[HN Gopher] The unstallable plane that stalled
___________________________________________________________________
The unstallable plane that stalled
Author : sni
Score : 112 points
Date : 2024-04-28 15:32 UTC (7 hours ago)
(HTM) web link (fearoflanding.com)
(TXT) w3m dump (fearoflanding.com)
| Waterluvian wrote:
| 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.
| BalinKing wrote:
| Indeed, passengers inflating their life jackets too early
| directly caused many of the deaths on Ethiopian Airlines Flight
| 961 [0]. This is why the modern safety briefing includes the
| bit about waiting until you've exited the cabin to inflate your
| life jacket.
|
| I have no clue how this applies to floatplanes, though--I'm
| curious for more details about when the article says "there are
| approved life jackets which could be used to deal with these
| circumstances".
|
| [0] https://en.wikipedia.org/wiki/Ethiopian_Airlines_Flight_961
| Someone wrote:
| > I'm curious for more details about when the article says
| "there are approved life jackets which could be used to deal
| with these circumstances"
|
| In context, that says:
|
| _"Floating and automatically operating life jackets aren't
| practical, specifically because of cases like this where the
| occupants have to dive out of the capsized aircraft in order
| to escape the cabin. However, there are approved life jackets
| which could be used to deal with these circumstances."_
|
| So, I guess there are approved life jackets that do not
| automatically inflate and are neutrally buoyant, thus
| minimally hindering attempts to leave a submerged plane while
| wearing one.
| BalinKing wrote:
| Yeah, I guess my main confusion is whether that means a
| normal (uninflated) airliner life jacket that you're just
| required to put on pre-emptively, or something more
| specialized.
| _trampeltier wrote:
| "Many of the passengers survived the initial crash, but they
| had disregarded, did not understand, or did not hear Leul's
| warning not to inflate their life jackets inside the
| aircraft, causing them to be pushed against the ceiling of
| the fuselage by the inflated life jackets when water flooded
| in. Unable to escape, they drowned."
| Waterluvian wrote:
| Definitely far up the list on horrible ways to die.
| fallingknife wrote:
| That seems strange to me. Why would they not simply take
| off the life jacket and swim out?
| Waterluvian wrote:
| The inflatable ones are often designed to be impossible
| to remove... at least not easily. They inflate into a
| thing that's kind of gently choking you.
| travisjungroth wrote:
| It sounds like the two surviving passengers would have died if
| they had life jackets on. I can't imagine getting out of an
| inverted, flooded 185 cabin with a life jacket on.
|
| I think there was some sense to not requiring life jackets on
| seaplanes. They're much more confined spaces than most pleasure
| boats, not to mention that you're usually _on_ a boat rather
| than _in_ it. The flooding is also usually just about instant
| as the airplane rolls over.
|
| Seems common for reactive legislation to not actually fix the
| situation that's being reacted to. Requiring shoulder harnesses
| during takeoff and landing (which is the case in the US) would
| have actually kept the deceased passenger conscious to escape,
| as said in the report. But they didn't change that law.
| lettergram wrote:
| 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 dangerous. You cannot jump out then, and will be
| killed by a tractor if it flips.
| artine wrote:
| 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.
| AnimalMuppet wrote:
| Or harm to other people _inside_ the vehicle.
| macintux wrote:
| 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.
| Waterluvian wrote:
| 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.
| roywiggins wrote:
| _Everyone_ ends up paying for that, in the form of
| insurance rates.
| lettergram wrote:
| They could just not cover injuries where a seatbelt isn't
| warn.
|
| That said, we have evidence that seatbelt wearing didn't
| impact insurance rates. Literally look at the rates over
| time, even after these laws were enacting, insurance
| rates rose fast as ever
| roywiggins wrote:
| That's not how emergency room care works. It doesn't
| matter whether it's covered or not, you're going to get
| treated; quite likely the hospital ends up eating the
| bill if insurance doesn't pay.
| VS1999 wrote:
| And healthcare insurance if you live in the US, and
| regardless of where you live it clogs up your entire
| healthcare system as Jimmy-no-seatbelt flies into the
| trauma center.
| Jiro wrote:
| That's an argument against a state-run healthcare system.
| It gives the state reason to classify arbitrary things as
| "increases the cost of insurance" and prohibit them.
| roywiggins wrote:
| In countries with universal healthcare you pay too, it's
| just called "taxes" instead.
| Waterluvian wrote:
| Not only that but I think there's also a meaningful
| quality to living in a society with excessive avoidable
| deaths. I personally think it contributes to a "shields
| up, guard up" culture that I've experienced and found
| exhausting.
| user_7832 wrote:
| > In the case of tractors for instance, wearing a seatbelt
| is downright dangerous. You cannot jump out then, and will
| be killed by a tractor if it flips.
|
| The "proper" solution would be to have a rollcage so that
| even a flipped tractor does not crush its occupants. Not
| having a roll cage (presumably to save $) is a result of
| weaker/less mandated safety procedures already. Cars have a
| roof crush test. The solution isn't "jump out when big
| machine starts tipping", it's "protect the humans in the
| machine".
|
| [0] - https://www.consumerreports.org/cro/2012/02/rollover-
| 101/ind...
| tzs wrote:
| It's not just you and your passengers that are less safe
| when you drive without seatbelts.
|
| If you have to make a sudden sharp swerve when driving
| centrifugal forces try to move you from in front of the
| steering wheel, which can make it harder for you to remain
| in control. That increases the danger to nearby vehicles
| and pedestrians (and to nearby property that you might
| hit).
|
| Seat and shoulder belts help keep you in place in front of
| the steering wheel.
| andrewaylett wrote:
| 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.
| eesmith wrote:
| Which vernacular is that?
|
| In boating a life jacket does not need to be inflatable.
| https://uscgboating.org/recreational-boaters/life-jacket-
| wea... says:
|
| > There are four basic design types: Inherent, Inflatable,
| Hybrid, and Special Purpose.
|
| > There are two main classes of PFDs.
|
| > * Those which provide face up in-water support to the user
| regardless of physical conditions (lifejackets).
|
| > * Those which require the user to make swimming and other
| postural movements to position the user with the face out of
| the water (buoyancy aid).
|
| It mentions both "Foam filled lifejackets" and "Inflatable
| lifejackets".
| andrewaylett wrote:
| Seems like it's maybe a UK thing, and my (fairly limited)
| water-sports experience is kayaking and small sailboats.
|
| Isn't the English language fun?
| daedalus_f wrote:
| I've heard that distinction used in the UK.
|
| The other down side of buoyancy aids I was told about is that
| many (most?) will not turn you face up if you are
| unconscious. Gives useful extra mobility for sports but can
| be fatal if the wearer is unconscious.
| brazzy wrote:
| It depends on the design of the specific device. A buoyancy
| aid with a foam collar will do it, but is less comfortable
| to wear. With an inflatable life jacket, to collar is not
| noticeable until it inflates.
| ramesh31 wrote:
| >"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 lapse in keeping the wings level to stall
| out at that speed.
|
| >The indirect causal factor was the pilot's lack of experience
| with stalling the aircraft. He told the investigation that he had
| never stalled the aircraft, which meant that he was unable to
| recognise the stall during the take-off.
|
| It's this lack of stick and rudder skills at the root of the
| incident.
| travisjungroth wrote:
| > 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 hangar roof
| collapse but probably happened during repairs done previously
| in the USA. As a result, the aircraft had a tendency to roll
| and had been uncomfortable to fly because of a lack of aileron
| trim. This might explain why the pilot had the aircraft trimmed
| full right rudder on take-off: to correct for this roll.
|
| He may have actually had too much rudder. They don't say this
| explicitly, but correcting for roll with rudder means you'll be
| cross controlled.
|
| He was dangerously near stall speed without realizing it. Some
| turbulence could cause a small partial stall.
|
| If the airplane was straight, it would have just dropped the
| nose a bit and corrected. But with a twist in one wing and 2/3
| of rudder trim engaged, it's more like it entered a snap roll.
| One wing was stalled, one was still making lift.
|
| The airplane felt fine to the pilot, but it was essentially
| modified to be a snap roll machine. I don't think a stock 185
| would have even been capable of what happened here.
| ramesh31 wrote:
| Kind of my point though. The pilot was disengaged from the
| controls, and relying on trim settings for takeoff.
| Regardless of the different roll characteristics, if he had
| been actively controlling the yoke at the time rather than
| needing a split second to react and correct, the accident
| probably would not have occurred.
| travisjungroth wrote:
| I _really_ doubt that. He was still "actively controlling"
| the yoke. This is a back country 185, it's not like he had
| the autopilot engaged.
|
| In my experience as a flight instructor, pilots having the
| airplane trimmed out properly generally only improved
| control.
| toast0 wrote:
| 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.
| H8crilA wrote:
| 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, include some fly-by-wire
| setups which limit the actuation of flight surfaces so that it
| should be theoretically impossible to put an aircraft in that
| situation, and rumored properties of some abnormal constructions
| like the An-2. Although even there you should repeatedly get
| comfortable with what happens in/around a stall, at least in
| simulators.
|
| The fact that air started to separate and the end of the wing,
| and not at the root, is scary. It means the pilot wouldn't get
| the normal warning in the form of airframe shaking. Bad
| modification.
| golergka wrote:
| Edit: It seems that I completely misread what Wikipedia said,
| disregard this comment.
| H8crilA wrote:
| https://aviation.stackexchange.com/questions/65718/what-
| make...
|
| There are many ways of totalling a plane beyond a stall.
| cjbgkagh wrote:
| 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.
| Tuna-Fish wrote:
| Wasn't AN-2 the plane where the manual advises that if you
| need to land and cannot see your landing site, you should
| fly low and slow and intentionally stall the plane?
| cjbgkagh wrote:
| I don't know but that would make sense, landing at the
| speed of a parachute is better than crashing. Not sure on
| the exact numbers but a parachute sink rate of 5m/s is
| over the usual landing touch down sink rate of 1m/s. I
| would guess at that rate there might still be some damage
| to crew and airframe. If done skillfully I would image it
| would be possible to trade some forward speed for a
| slower sink rate right before touchdown to make for much
| softer landing.
| sfeng wrote:
| Canard aircraft, for example, stall the canard first, resulting
| in the nose dropping, preventing the main wing from ever
| stalling.
| maximilianburke wrote:
| The main wing can still be stalled in a canard; it's not easy
| but it is possible and when it happens it's almost
| unrecoverable because the canard will be stalled too and no
| flying surfaces will have sufficient lift to correct the
| condition. It's a condition called "deep stall"
| brazzy wrote:
| IIRC non-canard aircraft can have this happen when the
| stall causes the plane to fall at an angle where the wake
| turbulence of the wings covers the elevators.
| Wistar wrote:
| Usually in a cross-controlled "slip" where the fuselage is
| held at a fairly dramatic angle relative to the slipstream
| (relative wind) and the fuselage "blanks out" one side of
| the main wing.
| t0mas88 wrote:
| Very bad modification. And wrong (but natural) response from
| the pilot trying to pick up the dropping wing with aileron
| input. That would have made the asymmetric stall worse.
| overspeed wrote:
| > His opinion was that the Cessna 185 simply didn't stall.
|
| There's your problem. Don't opine on operating characteristics of
| a production aircraft. Read the handbook. This incident was
| caused by poor airmanship.
| nickff wrote:
| It seems like he was asked a question which compelled him to
| opine. You seem to be assuming that he went 'out on a limb' of
| his own accord, without any basis for that assumption.
| jcalvinowens wrote:
| 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 still: 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.
|
| The 40lbs of gas I burn flying for an hour decreases the stall
| speed by more than 1mph on those Citabrias I fly.
|
| EDIT: I was mistaken, this isn't a requirement in Europe either.
| macintux wrote:
| 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?
| hluska wrote:
| The plane had a cargo pack and a Robertson STOL. Cargo packs
| are essentially for bush planes and as an example, the 1975
| Skywagon's owners manual even had one diagrammed. Robertson
| STOL's are extremely common in Northern Canada to the point
| that even as a passenger I know about them.
|
| It's nothing too radical.
|
| Edit - Here's a copy of the 1975 owners manual:
|
| https://www.seaplanescenics.com/documents/1975-cessna-185f-p.
| ..
| jcalvinowens wrote:
| My understanding is that in the US, part of the modification
| would be updating the plane's official operating limitations,
| and there could be a new stall number. Still a number from
| the manufacturer, not a number empirically determined by
| testing that specific airplane. For special one-off
| modifications, I don't know: I've always been told that's
| almost impossible with certified airplanes.
|
| One Citabria I've flown had vortex generators installed on
| the leading edge of the wings, but the club sold it over a
| year ago and I don't remember if it listed a modified stall
| speed. I do remember it said "not airworthy if more than N of
| the VGs are broken off", I think it was three?
| dghlsakjg wrote:
| 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.
| BruinsInSeven wrote:
| How do you determine a margin without some form of a
| baseline?
| dghlsakjg wrote:
| You read the operator's handbook which will give you that
| information.
|
| In a certified aircraft the manufacturer has already done
| the test flying
| WalterBright wrote:
| Don't forget ice!
| greedo wrote:
| And temperature...
| KolmogorovComp wrote:
| > 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
| ever really know what the stall speed is until you stall
|
| The manufacter speed already take into account the afore-
| mentioned parameters into account, and the resulting speed
| is the worst case scenario, if not told otherwise (usually
| max weight, max forward CG).
|
| One should not fly with an arbitrary speed margin, but
| instead use well-known speedq (1.3Vs, 1.45Vs, where
| Vs=stall speed in the given config) depending on the flight
| phase, and remember well the bank angle limit associated
| with them.
| dramm wrote:
| Radical has all the wrong implications. It's a "major
| alteration" in a regulatory sense, done from an approved kit
| of parts, with a very well documented installation and post-
| installation operation and maintenance procedures.
|
| The aircraft was modified with a Robertson STOL kit. A common
| type of modification to make to a "bush aircraft". In the USA
| the modification is covered by an STC (Supplemental Type
| Certificate), the installation needs to be supervised and
| approved by an A&P technician with IA (Inspection Authority).
| The STC will modify the airspeed indicator markings,
| including the stall speed markings (bottom of green and white
| arcs), and modify the approved flight manual/pilot operating
| handbook and maintenance documentation for the aircraft.
| Since this is a major alteration (in a 14CFR regulatory
| sense) that modifies the flight characteristics of the
| aircraft it needs to be test flown after the work, and the
| STC will also separately requires this. I expect/hope the STC
| includes instructions for checking stall characteristics
| including airspeed. In European countries a similar level of
| regulation/documentation is followed based on the USA STC.
|
| Give the description of the pilot's sad lack of understanding
| of basic operation of the aircraft I am doubting they even
| read the pilot operating handbook.
| avianlyric wrote:
| As noted in the article, the plane had been modified with
| far more than just the STOL kit.
|
| > A further issue was that his Cessna 185 had been
| extensively modified. The addition of floats, cargo pack,
| short take-off and landing kit and a three-blade propeller
| had never had their combined effect documented.
|
| That's a lot of things that modify the flight
| characteristics of a plane, all interacting together in
| what seems to be a previously untested configuration.
|
| I can completely see how each individual modification might
| modify the planes flight characteristics in a well know
| manner. But I struggle to see how anyone could
| realistically predict the result of all the modifications
| without some basic empirical testing.
| hinkley wrote:
| Decreases the stall speed? How does that work?
| ketralnis wrote:
| Things that can influence stall speed include weight, power,
| center of gravity, flaps/landing gear configuration, and
| more.
|
| Why? Well, stall speed isn't a real thing. There isn't a
| _speed_ at which you stall, that 's not how it works. It's a
| convenient short-hand that we use for the more complicated
| reality. The physical reality is that stalls happen at a
| particular _angle of attack_ (AOA) into the apparent wind.
| That is, the angle of your wings relative to the airflow. Up
| to the critical angle a higher AOA means more lift to
| counteract gravity. As you slow down you generate less lift
| because there 's less airflow over the wings. So as you slow
| down, in order to generate a similar amount of lift you have
| to increase your AOA. If you keep slowing down and adjusting
| your AOA to compensate, you'll reach a speed that's low
| enough and therefore AOA high enough that adding more AOA no
| longer adds more lift (the air no longer flows smoothly over
| the wing). That's the stall speed, the speed at which more
| AOA no longer generates more lift. But it's the AOA that's
| the problem, not the airspeed.
|
| In addition to lower speeds needing more AOA, you also need a
| higher AOA if you weigh more. A wrong but illustrative way to
| think about it might be that you need the engine's thrust
| pointed more towards the ground the more you weigh. That
| means that as you burn fuel (lose weight) the AOA that will
| stall you doesn't change, but the excess AOA available due to
| your weight-change does so in effect the air speed at which
| you would be near the critical AOA to stay airborn does
| change.
|
| Stall speed is still a useful concept especially while
| landing but it's misleading outside of landing and when
| anything else is remotely unusual like weight or
| modifications to the plane. For this reason the FAA has been
| trying to get AOA indicators installed in planes and to train
| pilots to look at those instead of thinking about stall
| speeds https://www.faa.gov/sites/faa.gov/files/2022-01/Angle%
| 20of%2...
| t0mas88 wrote:
| The published speed is at maximum takeoff weight, with the
| most unfavourable center of gravity (usually most forward)
| and idle power
|
| If the conditions are better (not at max weight, rear center
| of gravity, engine power adding more airflow over the wings)
| you can fly below the published stall speed number.
| hinkley wrote:
| Yeah I was thinking backward. Lower stall speed is better,
| not worse behavior.
| matheusmoreira wrote:
| This is a good resource:
|
| https://ciechanow.ski/airfoil/
|
| Useful to think of the airplane as standing still while the
| engine accelerates the air around it. To fly, you need the
| air to move over the wings quickly and in the right
| direction.
|
| You can sort of trade how fast you need the air to go for how
| ideally the air is flowing over the wings. If you angle the
| wings just right against the air flow, and/or you bend them
| out of shape just right with flaps, you can slow down _a lot_
| while relying on the air itself to carry your plane. If you
| 're flying against the airflow, you need to go faster.
|
| This is usually done during take off and landing. The pilot
| lowers the flaps when approaching to land and flares the
| aircraft before touchdown, all to make the air flow
| efficiently into the wings, thereby allowing the aircraft to
| slow down without falling straight down like a stone.
|
| That's why weather is so important for flights. Pilots need
| to be ready to call TOGA and go maximum thrust at a moment's
| notice just in case some crosswind or heat wave or something
| screws up the direction of the air flow just as they're about
| to land. Many an admiral cloudberg article has been written
| due to that sort of thing. You angle the plane just right,
| slow it down just to the edge of stalling, then some
| phenomenon happens and increases your stall speed past your
| current speed...
| sokoloff wrote:
| 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).
| t0mas88 wrote:
| European pilot here :) it's also not a European thing. It works
| the same here as it does in the US, you use the published
| number in the flight manual.
|
| But this plane had significant modifications done. And if you
| do things that significantly change performance, you'll need to
| get updated performance data. Or the provider of the
| supplemental type certificate that allows the modification has
| to provide an updated flight manual with that data.
| WalterBright wrote:
| > 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 tight as you can requires getting exactly on that
| edge of the burble.
|
| It's the same thing as in automobile and motorcycle racing. How
| close you can get to a slide without sliding is the difference
| between victory and ignominy.
| peteradio wrote:
| Imagine dogfighting in a Cessna! I imagine the arms to be
| pilot wielded colt 45s and first officer to be a jug of
| whiskey.
| logical_proof wrote:
| Love this description lol
| buildsjets wrote:
| 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...
| dekhn wrote:
| if you like that idea and science fiction, see the second
| book in the Greatwinter trilogy by Sean McMullen (read them
| in order, though)
| jcalvinowens wrote:
| Sure, that's why I said "airplane like this": in car terms,
| the plane we're talking about here is a minivan.
| sokoloff wrote:
| > 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
|
| Citabria's are often flown in aerobatics (Citabria backwards is
| airbatic and for a while, they were the only aerobatic aircraft
| being commercially manufactured in the US) and a lot of
| aerobatic maneuvers involve stalling the wing.
| SR2Z wrote:
| Yes, but anyone doing aerobatics so close to the ground that
| they can't recover from a stall is understood to be doing
| that at their own risk.
|
| Anyone doing the above with unfavorable wind has a death
| wish.
| jcalvinowens wrote:
| You don't really look at the airspeed indicator for that, you
| _feel_ the stall in the reversible controls. That feel is
| incredibly precise.
| leobg wrote:
| Stick and Rudder (Wolfgang Langewiesche 1972):
|
| > There are situations in flying when he who "ducks," he who
| flinches, is lost. The most important example is the recovery
| from a stall at low altitude-getting that stick forward and
| pointing the nose at the ground; that does require courage, and
| no two ways about it. [...] It might seem that learning to fly
| the conventional airplane must necessarily be mostly a matter of
| drill, like animal training, like making a dog not eat when he
| wants to eat, making him jump through a flaming hoop when he does
| not want to jump. [...] But another view of the problem is also
| possible. It may be that our common sense, our natural reactions
| mislead us simply because they are working on the basis of wrong
| ideas in our minds concerning the wing and how it really flies,
| the controls and what they really do. [...] Perhaps what happens
| when the beginner reacts wrongly in an airplane is similar to
| what happened in the early days of the automobile, when a man
| trying to stop in an emergency would pull back on the wheel as if
| he had reins in his hands and would even yell "Whoa." There was
| nothing really wrong with his reactions, with his intentions; the
| only thing wrong was the image in his head that made him see the
| automobile as a sort of mechanized horse, to be controlled as
| horses are controlled. Had he clearly seen in his mind's eye the
| mechanical arrangement we take for granted now-the clutch that
| can disconnect the motor, the brakes that can clamp down on the
| wheels; had he clearly appreciated that the thing was a machine
| and had no soul at all, not even a horse's soul, and that thus
| there was no use in speaking to it-he would then have done the
| right thing without difficulty. It may be that, if we could only
| understand the wing clearly enough, see its working vividly
| enough, it would no longer seem to behave contrary to common
| sense; we should then expect it to behave as it does behave. We
| could then simply follow our impulses and "instincts." Flying is
| done largely with one's imagination! If one's images of the
| airplane are correct, one's behavior in the airplane will quite
| naturally and effortlessly also be correct.
| the__alchemist wrote:
| 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.
| sumofproducts wrote:
| I was very skeptical of this until I had the chance to fly one
| of those brand-new C172 models that come equipped with 'em.
| They're so convenient!
|
| Sure, ye olde haptic feedback + inner ear + stall horn/shaker
| combo has always worked for me--but if you are a new or
| overwhelmed or complacent or unlucky pilot, having a big angry
| indicator sitting atop the glare shield furiously (visually &
| audibly) informing you of the approaching cross-control stall
| that is about to bury you in your base-to-final grave makes
| danger IMPOSSIBLE to miss.
|
| The LEDs were bright enough to be clearly visible even under
| direct sun, but the Geiger-esque clicking and chattering
| increasing in urgency as I approached critical AoA made it for
| me. No need to put your head down or even alter your scan to
| include it: you can hear trouble coming!
| ultrarunner wrote:
| 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 to be
| worth. Food for thought: this also applies to shoulder
| harnesses in many cases.
|
| Aviation could be cheaper, safer, and better in general if the
| FAA was not stuck in the 60s.
| sokoloff wrote:
| AoA indicators are able to be installed in certified aircraft
| as minor modifications, per the FAA policy from 2014.
|
| There are FAA regulations that are overly conservative IMO,
| but I think the FAA has a sensible stance on AoA indicators.
| almostnormal wrote:
| CS-SC251c in the EU.
| jrockway wrote:
| 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 about it. Safety and avionics upgrades on these
| old airframes are definitely in the financial reach of many
| readers of this forum, and I'm sure many people are flying
| "old" airplanes that have AoA sensors and IFR-certified glass
| panels and backups. Day to day they probably feel a lot like
| airline pilots.
| andoando wrote:
| But we got a nice tea kettle whistle to tell us were about to
| die.
| buildsjets wrote:
| I've always thought it sounded like a kazoo. Or sometimes a
| harmonica.
|
| But I like the imagery of a a little tea kettle on a hob
| under the panel.
| gameshot911 wrote:
| Gentle reminder that it's good practice to define your acronyms
| at least once, particularly for audiences they may not be SMES.
| talkingtab wrote:
| 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!
| hinkley wrote:
| Some of those Cessnas have a stall speed so low they can fly
| backward on a windy day.
| Wistar wrote:
| 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.
| 1letterunixname wrote:
| You forgot to unfurl the course sails and get out and push.
| 20after4 wrote:
| I'm sure it's happened a few times with unsecured planes in a
| windstorm.
|
| It would be a neat trick to see a pilot pull that off
| intentionally and under control.
| int_19h wrote:
| 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 (40 mph) and
| when the airplane slows to a forward speed of about 40 km/h (25
| mph), the airplane will sink at about a parachute descent rate
| until the aircraft hits the ground." As such, pilots of the
| An-2 have stated that they are capable of flying the aircraft
| in full control at 48 km/h (30 mph) ... This slow stall speed
| makes it possible for the aircraft to fly backwards relative to
| the ground: if the aircraft is pointed into a headwind of
| roughly 56 km/h (35 mph), it will travel backwards at 8 km/h (5
| mph) whilst under full control."
| 1letterunixname wrote:
| A certain STOL-modified Piper Cub barely needs a runway longer
| than a driveway. https://youtu.be/hPakbghLe38
| ambicapter wrote:
| > 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"?
| jiveturkey wrote:
| 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.
| cromulent wrote:
| The report of the investigation:
|
| https://turvallisuustutkinta.fi/material/attachments/otkes/t...
| TomK32 wrote:
| It's amazing how much work they've put into creating this quite
| unique configuration just to find out the stall behaviour.
| ordu wrote:
| I believe it is normal for flight incidents investigations. I
| read a lot of Kyra Dempsey writings[1] on accidents and there
| is a lot of examples of a detailed investigations probing all
| possible hypotheses even those which are not very probable.
| They need to know for sure.
|
| [1] https://admiralcloudberg.medium.com/
| dramm wrote:
| What a horrible click-bait title. There is nothing about a C185
| or one modified with a STOL kit that is unstallable. A better
| title would be something like "Clueless pilot stalls aircraft.
| Which unfortunately is not an uncommon thing.
| LeifCarrotson wrote:
| I wonder if they're practicing modern journalism strategies
| that are worried about libel suits? Or it's so obviously satire
| to them that they don't need to clarify? When they write:
|
| > _However, the investigation discovered that despite his
| experience, he had never practised stall recovery on the Cessna
| 185. The pilot had no knowledge of the aircraft's stall
| behaviour at all. His opinion was that the Cessna 185 simply
| didn't stall._
|
| In writing targeted at lay readers, I would expect this to be
| followed with something like "This opinion, of course, is
| complete lunacy. All aircraft can stall. Practicing stall
| recovery should be a normal part of pilot training."
| ordu wrote:
| I believe this article doesn't need such clarifications. It
| says in unambiguous terms that Cessna had stalled, with an
| obvious logical implication that a pilot was dead wrong. The
| article even discusses differences of how the stall occurs in
| modified and unmodified versions of a plane. To not get the
| message a reader must be not a lay person, but an
| exceptionally dumb one.
| axus wrote:
| It was the pilot who believed this Cessna "never stalled". And
| so he did not recognize and had no idea what to do when it did.
| tomaskafka wrote:
| "As a result, the aircraft pitches up unless the pilot controls
| the flight path using the elevator. If this pitch up is not
| controlled, the aircraft is at risk of exceeding the stall angle
| of attack."
|
| This has been happening for me in MSFS, and I considered it a
| really weird behavior - why can't I take off in a same way as
| from the runway? Now I know.
| t0mas88 wrote:
| > It is common for flight operations in the wilderness to have
| the take-off weight close to the maximum.
|
| It is common for the majority of flights in general to have take-
| off weight close to the maximum, not just bush flying.
|
| The same goes for the remark that "center or gravity was close to
| the forward limit", that sounds like a risk but it is not. If
| it's exactly at the limit, that's fine and perfectly safe to fly.
| If it's over the limit, it's illegal to fly.
| buildsjets wrote:
| It is not uncommon for flight operations in the wilderness to
| be up to 15% heavier than the certified maximum limit, and
| still be perfectly legal. Relevant regulation: 14 CFR SS 91.323
| -
| https://www.ecfr.gov/current/title-14/chapter-I/subchapter-F...
| t0mas88 wrote:
| Interesting, tnx. We don't have such a general exception in
| EASA. Only possible with a special permit and a lot of
| paperwork for a ferry flight or similar.
| buildsjets wrote:
| It's magical how the airframe gets 15% stronger just by
| arriving in Alaska!
| BXLE_1-1-BitIs1 wrote:
| Stalling with a wing drop at 15m, you will be hitting the ground
| or water before recovering, even with perfect technique.
|
| It seems his takeoff technique was adequate for thousands of
| takeoffs until a gust hit at the wrong time and place and yanked
| the rug out from under him.
| 1letterunixname wrote:
| The mindset of that pilot inherently dangerous and complacent. A
| friend of mine was a casual GA pilot in college. He was
| constantly practicing failure modes and making contingency plans
| such as engine failure at different points of takeoff and
| practicing stall recovery at various speeds, altitudes, bank
| angles, and AoAs.
| buildsjets wrote:
| 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 the recovery must be handled
| in a specific sequence to avoid overstressing the airplane or
| losing directional control, are not intuitive and have never been
| a very strong point among pilots, or even instructors. As a
| result, you have poorly educated instructors passing along old
| folk tales to new pilots, who then take them as gospel.
|
| This has been exacerbated over the years by the segregation of
| the pilot population into two separate groups, who often receive
| training that stresses different objectives.
|
| Part 141 flight schools are the typical staring point for airline
| pilots. In these schools, even when flying little Pipers and
| Cessnas, stall avoidance is the primary method which is taught.
| Pilots are instructed to initiate a "stall recovery" at the
| "first indication of stall", which is taught to be stall warning
| horn indicator sound happening. The goal is to recover with no
| loss of altitude, and the technique is to add power to power out
| of the indicated stall immediately upon hearing the stall warning
| indicator, and use the elevator to keep the airplane at the same
| altitude. The problem is that the stall warning horn indicator
| typical starts sounding about 5 knots in advance of a fully
| developed stall when flying more or less straight and level. So
| these pilots never experience a fully developed stall, just an
| approach-to-stall, and often develop an extreme fear of entering
| an actual stall. This recovery technique also only works in an
| airliner in the case of an approach-to-stall or at most a very
| shallow stall. To recover an airliner from a fully developed
| stall, you must use the same techniques as you do in a Cessna
| 172, which is to drop the nose to lower the angle of attach and
| trade some altitude in for airspeed. This was vividly
| demonstrated by the five co-captains of Air France Flight 447,
| who tried to power their way out of a fully developed stall, that
| could have been easily recovered from by a typical student pilot
| using Cessna techniques.
|
| I learned to fly in a Part 61 school, which typically are things
| like flying clubs and independent flight instructors teaching
| people who mostly fly for fun, or for light commercial use like
| charters, and will be mostly flying light propeller aircraft. In
| this environment, the aircraft have a much lower power to weight
| ratio, you cannot power your way out of even an approach-to-
| stall. Instead of stall avoidance, stall entry, recovery, and
| exit is taught. Instead of the goal being to minimizing altitude
| loss, maximizing aircraft control is taught. The goal is to
| prevent a poorly-handled stall from developing into a spin, which
| will usually result in a fatal accident like this one did. So if
| you learned in a Part 61 school, instead of starting recovery as
| soon as you heard the stall horn, you kept going until a full
| stall, and the expectation is that the student would say "STALL"
| when they identified that the airplane had entered a fully
| developed stall, based on changes in the handling characteristics
| and sudden drop in altitude. The student would then initiate a
| recovery by pushing the nose down to reduce the angle of attack,
| smoothly adding power and right rudder at the same time to add
| airspeed and counteract for yaw, and then recover from the
| resulting shallow dive with no more than 200' loss of altitude,
| but keeping the airplane under perfect directional control. So in
| part 61 schools, instead of recovering as soon as you heard the
| horn blip, you spent a lot of time with it going off in your ear.
| In fact my instructor used to pull the circuit breaker for it
| after it went off, as we already knew we were going to be
| spending a lot of time in an incipient stall condition, and could
| tell more from the changes in sound of the air going past us than
| some buzzer. But even in this environment, there are some
| instructors who just don't like doing stalls, so spend the
| minimum required amount of time teaching and practicing them.
|
| If you are a pilot who learned in a Part 141 school, or in Part
| 61 but didn't spend a lot of time in deep stalls, one of the best
| investments you could make in yourself is to find an experienced
| instructor and ask to spend an hour doing "Falling Leaf" stalls,
| where you alternately keep the airplane in a deep stalled
| condition, and then recover while you really practice your rudder
| coordination. They're fun! You will loose your fear of stalls and
| develop skills/instincts that might save you in an situation like
| this pilot ended up in. You don't need a fancy aerobatic
| airplane, a Cessna 172 will work fine, but I prefer a 150 because
| it does not handle like a minivan.
|
| Here's a good video on YouTubes to show what it would typically
| look and sound like during a lesson:
| https://www.youtube.com/watch?v=Ocv2YDLk5t0 Note that this is not
| an example of a perfectly textbook executed falling leaf, it's a
| student pilot performing them with varying degrees of competence
| (some good, some not.. keep them ailerons neutral!) and an
| proficient instructor allowing them to make some mistakes and
| experiment within the safe bounds of aircraft controlability. So
| a typical lesson with a good instructor.
| howard941 wrote:
| > instead of recovering as soon as you heard the horn blip, you
| spent a lot of time with it going off in your ear. In fact my
| instructor used to pull the circuit breaker for it after it
| went off, as we already knew we were going to be spending a lot
| of time in an incipient stall condition, and could tell more
| from the changes in sound of the air going past us than some
| buzzer.
|
| This is sort of the way I was taught. In primary training we'd
| always wind up doing a lot of minimum controllable airspeed
| work and then move on to power on stalls/departures and low
| power stalls/approaches. Recognition was pretty easy with the
| buffeting followed by the nose dropping. Coordination and
| control were the goals. Later on we'd also do accelerated
| stalls. I _hated_ doing low speed work so my instructor made us
| do it every time even after I started doing them without him in
| the airplane.
| simonblack wrote:
| 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 flying speed. Practically no
| climb at all possible though. I did a very quick and low circuit,
| landed and offloaded.
|
| Funny how those little tense moments stay with you for ever. :)
| rayiner wrote:
| I love the thoroughness annd precision of aircraft accident
| investigations. Amazing watching these folks do their jobs.
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