Spin a Jet Transport?

[Graybeard]

Spins are being touched on in AF447 over in R&N. At least one old pilot has stated it is not possible to spin a jet transport in the normal fashion. I don't know why not. In fact, others say it is easier to spin a swept wing plane.

My aerodynamics training consist of a single college course way back when, but the fundamentals remain. I remember that you get into a flat spin if you stall the wing with the cg, Center of Gravity behind the C/L, Center of Lift.

The A-330, MD-11 and other long haul transports carry fuel in the tail in order to cruise with aft cg, for efficiency. That fuel is burned off or moved forward to keep cg within limits as the main fuel is used up. What could go wrong with that?

GB

[ClippedCub]

Seems the 707 did inadvertant part/full snap rolls a couple of times. Slung an engine in one case if I remember.

[Jumbo Driver]

I think under-wing podded engines would almost certainly detach as they are not designed for that degree of sideload, so that would leave only a fuselage-mounted or wing-root engined aircraft as a possibility.

However, my instinct is to say that I do not think such a manouevre would be either aerodynamically or structurally survivable in a conventional swept-wing jet transport.


JD

[filejw]

Not spin? You can spin a jet, now whether you come out of it in one piece that's a different story...

[24victor]

Spins

I think under-wing podded engines would almost certainly detach as they are not designed for that degree of sideload, so that would leave only a fuselage-mounted or wing-root engined aircraft as a possibility

.

Didn't the A300 in New York enter a flat spin and spit the engines off after the vertical stab departed?

24V

[welliewanger]

Correct me if I'm wrong...
During a spin the wings are stalled.
Stalled swept wings (not just when the warner is shouting "stall", but fully stalled wings) will "super stall" or "deep stall" which cannot be recovered from.
Therefore, even if a spin is possible (I can't see why it wouldn't be) recovery may be a little more tricky.

[JABBARA]

Any aircraft spins, only tendency differs.

Two ingredients for spin: Stall and skid. Why?

Imagine the right side of CL vs. AOA curve which represents the stall part after CLmax. At this side, curve steeply drops down, this means any different AOA between right and left wing will cause quite differnt CLvalues between the wings. The result is quite different Lift creation over the wings causing an endless autoratation. This autorotation cannot be stopped with ailerons because they re already stalled and ineffective. What causes to different AOAs between left and right wings? Answer: Skiding or slipping. i.e improper rudder use or rudder trim.

Deep Stall is another term used for -usually- high mounted horizontal tail planes (like MD 80s). The phenomena is: when the wings are heavily stalled, the turbulent flow leaving the trailing edge, may pass over horizontal stabilizer as stalling it as well. So, now no pitch down moment can be commanded through elevator. So airplane remains at this endless stall.

[Gillegan]

Jabbara,
Excellent description of a spin.

[muduckace]

All this spin info is great. A major factor in the info we have is if the aircraft was in a spin as a result of vertical stabilization/rudder failure or (more probable) A/S indications conducive to entering a severe storm.

I doubt the spin scenario and am partial to the latter. Obvoiusly the spin could have resulted from horizontal loads created in a high altitude stall resulting in a spin in said volitile conditions.

The inital factor was the influential key.

[4dogs]

Spinning large aeroplanes

Perhaps the suggestion that you should not get a large aircraft into a spin is not based on the aerodynamics of the spin but rather on the stall prevention systems of stick shaker and stick pusher? To get to the stall, you have to avoid reacting to the shaker then override the pusher and to get to the spin, you need to introduce large amounts of yaw.

None of those actions fall within normal operating techniques.

[FE Hoppy]

a Nimrod(Comet 4 ish) bent a wing back in 89 when routine stall practice turned into a spiral dive. The recovery put the port wing about 12 inches further swept than the Stbd.

[testpanel]

SPIN

So, lets (try) to be clear,
In order to spin an A/C you first need to stall it...

Then WHY and HOW would/could they GET CLOSE TO THE STALL in the first place?? They should never be that close.

Ok, I know, FBW, Coffin-corner, "heavy", pitot-tubes etc etc.
I once was told: Pitch and power = Performance, or doesn´t it work that way on heavy-jets?

btw, imho they never ever should have flown there/try-to fly-through-it..
may they RIP.....

[SNS3Guppy]

China Airlines Flight 006, B747SP N4552V, February 19, 1985

China Airlines B747SP Loss of Power and Inflight Upset

[Brian Abraham]

The RAAF lost a 707 29 OCT 1991 attributed to simulation of asymmetric flight resulting in a sudden and violent departure from controlled flight ie spin. Double asymmetric with rudder hydraulics off if I recall. Searched some months ago for a authoritative report with no luck. Anyone help?

[ClippedCub]

747 stalls with auto-slat out of adjustment showing wing tip stall tendency. In the video, roll stops when the flow becomes attached, and dihedral effect levels the aircraft.

For stall/spin, wing roll-off not only converts AOA to yaw angle, but also creates a plunging effect, increasing side slip.

[ClippedCub]

The RAAF lost a 707 29 OCT 1991

Found this,

ASN Aircraft accident Boeing 707-368C A20-103 East Sale, VIC, Australia

Might give more information for a search.

[desmotronic]

The raaf 707 departed controlled flight when demonstrating vmca with 1inop and a second engine on the same side was intentionally shut down with insufficient ias< VMCA(2inop)

not sure if this was a spin per se or if it rolled over without enough height to recover.