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AOA on a floatplane

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AOA on a floatplane

Unread postby gear » Tue Aug 18, 2015 9:10 pm

I don't know anything about angle of attach indicators but I'm hoping that someone here can educate me. I'm thinking of adding one on my 182. Can someone explain firstly how they work, and secondly do the floats influence how the AOA works and performs, or is having floats irrelevant to the operation? Finally, can anyone recommend a brand? Cost not a significant consideration.

With all the talk about the FAA promoting them, and Kevin's death, it's got me thinking that I should take whatever help I can get to stay safe.

Thanks in advance.

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Re: AOA on a floatplane

Unread postby Mikey » Wed Aug 19, 2015 2:11 am

Hi.
Let's look at this a bit differently.
As you fly now what tells you that your angle of attack is to high?
Buffeting
Lack of control authority
Unable to maintain height
The stall warning possibly blaring at you.
Possibly a very high nose attitude.

All that sort of thing.

So we fit the wizbang new indicator and we have all the above things going on one day but the fancy new gauge says different , then what do you do?

I'd lessen the nose attitude relative to the airflow ( turns etc)

Is that what you would do?

I wouldn't bother with it, I fly jet planes for a living and I don't have one.
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Re: AOA on a floatplane

Unread postby jjbaker » Wed Aug 19, 2015 2:40 am

Hi Garth,

In hopes that Klaus will go into the technical & installation side of things as well as the topic of installation on float & seaplanes I think Alpha Systems has a good selection of available units with its top seller being the ~ $2K Eagle Kit. Garmin produces the GI 260 AOA, a normalized system, maybe Aircraft Spruce has a more complete listing of currently producing manufacturers.

Important to note is that any AOA system is really only as good or bad as its calibration, I know Alpha Systems devices are installed on various 182's, functionally unaffected by Vortex Generators. I believe that getting the calibration done right is imperative - besides developing a feeling as to when to include the indicator in the scan. The best tool in the shed is the one that gets the job done. This is why I liked the sound alert when finally flying a plane with such a system installed in 2014. I had my own version of confirmation bias on this topic until I saw the system in action. Then again, respect for the planes AOA and how much exactly you may ask from a wing in any given circumstance isn't something that should solely depend on some electronic device. IOW's like every electronic device it bears the risk of becoming a crutch for people and it may help with flying closer to the edge by default. Complacency is the #1 killer in the industry. The more toys and tools we train with the more issues we will have when we loose any of them.

As always, the camps on whether to install AOA indication equipment (or not) are divided, some advocate its use as a "holy cow" along with dozens of other gadgets installed in their airplanes, most who have flown airplanes equipped won't diss the system. I believe the FAA has made AOA indicators a less complicated topic, stating that most AOA system installations can be treated as a minor alteration. Whenever the FAA makes the entry into something new easier its time to consider its usefulness. They are pushing hard for AOA indicators as people keep pulling planes into the ground.

All in all it really depends on how well you think you know your airplane and just how frequently you fly in conditions that make precision equipment a necessity. Like always, you can't constantly operate in conditions close to the edge where your life depends on a couple inches of AOA display without getting bitten eventually.

There's no way of telling if Kevin would still be around today if his 185 had had a AOA indicator installed. There comes this magic moment when too much is just too much and seeing the pictures of the wreckage they pulled out of the woods makes me think that airplanes with "different than book" characteristics should have one of those things installed...

Hope this helps...
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Re: AOA on a floatplane

Unread postby cubdriver2 » Wed Aug 19, 2015 11:56 am

gear wrote:I don't know anything about angle of attach indicators but I'm hoping that someone here can educate me. I'm thinking of adding one on my 182. Can someone explain firstly how they work, and secondly do the floats influence how the AOA works and performs, or is having floats irrelevant to the operation? Finally, can anyone recommend a brand? Cost not a significant consideration.

With all the talk about the FAA promoting them, and Kevin's death, it's got me thinking that I should take whatever help I can get to stay safe.

Thanks in advance.

Garth


I think an angle of " attach " indicator would be cool if you had in air adjustable float brackets, less for speed and more for the water. :cowwave:

I flew a Top Cub with and AOA indicator above the panel. I didn't like it. Looked like one more distraction for landing gear down in the water. In a Cub just leave the bottom door open, it's an AOA indicator that came with the plane back in 1938

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Re: AOA on a floatplane

Unread postby CFII » Wed Aug 19, 2015 5:48 pm

For pilots that are shaky on their flying skills, I could see where a properly installed and calibrated one could be helpful, as long as the pilot doesn't depend on its information on a day when he needs it and the thing partially seizes up. I personally can't imagine depending on the one I have in a situation where things are happening and changing rapidly. It was in my whiz bang glass panel thing so we installed it.
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Re: AOA on a floatplane

Unread postby gear » Wed Aug 19, 2015 11:08 pm

All good points. Mike - I agree - jets don't have AOA indicators, but a lot of them do have shaker sticks etc. which to me is a form of that - it is an external device outside your pilot skills that helps you prevent a stall.

I look at myself and say "i have 900 hours, I know the signs of a stall, I don't need that". But, when I read about stall accidents with guys with way more experience than me, I second guess sometimes. Will I get complacent one day? Would this help? I have no idea, but it sure has we wanting to understand them better. I guess I'd still like to know - by strapping a set of float to a plane, does that influence the AOA?

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Re: AOA on a floatplane

Unread postby cubdriver2 » Wed Aug 19, 2015 11:43 pm

Every plane that has a mechanical connection to the elevator has5 a stick shaker, pilot just needs to learn how to read it. Embrace the stall up high, it will teach you how every airplane lands down low. Almost evert landing I do has a stall involved from 100' up. Back pressure, buffet, relax stick slighty and fly, back pressure, buffet, relax stick..................all the way down.

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Re: AOA on a floatplane

Unread postby jjbaker » Thu Aug 20, 2015 3:11 am

Lets stick to the topic of AOA indicators, please. Maybe start a separate topic on their necessity and usefulness.

Garth, there is a probe to be mounted and calibrated and again, this is done for each aircraft individually.
Adjusting for the floats and other equipment, from what I can tell, is a matter of calibration and subject to test flights.

Using an AOA indicator is not a sign for shaky piloting skills and they are used on jets and military aircraft.
As long as your aircraft is not able to HOVER on its prop, you have a chance to get behind the power curve and end up with a snapping airplane.

Some say this is what happened to Kevin - who had plenty of experience and skills...

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Re: AOA on a floatplane

Unread postby KlausNW » Thu Aug 20, 2015 4:23 am

I wish there was some statistic on AOA's but the FAA is pushing them on the aviation community with the hope that they are the next moving map GPS. There is nothing documented pro or con yet on AOA's. I'm going to stand back and watch for a while, lets watch and see if they prevent the short final stall accident.

Some of us leaned to fly the plane and don't stall spin out of the sky but the new generation of pilots will be taught to watch the gadgets and screens. If they have less accidents with less training hours, obviously these gadgets work. If the gadgets don't work we'll read about it.

Just figure you're a Gennie pig if you install a new technology. Nobody knows nothing til we have numbers.
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Re: AOA on a floatplane

Unread postby CFII » Sun Aug 23, 2015 8:05 pm

gear wrote:All good points. Mike - I agree - jets don't have AOA indicators, but a lot of them do have shaker sticks etc. which to me is a form of that - it is an external device outside your pilot skills that helps you prevent a stall.

I look at myself and say "i have 900 hours, I know the signs of a stall, I don't need that". But, when I read about stall accidents with guys with way more experience than me, I second guess sometimes. Will I get complacent one day? Would this help? I have no idea, but it sure has we wanting to understand them better. I guess I'd still like to know - by strapping a set of float to a plane, does that influence the AOA?

Garth


The only way to know for sure unless someone else has tested the exact same conversion, is to properly flight test and recalibrate the AoA if necessary after modifications are complete.
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Re: AOA on a floatplane

Unread postby gear » Mon Aug 24, 2015 11:20 pm

So still trying to understand, if you have to calibrate the AOA to your configuration in your plane, what are you getting with this that you don't get with a properly calibrated stall horn? Is the only difference is one is audible and one is visual?
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Re: AOA on a floatplane

Unread postby KeithSmith » Mon Aug 24, 2015 11:55 pm

I don't have any experience with AOA indicators in light airplanes, but I have used them in jets. If everything is going right, it's just another indicator on the panel. However, when things aren't going as planned, it's an excellent quick reference for speed to fly on approach.

I understand that naval aviators will fly the AOA indicator on the way in as if it were primary. We're taught to fly the airspeed and use the AOA indicator as a backup reference. I wish I could tell you the logic behind why one or the other is preferable, but I can't.

There was an event not long ago when the private owner of a CE-525 had an AOA sensor lock up and give him false indications. It also meant the stick shaker didn't function. One thing lead to another and he just about pulled the wings off the airplane. Transport category jets have redundant systems, but the smaller CE-525 had a single sensor.

However, even transport category jets get in trouble with less than ideal pilots at the control. Air France 447 is testament to that fact:

https://en.wikipedia.org/wiki/Air_France_Flight_447

It's a bit like Joe Patroni told the captain of a Boeing 707 in the movie Airport, "I know every inch of the 707! Take the wings off this and you could use it as a TANK! This plane is built to withstand anything ... except a bad pilot."

I guess basically I'd say the AOA indicator in a Cessna 182 wouldn't be of much value unless I were going into really tight spots. But, if I were going into really tight spots, I'd have to stop and ask myself why I was doing that in the first place.
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Re: AOA on a floatplane

Unread postby CFII » Tue Aug 25, 2015 5:40 pm

gear wrote:So still trying to understand, if you have to calibrate the AOA to your configuration in your plane, what are you getting with this that you don't get with a properly calibrated stall horn? Is the only difference is one is audible and one is visual?


A graduated visual graph has been on the few AoAs that I've looked at as opposed to a stall horn which is mostly either on or off however, if you listen closely many of them start to faintly whine as they approach a stall then get louder as the stall matures.
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Re: AOA on a floatplane

Unread postby skimmerone » Tue Aug 25, 2015 7:08 pm

I installed a Safeflight AOA in a Lake Amphibian in maybe 1975 and I calibrated it. There were certain characteristics of that vintage Lake that did not have the wing fillets (batwing) installed that would create a stall burble well above actual stall speed. I took this into effect when calibrating it. I have always felt that the calibration was only as good as the one who calibrated it. The Lake flaps down is capable of 60 degree banks at 60 mph, providing you are not trying to climb at the same time, because of the slotted flap system. None of this was made any better by the AOA system and I personally thought it was a waste of money.
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Re: AOA on a floatplane

Unread postby KlausNW » Wed Aug 26, 2015 12:22 am

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Re: AOA on a floatplane

Unread postby gear » Thu Aug 27, 2015 7:07 pm

Very good video and answers a lot of my questions - thanks for posting
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