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Stall warning

Andrew M

Andrew M

Well Known Member
I am at the point where I am prepping all the stall warning stuff and I got to thinking.....
Imagine two warning systems installed, the first standard, set to go off at 3KTS above stall, the second 8KTS above. Each one piped into a different ear (stereo). This would allow me to fly that "sweet spot" low and slow with my head out of the cockpit, and maneuver.
The advantage is I don't have to have an eye on an AOA, this uses another sense and frees up my eyes.
My question is, is this type system airspeed/weight sensitive...example only works at one load and straight and level, or is it as accurate as an AOA, any airspeed and load, bank angle.
Any other questions I should be asking?
 
I cannot speak for other systems, but my Dynon D180 with AOA system has progressive settings... the audio alert gets more intensive as the AOA increases.

Critical AOA is independent of weight, bank angle, and speed.

You can review the appropriate chapter of their installation manual. These are available on their website.

Don
 
Andrew M said:
I am at the point where I am prepping all the stall warning stuff and I got to thinking.....
Imagine two warning systems installed, the first standard, set to go off at 3KTS above stall, the second 8KTS above. Each one piped into a different ear (stereo). This would allow me to fly that "sweet spot" low and slow with my head out of the cockpit, and maneuver.
The advantage is I don't have to have an eye on an AOA, this uses another sense and frees up my eyes.
My question is, is this type system airspeed/weight sensitive...example only works at one load and straight and level, or is it as accurate as an AOA, any airspeed and load, bank angle.
Any other questions I should be asking?
Click to expand...


This might sound a bit harsh but flying at 3 to 8 knots above stall speed low and slow while maneuvering is a regime I would try and avoid. Set your stall warning for 1.15 above stall speed and stay above it flying low and slow. Preferably well above it. There are thousands of reasons why 1.3 times the stall speed is the minimum normal approach speed, most written in blood.
George
 
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I completely disagree. Being able to fly your plane slow is a key skill, especially for landing.

I recently saw this document posted on the thread for the person that flipped his RV over on it's back and I thought it was a great: http://www.vansairforce.net/safety/HowToLandAnRV.pdf

"Any pilot who is capable of controlling his airplane for a prolonged time within 5 mph of stall speed should have little trouble landing."

The only RV I've landed is an RV-10, and I saw no adverse behaviors that would make me think flying at MCA should be avoided. Judgment needs to be used here though. Don't fly at MCA when conditions aren't favorable. I'd recommend going to a good instructor that has some bush flying experience to help you if you're in doubt.

I like your idea about the different audible warnings. With enough practice, you wont need any stall warning indicator because you will "feel" the stall coming by the seat of your pants after you get to know your plane really well.

This will all come in very handy when/if you ever have an emergency off airport landing. You will want to be very slow when you touchdown in that case.

I too often see folks blazing in on fast airplanes taking 3000 ft + to stop a RV/Bonanza/Cessna when they could have executed a proper full stall landing. Sometimes a long landing is intentional to save on long taxis, but my experience is these folks blazing it in get white knuckled when it comes time to fly the airplane slow. I wouldn't want to be a passenger in their plane when it comes time for them to plop it in a field in an emergency.
 
Each person can have their own comfort zone. My aircraft stalls at 50 knots. Flying around low and slow while maneuvering between 53 and 58 knots has little to do with a proper approach and landing. Yes you need to know how to fly slow. You should be comfortable in all modes of flight. At low altitude the only time I want to see 3 knots above stall is with the wheels 1 foot or less above the runway.
I practice slow flight. Actually did a bunch the last two weeks. I don't do it at low altitude. I also practice stalls again at a safe altitude. 3 knots above stall at low altitude while turning ect is a a great way to become a statistic. I don't care how good you are. There is not much to be gained by slowing to 53 knots verses 70 knots where you have some margin for the wife and kids. I don't know anyone who flies approaches at those kind of slow speeds. Starting to slow over the fence to those speeds in a stable configuration for a short landing is a whole different animal then cruising around low and slow and turning at those speeds. One wind gust could ruin your day with a 3 knot margin at 100 feet.

George
 
Reset

All who replied, thanks for helping me consider this idea,
Don, thanks for the link.
Gene, I am flying a Aeronca Chief.:)
George, reset so first starts at 1.3, second to 1.15.:eek:
Anyone, will it perform like AOA, independent of load, airspeed, and bank angle?
 
That depends on what kind of system it is. If it's set by a given airspeed, it'll basically only be really accurate for 1G flight at a specified weight.

A stall-warning tab (like the kit Van's sells) or an AOA-based sysem like Dynon has should work for all G loads and weights.
 
My -9 didn't come with a stall warning and I found the airplane talks so well, it really isn't needed, unless you are deaf.

The AoA in the Dynon, either the classic or SkyView, is spot on, regardless of weight.

I never look at the graphical depiction but rely on the audio beeping, which grows as you approach the stall. It is good enough that I would forgo the weight and complexity of the stall warning that Van's now ships with the kit.
 
I love my AFS AOA, but ...

Would really like a progressive audio warning/ tone. It does give an "angle, angle, push" annunciation at I believe 1.3 Vs. Sure wish advanced could add the tone.
 
Nice

N941WR said:
I never look at the graphical depiction but rely on the audio beeping, which grows as you approach the stall. It is good enough that I would forgo the weight and complexity of the stall warning that Van's now ships with the kit.
Click to expand...

Very interesting. Does it beep beep progressively faster until a single tone at stall?

My intention is to get it flying as low cost as possible, (probably with glass), and add features as experiance and funds allow. I can take the weight hit on the little nose riblet sender mount, and just pull the sender and wires once the pitot is upgraded and AOA added.
 
Andrew M said:
Very interesting. Does it beep beep progressively faster until a single tone at stall?...
Click to expand...
Yes, that is exactly what it does.

Order the Gretz mount. It works great with the Dynon Pitot and allows you to adjust the pitot up or down, as needed. A bit costly but well worth it!

You will also need to run both a pitot and AoA line from the wing into the fuselage. For that I went with the Safe Air 1 kit, including their static port. The only change I made was to mount their static port on the outside of the fuselage.

The only catch is that if you are going to install a SkyView, the pitot and AoA lines need to be run into the tailcone. (Mine go under the seat pan and baggage compartment.)
 
Afs recommends 1.15 above actual stall speed for the angle alert. When you calibrate the unit you can set it to the value you want. If yours is set to 1.3 I would lower it since you would be getting the warning near normal approach speed. You want the warning to come on when you have clearly allowed the aircraft to get slower then desired not as a matter of routine. In the rv6 a full stall landing has the tailwheel touching down before the mains so most 3 points are slightly above stall and that is where I get the warning. If I hear it anytime other then in the flare I know I have done something very wrong and a immediate correction is required.
I agree on a option for a graduated warning however it's not available on the AFS. It is however measuring actual AOA. Many of the other units are giving a derived AOA by measuring AS and G force. If you had a AS failure you would not be able to use the AOA as a backup on those units as you can with the system from AFS.
Now I just need to figure out how to get it to stop talking while rolling out. It gets old trying to hear tower instructions over her voice. I think the dynon version giving actual AOA does a better job in this regard.



George
 
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sailvi767 said:
...Now I just need to figure out how to get it to stop talking while rolling out. It gets old trying to hear tower instructions over her voice. I think the dynon version giving actual AOA does a better job in this regard.
George
Click to expand...
George, check your manual, the SkyView has a setting to turn the thing off when the speed dropped below an adjustable limit.
 
sailvi767 said:
Now I just need to figure out how to get it to stop talking while rolling out. It gets old trying to hear tower instructions over her voice. I
George
Click to expand...

Put a toggle switch in the audio out line and label it "AOA audio".

Bevan
 
Bevan said:
Put a toggle switch in the audio out line and label it "AOA audio".

Bevan
Click to expand...

Only one problem with that, when the NTSB performs the post crash investigation they will be sure to mention the "AOA audio" switch was found in the "off" position. Better to turn it off when the airspeed is below a preset level, a level that is well below the stall, like 35 Kts.
 
hybrid AOA

I have an AOA setup that may be of interest to those with the mechanical LRI system. This is a great backup system because it is independent of aircraft power and pitot. The aircraft can be safely landed with only the LRI and no other instruments.

http://thervjournal.com/liftreserve.htm

However, there is no audible alarm--unless you also have a Dynon in the panel. I found the LRI probe will drive the Dynon AOA display very nicely. So now I have the LRI mechanical display and also the audible alarm originating in the Dynon. The Dynon AOA port is simply teed into the LRI low-pressure line. The LRI is calibrated as usual by flying stalls and adjusting the probe angle until the indicator reads as desired, then the Dynon calibration routine is run. Works like a charm.
 
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