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Stall Warning

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John Pulis

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Nov 18, 2019
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I am looking for a generic stall warning for my home built. I have a vane from a Cherokee but it does not match the wing airfoil so it will be difficult to incorporate. Any suggestions?

JP
captjlp@gmail.com
 

Victor Bravo

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He beat me to it :)

Although I will agree that there are probably SOME homebuilt airplanes where safety would benefit from a buzzer.

What type of homebuilt aircraft are you referring to specifically?
 

Dan Thomas

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Any stall warning or lift reserve indicator (AoA indicator) will need calibrating, which means that test flights to determine the stall and subsequent adjustments to the switch vane or other pickup devices will be necessary.

So one needs to get the test flights done on a new homebuilt, and get comfortable flying it, before starting to explore the stall behavior if one hasn't done much of that before. An instructor aboard would be wise, or go get a bunch of stall/spin training. American students get little or no stall/spin training in the PPL and they shouldn't be fooling with it if they're not proficient. Canadians get much more of it, especially in the CPL training.

Stall warnings or AoA indicators won't save the pilot in some situations. The impulsive buzz job and hard pull-up is an classic way to get a vicious accelerated stall and spin into the ground. The warning stuff goes off right as things come apart. It's proof that too many pilots really don't understand AoA at all.
 

cluttonfred

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A simple stall warning buzzer and light would be easy to cobble together using a limit switch, homemade vane, LED light, buzzer, push to test button, and a 9V battery.

https://www.kitplanes.com/build-your-own-stall-warning-device/

As has been mentioned, a lift reserve indicator would be more useful in providing information valid at all speeds and conditions. You can put one together using a $50 Dwyer 2-5002 Minihelic II Differential Pressure Gauge (0-2" w.c.), some hose, a few brackets and a homemade probe of bent tubing or drilled aluminum or nylon. No power required! I like the ones that tilt the Dwyer gauge 90 degrees and glue a paper wing section to the needle represent angle of attack.

https://www.eaa.org/eaa/news-and-publications/eaa-news-and-aviation-news/bits-and-pieces-newsletter/07-2015-my-pov-of-a-diy-aoa-lri-indicator-fwiw-ymmv-lol

There are other articles and approaches out there and you could certainly have both devices if you wanted.

PS--It would be fun if someone would come up with an off-the-shelf, non-electric audible stall warning kit like the Cessna air horns. Maybe an intake tube on an adjustable bracket connected to a hose that goes to a...kazoo? Seriously!
 
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Mcmark

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Owings, MD
"The one in your britches?"

What he said!!! They all talk to ya. I unplug the buzzer cause I can't hear what it's trying to say. The light I can live with.
 

BJC

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Does the Sidewinder have washout?

An option is to use small stall strips on the inboard wing. Properly placed, they initiate the stall inboard, which is generally desirable, but they also create turbulence that can be felt in the stick before the entire wing stalls.


BJC
 

Daleandee

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Perhaps an aoa indicator can be fitted with a buzzer.
I have an LRI (Lift Reserve Indicator) on my panel and find it quite useful. It does give a very good indication of where the wing is relative to lift and it's accurate without regard to weight, temperature, density altitude, etc. but it doesn't have an audible warning.

I was looking at the Dwyer site and they do have differential pressure gauges that have switches with settable pressure points that drive LED lights on the gauge itself. Don't know what it would take to carry that signal out to a relay for a buzzer but it sounds doable.

http://www.dwyer-inst.com/Product/Pressure/DifferentialPressure/Gage-Switches-Dial/SeriesMP

[edit] or perhaps; http://www.dwyer-inst.com/Product/Pressure/DifferentialPressure/Gage-Switches-Dial/Series3000MR-3000MRS

You would still need the probe but those are pretty easy to make ...

Dale
N319WF
 
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cluttonfred

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Yup, but the switch option adds $200 to the price of the gauge! A 9V battery system or something like that would be a lot cheaper ($20?) and provide a backup to the LRI, which is already a backup to the ASI. ;-)
 

Daleandee

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Yup, but the switch option adds $200 to the price of the gauge! A 9V battery system or something like that would be a lot cheaper ($20?) and provide a backup to the LRI, which is already a backup to the ASI. ;-)
How should I reply:

1) Yes sir ... you are correct! :bow:

2) It's only money and you can't take it with you. :grave:

3) Cut a hole in my leading edge ... have you lost your mind? :)


Dale
N319WF
 

Pops

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I can built one for about $60 of parts using a differential pressure sensor IC that runs on 5 Volts. With LED indication or a meter. Mounted on an inspection panel with 4 penlight batteries or a 12 V to 5 V voltage regulator.
 

dmar836

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I would be interested to know what type of homebuilt this is.
Dave
 

Rockiedog2

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Smith Sidewinder
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It’s a hot looking hi performance retract IIRC
 

Victor Bravo

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OK, this is starting to make more sense for a Smyth Sidewinder than many other HBA's.

A very inexpensive stall warning indicator is a stall strip on the root leading edge of the wings, calibrated to separate the airflow at the root about 5-8 MPH before stall in 1G level flight.

You should hear and feel a strong buffet when it's set up right.

This has the added benefit of forcing the stall to begin at the root, adding a little safety.

The cost will be about 17 cents worth of aluminum and an hour of time, plus another two hours of "trial and error" testing.
 
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BJC

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Does the Sidewinder have washout?

An option is to use small stall strips on the inboard wing. Properly placed, they initiate the stall inboard, which is generally desirable, but they also create turbulence that can be felt in the stick before the entire wing stalls.
OK, this is starting to make more sense for a Smyth Sidewinder than many other HBA's.

A very inexpensive stall warning indicator is a stall strip on the root leading edge of the wings, calibrated to separate the airflow at the root about 5-8 MPH before stsall in 1G level flight.

You should gear and feel a strong buffet when it's set up right.

This has the added benefit of forcing the stall to begin at the root, adding a little safety.

The cost will be about 17 cents worth of aluminum and an hour of time, plus another two hours of "trial and error" testing.
Yup.

BJC
 

Rockiedog2

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The idea is to get at least a tickle of buffet across the horizontal/elevator. From flow separation over the wing root area
 
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Rockiedog2

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You can trial error it with angle and duct tape then if you build it right permanent attach it in the right place with 3M double sided tape
 

Pops

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My Falconar F-12 had no stall warning at about 68 mph and the nose would drop down at about a 45 deg angle and would spin in either direction, to the downwind.
Always had to stop the spin. Then received a notice from the plans seller for a strongly recommended small stall strip on the leading edge about 2' out the wing from the fuselage sides. Then stalled like a Cherokee. Would have never believed the difference along with a nice prestall buffet. Different airplane.
 
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