Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

The unstallable plane that stalled

fearoflanding.com

Post reply on HN
Print view View original

21–30 of 183 posts

Re: The unstallable plane that stalled

#21

Post by cjbgkagh »

golergka wrote: post #11
H8crilA wrote: post #9

Just so we're clear, there's practically no such thing as an "unstallable plane". If some pilot believes that then their license should be revoked. Even jet engines can experience stalls internally on the compressor blades, and even helicopters can experience stalls on their retreating blade. I would compare it to someone believing that their car cannot possibly lose traction. Exceptions, which of course must exist,…

Edit: It seems that I completely misread what Wikipedia said, disregard this comment.

Over 18k An-2 were produced during the time of 1947-2001. It’s an unusual plane due how old it is and that many are still in operation so general stats should take that into account. It’s well known for being nearly impossible to stall with a stall speed of 30 knots - if it does stall it’ll sink at the rate of a parachute which is still faster than you’d want to hit the ground for a landing. It’s also easy to pick up that speed by dipping the nose. If someone crashes an an-2 by stalling it they had to really work hard to do it. Any pilot that did this would be considered unsafely inept to an almost unimaginable degree.

This article is the first I'm hearing of a Cessna 185 being considered unstallable and I do wonder it that title was picked for engagement. Float planes are extra dangerous with more that can go wrong and less margins for safety.

Re: The unstallable plane that stalled

#22

Post by AnimalMuppet »

artine wrote: post #19
lettergram wrote: post #10

Earlier quoted context omitted.

My reflex is to never mandate safety procedures. To put it simply, why should the state use force to mandate something like safety. The implication being if someone refuses the force of the state is used on them… which is definitely not good or improving safety. Mandating the seatbelts exist, sure. Mandating people wear them? Idk about that. In the case of tractors for instance, wearing a seatbelt is downright danger…

Mandating the wearing of seatbelts isn’t entirely about protecting the person wearing the seatbelt. An unbelted occupant becomes a projectile in a sufficiently violent collision, and that projectile can cause harm to people outside of the vehicle.

Or harm to other people inside the vehicle.

Re: The unstallable plane that stalled

#23

Post by andrewaylett »

Waterluvian wrote: post #2

Life jackets seem like they’d be problematic in an enclosed cabin where their use is if you’ve crashed and are taking on water. That’s a bit different compared to a pleasure craft or other vessel that has an outside deck and likely more time to react. But I don’t really know things. Perhaps most float plane emergencies that require life jackets don’t suffer from my perception of the issue.

In my vernacular, I distinguish between "life jackets" and "buoyancy aids". Apparently most people don't.

A buoyancy aid has a foam core, and always provides buoyancy. It's the sort of thing you'd wear while kayaking, but it's far too bulky to want to wear it unless you expect to go in the water.

A life jacket is inflatable, and normally automatic. If you're at risk of falling in, and to do so would be dangerous, you should probably wear one of these -- if you go in the water, it'll inflate automatically. This isn't suitable if you might get wet without wanting the life jacket to inflate, though, and you can get equivalents with manual inflation. The ones you get on aircraft are cheaper than ones you're expected to re-use by wearing multiple times but in neither case will you inflate it multiple times.

The downside of a manually-inflated life-jacket is that you need to be conscious to inflate it. The downside of an automatic life-jacket is that if you get wet, it'll inflate. The downside of the buoyancy aid is that it's always bulky, but on the other hand if you're wearing it, it'll always work.

Re: The unstallable plane that stalled

#24

Post by the__alchemist »

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.

Re: The unstallable plane that stalled

#25

Post by talkingtab »

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!

Re: The unstallable plane that stalled

#26

Post by macintux »

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…

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?

Re: The unstallable plane that stalled

#27

Post by ambicapter »

> 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"?

Re: The unstallable plane that stalled

#28

Post by macintux »

artine wrote: post #19
lettergram wrote: post #10

Earlier quoted context omitted.

My reflex is to never mandate safety procedures. To put it simply, why should the state use force to mandate something like safety. The implication being if someone refuses the force of the state is used on them… which is definitely not good or improving safety. Mandating the seatbelts exist, sure. Mandating people wear them? Idk about that. In the case of tractors for instance, wearing a seatbelt is downright danger…

Mandating the wearing of seatbelts isn’t entirely about protecting the person wearing the seatbelt. An unbelted occupant becomes a projectile in a sufficiently violent collision, and that projectile can cause harm to people outside of the vehicle.

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.

Re: The unstallable plane that stalled

#30

Post by toast0 »

travisjungroth wrote: post #8
ramesh31 wrote: post #3

>“I let it lift off by itself. It was well-trimmed and it lifted off normally by itself.” It sounds like the pilot wasn't fully prepared and engaged to compensate for propeller torque at the moment the aircraft left the surface of the water. At full takeoff power in a single engine aircraft this can be very intense and jarring, particularly with a high pitch ascent and full prop pitch. All it took was a momentary lap…

> The pilot had set the trim so that the aircraft would lift off from the step and begin to climb away. The rudder trim was set almost as far right as it could go. The pilot described the take-off as quick and easy. “I let it lift off by itself. It was well-trimmed and it lifted off normally by itself.” Further down. > The maintenance team discovered an incorrect right wing geometric twist, which was unrelated to the…

Note that the twist had been repaired before the accident.

> When they repaired the damage to the right wing, they also corrected the geometric twist, removing the aircraft’s tendency to roll.

However, since the repairs were completed five days before the accident, the pilot may have set the rudder based on pre-repair experience with the plane. He may not have been informed of the change in twist, or may not have understood it.

Post reply on HN