Talk:Deep stall

Deep stalls are only unrecoverable in conditions where the aeroplane in question has a too aft CG. The majority of aeroplanes are designed to have a CG range forward of the CP range (aside from canard wing designs of course). The only way to sustain a stall is with elevator, if this becomes "ineffective" such as is shown in the diagram, then a combination of forward CG and aerodynamic weathercocking of the wings will produce a pitch down moment - thus reducing angle of attack and rendering the elevators once again effective.

For example, if you pull back to stall and hold the elevator steady, you will get your stall induced pitch down moment, which will be soon followed by a pitch up moment as the angle of attack is reduced and elevator effectiveness is increased. Holding the controls in this fashion will produce pitch occilations as the aeroplane repeats this cycle - Provided you're quick on the rudders to stop any possible wing drops.

It's worthy to note that the examples of aircraft supposedly lost to this condition were all prototypes - I would question the CG limitations used during these flights before blaming it on aerodynamics.

Also I would suggest that a more realistic angle of attack whould be used for the diagram depicting the stall. The person who drew it had to use 45° angle of attack to justify the elevators not being effective visually. If you hadn't noticed a stall before that, then there's something very wrong with you. Unless of course your CG was too far back and there's nothing you could do but increase power and hope.

The note at the end about paragliders is proof enough. They don't have a tailplane at all, so how do they deep stall, according to the author of the article's explanation, without an elevator being rendered ineffective in the "shadow" of the wings? They work on shifting CG don't they?... mmmm...

InvertedSpin 04:05, 6 November 2005 (UTC)

Rear-mounted Engines?
I like the diagram and the article itself is pretty good however it doesn't mention that a deep-stall is most dangerous to aircraft with T-tails and rear-mounted engines. When an aircraft such as this enters a true deep-stall, the engine air-intakes also enter the 'dead', turbulent, air in the 'shadow' of the wing and are deprived of sufficient airflow - this causes surging and a dramatic reduction in thrust. This is what can make recovery impossible, as without effective elevator or throttle control the pilot can do little to get out of the stall and the aircraft usually descends belly-first into the ground - that's why deep-stalls in these types of aircraft are so dangerous and why the manufacturers went to the trouble to develop stick-pusher systems. Ian Dunster 11:44, 13 December 2005 (UTC)

Trident?
I thought it was the Trident prototype that was lost to a deep stall first - rather than the BAC One Eleven. I'm not entirely certain of this though. The production Trident could deep stall - one crashed at Staines, London in a deep stall. Ali0th 10:41, 20 June 2006 (UTC)