T-Tail Deepstall
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Joined: Feb 2018
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From: UK
T-Tail Deepstall
Hello everyone
Could a T-Tail straight wing aircraft like many of todays turboprop suffer from deep-stall or is that something thats exclusive for the t-tail and swept wing aircraft?
Could a T-Tail straight wing aircraft like many of todays turboprop suffer from deep-stall or is that something thats exclusive for the t-tail and swept wing aircraft?
Joined: Aug 2001
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From: se england
The Dash 8 may have it but if the crew dont understand it you get the awful Colgan crash , was it in Buffalo NY some years ago. A dash 8 t just fell out of the sky in a flat attitude killing all on board and several on ground . A graphic illustration that its not just jets or swept wings that can suffer this problem
Joined: Jan 2004
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From: Here and there
pax britanica
That was largely because the captain flying held the stick back against the pusher all the way down to the ground. It was an unfortunate accident where if they had just sat back and done absolutely nothing for a bit they would have been fine. The stick shaker activated early because the anti ice was turned on and the captain induced the pusher by heaving back on the stick. Pure piloting muppetry.
The Dash 8 300 also has a pusher but the smaller 200 and 100 don’t.
That was largely because the captain flying held the stick back against the pusher all the way down to the ground. It was an unfortunate accident where if they had just sat back and done absolutely nothing for a bit they would have been fine. The stick shaker activated early because the anti ice was turned on and the captain induced the pusher by heaving back on the stick. Pure piloting muppetry.
The Dash 8 300 also has a pusher but the smaller 200 and 100 don’t.
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Joined: Feb 2018
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From: UK
"The National Transportation Safety Board determines that the probable cause of this accident was the captain's inappropriate response to the activation of the stick shaker, which led to an aerodynamic stall from which the airplane did not recover." - From the Colgan Air crash Flight 3407
The NTSB findings suggest that inappropriate response to stick shaker was the cause for the crash which could have been avoided if the pilot reduced the AoA, a Deep stall would be impossible (or almost impossible) for the pilot to recover from, so its reasonable to believe that the DASH8 suffered a normal stall and not a deep stall.
The NTSB findings suggest that inappropriate response to stick shaker was the cause for the crash which could have been avoided if the pilot reduced the AoA, a Deep stall would be impossible (or almost impossible) for the pilot to recover from, so its reasonable to believe that the DASH8 suffered a normal stall and not a deep stall.
Joined: Mar 2006
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From: England
#2, it’s not the magnitude of AoA which is the problem, it is if the control surface used for stall recovery (tail/elevator) is masked by the wing downwash and thus less effective.
#3 - #5, perhaps the main reason for having a stick push is that the aircraft’s natural stall warning or stall characteristics do not meet the certification requirements - particularly pitch down.
I do not recall that spin prevention specifically was considered. The aircraft will not spin unless stalled, stick push minimises the duration of a stall or avoids altogether.
Straight wing vs swept should not be an issue, the dominant factor is the inability to effect a nosedown pitching moment.
Both the BAe146 and HS125, relatively straight wing, were predicted to suffer deep stall based on wind tunnel testing. Both aircraft had stick pushers, but flight testing did not discover any deep stall situation.
#3 - #5, perhaps the main reason for having a stick push is that the aircraft’s natural stall warning or stall characteristics do not meet the certification requirements - particularly pitch down.
I do not recall that spin prevention specifically was considered. The aircraft will not spin unless stalled, stick push minimises the duration of a stall or avoids altogether.
Straight wing vs swept should not be an issue, the dominant factor is the inability to effect a nosedown pitching moment.
Both the BAe146 and HS125, relatively straight wing, were predicted to suffer deep stall based on wind tunnel testing. Both aircraft had stick pushers, but flight testing did not discover any deep stall situation.
Joined: Oct 2004
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From: Near sheep!
pax britanica
That was largely because the captain flying held the stick back against the pusher all the way down to the ground. It was an unfortunate accident where if they had just sat back and done absolutely nothing for a bit they would have been fine. The stick shaker activated early because the anti ice was turned on and the captain induced the pusher by heaving back on the stick. Pure piloting muppetry.
The Dash 8 300 also has a pusher but the smaller 200 and 100 don’t.
That was largely because the captain flying held the stick back against the pusher all the way down to the ground. It was an unfortunate accident where if they had just sat back and done absolutely nothing for a bit they would have been fine. The stick shaker activated early because the anti ice was turned on and the captain induced the pusher by heaving back on the stick. Pure piloting muppetry.
The Dash 8 300 also has a pusher but the smaller 200 and 100 don’t.
We can't change the past, but we can just keep learning.
Joined: May 2001
Posts: 1,424
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From: London,England
See the sticky thread at the top of the Tech Log forum for a link to some great podcasts of a detailed interview with Davies about test flying a large variety of airliners for the CAA. His tells the story of spinning the Brittania, scary stuff, and some great stories about dealing with various manufactures when things didn't go to plan.
D P Davies interviews on certificating aircraft
D P Davies interviews on certificating aircraft
