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The unstallable plane that stalled

fearoflanding.com

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Re: The unstallable plane that stalled

#121

Post by stordoff »

gameshot911 wrote: post #99
the__alchemist wrote: post #24

Soapbox: Stall speed is an approximation. It's baffling that GA aircraft don't have one of the most safety-critical measurements: AOA. Stall airspeed varies with a number of factors; this includes the mods described in the article, and weight change from burning fuel, passengers, payload etc. AOA is more invariant to that as a metric for choosing stall speed, speed down final etc.

Gentle reminder that it's good practice to define your acronyms at least once, particularly for audiences they may not be SMES.

SMES = Subject Matter Experts? (searching SMES/SME mostly brings up small and medium-sized enterprises)

Re: The unstallable plane that stalled

#122

Post by ryandrake »

dghlsakjg wrote: post #83
BruinsInSeven wrote: post #58

Earlier quoted context omitted.

How do you determine a margin without some form of a baseline?

You read the operator’s handbook which will give you that information. In a certified aircraft the manufacturer has already done the test flying

Your airplane can also be in the "experimental" category, which generally means "homebuilt" so the stall speeds and characteristics can only be determined through test flight. I made the decision to empirically demonstrate stall speeds on the very first flight of my homebuilt, before attempting to land, so I knew for sure what they were.

Re: The unstallable plane that stalled

#123

Post by rayiner »

jiveturkey wrote: post #44
ambicapter wrote: post #27

> Cessna aircraft have a hinge line on the upper surface. As a result, turning the aileron down causes a sharp angle on the upper surface. The air is unable to flow around such a sharp edge and stays attached. The result is a sudden right wing tip flow separation. Should this say "The air is unable to flow around such a sharp edge and does not stay attached"?

I also caught this seeming error. It stood out especially since the rest of the article is so well written. I don't know anything about flying so I thought it was perhaps a lay misunderstanding on my part.

I think it’s just a typo and the author meant to write “doesn’t stay attached.” In a stall the flow detaches: https://youtu.be/3Ahtc-uePY4?si=CPvBpZwx2YbPLFb3

Re: The unstallable plane that stalled

#124

Post by dabluecaboose »

wizzwizz4 wrote: post #116
buildsjets wrote: post #106

Earlier quoted context omitted.

One of the last aircraft shot down in the European theater of WWII was a Piper Cub that shot down a Fieseler Storch with a .45 pistol. They landed next to the crashed Storch, captured the pilot, and treated his injuries. Then handed him over to the Russians, who I am sure also treated him in accordance with the provisions of the Geneva convention. https://theaviationgeekclub.com/that-time-a-usaaf-piper-l-4h...

Perhaps in accordance with the spirit, but the Geneva convention was in 1949, so those provisions didn't exist yet.

There were several Geneva Conventions prior to the 1949 one; the "Convention relative to the Treatment of Prisoners of War" was signed in 1929.

https://ihl-databases.icrc.org/en/ihl-treaties/gc-pow-1929

Re: The unstallable plane that stalled

#125

Post by the__alchemist »

lovecg wrote: post #117
the__alchemist wrote: post #24

Soapbox: Stall speed is an approximation. It's baffling that GA aircraft don't have one of the most safety-critical measurements: AOA. Stall airspeed varies with a number of factors; this includes the mods described in the article, and weight change from burning fuel, passengers, payload etc. AOA is more invariant to that as a metric for choosing stall speed, speed down final etc.

I’ve been thinking that now that we have glass cockpits the airspeed indicator could automatically reflect the current stall speed under all conditions. I.e. green arc could shrink in a steep turn, etc.

I concur that this would be an equivalently-useful mechanism to displaying AOA directly.

Re: The unstallable plane that stalled

#126

Post by teeray »

the__alchemist wrote: post #24

Soapbox: Stall speed is an approximation. It's baffling that GA aircraft don't have one of the most safety-critical measurements: AOA. Stall airspeed varies with a number of factors; this includes the mods described in the article, and weight change from burning fuel, passengers, payload etc. AOA is more invariant to that as a metric for choosing stall speed, speed down final etc.

My favorite anecdote I heard of from a flight instructor is that of a cargo plane taking off that had some heavy vehicle tied down in its hold. It broke free of its straps during takeoff and rolled to the back of the aircraft, which shifted the CG such that the plane entered an unrecoverable stall and crashed.

Re: The unstallable plane that stalled

#127

Post by schoen »

int_19h wrote: post #87
talkingtab wrote: post #25

Non sequitur from non-pilot: I was once in Duluth, MN in the bitter cold and watched a Cessna with skis (for landing on the frozen lakes of the Boundary Waters) land at the airport. It was the utterly bewildering to see how slowly it was going in the air. And how little distance it took to stop. Short Landing Kit I assume. I've seen ducks and geese come into land on lakes at higher speeds!

There are quite a few planes specifically designed for that kind of thing, e.g. https://en.wikipedia.org/wiki/Antonov_An-2 : "According to the operating handbook, the An-2 has no stall speed. A note from the pilot's handbook reads: "If the engine quits in instrument conditions or at night, the pilot should pull the control column full aft and keep the wings level. The leading-edge slats will snap out at about 64 km/h…

I once got to ride in an An-2 on a tourist sightseeing flight. I've always remembered the sense that the pilot didn't even bother to line up with the runway ahead of time when landing, but simply took a gentle turn onto it upon reaching it, at roughly the speed of a car.

I'm sure this is a slight exaggeration in my memory, but it really was able to fly incredibly slowly and take turns in an incredibly short distance.

Re: The unstallable plane that stalled

#128

Post by schoen »

Wistar wrote: post #72
hinkley wrote: post #38

Earlier quoted context omitted.

Some of those Cessnas have a stall speed so low they can fly backward on a windy day.

I have been a passenger in a C-170 with a STOL kit that flew backwards over a beach on the Washington coast. We landed well behind where we took off. The takeoff and landing were both nearly vertical. Had a steady wind from the ocean.

Was that intentional or unintentional?

Re: The unstallable plane that stalled

#129

Post by SoftTalker »

dghlsakjg wrote: post #52
macintux wrote: post #26

Earlier quoted context omitted.

I'll admit to complete and total ignorance, but: > ...we just use the number the manufacturer publishes. From the article it sounds like this plane was radically modified, to the point where the manufacturer's stall speed would be irrelevant. Why wouldn't you want to confirm for yourself where the speed is after so many changes?

Stall speed depends on so many factors that it can change significantly in a single flight. Weight, altitude, density altitude, angle of attack etc. are all going to have an effect. In other words, sure, you might want to confirm it, but you should also give yourself some margin since you don’t ever really know what the stall speed is until you stall.

As Juan Browne (blancolirio) likes to say, you can stall a wing at any airspeed and any attiude but only one critical angle of attack.

Re: The unstallable plane that stalled

#130

Post by throwawayben »

ambicapter wrote: post #27

> Cessna aircraft have a hinge line on the upper surface. As a result, turning the aileron down causes a sharp angle on the upper surface. The air is unable to flow around such a sharp edge and stays attached. The result is a sudden right wing tip flow separation. Should this say "The air is unable to flow around such a sharp edge and does not stay attached"?

I think it's just the "s" that got added: "the air is unable to [...] stay attached"
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