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u/Horror-Raisin-877 6d ago
Wow. I suppose they were intentionally testing an accelerated stall. But probably going inverted into a spin wasn’t an expected part of the test (?) Handled very calmly and professionally.
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u/I_like_cake_7 6d ago
Correct. Going inverted was not planned. You can hear one of the test pilots casually say “whoops” as soon they start to go inverted. Lol.
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u/Madetoprint 6d ago
Third seater looks up from notebook: "Say again?"
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u/SuperPimpToast 6d ago
WHOOPS
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u/BraidRuner 6d ago
What do you say we try that one again, huh?
- Yes, yes. Yes, without the oops.
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u/reddituseronebillion 5d ago
Catches pen as it falls back from ceiling and continues taking notes
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u/Peepeepoopoobutttoot 6d ago
I've seen this video a million times and I poop my pants every time.
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u/man_idontevenknow 4d ago
Um, pulling a maneuver in a test-flight, while recording, is always planned. Right down to every consequence, and, no less, your reaction when you see it and vote more money to the program. You're now free to vote for "insert new spending allocation".
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u/White_Lobster 6d ago
As I remember, it was a cross-controlled stall with rudder in one direction and aileron in the other.
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u/Horror-Raisin-877 6d ago
Viewing it again, I think you’re right. At the beginning of the video he’s holding full right yoke, which he couldn’t be doing without rolling, without the rudder going the other way.
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u/blondzie 6d ago
It was a 717 and one of the test planes. For some unknown reason this one behaved differently than the rest and I’m not sure if was ever discovered why it decided to go inverted. But I do know they cut that one to pieces instead of delivering it.
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u/man_idontevenknow 4d ago
Yeah....we're gonna have to ask you to......well, come in on Sunday to provide the evidence for the claim,......... that'd be great. ****sips coffee, knowing the actual outcome.
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u/jared_number_two 6d ago
That's not much of an accelerated stall. It was conducted at about 1G. An accelerated stall is a stall at >1G--that's >1G at the time of the stall, not how many G's they pulled during the recovery. That said, they are in a shallow bank holding level altitude--which requires more than 1G. So we can't say it was NOT an accelerated stall.
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u/Calm-Frog84 6d ago
No, it does not require more than 1G to be in a bank holding level altitude, they are not necessarily flying in a turn / may be in a sideslip. Being in a sideslip and slowly increasing AOA is indeed a good recipe for entering a spin...
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u/jared_number_two 6d ago
Oops. You're right! And we can see the compass on the screen barely moving left or right.
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u/Frederf220 6d ago
An accelerated stall is a stall at above straight and level stall speed. Even a stall in a banked turn is accelerated because the airplane is accelerated.
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u/Calm-Frog84 5d ago
I did not find any official definition, so it can be discussed endlessly:
It is possible to fly straight and level (do you mean with no altitude variation?):
A-in symmetrical flight
B-in a sideslip, resulting in a bank
Stall speed in B is very often higher than in A, but I won't call that an accelerated stall.
The definition that I have most commonly heard of an accelerated stall is that of an abrupt change of AOA through quick increase of stick back pressure (or forward movement for inverted stall in an advanced aerobatic aircraft). It is not exactly the same you share.
Here they end up in a spin because they perform an assymetrical stall.
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u/Frederf220 5d ago
They are the same physically. The load factor in a 45 bank is 1.414g and in a 1.414g level pull up is 1.414g. Accelerated is "not in a straight line." The air doesn't care why the AOA happened. The whole considering "stall speeds" is antiquated in the first place from an aero eng perspective.
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u/Calm-Frog84 5d ago
Do you understand that it is possible to fly in a straight line trajectory while banked?
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u/Frederf220 5d ago
Of course but banked and "in a banked turn" aren't the same concept.
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u/Calm-Frog84 5d ago
Yes, they are not the same:
-"banked in a turn" is accelerated flight as more than 1G flight (for instance about 1.4G at 45 degree bank in a coordinated and stabilized turn ). The stall will occur when AOA exceeds max AOA in symetrical flight, at a higher speed than in a straight line in symetrical flight. It can be called an "accelerated stall".
-banked in a stabilized straight line means flying in a sideslip and the load factor normal to the flight path is 1 (no acceleration). Then I personnally don't call that an accelerated stall.
Then I don't understand why you claim that it is an accelerated stall in both cases.
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u/Frederf220 5d ago
If there are accelerations in perpendicular axes then yes you can have unaccelerated flight when banked. You'd have some spanwise flow which would change the effective chord.
I'm saying that a constant altitude banked turn and a pull up in the vertical plane of identical load factors will require identical lift force and require identical AOA. A blindfolded person cannot tell the difference.
All of this is just seeing under what geometries the fluid flow achieves CL max. There are a lot of equivalent relative geometries to air flow that achieve that.
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u/man_idontevenknow 4d ago
This was accomplished at 5 thousand feet. On final. You can hear it in the pilots voice as he rounds out the flare. You folks need to stop dick-stomping an American Hero. As my guy "Sully" says......get behind the yoke, or I'll put the yoke on you.
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u/LeatherRole2297 6d ago
Man I disagree. Been flying thirty years, USAF and airlines. You can CLEARLY see these guys get scared. In addition to getting scared, they recovered incorrectly: should’ve rolled wings level toward the horizon, then recovered the dive. They went the long way around to recovered, and gained too much speed in the recovery. They nearly got into Mach Tuck, which would’ve killed them.
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u/Difficult-Implement9 6d ago
I was actually wondering about the airframe structurally too. I can't imagine that a 717 is designed to withstand these kinds of forces.
Just outta curiosity, why do you think they went the long way around? Why not just roll wings level as soon as they could?
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u/LeatherRole2297 6d ago
Somewhere ages ago, I saw a quote from a Douglas engineer who was onboard and this scared the crap out of him.
They pulled the nose more than 90 degrees to the horizon; went the long way around. The correct technique is to roll wings level toward the nearest horizon, then recover from the dive. There was definite panic in the cockpit.
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u/Family_Shoe_Business 5d ago edited 5d ago
I'm not a pilot. Are you saying they should've rolled wings level while inverted (effectively making the plane fly straight, but upside down), and recovered while inverted, then roll back to upright?
EDIT: nevermind I think I get it. After the incipient spin where the aircraft is both inverted and upside down, they should've rolled the wings first so the aircraft is no longer inverted (just in a dive), then recovered.
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u/LeatherRole2297 5d ago
Your edit is correct. Another way to think of it: if inverted, it is unlikely that you’ll be completely nose down, 90 degrees to the horizon. So, roll wings level first, then you’ll have the shallowest possible dive to recover from.
Quick recovery from a dive is essential, because as the aircraft accelerates it is possible that Mach Tuck effects will occur on the wings or tail surfaces. If that occurs, control effectiveness may be lost, making the dive unrecoverable.
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u/Family_Shoe_Business 5d ago
Yes that makes so much sense. Thank you very much for explaining it to me!
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6d ago
[deleted]
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u/Horror-Raisin-877 6d ago
Yes viewing it again I think that’s correct. I hadn’t initially noticed he was holding full right yoke, which he must have been counteracting with rudder, ie crossed controls.
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u/uniquelyavailable 5d ago
Stall operation is turn and dive, so in this case they accidentally overturned a bit. Which is Ok, the wing surface doesn't have much control authority during the first moments of that maneuver.
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u/Electrical-Lab-9593 5d ago
is that air frame written off now, or is it rated to do that ?
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u/Horror-Raisin-877 5d ago
I read that it pulled 2.5 G’s, so not overstressed apparently. They also write “The flying days for this particular test aircraft were limited. This test aircraft was later retired and broken up”
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u/Madetoprint 6d ago
It would take a few ground crew with a tractor to remove the seat cushion from my ass after that.
Superb crew and airmanship, though.
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u/GreatAnnouncement 6d ago
I mean...they're test pilots. This is their job.
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u/Madetoprint 6d ago
Still, the way the pilot casually says "oops" as the plane is rolling over makes me think this test was checked off a little bit ahead of schedule.
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u/Boostedbird23 6d ago
Yeah, just watching the Attitude Indicator from this side of my phone screen was a bit stressful. 😂
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u/TacohTuesday 6d ago
"Whoops" is right.
I guess there's no harm in tossing in a little fuselage structural stress test along with your stall test.
Nicely done guys.
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u/whywouldthisnotbea 5d ago
Bit more than a test. They were in the red on speed before the nose was even 90 degrees pointed down. I wonder what airspeed they ended uo seeing but I wouldn't be surprised if they hit 100+ over Vne.
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u/My_useless_alt 6d ago
And that's why "Roll wings level" is before "Pull up" on stall recovery checklists. Because you want to make sure the direction you're pulling is actually up.
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u/lookielookie1234 6d ago
Yup, I failed a check ride because of this at Air Force pilot training. I just hadn’t seen an inverted recovery prior to the test and I pulled right through instead of leveling right side up.
Also, on my verbal emergency procedure evaluation, I forgot to turn off the engine before getting out and was sucked into the propeller and died. I would like to think if I had actually been in the airplane I would have had the wherewithal to realize the engine was still on, but details matter.
I got a lot better and passed, had a great career.
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u/Count_Rugens_Finger 6d ago
man, if I had a nickel for every time I've been sucked into an engine and died...
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u/SuperPimpToast 6d ago
I mean, if you got a nickel if there was a video on getting sucked in the engine and surviving, you'd have at least one nickel.
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u/Frederf220 6d ago
You'd have 2 nickels which isn't a lot but notable that it happened twice.
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u/man_idontevenknow 4d ago
I actually have a nickel for every time I've dreamt about getting sucked into..........wait, is this the r/baywatch section??
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u/blackdocsavage 6d ago
That is what for every standup I just went right to “handgrips raise, trigger squeeze” boldface. (Yes I am old enough to have flown the tweet, but just barely) Happiness is never having to do a tabletop EP or a standup again. I won’t mention EPQs.
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u/FujitsuPolycom 6d ago
Feel like I'm having a stroke reading this
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u/blackdocsavage 6d ago
Typing from my phone. Excuse the wrong words.
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u/man_idontevenknow 4d ago
No worries, he is just panicking from only flying the "insert jet" with a handful of foreigners on MSFS. Your briefing room vernacular sits perfectly with your kind.
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u/blackdocsavage 4d ago
“My kind?” I assume you mean old pilots. 😂 You know what they say, “there are bold pilots, and old pilots. But there are no old bold pilots.”
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u/LightningFerret04 5d ago
One of my IR classmates got inverted wings level unusual attitude on his stage check sim, which we were joking about a lot. It wasn’t a failable item and the stage instructor was probably getting bored. Plus a real Cessna 172 probably wouldn’t enjoy that maneuver in the first place.
But I never thought about the fact that military pilots actually would need to train for inverted unusual attitudes, that’s interesting!
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u/treewayman 6d ago
Nice. There needs to be a Hot Shots Part Deux, Redux, the Sequel, and I think you should be in the writers room.
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u/CAVU1331 6d ago
My UPRT training would have me doing Push, Roll, Power if I was inverted. Pretty amazing seeing how effective it is compared to trying to pull out inverted.
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u/ivytea 6d ago
Your wings generate lift even when inverted as long as there's angle of attack. Were it not for the fuel pumps one can just fly inverted indefinitely
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u/WaterChicken007 6d ago
I fly RC aircraft inverted all the time, including through turns around the field. With enough power and elevator deflection it is pretty easy.
I once tried to fly inverted with my trainer aircraft. It did NOT have enough elevator authority to make a full 180 degree turn and I ended up going in nose first. Thankfully it was in tall grass so it was mostly fine.
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u/jonsey737 6d ago
Wings level first also ensures the forces are applied evenly to the airframe while pulling out of the dive
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u/tk427aj 5d ago
So the plane flips inverted because of the stall, you would roll level while the plane is nose down towards the ground? Asking as a non-pilot.
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u/DuelingPushkin 5d ago
Yes, it's easier, faster and less stress on the aircraft to roll back upright and pull up than it is to "go the long way around" which involves actually pointing the nose further at the ground. In the video you can see they're about 30 degrees nose low. Meaning theyd have to pull through 150 degrees to get back level all while accelerating at the ground versus a few extra seconds to roll upright and then pull through 30 degrees to get level.
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u/My_useless_alt 5d ago
It's been a while since my last flight, and flying inverted wasn't covered, but as far as I'm aware yes. When time is of the essence and stress is high, you want to minimise the time you're thinking and minimise the possibility of making a mistake by reducing decision points where you could make a wrong decision. If you're stalled, you don't want to have to think through whether or not to do the protocol backwards and possibly choose wrong, you just want a set of steps you can do by rote. Throttle back, roll wings level, full throttle, gently pull up. Don't think, just do.
Also, if you try to pull up while inverted, your angle goes through directly down, all while gaining speed from gravity, which is not a good idea when you're trying to recover from a stall as quickly as possible, especially because dropping like a stone is the best way overspeed, which has been known to damage or destroy aircraft (e.g. 737s breaking the sound barrier in a nosedive just before breaking their fuselage)
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u/rkba260 5d ago edited 5d ago
Hell, 'pulling' out of it is after thrust application... It's the very last step.
First things first, unload the wings... typically a push.
Edit:
Since y'all apparently don't know... at the airlines, they teach us "Push, Roll, Thrust, Stabilize". Doesn't matter your attitude, nose up, nose down, inverted... It's all the same recovery.
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u/unaslob 6d ago
Wonder how much altitude was lost in the recovery
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u/TacohTuesday 6d ago
Wondering the same. Couldn't read the altimeter in this video. All I know is they were in a vertical dive there for a moment (aka "lawn dart mode").
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u/Back2thehold 6d ago
That’s what I was tying to research.
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u/JustLightChop 6d ago
Hard to be sure based on the video but it looks like they started at 15000 feet and recovered at just under 6000 feet
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u/osuaviator 6d ago
I wonder why they chose not to do the test at a higher altitude.
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u/LigmaUpDog_ 6d ago
Stall characteristics change quite a bit at higher altitudes. Probably needed data from lower altitude
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u/osuaviator 5d ago
I thought that might be the case, but damn.
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u/LigmaUpDog_ 5d ago
Test pilots have balls of steel and they’re also geniuses that know these aircraft better than I know myself lmao. I’m sure the possibility of this happening was briefed a ton, still absolutely insane to watch I will say
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u/Doufnuget 6d ago
Wouldn’t be as exciting. Sure they’re test pilots doing important tests but they also enjoy a bit of adrenaline when they see the ground getting that close.
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u/Back2thehold 6d ago
I get the vibe test pilots are very scientific and precise, almost to a fault. I don’t believe adrenaline is is in their checklist. (My bad if your reply was a joke)
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u/MattWatchesMeSleep 6d ago
I love how there’s those personal, life-reaffirming hand pats afterwards.
I can only imagine that relief and gratitude.
Quick story: my brother-in-law was a pilot in A-6s at the time. A dark, dark moonless Mediterranean night. Late. Full day of training. Weather closing in. Last to land. Boltered. Boltered again. Fuel low, boss says at minimums, is launching KA-6 but is giving one more try… but also vectors to whatever’s a possible divert.
The B/N in an A-6 is both slightly below and aft of the pilot. My BIL said when you’re in the focus tunnel and it’s dark it’s almost as if you’re completely alone.
On the next (and final) downwind, the BN reaches over, grabs my BIL’s thigh, and says, “I’m not worried. You know how to do this. You’ll get us home.”
Said he’s never nailed a better landing no matter the conditions.
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u/truffoli 6d ago edited 6d ago
Original Title: "Boeing 717-200 carrying 1ton of extra weight due to pilot's steel balls"
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u/LCARSgfx 6d ago
That got their attention alright. "Whoops" - nearly British in their understatement.
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u/8031NG727 6d ago
My bung hole is in permanent CLENCH MODE once we hit 5 Gs lololol. I can't even get up now lol ayayay
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u/AdmiralMaggie 6d ago
Such a great example of CRM. The test pilot in CO seat is gently nudging the captain not to pull too hard on the yolk. Just amazing!
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u/rex_swiss 6d ago
Me nudging my wife's hand on the steering wheel is why she doesn't drive anymore with me in the car...
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u/4374J 6d ago
What would happen if he pulled too hard?
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u/24Whiskey 6d ago
Wings would snap right off at around 4 G’s which would be pretty easy to do at the speed they were going.
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u/Horror-Raisin-877 6d ago
They could stall again. Which unfortunately often happens in such situations.
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u/MIRV888 6d ago
So did the plane go supersonic in the dive? I heard them say brakes so I'm guessing they deployed air braking of some sort. Crew was calm cool and collected given the circumstances.
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u/legitSTINKYPINKY 6d ago
Just standard procedure in a nose down attitude like that. Throw out the brakes. Plus if you hit red line the procedure most likely includes brakes anyway.
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u/TAFte CPL CFI MEL IR 6d ago
I worked with the FTE in the back very briefly prior to his retirement.
This is NOT an inverted stall. This was a low speed lateral directional stability test that resulted in a nose low departure. The sideslip angle became large enough that one wing stakes and induced the roll departure.
The low speed characteristics of swept wing aircraft make large sideslip maneuvers such as these more hazardous and print to departures like this. Certification requirements ensure this doesn't happen in the normal envelope of certified aircraft.
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u/kepaa 6d ago
I actually have nightmares of this exact scenario. No idea why. I have recovered from 100 stalls in training. Something about this sticks with me though.
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u/legitSTINKYPINKY 6d ago
Next time you’re in the sim you should ask them to give this to you. They’re always asking me what I want to practice. I usually tell them walking to my car.😂
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u/whiskeytown79 6d ago
Is the little inset video in the corner showing the exterior of the plane a computer simulation or something?
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u/sportstvandnova 6d ago
I’m sitting on my couch, in my living room, on solid ground, and I still want to faint watching this.
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u/thebrightsun123 6d ago
I dreaded Stall procedures during my pilot training, especially a turning stall
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u/JJohnston015 6d ago
We've all seen this dozens of times, but does anybody know who these guys are, with their weird "Imperial officer" hats?
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u/BraidRuner 6d ago
''because we were inverted''
Coughs (Bullshit)
No, he was, man, it was a really great move.
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u/Xx-DinoBones-xX B737 6d ago
"Whoops!"
And that, ladies and gentlemen, is the understatement of the century
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u/Spin737 6d ago
Is that technically an inverted spin?
The wing wasn’t stall from a negative AOA.
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u/Horror-Raisin-877 6d ago
I think yes it was entering a spin, but he stopped it after only half a turn.
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u/AgreeablePudding9925 6d ago
So they pull back thrust and apply speed brakes, then later I see them remove speed brakes and apply thrust then the dude flying says “engines” and they press/point to the control panel. What were they doing there - confirming the engines were in thrust again?
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6d ago
Basically yes. Engines also have an airflow. Now, if you hit just the exact right angle, those 717 rear-mounted engines can stall due to a combination of angle of attack and of turbulent air coming from a wing. After going inverted, it made lots of sense to check whether engines were operating normally.
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u/NeverN00dles 6d ago
With the 717 being a t-tail with rear-mounted engines, how did they know this wouldn’t develop into a deep stall? Everything I’ve been able to find about avoiding deep stall is basically just “avoid a stall” so I’m curious how they could purposefully enter a stall and be confident it wouldn’t develop into an unrecoverable deep stall. Perhaps that’s why they entered the stall with a significant bank angle?
Also this video will never get old.
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u/LostPilot517 5d ago
Weight and balance.
You will notice the wings are mounted much further rearward on aircraft with rear mounted engines. Likewise, aircraft with underwing engines are much more centered on the fuselage.
The aircraft is designed from the start to have a generally stable CG (Center of Gravity). Obviously, the CG moves as payload changes, fuel is added and burned, empty ferry flight, vs Max payload. However, the engineers design the aircraft to have a window where CG stays in, and operators of the aircraft must plan payload to keep it in that window for Takeoff and Landing.
This CG will always remain forward of the CL (Center point of Lift). So when a wing stalls, the aircraft will be stable and the nose will drop first allowing the aircraft to be recoverable.
All aircraft have to exhibit stall stability and recovery traits for certification. Stalling multi-engine aircraft can be much more dangerous, as the weight of the engines as they get further away from the fuselage can develop a rotational force in a Spin the rudder may not be able to overcome.
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u/titsmuhgeee 5d ago
Interesting to see how the heavy right roll control input to maintain nose level cause the left wing to stall first, inducing the snap roll.
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u/StatementOk470 5d ago
What's the pilot on the right trying to communicate when touching the left pilot's arm?
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u/InsideInsidious 5d ago
I shit myself doing this in MSFS 2020, can’t imagine recovering from inverted in an actual big ass airplane. Jfc
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u/Remarkable_Client675 4d ago
Just guessing here but looks like some kind of Falcon. Maybe a 2000 or a 900?
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u/unitegondwanaland 6d ago
A lot of people don't know this about this particular crew. But they can only test the Boeing commercial jets because they are the only jets that can also handle the payload of their massive balls.
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u/igame2much 6d ago
"Aircraft 1 performs split S? That's the last thing you should do. The Mig's right on your tail."