Deep Stall?
 

Hi

Just read a book and followed most of it(who am i kidding) apart from when it talked about deep stalls? Have not got a clue what this is...just wondered if anyone could help?

Thanks

Tiger

And thanks to Genghis for the last post

Re: Deep Stall?
 

Try Google?

Re: Deep Stall?
 

A pleasure to have helped.

The term "deep stall" usually means an unrecoverable stall, where for whatever reason the aeroplane shows a complete disinclination to recover.

Speaking for myself, I've only ever seen it once, in a canard single seater with a very high thrustline. If you stalled it and left the throttle at idle, there was insufficient nose-down pitching moment to recover - I actually HAD to use thrust to unstall the canard - really quite disconcerting.

Probably the best known case of a deep-stall is the BAC 1-11 which killed a flight test crew when it stalled, but if memory serves correctly the mainplane blanked the tailplane so there was no elevator authority to pitch down. There's a nice explanation of this here.

G

Re: Deep Stall?
 

If you are flying a type which will deep stall, usually because of inadequate elevator effectiveness, try rolling inverted to recover.

Similarly if you get a mach tuck and full back stick becomes ineffective, let it carefully go under rather than continue the dive.

Re: Deep Stall?
 

Assuming that at such low speeds you have sufficient aileron authority to do so, and hoping that the transient sideslip during the roll doesn't put you into a spin.

G

Re: Deep Stall?
 

An additional factor in a deep stall with aircraft such as the BAC1-11 and DC-9 is that the turbulent airflow from the stalled wing prevents the engine developing adequate thrust to accelerate the aircraft out of the stall. Hence you end up in with a high angle of attack, no pitch authority to correct that and no thrust to accelerate out of it.

Re: Deep Stall?
 

Cheers folks

The wikipedia seems to have it all!

Thanks again

Tiger

Re: Deep Stall?
 

Actually, tiger26isfinals, the wikipedia is fairly limited.

The prototype BAC1-11 had tab activated ailerons and elevators, so it not only had no elevator authority in deep stall, but no roll capacity either. Incidentally, the test crew (who knew their tenure on the planet was limited) continued a commentary on their attempts to recover all the way down. The ultimate professionals!
The solution for the production aircraft included not only powered controls, but modified wingtips and wing roots to alter airflow, much more efficient stall warning vanes, stick push and fuel dip. In theory, in the model 217 anyway, one could power out of a deep stall if all other measures failed to stop you reaching that condition.

I never tried!!!

Cheers
Gru

Re: Deep Stall?
 

Grusome,

Good explanation but the 1-11 has NON powered ailerons..

Re: Deep Stall?
 

M5,

Humble apologies, either poor expression or too many type ratings in the intervening 35 years, can't remember which!

Cheers
Gru

PS Can't quite recall whether the differential speed brake/spoilers were on the prototype, but have a vague recollection that these were to provide roll at high AoA.

edited for PS

Re: Deep Stall?
 

Gru..

No problem... Just thought I would throw in my ounce of help!!..

Not sure re the Speed Brake/Spoilers but will find out in next couple of days.
If You check your PM's there will be a message for Yu later ..

TTFN

Re: Deep Stall?
 

Was there not also a Trident lost as a result of the same deep stall (or locked-in condition) problem ) - G-ARPY I think. That being the reason why such aeroplanes have a stick shaker (or pusher) to initiate recovery before the condition becomes locked in.

DGG

Re: Deep Stall?
 

I belive a trident was lost due to this. One of my instructors at Cosford was talking to me about it sometime ago now and metioned a Trident being lost. Was a VC-10 too or is that my imagination?

NS

Re: Deep Stall?
 

Trident deep stall accident

Re: Deep Stall?
 

NS
"Was a VC-10 too or is that my imagination?"

Sadly it was Your imagination.. !! (sadly that is, for Your Imagination) please check Your PM's..

On 1-11's both Stick Shakers and Stick Pushers are fitted ..

DND

Re: Deep Stall?
 

Date of Accident: 26 July 1993
Airline: Bombardier
Aircraft: Bombardier Canadair CRJ-100
Location: Byers, Kansas, USA
Registration: C-FCRJ

Accident Description: The aircraft was on a test-flight out of Wichita, Kansas. While performing a side-slip maneuver at 12,000 feet, the crew lost control of the aircraft and it entered a deep stall. Descending through 8000 feet, the Captain ordered the anti-spin parachute deployed. Due to a system misconfiguration by the Co-pilot, however, the chute fell free of the aircraft. Control was never regained and the aircraft crashed into a cornfield.

Re: Deep Stall?
 

With the deep stall case as was made recently aware with the 111 (By the way - what was the Javelin like?) the B727 was operated in the States I believe without a shaker and pusher. The first ones on the UK register were by Dan Air and the CAA made them fit aforesaid shaker and pusher at not inconsiderable expense. Or so I am told... Anyone?

Conan

Re: Deep Stall?
 

Conan, my recollection is spot on with yours.

You may recall that both AAL and UAL had high sink-rate, slow engine response accidents in one week (in Nov. 1965) with the 727-100. While not deep-stall events, they certainly increased the pucker factor with respect to T-tail transports.

(By sheer coincidence, that week was the 25th anniversary of another engineering slip-up: the Tacoma Narrows bridge collapse - "Galloping Gertie")
:oh:

Re: Deep Stall?
 

Javelin web site.

Didn´t realise the gate guard from Stanmore had been saved. It was in very poor shape and I thought it would have cut up. But if you look at the list of survivors, it´s now at Thunder City in SA. Anyone any information or photos of how she was moved and what work had to be done?

Interesting thread.

The 1-11 would show auto-ignition first, then the shake, followed by the push. Nitrogen pushed the controls via a ram piston.

We routinely took the 1-11 through to the push on base training. In the days before sims of course. It was a fairly gentle change of pitch at stalling speeds.

An acquaintance of mine heard the tape and described their voices changing as they kept the report going. The crash footprint was not much longer than the aircraft.

The spoilers came out at an aileron angle of >4degrees I think. At 250 kts, the rate of roll was quite unbelievable for an airliner.

Even assuming that this system had been available on the prototype, the airflow would have been such that the spoilers would not have done much.

I think the push in Pappa India went off several times did it not?