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The unstallable plane that stalled

fearoflanding.com

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Re: The unstallable plane that stalled

#141

Post by vdqtp3 »

jrockway wrote: post #115
ultrarunner wrote: post #53

Earlier quoted context omitted.

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…

I don't think that's completely true. There is a combination of market size and regulatory burden; not a lot of people are buying GA aircraft (compared to say, the number of people buying iPhones), so there isn't an enormous financial incentive to get people out of their C172 or Bonanza. I also think that these old airplanes are really ships of theseus. Maybe there are some original stickers and seats, but that's abo…

> many people are flying "old" airplanes that have AoA sensors and IFR-certified glass panels and backups

Yes and no. They're out there, but they aren't as common as you'd think or hope. AoA in particular is rare. There's an awful lot of planes that are still running GNS430 or GNS530s (probably more than any other single setup), and more than a few with the original nav/comm equipment like the KX170B. A real glass panel (something like the G1000 or G3X) is really rare in an old plane. Maybe 5-10%?

Re: The unstallable plane that stalled

#142

Post by vdqtp3 »

Dylan16807 wrote: post #120
simonblack wrote: post #100

So many factors that could be blamed in this story. As in every other aircraft accident. But EVERY plane will stall. THERE IS NO SUCH THING AS AN 'UNSTALLABLE' PLANE. I once overloaded a plane inadvertently, by having a heavy load plus a full weight of fuel. At the point of lift-off, the stall-warning started screaming at me as I started to go into the climb. Training kicked in and I pushed the nose down to maintain…

EVERY? Is a plane with a thrust-to-weight ratio over 1 able to stall at full throttle?

Yes

Re: The unstallable plane that stalled

#143

Post by dghlsakjg »

ryandrake wrote: post #122
dghlsakjg wrote: post #83

Earlier quoted context omitted.

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.

I also have a homebuilt, and went and found out my stall speed.

But most homebuilts will still have a stall speed for planes built to plan.

In any case, this is an article about a Cessna. Where the stall speed is in the POH and also marked on the ASI.

Re: The unstallable plane that stalled

#144

Post by analog31 »

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'm not a pilot, but now I'm curious. What do you actually do if the plane stalls, or is about to do so? Other than die?

Re: The unstallable plane that stalled

#145

Post by simonblack »

Dylan16807 wrote: post #120
simonblack wrote: post #100

So many factors that could be blamed in this story. As in every other aircraft accident. But EVERY plane will stall. THERE IS NO SUCH THING AS AN 'UNSTALLABLE' PLANE. I once overloaded a plane inadvertently, by having a heavy load plus a full weight of fuel. At the point of lift-off, the stall-warning started screaming at me as I started to go into the climb. Training kicked in and I pushed the nose down to maintain…

EVERY? Is a plane with a thrust-to-weight ratio over 1 able to stall at full throttle?

A stall is a loss of lift from an aerofoil due to a high Angle of Attack causing a separation of the airflow from the aerofoil. No laminar flow = no lift.

There is such an animal as a high-speed stall, where the angle of attack is greater than 15 degrees. Can happen when a gung-ho pilot makes a high speed dive over his girl-friends house and leaves it too late and too low to pull out gently.

('Gently' being a pull back on the controls such that the Angle of Attack is less than 15 degrees, and curves enough to pull smoothly out of the dive, go into a climb and away to safety.)

He pulls back too hard on the controls. The angle of attack goes over 15 degrees, there is no 'lift' to stop the dive, and the plane continues the trajectory straight into the girl-friend's house.

Whether that has ever actually happened, I do not know. But that was the warning not to be a smart-arse as told to me by my CFI.

Re: The unstallable plane that stalled

#146

Post by Toutouxc »

analog31 wrote: post #144
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'm not a pilot, but now I'm curious. What do you actually do if the plane stalls, or is about to do so? Other than die?

You decrease the angle of attack, i.e. you let the nose drop a bit. When the stall has fully developed into a spin, you perform the spin recovery procedure for your aircraft. Hopefully you still have some altitude left.

Re: The unstallable plane that stalled

#147

Post by JumpCrisscross »

WalterBright wrote: post #68
jcalvinowens wrote: post #17

It is not necessary to empirically determine a specific airplane's stall speed in order to operate it safely. It's not required in the US, we just use the number the manufacturer publishes. It's normal for airplanes of the same model to fly differently: I fly a little fleet of six Citabrias, and their stall characteristics are radically different. You'd expect more uniformity from a modern aluminum airplane, but stil…

> 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…

> An experienced pilot can feel the stall coming on with a bit of a "burble" in the stick

Stall recovery has also been an essential part of my flight training.

Re: The unstallable plane that stalled

#148

Post by jillesvangurp »

buildsjets wrote: post #94

I've been involved in general aviation since the late 1970s, currently commercial/twin/instrument rated, have a degree in aerospace engineering, and do what my username says for a living. So I know airplanes, and why they do the things they do. But an appreciation for what is physically occurring during a stall, how the resulting balance of forces influence the aircraft handling during a stall and recovery, and why t…

Here's another video of an instructor teaching a student falling leave stalls: https://www.youtube.com/watch?v=CpBX-B5mQ18

Not a pilot but I've dabbled a lot with flight simulators over the years. This is one of those things simulators struggle with. Even X-plane will just spin irrecoverably and crash when you try stuff like this.

Re: The unstallable plane that stalled

#149

Post by taneq »

jcalvinowens wrote: post #17

It is not necessary to empirically determine a specific airplane's stall speed in order to operate it safely. It's not required in the US, we just use the number the manufacturer publishes. It's normal for airplanes of the same model to fly differently: I fly a little fleet of six Citabrias, and their stall characteristics are radically different. You'd expect more uniformity from a modern aluminum airplane, but stil…

> It's normal for airplanes of the same model to fly differently

In my experience any equipment this large is effectively handmade, with all the variability implied by this. I'd hope aircraft are made to tighter tolerances than the stuff I work with but a couple of millimeters is often enough to have a noticeable effect on things like actuator travel.

> 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.

This is exactly my takeaway as well. Rather than trying to determine the characteristics of the machine to the n'th degree, assume a realistic degree of variation and design for it accordingly.

Re: The unstallable plane that stalled

#150

Post by hakfoo »

schoen wrote: post #127
int_19h wrote: post #87

Earlier quoted context omitted.

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.

You'd think that sort of handling would make for some interesting use cases-- aerial photography for example, maybe some sorts of cropdusting where the slower speed offers more precision.

I wonder if there's anything else built that fits that market today, since I suppose it's a hard-sell to convince Western pilots and businesses to buy Soviet old-stock.

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