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The unstallable plane that stalled

fearoflanding.com

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Re: The unstallable plane that stalled

#131

Post by aaronharnly »

teeray wrote: post #126
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.

I’m not sure if this is the one your instructor was referencing, but there was a fairly notorious such event in Afghanistan about a decade ago.

https://en.wikipedia.org/wiki/National_Airlines_Flight_102

https://www.faa.gov/lessons_learned/transport_airplane/accid...

Re: The unstallable plane that stalled

#132

Post by wlonkly »

teeray wrote: post #126
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.

There is a video which makes its way around the Internet regularly of this crash[1] which was attributed to exactly that, killing all seven on board. (Which makes it pretty heavy for an anecdote, admittedly.)

[1] https://en.wikipedia.org/wiki/National_Airlines_Flight_102

Re: The unstallable plane that stalled

#133

Post by foobar1962 »

Waterluvian wrote: post #46
macintux wrote: post #28

Earlier quoted context omitted.

Heck, I recently saw a video (may be an old one) of a driver who fell out of his car while showing off his acceleration. Now the entire car is an uncontrolled projectile.

Interesting that pleasure craft have dead-man switches you can optionally affix. They’re also designed to turn anti-clockwise forever if nobody is at the wheel. I guess because there aren’t seatbelts and these boats are usually open-top.

> pleasure craft... turn anti-clockwise forever if nobody is at the wheel.

That's probably a result of the "paddle wheel" effect of the propellor rotating through the water: a bug not a feature.

Re: The unstallable plane that stalled

#134

Post by KennyBlanken »

peteradio wrote: post #70
WalterBright wrote: post #68

Earlier quoted context omitted.

> nobody should be flying an airplane like this so close to the edge the exact stall speed needs to be known numerically within one knot. An experienced pilot can feel the stall coming on with a bit of a "burble" in the stick. My dad (fighter pilot) told me that knowing exactly where the stall point is is life and death. When you're in a dogfight, the winner often is the one that can turn inside the other. Turning as…

Imagine dogfighting in a Cessna! I imagine the arms to be pilot wielded colt 45s and first officer to be a jug of whiskey.

https://en.wikipedia.org/wiki/Cessna_A-37_Dragonfly

https://en.wikipedia.org/wiki/Cessna_O-2_Skymaster

https://www.airforce-technology.com/projects/ac-208-combat-c...

Re: The unstallable plane that stalled

#135

Post by mango7283 »

stordoff wrote: post #121
gameshot911 wrote: post #99

Earlier quoted context omitted.

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)

Yes, subject matter expert is what it means in that context.

Now I need an SME in linguistics to tell me if the usage as an acronym on that sentence is irony or not.

Re: The unstallable plane that stalled

#136

Post by resolutebat »

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.

The current Geneva Convention was in 1949, but the original Geneva Convention dates back to 1864.

Of course, the previous poster is noting that the USSR blithely disregarded the conventions for others' POWs as well as its own: most returning soldiers were considered traitors to the Motherland and summarily executed or sent to the Gulag to die more slowly.

Re: The unstallable plane that stalled

#137

Post by KennyBlanken »

ultrarunner wrote: post #53
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.

Soapbox next to your soapbox: GA planes are old specifically because of the FAA and their overly restrictive regulations. The cost involved to create an AoA sensor & readout is minimal and at least one company has done it with an IMU only. The cost to certify, sell, and install an AoA sensor (in terms of both money and time waiting to get on the schedule of an FAA-blessed installer) is more than most people find it t…

The FAA is stuck in the 60's because there is a massive industry supporting the ancient technologies in general aviation.

Modern stuff, like you point out, is far more reliable, cheaper, lower power consumption, and more functional. That better reliability means less need for aircraft mechanics and avionics shops.

Nobody would want their discreet component transponder overhauled if it could be replaced with a cheaper unit that uses modern wizardry like logic chips or even (gasp) a microcontroller.

Ditto for leaded fuel air cooled piston engines with manual mixture controls that require teardowns all the time. That bullshit is only still around because Continental and Lycoming want it to.

Re: The unstallable plane that stalled

#138

Post by vdqtp3 »

KolmogorovComp wrote: post #110
dghlsakjg wrote: post #52

Earlier quoted context omitted.

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.

> angle of attack etc This is wrong. The angle of attack is not a parameter of the stall speed, it is the cause of the stall (for a given configuration, assuming well below transonic speed). This is why for example, for precise handling you should use an angle-of-attack indicator (a large majority of fighter jets and more generally military aicraft have it). > you should also give yourself some margin since you don’t…

> The angle of attack is not a parameter of the stall speed, it is the cause of the stall

You're right of course, based on the real definition of angle of attack which is based on relative wind. When people say angle of attack is a parameter of stall speed, they're separating speed from pitch.

This isn't really useful but people seem to struggle with the concept of relative wind, so it's a kind of shorthand.

Re: The unstallable plane that stalled

#139

Post by vdqtp3 »

sokoloff wrote: post #90
hinkley wrote: post #36

Earlier quoted context omitted.

Decreases the stall speed? How does that work?

The Robertson STOL mod droops the ailerons with flaps, changing the effective angle of incidence of the wing. A friend had a Robinson-equipped 182 and we could quite comfortably operate in/out of Marlboro Airport (1650' paved with trees at one end and a fence at the other).

That's not TERRIBLY impressive, considering a stock 182P has a 50' obstacle take off distance of 1350' of at max gross on an ISA day

Re: The unstallable plane that stalled

#140

Post by dghlsakjg »

vdqtp3 wrote: post #138
KolmogorovComp wrote: post #110

Earlier quoted context omitted.

> angle of attack etc This is wrong. The angle of attack is not a parameter of the stall speed, it is the cause of the stall (for a given configuration, assuming well below transonic speed). This is why for example, for precise handling you should use an angle-of-attack indicator (a large majority of fighter jets and more generally military aicraft have it). > you should also give yourself some margin since you don’t…

> The angle of attack is not a parameter of the stall speed, it is the cause of the stall You're right of course, based on the real definition of angle of attack which is based on relative wind. When people say angle of attack is a parameter of stall speed, they're separating speed from pitch. This isn't really useful but people seem to struggle with the concept of relative wind, so it's a kind of shorthand.

This is what I was getting at. Thanks.

Also there’s planes that have slats and other devices that effectively change the angle of attack of the wing.

And then there’s planes that direct prop wash over the wing so that the power on stall speed is much lower than power off despite the angle of attack being different.

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