Dear All,
I am not a qualified pilot although I was taught how to handle an a/c in flight.
My A Level Physics was 50+ years ago.
I am investigating several accidents to one particular type of a/c. This a/c has long, thin, wings and one jet engine (obviously centrally mounted).
When under instruction on how to fly an a/c, stalls were demonstrated to me. Now as I understand it a stall occurs when there is insufficient airflow over the wings to provide the necessary lift. This happens when airspeed decays below critical limits and/or Angle Of Attack increases above critical limits. This normally results in the a/c starting to fall out of the sky (sorry to be simplistic!). One wing usually drops. I regret that on the a/c I was taught to control (many, many, yrs ago!) I cannot remember which wing went down first – there were usually a significant number of “expletives deleted” from both Instructor and Pupil when it happened!!
My question is; would the direction that the jet engine was revolving in on the a/c under investigation have any effect upon which wing dropped first (assuming that the stall occurred with the wings level).
If I display extreme ignorance then I apologise – but do particular a/c have a tendency to drop a particular wing in a stall? If so why?
TIA
Resmoroh
By: Resmoroh - 24th October 2008 at 15:05
Many thanks for all the replies. Much good info therein (glad I’m not the only one who’s fallen off the top of a loop!!!! – mine was in an AEF Chipmunk at Benson being flown by the late Air Marshal Sir Kenneth Hayr (then masquerading as a Fg Off RAFVR(T)). His “expletive(s) deleted” were something along the lines that he didn’t mind being killed in an aircraft accident but it would do his reputation no good at all to learn that a bloody Met Man had “Had Control” at the time!!!!!!!!!!!!!!) However, I digress!!!
Your responses have shown me ‘the paths of righteousness’. I can now go into battle with the US authorities (you’ve probably guessed the a/c!!) to try to extract the relevant ‘bits of paper’!! Could be an interesting exercise. The US Air Attache has been very helpful!!! US Freedom Of Information Acts have been mentioned! Could be minefield of admin niff-naff and trivia – and I’m 72!! In the event that we discover anything startlingly new about the U-2 Akrotiri prang I will let you know.
S’nice having experts at my beck and call. I thank you.
Rgds
Resmoroh
By: Moggy C - 23rd October 2008 at 23:39
PS: I enjoyed the thread title.
Moggy
By: Monsun - 23rd October 2008 at 22:12
A few years ago when writing a book on the early RAF jets I got in touch with Bruce Spurr who was an instructor at CFS. Some of his observations might be of interest.
…..on one occasion after completing an air test on a Vampire T.11 which had required a climb to 42,000 ft to check pressurisation, I attempted to loop the aircraft from 40,000 ft. Naturally I ran completely out of airspeed before I was completely inverted at the top of the loop. Keeping the power on caused the high-revving engine to act as a gyroscope with, initially, torque reaction starting the aircraft to roll around the engine. The roll started very slowly, and only because at near zero airspeed there was little resistance to what bit of torque came from the engine,which had to be at near max rpm. This was followed by precessional forces causing other gyrations which can best be described as ‘tumbling’ as the aircraft tried to stabilise itself as its downward vertical speed began to increase. On further attempts the same thing happened if power was kept on, but if the throttle was closed the aircraft just fell backwards into a straight dive.
Hope this helps
Peter
By: Pondskater - 23rd October 2008 at 20:15
What he said.
A trainer is often fairly placid in handling (or dull!) The Cessna 150s I learnt in didn’t drop a wing unless there was power on. The wing which dropped was always due to the balance of the aircraft at the time.
I learnt to cheat by leaning very gently on one rudder pedal during my stall lessons creating a slight imbalance so I knew in advance which wing was going to drop. It was always my least favourite lesson – well that and spin training which is related of course.
By: low'n'slow - 23rd October 2008 at 19:19
Simply….Yes.
If there is any aerodynamic imbalance and one wing stalls before the other, then you get a wing drop.
It can happen on props, jets, or even gliders if you stall with a little bit of rudder or aileron input!
With a jet aircraft, I suspect that control input or weight imbalance would be a more likely cause than engine torque reaction. Particularly so with high-aspect ratio (long thin) wings.
Most single-engined propeller driven aeroplanes will exhibit some wing drop if stalled with even a small amount of power.
This is both due to torque reaction (the aeroplane trying to revolve around its engine) and assymetric airflow as the air being pushed back by the propeller corkscrews around the fuselage and hits one side of the fin.
With big propeller engines, you get BIG effects with power. Ask any P-51 pilot!!
Even small aircraft can get quite ‘sporting’ on occasion. The otherwise benign Tipsy Trainer will snap through half a turn of an incipient spin if provoked! And yes, you do use the expletives as part of the recovery process!
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October 23, 2008 at 5:16 pm