Archammer
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A new Safe Flight AOA/Speed controller may help lower stall/spin accident rates in GA Aircraft.
http://youtu.be/bzLc-8brz2M
http://youtu.be/bzLc-8brz2M
New AOA/Speed controller for GA aircraft
- Thread starter Archammer
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Piloto
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No doubt that AOA may add some safety margin but it will not be as useful as air speed indication. Typical stall accidents happens when turning base to final and the AOA can not predict in advance the stall. But having a safe airspeed margin will prevent the stall when turning. The goal is to prevent the stall in advance from happening not to react to it just before the event. That is why there are target speeds for landing. Obviously the AOA didn't help on the B777 that crashed in KSFO.
José
José
dukeblue219
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Wait... what? Isn't the AOA indicator the ONLY tool which will show you that the wing is close to a stall? The airspeed indicator will happily show 70 knots if you're on a slow base leg in a 172... and it will continue to show 70 knots as you wrench the plane into a tight base-to-final turn, kick in the rudder, and stall/spin it into the ground.
I don't know if THIS tool will prevent any accidents, but as far as I understand it, AOA is a much better tool for detecting an approaching stall than the airspeed indicator.
Remember, the plane can stall at any airspeed but has only one critical angle of attack.
Ted
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iFlyNothing
You have that backwards. AoA will tell you as you're intering the turn that you're about to stall. The ASI will keep you blissfully unaware without extra thought.
No tool will fix a pilot who's bound and determined to crash through acts of sheer stupidity, which is what that 777 proved. But that 777 also has far more safeguards to help prevent a stupid pilot from being stupid.
Piloto
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I think you misunderstood what I meant. You want to avoid being close to the stall condition. The only way you know you have a safe margin is by having an speed margin. An AOA does not tell you that safety margin but the airspeed indicator does. And in any case all planes are equipped (FAA required) with a before stall warning indicator/annunciator and stall strips. When I hear the stall horn I know I am close to stall. How is this gadget different?
José
José
geneseib
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Certainly works well on the Boeing 777
Ted
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An AoA indicator has a range that's color-coded, and some also have a verbal warning. The one I'm looking at has "Getting slow" as AoA increases followed by "Too slow" when you need to push the nose down right then. A stall horn only gives a warning within a very small window before a stall happens. AoA actually gives much more warning.
An airspeed indicator is multi-step. You need to know the stall speed for your condition (which could be much higher than the bottom of the green or white arcs) and then you see your speed margin. The first part is the hard part. If an ASI had a barber pole for the bottom end of the arc in the same way that turbines have. A barber pole for Vne, then yes, that would work well.
Samwise
Filing Flight Plan
No, this in incorrect. An AOA indicator tells you exactly how much of a margin above a stall you have, in degrees of AOA from stalling. It is a very direct way of determining how close the wing is to stalling.
You should read a book called Stick and Rudder.
Which brings up a question of mine: a wing stalls at a slightly different AOA with different flaps settings, right? Does an AOA indicator account for this?
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dukeblue219
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The problem with your statement is that airplanes don't just have a "stall speed." You'd have to memorize the stall speeds at every condition in order to use the ASI as a warning that you're close to stalling.The AOA indicator will directly tell you how close the wing is to stalling.
If you fly a 172 with a dirty stall speed of about 47 kias, dthe stall speed in a level, 45-degree bank is 66 kias. If you fly a base leg at 75 kias and overshoot the runway centerline, it's human nature to make a steep turn back to the runway. If you make that at a steep-but-plausible 45-degree bank, you're now a LOT close to your stall speed than you were before the turn. The plane is going to want to nose-down and maintain speed, but if you fight it and pull back to keep the turn tight and the nose up, your airspeed will rapidly decay below 66kias. Sure, it's above your normal final approach speed, but it's below the stall speed for that condition of flight and boom, you stall.
We can fly perfectly safely by using a combination of airspeed, bank angle, and the feel of the plane, but the AOA indicator absolutely gives a piece of information you cannot get anywhere else, which is how close the wing is to a stall at any phase of flight.
Archammer
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Piloto
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We can fly perfectly safely by using a combination of airspeed, bank angle, and the feel of the plane, but the AOA indicator absolutely gives a piece of information you cannot get anywhere else, which is how close the wing is to a stall at any phase of flight.
Isn't that what you get with the stall warning alarm. When I land at very short runways like MYCC (1320ft with water at both ends). I slow down on short final to the point of sounding the stall warning intermitently. This assures me that I am at the lowest possible speed for touchdown. Being focus on the runway edge leaves you no time to look at an AOA dial. This is where the aural feed back is most helpful. And you do not want a voice but a tone that triggers when approaching the stall. If you want an earlier warning you can adjust the stall vane which is what I did and works beautiful. How is this gadget better than what I already have.
José
Isn't that what you get with the stall warning alarm. When I land at very short runways like MYCC (1320ft with water at both ends). I slow down on short final to the point of sounding the stall warning intermitently. This assures me that I am at the lowest possible speed for touchdown. Being focus on the runway edge leaves you no time to look at an AOA dial. This is where the aural feed back is most helpful. And you do not want a voice but a tone that triggers when approaching the stall. If you want an earlier warning you can adjust the stall vane which is what I did and works beautiful. How is this gadget better than what I already have.
José
ajstoner21
Cleared for Takeoff
You should not be relying on those warning systems to land.
Especially if you are altering the stall warning system. Which im sure is probably illegal. Im certain there is a FAR in part 23 or 25 that says how soon the stall warning goes off. I can look it up later...
bqmassey
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These statements are completely incorrect.
You stall warning system is an AoA indicator. The problem is that it's binary. You're either below that certain AoA (no horn) or above it (horn).
These AoA devices are not binary. They give you an idea of how large your approach safety margin is regardless of weight and load factor, which neither your stall horn or ASI can do. They can give you best range and best glide regardless of weight and load factor, which neither your stall horn or ASI can do.
And just like your stall warning system, they can be used to drive both aural and visual warnings.
Piloto
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Sec. 23.207 Stall warning.
(a) There must be a clear and distinctive stall warning, with the flaps and landing gear in any normal position, in straight and turning flight.
(b) The stall warning may be furnished either through the inherent aerodynamic qualities of the airplane or by a device that will give clearly distinguishable indications under expected conditions of flight. However, a visual stall warning device that requires the attention of the crew within the cockpit is not acceptable by itself.
(c) During the stall tests required by Sec. 23.201(b) and Sec. 23.203(a)(1), the stall warning must begin at a speed exceeding the stalling speed by a margin of not less than 5 knots and must continue until the stall occurs.
(d) When following procedures furnished in accordance with Sec. 23.1585, the stall warning must not occur during a takeoff with all engines operating, a takeoff continued with one engine inoperative, or during an approach to landing.
(e) During the stall tests required by Sec. 23.203(a)(2), the stall warning must begin sufficiently in advance of the stall for the stall to be averted by pilot action taken after the stall warning first occurs.
(f) For acrobatic category airplanes, an artificial stall warning may be mutable, provided that it is armed automatically during takeoff and rearmed automatically in the approach configuration.
ajstoner21
Cleared for Takeoff
Thank you for looking it up.
Is there some place in the FAR's that gives you permission to alter that? Did you get an A&P IA to do the alteration, if it is one? Perhaps I'm ignorant when it comes to altering stuff like that. I really do apologize if that's a common thing. I just never heard of anyone doing that before.
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Greg Bockelman
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Did the airplane stall?
dukeblue219
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Yep, the visual AoA indicator is not sufficient on its own, apparently.
You get either "BZZZZZ" or nothing at all. A better AoA gauge gives you a full analog display. It's not that there's anything wrong with a stall warning system like most of us have, just that this product might be an improvement. Either way, neither of them is really operating based on airspeed, which has nothing to do with a wing stalling.
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dukeblue219
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Are you slowing to a particular, short-field approach speed and flying the plane based on feel, or are you just slowing until you hear the buzzer? What if you hit a bug one day and it plugs the stall warning vane?
This might be the sort of thing you don't want to publish on the internet.
Samwise
Filing Flight Plan
Sometimes I do that too, when trying to get into short places if conditions are right. It actually works pretty well, in my experience. It is just that an AOA indicator would work better than the stall horn as others have indicated. That being said, most people that operate in and out of such places that require operating very close to the stall do so without an AOA indicator.
Anyone know the answer to this?>> a wing stalls at a slightly different AOA with different flaps settings, right? Does an AOA indicator account for this?
Piloto
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Andrew in the court of law you are not forbidden to do an action unless it is prohibited by law. I am a retired DER on transport aircraft systems.
José
ajstoner21
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Ok then as a der, I would think you should know this then. what gives you the authority to change the way an airplane or its warning system was designed? Educate me. I'm trying to learn here. On the surface, to me, it doesnt sound like something to just arbitrarily adjust.
Is adjusting the stall vane an owner maintenance item? Did you need an A&p or some kind of field approval? As a der, did you have to submit anything to the faa?
I'm not trying to sound like I'm arguing or fighting, im honestly curious how that works.
PilotAlan
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Those requirements are from Part 23. Remember those requirements are only true for Part 23 certified aircraft. CAR 3 and earlier have different requirements (Early CAR3 Cherokees have a stall light on the panel, audible warning not required even now).
Piloto
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I slow down 3nm before touch down looking at the airspeed at which the horn comes up. If the speed looks good (67kts) then I continue with an intermittent horn. The horn on/off is very sensitive to the pitch angle. After crossing the runway end I cut power and raise flaps to improve braking. The limitation to this procedure is crosswinds and gusty conditions.
José
dukeblue219
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Oh, ok. Sounds reasonable. I incorrectly read into your previous post that you were using the stall horn as your primary reference.
Piloto
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My best advice is to read on the FARs. And btw they don't address all the issues related to the certification of an aircraft.
José
ajstoner21
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Thanks for dodging the question.
comanche pilot
Pre-takeoff checklist
I fly a 1960 Comanche 180 which has no stall indicator whatsoever, other than the stall characteristics felt through the airframe and flight controls. I would like to install an AOA indicator eventually.
Samwise
Filing Flight Plan
I primarily use my stall horn as a secondary, primary reference.
Skylane81E
Final Approach
Ok,
What does the Maintenance Manual say?
"Each person performing maintenance, alteration, or preventive maintenance on an aircraft, engine, propeller, or appliance shall use the methods, techniques, and practices prescribed in the current manufacturer’s maintenance manual or Instructions for Continued Airworthiness prepared by its manufacturer, or other methods, techniques, and practices acceptable to the Administrator,"
JohnAJohnson
Cleared for Takeoff
Sam, some AOA indicator systems (all of the big boys, military stuff, the executive jets, etc. and a few small GA experimental systems) take into account flap settings, because it does matter. Most of the GA types, such as the one on my plane (Alpha Systems AOA System Enhanced Classic 4" Horizontal Display, pictures are here, above the ADI), do not. Instead, it is calibrated with the aircraft clean, at Vs, Minimum controllable flight, and a few other speeds. Here's what mine looks like, and what the lights signify:
Today, on base and final I went as slow as I could without going below the 8th light. The AOA indicator is just below my visor and in my peripheral vision. I can do this no matter the fuel, cargo load, or bank angle, and not stall. I am conditioned to push forward when the lights start to go to the left. In an emergency, I can fly a true "Best Glide" regardless of payload, or any other factor just by keeping the 10th light lit. I can climb out like a batoutahell by rotating when the red lights turn to blue and by maintaining the climb with the 8th LED lit. All, regardless of weight or bank angle.
A "Ding Dong" "Getting Slow" comes through the com system if speed is below 8, followed by a "Too Slow" announcement when below the 7th LED.
With any amount of flaps extended, you have a safety margin above and beyond the clean configuration so I don't really need (or would want) to have flap position factored in.
An airspeed indicator cannot do any of this for you.
This system cost me ~ $1,000 and I did the install myself, with a logbook entry only, signed off by an A&P friend.
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patrick wentworth
Pre-takeoff checklist
I added a small glare shield to the top of mine, and put it on top of my 172s glare shield:
[/url] aoa glare shield 2 by Oclipat, on Flickr[/IMG]
A view of how it looks during flight:
[/url] View up the coast on a lovely day- Angle of attack display to the right of Zaon by Oclipat, on Flickr[/IMG]
A view of how it looks during flight:
iflyforfun
Pre-takeoff checklist
Today, on base and final I went as slow as I could without going below the 8th light. The AOA indicator is just below my visor and in my peripheral vision. I can do this no matter the fuel, cargo load, or bank angle, and not stall. I am conditioned to push forward when the lights start to go to the left. In an emergency, I can fly a true "Best Glide" regardless of payload, or any other factor just by keeping the 10th light lit. I can climb out like a batoutahell by rotating when the red lights turn to blue and by maintaining the climb with the 8th LED lit. All, regardless of weight or bank angle.
A "Ding Dong" "Getting Slow" comes through the com system if speed is below 8, followed by a "Too Slow" announcement when below the 7th LED.
You clearly have no idea what your talking about. Well informed people have told us that airspeed is all that matters and is primary. What you're talking about makes no sense. All pilots have every configuration memorized and know exactly how their airplane will handle in all configurations and thus airspeed is primary. Everyone knows the exact airspeed to use at every load condition and bank angle. You must be confused since all this amazing information put right in your peripheral vision that tell the exact relationship between your current angle of attack and the critical angle of attack clearly provides no benefit relative to knowing your airspeed.
JohnAJohnson
Cleared for Takeoff
Nice! Wish I'd have thought of that. I wanted mine above the glare shield, but was worried about glare. You solved that one ingeniously.
Frank
Pre-takeoff checklist
An AOA might also be a good cross reference with the ASI. Consider what would happen if the static port were blocked on a hot day on descent, or if the alternate static port were under the instrument panel and was functioning as the only static port. In either case your static pressure would be low and your ASI would read higher than actual, but not by much. Because of the heat, your groundspeed would look normal or even fast, while your airspeed was lower than you wanted for landing. An AOA would show that your aircraft was not coming in at the desired speed, because the AOA would be higher than normal.
Sam, some AOA indicator systems (all of the big boys, military stuff, the executive jets, etc. and a few small GA experimental systems) take into account flap settings, because it does matter. Most of the GA types, such as the one on my plane (Alpha Systems AOA System Enhanced Classic 4" Horizontal Display, pictures are here, above the ADI), do not. Instead, it is calibrated with the aircraft clean, at Vs, Minimum controllable flight, and a few other speeds. Here's what mine looks like, and what the lights signify:
Today, on base and final I went as slow as I could without going below the 8th light. The AOA indicator is just below my visor and in my peripheral vision. I can do this no matter the fuel, cargo load, or bank angle, and not stall. I am conditioned to push forward when the lights start to go to the left. In an emergency, I can fly a true "Best Glide" regardless of payload, or any other factor just by keeping the 10th light lit. I can climb out like a batoutahell by rotating when the red lights turn to blue and by maintaining the climb with the 8th LED lit. All, regardless of weight or bank angle.
A "Ding Dong" "Getting Slow" comes through the com system if speed is below 8, followed by a "Too Slow" announcement when below the 7th LED.
With any amount of flaps extended, you have a safety margin above and beyond the clean configuration so I don't really need (or would want) to have flap position factored in.
An airspeed indicator cannot do any of this for you.
This system cost me ~ $1,000 and I did the install myself, with a logbook entry only, signed off by an A&P friend.
This has got to be one of the best values in aviation. I love your write-up here.
Maybe some day, you'll be responsible for saving my life, or that of my airplane.
JohnAJohnson
Cleared for Takeoff
I think it is too. Very functional. Last winter I added Vortex Generators and the AOA Indicator system, striving for a controllable plane at the lowest speeds possible. The VGs help some but I can easily live without them. The AOA Indicator however... "From my cold dead hands"...
Piloto
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Sam, some AOA indicator systems (all of the big boys, military stuff, the executive jets, etc. and a few small GA experimental systems) take into account flap settings, because it does matter. Most of the GA types, such as the one on my plane (Alpha Systems AOA System Enhanced Classic 4" Horizontal Display, pictures are here, above the ADI), do not. Instead, it is calibrated with the aircraft clean, at Vs, Minimum controllable flight, and a few other speeds. Here's what mine looks like, and what the lights signify:
Today, on base and final I went as slow as I could without going below the 8th light. The AOA indicator is just below my visor and in my peripheral vision. I can do this no matter the fuel, cargo load, or bank angle, and not stall. I am conditioned to push forward when the lights start to go to the left. In an emergency, I can fly a true "Best Glide" regardless of payload, or any other factor just by keeping the 10th light lit. I can climb out like a batoutahell by rotating when the red lights turn to blue and by maintaining the climb with the 8th LED lit. All, regardless of weight or bank angle.
A "Ding Dong" "Getting Slow" comes through the com system if speed is below 8, followed by a "Too Slow" announcement when below the 7th LED.
With any amount of flaps extended, you have a safety margin above and beyond the clean configuration so I don't really need (or would want) to have flap position factored in.
An airspeed indicator cannot do any of this for you.
This system cost me ~ $1,000 and I did the install myself, with a logbook entry only, signed off by an A&P friend.
Is this device FAA approved? I could not find it either on the PMA, STC or TSO listing under Alpha Systems.
José
gismo
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It is "FAA approved" but only to the extent that the FAA has officially recognized that the installation is a minor modification and does not require a STC.
NineThreeKilo
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NineThreeKilo
Oh jesus!
How about learn to fly the damn plane lol
Maybe if he wasnt soooo busy looking at all the flashing lights and dials he could have hit that center line
How about learn to fly the damn plane lol
Maybe if he wasnt soooo busy looking at all the flashing lights and dials he could have hit that center line