introduced slipping and skidding errors into the mix.

THAT is precisely the problem with these things on single engine propeller driven aircraft.

MTV

I agree that slipping or skidding will introduce some error into the AOA. It will also introduce the same error into the Pitot, airspeed system.

Most of the time I am not slipping or skidding so the AOA is accurate.

It is important information for me but not the only information.

flyer