If I remember correctly, once upon a time a Trident spun in after entering a deep stall with a not very pleasant ending.
I was wide awake in bed this morning at around 03.15 thinking about this topic…as you do !….and got to wondering what the recovery technique is ?. Do you firewall the loud levers and hope you get enough thrust to push the nose over ? do you attempt to drop a wing to convert the stall into a ‘recovery from unusual attitude exercise?.
My thoughts on recovery centered around selecting full reverse thrust on the engine’s that have it fitted. My reasoning being that if the plane is falling tail first and you you dont have enough puff to climb vertically, you arent likely to have enough to arrest the rate of decent and enable the nose to be lowered.
If you selected full reverse thrust and full up elevator, would it ‘pull’ the tail out from underneath the plane ?
Dunno. Over to you guys (and I aint gonna logon at 03.15 to finfd the answer tommorrow morning either !!!)
By: wysiwyg - 13th October 2003 at 09:35
Sorry Kenneth, the left side was mentioned in a post AFTER the one I quoted but I see what you mean now!
Moondance – thanks for the link, didn’t know anything about that one.
By: Moondance - 13th October 2003 at 09:21
I think the original poster was referring to the loss of G-ARPY at Felthorpe on a pre-delivery test flight http://aviation-safety.net/database/1966/660603-1.htm
Strictly speaking, the cause of the loss of G-ARPI is beyond doubt, in that the droop (slats) was retracted too early, but, due to lack of CVR, the exact circumstances in the flightdeck were a matter of conjecture http://www.dft.gov.uk/stellent/groups/dft_avsafety/documents/page/dft_avsafety_502559.hcsp#P32_954
By: paulc - 13th October 2003 at 07:36
Wysiwyg,
I think it is the Staines Trident crash in the mid 70’s that is being reffered to – the cause was never 100% discovered as (in many crashes) a number of things happened in combination to cause a big problem – such as was the Captain (Charles Key) suffering a heart attack during climb out, did the first officer retract the slats too early for the airspeed, was the stick shaker disconnected because it kept givn false info and was considered unreliable etc . Another reason why this crash was never fully undertstood – the aircraft did not have a cockpit voice recorder fitted so the actions of the crew can only be ‘guessed’
You are also correct in mentioning the Bac1-11 as the prototype of this crashed after getting into a deep stall – Mike Lithgow was in command.
By: Kenneth - 12th October 2003 at 18:46
I am viewing in the way that Geedee describes, i.e. from the left. Reverse thrust results in a force that “pushes” backwards on the engines, which are mounted above the CoG. Hence, in my opiníon, a pitch-up is the result.
By: wysiwyg - 12th October 2003 at 16:13
Originally posted by Kenneth
…if you would employ full reverse thrust on a Trident you would create a clockwise moment about the CoG (when the a/c seen from the side)…
Which side of the aircraft you are viewing it from? Might be better to define as the effect you imagine to be a relative pitch up or down. If the situation was that dire I’d give anything a go and personally think a bit of reverse may well encourage a reducing angle of attack.
I may be wrong but wasn’t this accident a 1-11?
Regards
wys
By: geedee - 11th October 2003 at 19:24
I agree with your description of a deep stall.
Surely you mean an anti-clockwise rotation ?
Lets assume you are viewing the unfortunate plane from the left hand side (cockpit to the left of your computer monitor) and tailplane towards the right hand side.
In a deep stall the nose is going to be pointing somewhere up towards the top left hand corner of your monitor.
What I dont know is how much percentage of the available thrust can you use with the reverser’s engaged before you blow them overboard.
If you then pile on reverse gear, the thrust is going to be directed towards the left hand side of your monitor and should….theoreitically, and with assitance from the elevator which should beome ‘unblanked’ in the process…..pull the tail up and towards the right hand side. This would bring the nose down and enable a fauirly conventional…if not a bit steep… normal stall recovery ?. Hate to think how much height you would lose !.
If I was in a real life situation (dont tell the crew on the Tristar that I’m flying back in, to UK on next Saturday !!!) I would personally try the reversing bit first.
By: Kenneth - 11th October 2003 at 18:46
If I understand it correctly, a deep stall is a condition in which the aircraft is stalled and the airflow over the wings disrupt that over the tailplane to such an extent that the elevators do not work, i.e. they cannot change the pitch angle of the aircraft. Therefore, the elevators cannot be used to lower reduce the angle of attack such that the wing is no longer stalled. As I see it, if you would employ full reverse thrust on a Trident you would create a clockwise moment about the CoG (when the a/c seen from the side) which would only aggrave things as it would increase the angle of attack.
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October 11, 2003 at 5:11 pm