Lnewqban

I just watched this new movie, "Flight", which is currently exhibited in movie theaters.

After suffering some turbulence that damages the elevator (stuck in down position), the pilot saves his airliner from an uncontrolled dive by inverting flight.

Question: Is this possible in real life?

Copied from http://en.wikipedia.org/wiki/Flight_(2012_film)

"Plot

.......During takeoff the flight encounters intense turbulence.
After reaching cruising altitude, Copilot Ken Evans (Brian Geraghty) flies the plane............
A few minutes before final descent Whip (the captain) is jolted awake by a mechanical noise.
The plane goes into a steep dive, and after exhausting all other options, Whip rolls the plane into an inverted position to bring it out of the dive and then maneuvers the plane right-side up just before crash-landing in a field.
He loses consciousness upon impact."

tailskid

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I bet they can - but not for long

ByLoudDesign

I would think that any A/C could do it. There is got to be a minimum flight envelope that A/C must pass to be air worthy! I would think that it would include roll overs and inverted flight to prove the airframe air worthy! I suspect that is altered by intended use,but not much, as there is no way to predict that a airliner may not end up rolling over or in a situation where they need t stay inverted!

tschuy

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I doubt that it can be done very long.... For one the fuel systems in airliners are not design to supply fuel when inverted. The engines would flame out from lack of fuel.

ByLoudDesign

You mean they do not use clunks!!! LOL!!!

stuntflyr

MD-80 load limits are +2.5 -1.0. Not much for maneuvers inverted. It takes 3 G to do a loop, so to recover from an outside loop it takes 3 G. I imagine the airplane could do one outside corner at 3G to level flight, roll rightside up and belly land to a stop, maybe. The G limits require no structural deformation, if it would survive (wings and tail stay on the fuselage) it might make it but with much deformation to the structure!

The way I understand the "stunt" in the movie is that it has a jammed stabilizer/elevator like the Alaska Airlines crash of Santa Monica Bay in 1988 or so (which did do an ouside bunt to inverted and stay relatively intact until impact), and the movie makers probably liked the 1970 Hullavington World Championships story of Neil Williams saving the day when his Zlin broke an lower spar boom and he flew inverted to the grass and then performed a perfectly timed slow roll to meet the earth gently enough to survive as the wing collapsed. According to my friends that have seen the movie the timing is all wrong for the scenario but agree it's the best scenario.
Chris...

P.S. There is no such thing as "intense" turbulence in aviation, there is Light, Moderate, Severe, and Extreme. Extreme is defined as damage is taking place to the structure and Severe means the airplane is momentarilly out of control. Moderate displaces things about the cockpit, Light doesn't do anything but move the airplane a little. Most times airline pilots turn the seat belt sign on because of much less than Light turbulence.

FLYBOY

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I have a friend (no longer alive due to old age) that helped start Japan airlines.. He once rolled a 747. Was teaching and pulled an outboard engine and the student did the wrong thing, it started to roll and you can't just roll it back and stop or it will shear the engines, so he went all the way around and then stopped it. Lost over 25000 feet doing it he said, but lucky he started at about 40,000. It was a long time ago and it sounds way too much, but I heard him tell the story many times and it never changed. I was reading the encyclopedia of aviation many moons ago when I was in High school and I saw a picture of a B-17 in the war, and wouldn't you believe, it was him in the cockpit. That was too cool.

Lnewqban

Thanks for all the responses and the extraordinary story of Flyboy's post.

FLYBOY

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That guy was amazing to listen to. Wish he was still alive. He needed to write a book, Had to ditch in a b-17 once, and way wierd stories.

raptureboy

Thanks! Now I don't have to waste my time and money going to see another made for hollywood movie I'll wait for the netflix release. I got to meet a B-17 ball turret gunner who plane was shot down over france on his 2nd mission. He survived the initial attack of a 190 and after climbing out of his turret wounded he found most of the crew dead, and then the plane rolled over and the tail snapped off. He managed to crawl his way to the tail and open his chute and throw it out the hole and was pulled from the plane, barely 1000 ft from the ground. He broke his ankle on impact but survived the rest of the war as a POW. In the 1980's he met the German pilot who shot him down.Now that's astorythat would make a great movie.

eddieC

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Boeing test pilot Tex Johnson rolled the 707 on a demo over Lake Washington.

http://www.youtube.com/watch?v=-vHiYA6Dmws

Sport_Pilot

Lockheed C130's have been rolled and looped. Most airliners and cargo aircraft can take the G's if lightly loaded as the stress limits are for aircraft at or near gross load.

eddieC

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Uh,... sorry, no.  Load limits apply to fixed items of the aircraft, not just the wings and such. By 'taking the G's', do you mean a bit higher G to reach the load limit at gross? If so, then no.   
Most airliners are stressed for +2.0, -0.0 G.  The fixed items, like engines, batteries, etc., still feel their normal weight, so 2G is 2G. The airspeed may vary based on weight for certain maneuvers. Review maneuvering speed and limit load factors. Q:  In turbulence, can you go faster, or slower, if the airplane is lightly loaded ?
Can you post proof on the C130 aerobatics?

Sport_Pilot

I have no proof but have been told this by either Lockheed employees or Air Force pilots. By lightly loaded I mean no cargo or passengers, Gross load means at the maximum weight with payload.

Not sure your stress for airliners are correct, I believe it to be less positive and at leastsome negative G. With 0 negitive G then the first turbulance giving a negative G load could crash the plane.

Bob Hoover used to loop a twin engine Aero Commander 500 with the engines off. He never exceeded the 2 G rating of the aircraft.

eddieC

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I notice you ignored my question and continued on in attempt to justify your guesswork. It shows you don't really know, but have plenty of vague, incorrect assumptions.

Then you have no proof, no knowledge of the points made, hearsay you think, you recall? Please spend an hour looking at the regs, they're there for all to see.
FAR 25.337 Transport Category Aircraft Load Limits: A lot of engineering, but boils down to + 2.1G, - 1.0G . This has changed over the years, some can be + 2.5G, - 0.0G depending on date of manufacture and what the maker applied for.
FAR 23.337 Normal Category Aircraft Load Limits: +3.8, -2.0 for most of the GA aircraft out there. Again, can vary slightly by model.

Really? See the facts above.
You're confusing limit load with ultimate load. Many airliners are certified -0.0G, some -1.0G. Next time you fly, ask the FO. The Captain probably has forgotten.
The Aero Commander 500-series has a limit load of +3.8, -2.0 as explained above, not '2G'. I fly a 1956 AC 560F in Scottsdale occasionally, very nice airplane with GO-480 Lycomings that snarl like a stock car.

The point I'm trying to make (and which you chose to ignore) is that a lightly-loaded aircraft will reach its G limits at slower speeds. It's one reason one slows down during turbulence.

You really should google some things before posting conjecture.

rs917

The latest issue of FLYING magazine has an article with the exact same title as this thread. Check it out.

rs917

Just saw this...sorry, haven't seen the movie.

As per my post above, I DO NOT think that it would be possible to bring any large airliner out of a dive by flying inverted. Reference my points on airfoil shape, etc.

Lnewqban

Thanks for your posts; very interesting.

However, the quoted sentences confuse me.

Mass is mass, weight is a force and G is an acceleration.

g is the gravitational acceleration (32.2 ft/s/s).

For bodies accelerating, decelerating or turning, additional G is generated.
That additional G can oppose or reinforce the natural or gravitational acceleration.

Any body accelerated to 2G will "feel" twice its "natural weight".

Since "one slows down during turbulence", shouldn't an aircraft "reach its G limits" at higher speeds instead?

Lnewqban

Great video and post, rs917 !!

hugger-4641

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A lightly loaded aircraft can reach its "G" limit at a lower speed because it can "accelerate" or change directions quicker than it can if heavily loaded. I think we are confusing "G" with wing loading.
Maybe this analogy will help: At the same airspeed, a fully fueled and ordinanced F-15 can not turn as quickly as an empty one can. Thus, the empty F-15 can reach the same G load as the heavy one at a lower speed than the heavy one.

Same concept as a race car in a corner. Say a Porche 911 and a Lincoln Town Car both turn as sharply as they possibly can at 120mph. The Porche is lighter and will turn sharper than the Lincoln, so it will achieve a higher "G" force in the turn. Hope that explaination helps.

eddieC

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Good explanation, Jerry, thanx. 

hugger-4641

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Exactly right EddieC. I don't remember the flight number, but there was an Airbus a few years ago, I believe a 380, with a composite tail that came off the plane because the pilot was above "manuevering" speed and cycled the rudder back and forth in an attempt to get rid of vortex turbulence. I don't think the elevator surface was composite, but the rudder was. If the elevator surface is composite, I highly doubt it would withstand inverted flight. I'm sure someone will correct me if I'm mistaken.

rino

My Feedback: (121)

Just face it. No way could that be done. No upside down airliners. They were designed to carry a lot of weight right side up.

RV7guy

I have a Van's RV7. It is aerobatic and rated at +6 -3. I have a G meter in the EFIS. I have logged +4 G's in turbulence. I would think that airliners would be rated for greater than +2 G's.

Darwin N. Barrie
Chandler, AZ
Team Futaba

Hossfly

The problem with inverted flight in a jet airliner is not the G loading as much as it is that the fuel pumps are in SUMPS and will not pump fuel within a few seconds of
any negative G loads.

Boeing tried to circumnavigate that with the B-47 Stratojet (Here 1200+ hours and 3+ years combat-ready) but when pilots had to transfer fuel now and then for LOAD factors, the machine simply blew up when the pumps were turned off and then restarted to move small amounts of fuel from an "empty" tank to another tank. The B-47 was extremely CG sensitive. Boeing had to reset tanks in a sump. AFAIK, all jet airliners are so configured. (Here, 727, 737, DC-8 and DC-10) Now the only real blunder there, is the hydraulic system in the DC-10, absolutely criminal! OOPs, there was the Boeing 737 100/200 yaw-damper problem. Another one washed over. $$$$ do wunnerful things!!! [&o] [&o][:@] Oh Yes, I have heard all the FAA BS. Don't waste time trying to rectify their BS.

BTW any pilot could do a decent barrel (maybe a lttle tight) roll using not more than 1.5 G load throughout the maneuver. There is no negative G in a barrel-roll.
Aileron roll is another story. In an "airsow roll" there will be a moment or so negative G, but not any appreciable amount. I only ever did one formation airshow, and that was in a T-33. Whole 'nother ball game.

BTW in most machines, limits of Rolling Gs are less than Positive G limits and negative Gs are the least of all. Back in my time for combat machines, fighter types was 7.3 Positive, 4 rolling, and 3 Negative. But that was a LLOOONNNNGGG time ago. Feb. 1968 to be exact. [>:]