What exactly is "stall"
Joined: Jun 2001
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From: Australia
So, anyone actually stalled with no premeditation?
Once at 200' above water during a steep turn. Gave myself a fright, but happily the instinctive correct actions meant I only lost about 20' or so. Mind you, I've taken care not to do it again...
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er...having fun? I've taught a lot of stalls in a previous life instructing, but thankfully never practiced it on my current type. The Stick push system would see to that anyhow (BAe146).
I've just read Neil Armstrong's Biography (Xmas Pressy to myself) and he spent a lot of time perfecting the low L/D approach technique that was used on the X15 and would have to be used if you tried to land Concorde without power too. NASA use it for the Shuttle orbiter as well.
Basically a high speed dive for the runway with last minute gradual pull out with last minute gear and landing flap selection. Helps if you have a 20mile long Dry Lake runway and you aim a mile or so in as well
Not really anything to add useful to the previous posts, but the high AOA drag approach was used recently very sucessfully by Burt Rutan on his Spaceship 1 concept demonstrator X prize winner too. All very clever.
One of the real problems with trying to Mush a C150 down like suggested is that you don't have windows in the floor! Best left to MS Flight Sim and if you are a young pilot building hours and reading this, please don't try this out for real!
I've just read Neil Armstrong's Biography (Xmas Pressy to myself) and he spent a lot of time perfecting the low L/D approach technique that was used on the X15 and would have to be used if you tried to land Concorde without power too. NASA use it for the Shuttle orbiter as well.
Basically a high speed dive for the runway with last minute gradual pull out with last minute gear and landing flap selection. Helps if you have a 20mile long Dry Lake runway and you aim a mile or so in as well
Not really anything to add useful to the previous posts, but the high AOA drag approach was used recently very sucessfully by Burt Rutan on his Spaceship 1 concept demonstrator X prize winner too. All very clever.
One of the real problems with trying to Mush a C150 down like suggested is that you don't have windows in the floor! Best left to MS Flight Sim and if you are a young pilot building hours and reading this, please don't try this out for real!
Joined: Jun 2006
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From: Europe
Without.
Try doing this in a Cessna with power; you simply won't lose altitude. Why? See below.
Is a forward CG all that forgiving? Inverted stall of tailplane should lead the craft into a nosedive, which is the fastest way down...[/quote]
What I more correctly meant to say is that Cessna trainers in general are very forgiving machines with a lot of room for student error built into them. With your typical two crew loading, and CG well within limits, the nose will tend to break about at the same time as the stall progresses into a degree where you are no longer able to maintain altitude. With a CG closer to the forward limit, the nose will actually break prior to losing aileron control; meaning that it is virtually impossible to stall the wing to a degree so significant it would cause excessive RoDs. As earlier stated, power off-full elevator back pressure will yield about 500fpm and limited, but some, aileron control, while full power, full elevator back pressure will yield level, however somewhat erratic flight, or at worst a slight descent.
Try doing this in a Cessna with power; you simply won't lose altitude. Why? See below.
Is a forward CG all that forgiving? Inverted stall of tailplane should lead the craft into a nosedive, which is the fastest way down...[/quote]
What I more correctly meant to say is that Cessna trainers in general are very forgiving machines with a lot of room for student error built into them. With your typical two crew loading, and CG well within limits, the nose will tend to break about at the same time as the stall progresses into a degree where you are no longer able to maintain altitude. With a CG closer to the forward limit, the nose will actually break prior to losing aileron control; meaning that it is virtually impossible to stall the wing to a degree so significant it would cause excessive RoDs. As earlier stated, power off-full elevator back pressure will yield about 500fpm and limited, but some, aileron control, while full power, full elevator back pressure will yield level, however somewhat erratic flight, or at worst a slight descent.
Mach 3
Joined: Aug 1998
Posts: 624
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From: Stratosphere
On a different subject, while the SU35 is fully controllable in pitch, roll and presumably yaw during its high AoA manoeuvre, I have seen a real-life example, and it appears the pilot has very limited control over the velocity vector during the manoeuvre. Is this the case SR71 or JF?
The rates generated are no doubt less than when the aerodynamic control surfaces are not stalled but nevertheless this aircraft is doing things aircraft shouldn't!
The smoke obviously gives an indication of what the AOA is doing...
I've seen the X-31 in action and much footage of the F-18HARV but the most impressive display(s) I've seen have been the Su-35. And this is a 30T fighter!
Thread Starter
Joined: Aug 2005
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From: Estonia
If you fly a plane along the back of power curve, with increasing AoA, increasing drag and sink rate, when can the plane be said to have stalled? Especially when dirty, flow separation might say little. The airflow might be able to follow the topside of the main wing, but then be unable to turn along the flap upper surface and separate at that point. Or the airflow might be separated and turbulent at wing roots, yet attached to wingtips... which is desired and sought by means like wingtip washout.
Surely stall speed is something which applies to the whole airframe, in total?
Surely stall speed is something which applies to the whole airframe, in total?
Joined: Aug 2000
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From: UK
The power curve has nothing to do with it. If you want a more practical definition of aircraft stall than flow separation over particular components, it's when the lift coefficent decreases with increasing AOA. In that sense, because the whole airframe can produce lift, you could say it's an airframe issue.
The Analog Kid
Joined: Aug 2004
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From: Brecon Beacons National Park
Oh, yuss - several times 
Unfortunately the last time was most unintentional at about 50 feet, only 80% of the wing stalled and thus I had both turn and rapid descent when I hit the hill, being fortunate in only gaining myself a week in hospital and a smashed wrist, which a year later still won't go more than 25 degrees backwards and will always have a plate in. Hey-ho. Could be a lot worse.
Now, I realise this started off about powered flying but we've dipped in to hang gliders and gliders, so here's a paraglider's various notes on stalling
We also refer to two types of stall - parachutal and full. One way of getting out of a parachutal stall is to deliberately full stall by pulling the controls down hard and holding them for a couple of seconds, the wing falls behind you in a "bag of washing", you let up and prepare to brake the inevitable dive as the wing reinflates as you pendulum underneath it. Interesting manoevre I carried out for the first time in 10 years in the Himalaya last year, having ended up parachutal after a cascade of upsets but with a couple of thousand feet to spare. The previous unintentional stalls I've had have all been this type of full stall and you get used to the recovery characteristics of your particular wing; as long as you have clearance it doesn't really phase you.
The only time a paraglider pilot would deliberately full stall a wing for descent reasons would actually be collision avoidance at very close quarters (this is by no means a standard procedure but I've heard it advocated by some very experienced pilots as a method of last resort).
We do use a form of stall to descend rapidly called a B line stall: the B lines are the second row of lines across the span (working from the front to back of the wing) and normally carry the majority of the weight; thus pulling them "breaks the back" of the glider across the whole span and can produce descent in excess of 1000fpm; wing-dependent, it can take an awful lot of strength to hold in for any length of time - and as you'd be doing it to avoid being sucked upwards you may have to hold it in for a very long time - and you don't feel particularly in control because you're not really actively piloting. Have done this several times, although it's not my favourite manoeuvre, the most concerning being B-lining to avoid being sucked into a snow storm in front of Hay Bluff a couple of years ago.
Turning to comments made about diving, paraglider pilots would certainly mainly prefer to rapidly descend using a spiral dive, which when "locked in" will get you up to 1200-1300fpm descent with full control.
All in all, paraglider pilots get very used to feeling for the stall and will also use it for landing in certain circumstances, "mushing" the wing onto the deck and even very occasionally just pulling the whole thing in with a couple of feet to go; for preference though, if I'm two foot off the deck and I want to be on it landing in strong winds, I'll stall one side at the same time as I deliberately collapse the other side by yanking hard on the A risers - this turns the wing as it falls, so it hopefully doesn't reinflate and drag you backwards across whatever site or field it is you're landing on!
Unfortunately the last time was most unintentional at about 50 feet, only 80% of the wing stalled and thus I had both turn and rapid descent when I hit the hill, being fortunate in only gaining myself a week in hospital and a smashed wrist, which a year later still won't go more than 25 degrees backwards and will always have a plate in. Hey-ho. Could be a lot worse.Now, I realise this started off about powered flying but we've dipped in to hang gliders and gliders, so here's a paraglider's various notes on stalling
We also refer to two types of stall - parachutal and full. One way of getting out of a parachutal stall is to deliberately full stall by pulling the controls down hard and holding them for a couple of seconds, the wing falls behind you in a "bag of washing", you let up and prepare to brake the inevitable dive as the wing reinflates as you pendulum underneath it. Interesting manoevre I carried out for the first time in 10 years in the Himalaya last year, having ended up parachutal after a cascade of upsets but with a couple of thousand feet to spare. The previous unintentional stalls I've had have all been this type of full stall and you get used to the recovery characteristics of your particular wing; as long as you have clearance it doesn't really phase you.
The only time a paraglider pilot would deliberately full stall a wing for descent reasons would actually be collision avoidance at very close quarters (this is by no means a standard procedure but I've heard it advocated by some very experienced pilots as a method of last resort).
We do use a form of stall to descend rapidly called a B line stall: the B lines are the second row of lines across the span (working from the front to back of the wing) and normally carry the majority of the weight; thus pulling them "breaks the back" of the glider across the whole span and can produce descent in excess of 1000fpm; wing-dependent, it can take an awful lot of strength to hold in for any length of time - and as you'd be doing it to avoid being sucked upwards you may have to hold it in for a very long time - and you don't feel particularly in control because you're not really actively piloting. Have done this several times, although it's not my favourite manoeuvre, the most concerning being B-lining to avoid being sucked into a snow storm in front of Hay Bluff a couple of years ago.
Turning to comments made about diving, paraglider pilots would certainly mainly prefer to rapidly descend using a spiral dive, which when "locked in" will get you up to 1200-1300fpm descent with full control.
All in all, paraglider pilots get very used to feeling for the stall and will also use it for landing in certain circumstances, "mushing" the wing onto the deck and even very occasionally just pulling the whole thing in with a couple of feet to go; for preference though, if I'm two foot off the deck and I want to be on it landing in strong winds, I'll stall one side at the same time as I deliberately collapse the other side by yanking hard on the A risers - this turns the wing as it falls, so it hopefully doesn't reinflate and drag you backwards across whatever site or field it is you're landing on!
Joined: Jun 2001
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From: Australia
Thanks for the link SR71 - very impressive as you say, and clearly in control of the velocity vector.
To the CAA: following the syllabus, legally.
To my employer: following the syllabus, legally. Sorry about the carelessness though...
To you:
So what were you doing in a steep turn 200' above water? Guess its your life but why risk a perfectly serviceable aircraft?
To my employer: following the syllabus, legally. Sorry about the carelessness though...
To you:
er...having fun?
Thread Starter
Joined: Aug 2005
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From: Estonia
Power is work divided by time. And work is the product of force and distance. So the power is the product of speed and force. Either the product of drag and airspeed or the product of weight and rate of descent - those two products have to be equal.
When a plane is gliding with zero engine power, its rate of descent is given by the power curve.
When a plane is gliding with zero engine power, its rate of descent is given by the power curve.
Joined: Dec 2006
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From: The No Transgression Zone
some math take Vs as the fundamental stall speed now given that the maneuver speed Va- the maximum speed at which it is possible to stall without sustaining the limiting loads of the airplane the relationship
Va = Vs*Sqrt of n where
n='g'
shows that any airplane stalled at 1*Vs will attain 1 g, 2Vs 4 g's'
3Vs 9g's 4Vs 16 g's etc. if you give the plane a stalling incidence at 4 times the 1'g' stall speed you'll subject the plane to load far beyond even ultimate loads that goes for F16s too!!!
Note: a snap roll is really more of a a horizontal spin not stall
Va = Vs*Sqrt of n where
n='g'
shows that any airplane stalled at 1*Vs will attain 1 g, 2Vs 4 g's'
3Vs 9g's 4Vs 16 g's etc. if you give the plane a stalling incidence at 4 times the 1'g' stall speed you'll subject the plane to load far beyond even ultimate loads that goes for F16s too!!!
Note: a snap roll is really more of a a horizontal spin not stall
Joined: Sep 2002
Posts: 2,188
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From: La Belle Province
some math take Vs as the fundamental stall speed now given that the maneuver speed Va- the maximum speed at which it is possible to stall without sustaining the limiting loads of the airplane the relationship
Va = Vs*Sqrt of n where
n='g'
shows that any airplane stalled at 1*Vs will attain 1 g, 2Vs 4 g's'
3Vs 9g's 4Vs 16 g's etc. if you give the plane a stalling incidence at 4 times the 1'g' stall speed you'll subject the plane to load far beyond even ultimate loads that goes for F16s too!!!
Note: a snap roll is really more of a a horizontal spin not stall
Va = Vs*Sqrt of n where
n='g'
shows that any airplane stalled at 1*Vs will attain 1 g, 2Vs 4 g's'
3Vs 9g's 4Vs 16 g's etc. if you give the plane a stalling incidence at 4 times the 1'g' stall speed you'll subject the plane to load far beyond even ultimate loads that goes for F16s too!!!
Note: a snap roll is really more of a a horizontal spin not stall
Joined: Dec 2005
Posts: 121
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From: No. Cal, USA
Great information and experiences. I'm a light sport student pilot and I've tried to do stalls in both the planes I'm training on, an Evector SportStar and a Flight Design CTSW. In both cases, the closest I can come to a power-off stall is the plane galloping along in a absurdly nose high attitude while gaining and loosing about 20 feet per gallop. I expected something of the thrill level I got when I was flying with a helicopter pilot practicing autorotations. Not even close.
So can anyone say what it's like to stall an airliner?
So can anyone say what it's like to stall an airliner?
Joined: Feb 2002
Aviation Qualifications: AME
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From: UK
As an apprentice I was lucky enough to go on a B757 CAA test flight post modification. Over the North sea we were told to strap in and, sure enough the aircraft was deliberatly stalled several times. All suprisingly gentle and to be honest a bit disapointing. Nice work Mr Boeing.
Joined: Feb 2005
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From: flyover country USA
Great information and experiences. I'm a light sport student pilot and I've tried to do stalls in both the planes I'm training on, an Evector SportStar and a Flight Design CTSW. In both cases, the closest I can come to a power-off stall is the plane galloping along in a absurdly nose high attitude while gaining and loosing about 20 feet per gallop...
Are these types tri-gear or taildragger? It sounds to me like you can't really do a full-stall landing in them.
Joined: Dec 2005
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From: No. Cal, USA
Both are tricycle gear. The landing technique I've been taught is to flare about one foot above the runway, hold the nose up and let the main gear settle onto the runway as the speed bleeds off. Of course, being a student, "settle" is somewhat subjective
When I took a familiarization flight in the CTSW, the first thing I asked to see was the stall. The pilot tried a couple times to stall it at idle then increased the rpms by about 500 and got a little break.
I understand that full stall landings are possible with flaps and power, but not for a student at my progress level.
When I took a familiarization flight in the CTSW, the first thing I asked to see was the stall. The pilot tried a couple times to stall it at idle then increased the rpms by about 500 and got a little break.
I understand that full stall landings are possible with flaps and power, but not for a student at my progress level.
