Engine quit late downwind at Bankstown 6/6/09
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he just had a high sink rate as he ran out of energy extending the glide.
Yeah... that's called a stall...
Yeah... that's called a stall...
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So when you hear "sink rate" in that lovely american accent, it really should be saying "stall" right?
You can have a high sink rate without being in a stalled condition, I'm sure you have been there many times before along with myself
Sure, but in that case you haven't run out of energy. When the stick shaker goes off, THEN you have run out of energy and need to apply more coal to the boilers... Unless of course you are in turbulence/microburst/windshear...
So when you hear "sink rate" in that lovely american accent, it really should be saying "stall" right?
You can have a high sink rate without being in a stalled condition, I'm sure you have been there many times before along with myself
Sure, but in that case you haven't run out of energy. When the stick shaker goes off, THEN you have run out of energy and need to apply more coal to the boilers... Unless of course you are in turbulence/microburst/windshear...
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Although we call bank angle to the PF anything over 30 degrees which is where you may have got that from.
We do too, but no, I got that figure from the NZ CAA Instructors Handbook
Although we call bank angle to the PF anything over 30 degrees which is where you may have got that from.
We do too, but no, I got that figure from the NZ CAA Instructors Handbook
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Back to the crew bus matey, you're holding up the skipper
I AM the skipper!
Back to the crew bus matey, you're holding up the skipper
I AM the skipper!
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Ultralights
What is it, bozo night here on PPRuNe? The point is the phrase "ran out of energy", which is when you no longer have enough speed or inertia to maintain your AoA below the critical angle. If you have energy, you aren't stalled but might be in a high sink rate. If you have run out of energy, you are stalled. Or don't they teach you that in ultralight school? it's pretty obvious who needs a better instructor.
The GG
No, I didn't say it did, I said it indicates that you have run out of energy. A stall is a (slightly) later consequence of that.
A stick push indicates that you have reached the critical angle and are either stalled or nanoseconds away, and removes the decision from you hands, so you will never get to the "eventual stall". Not sure why all the horns wouldn't wake you up, but there you go...
That's coz we aren't all descended from criminals...
Gawd no, you wouldn't find me flying for that sorry excuse for an airline!
if you cant tell the difference between a Stall, and a high sink rate, then i suggest you go back and get a better instructor, read the BAK Book again, or get out of an aircraft altogether.
The GG
The stick shaker does not mean you are stalled
A stick push indicates that you have reached the critical angle and are either stalled or nanoseconds away, and removes the decision from you hands, so you will never get to the "eventual stall". Not sure why all the horns wouldn't wake you up, but there you go...
I always thought you lot were as soft as Nannas scones
You weren't that Jitstar Captain having trouble with his terrain mode on the wx radar were you??
If you have energy, you aren't stalled but might be in a high sink rate. If you have run out of energy, you are stalled. Or don't they teach you that in ultralight school? it's pretty obvious who needs a better instructor.
Energy hasn't really got anything to do with a stall, a stall is simply an AOA issue, exceed the critical angle and you will stall.
I think you are like many Pilots who think of a stall as an Airspeed problem rather than it's true nature. This is partly due to being taught stall recovery in a low airspeed configuration. Any time you exceed the critical angle of your aerofoil fast or slow you will stall.
A stick push indicates that you have reached the critical angle and are either stalled or nanoseconds away, and removes the decision from you hands, so you will never get to the "eventual stall". Not sure why all the horns wouldn't wake you up, but there you go...
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You weren't that Jitstar Captain having trouble with his terrain mode on the wx radar were you??
Gawd no, you wouldn't find me flying for that sorry excuse for an airline!
You weren't that Jitstar Captain having trouble with his terrain mode on the wx radar were you??
Gawd no, you wouldn't find me flying for that sorry excuse for an airline!
The rest are here on the mainland
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Heard of a Dynamic stall?
Energy hasn't really got anything to do with a stall, a stall is simply an AOA issue, exceed the critical angle and you will stall.
You can quite happily fly along with the stick shaker going bazerk, it does not mean you will stall, it just means that if you increase the AOA any further you will.
Quite often the stick shaker will activate on a go around.
I thought all you kiwis wanted a piece of Jitstar pie! 500 applicants, thats just about everybody left in the whole country isn't it
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I thought all you kiwis wanted a piece of Jitstar pie!
*Note: cheese will cost the purchaser an additional $6 if booked via the internet, $12 at checkin. cheese may not be available on all or any flights. Sauce $15. 300% surcharge may (we really mean will) apply.
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Lucky Jetstar isn't like Ryanair, where they would charge same as J* for the pie but then charge you again to use the dunny when said cheese pie gives you an urgent desire visit the little room...
Umm, this is all a bit tedious, BUT,
A stall is not always a low energy state. It is when the critical angle is exceeded. Thats about it really.
There's been a lot of crap in these last couple of pages.
I must admit, i thought the guy sounded proficient and calm on the radio and everyone survived the landing. Even the aeroplane. Unfortunately, when i had my engine failure at Bankstown, many years ago, the aircraft was a write-off.
A stall is not always a low energy state. It is when the critical angle is exceeded. Thats about it really.
There's been a lot of crap in these last couple of pages.
I must admit, i thought the guy sounded proficient and calm on the radio and everyone survived the landing. Even the aeroplane. Unfortunately, when i had my engine failure at Bankstown, many years ago, the aircraft was a write-off.
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A stall is not always a low energy state. It is when the critical angle is exceeded. Thats about it really.
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God..there are way to many non-experts on here...
To me it looks simple, the guy got VERY VERY lucky in the last stages of the incident.
He put himself in a position to make the field, but managed to stall very close to the ground..with a fortunate outcome.
Have only had the pleasure of a partial failure in a lightie (A Pawnee) whilst towing a glider.
To me it looks simple, the guy got VERY VERY lucky in the last stages of the incident.
He put himself in a position to make the field, but managed to stall very close to the ground..with a fortunate outcome.
Have only had the pleasure of a partial failure in a lightie (A Pawnee) whilst towing a glider.
people usually pay me for my flying and advice.
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OK then... why is the AOA increasing? Couldn't have anything to do with decreasing energy and the need to increase the AoA to maintain altitude, could
OK then... why is the AOA increasing? Couldn't have anything to do with decreasing energy and the need to increase the AoA to maintain altitude, could
If we don't do one of these 3 things we will not produce enough lift and begin to descend. We will not stall unless we exceed the critical angle of attack which usually happens if we increase the angle of attack to the point of the stall trying to maintain altitude in this scenario.
So i'll say it again the stall has nothing to do with the decreasing energy.
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I thought all you kiwis wanted a piece of Jitstar pie! 500 applicants, thats just about everybody left in the whole country isn't it
Just leaves more sheep for the rest of us...
I thought all you kiwis wanted a piece of Jitstar pie! 500 applicants, thats just about everybody left in the whole country isn't it
Just leaves more sheep for the rest of us...
i had written a reply, but ahhh fcukit. its really not worth it.. people usually pay me for my flying and advice.
Anyway isn't it about time Chimbu Chuckles jumped on this thread, gave a detailed explanation and set everyone straight?
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i had written a reply, but ahhh fcukit. its really not worth it.. 
people usually pay me for my flying and advice.
people usually pay me for my flying and advice.
Can't imagine anyone paying you for the crap you have come up with so far, but, you know, a fool and his money are easily parted, so maybe it's true... maybe... but you would really be better off manning up and admitting your error.
GG
OK well you say potato, I say the other thing. In the context of the incident we are talking about, you yourself said "from my comfy chair he just had a high sink rate as he ran out of energy extending the glide", so you clearly agree that he was running out of energy. The point on which we differ is whether he stalled or whether he somehow developed a high sink rate for some other reason. As there is no evidence that I can see that there is any reason for a high sink rate to develop, I'm going to go for the stall scenario as it seems a lot more likely. Neither of us are ever going to to know for sure. The main point is that he did run out of energy (and control) before he flopped it on.
Good to see they at least taught you a sense of humour
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Everything has two types of energy, potential and kinetic.
Potential in an aircraft's case is altitude and fuel in tanks. If the engine is not running as in this case then it is just altitude. Kinetic is airspeed.
Now we all agree on the ONLY thing that governs a stall is AoA. AoA has absolutely NOTHING to do with energy. An example. In the Pitts special I pole around the sky from time to time with symmetrical airfoils, on a perfect upline (if I could ever get one!) I can have 1kt of airpeed and still not not be stalled as AoA is zero, but I have very very little energy.
Now there is only ONE thing that governs AoA and that is stick (and thus elevator) position. It is known as the Stall Stick position. Regardless of airspeed the Stall stick position is exactly the same at a given CofG position. We can see in the last bit of the video that the elevator is fully up position (or very very close to it) so that alone tells you that the aircraft is stalled. The speed of the aircraft is irrelevant. Now please do not confuse the stall stick position with the amount of forced needed by the pilot to get to the stall stick position at different airspeeds, (ie very little as slow airspeeds - rising to damn near impossible at higher airspeeds) or to get there with different trim settings. I am not talking about pressure required, I am talking about the physical position of the control column and thus elevator.
And if anyone doubts this then jump into an aerobatic aircraft (just to be safer) and find the stall stick position in a nice 1G flight, then go to this position in ANY flight regime and the aircraft will again be stalled! Note an aircraft has two stall stick positions, a positive and a negative stall stick position, but with the Cherokee we won't worry about the negative stall stick position. (BTW please don't try this above Va as you might just exceed the design limits of the aircraft structure
.)
So the ONLY way the cherokee could not be stalled at this apparent slow speed (and we all seem to agree that it "flops" onto the ground and so has very little energy - read airspeed) would be if the stabilator was not fully deflected and the stick forward of the stall stick position. As it is fully deflected then the aircraft has to be stalled.
I reckon that during most pilots ab-initio training, we have all "dropped in" a landing from 5 or so feet (maybe even higher) and this appears to happen here, you can see that the tail and MLG touch at the same time and then due to the deceleration on the gound, inertia causes the nose to come down rather smartly!
Cheers
CB
Potential in an aircraft's case is altitude and fuel in tanks. If the engine is not running as in this case then it is just altitude. Kinetic is airspeed.
Now we all agree on the ONLY thing that governs a stall is AoA. AoA has absolutely NOTHING to do with energy. An example. In the Pitts special I pole around the sky from time to time with symmetrical airfoils, on a perfect upline (if I could ever get one!) I can have 1kt of airpeed and still not not be stalled as AoA is zero, but I have very very little energy.
Now there is only ONE thing that governs AoA and that is stick (and thus elevator) position. It is known as the Stall Stick position. Regardless of airspeed the Stall stick position is exactly the same at a given CofG position. We can see in the last bit of the video that the elevator is fully up position (or very very close to it) so that alone tells you that the aircraft is stalled. The speed of the aircraft is irrelevant. Now please do not confuse the stall stick position with the amount of forced needed by the pilot to get to the stall stick position at different airspeeds, (ie very little as slow airspeeds - rising to damn near impossible at higher airspeeds) or to get there with different trim settings. I am not talking about pressure required, I am talking about the physical position of the control column and thus elevator.
And if anyone doubts this then jump into an aerobatic aircraft (just to be safer) and find the stall stick position in a nice 1G flight, then go to this position in ANY flight regime and the aircraft will again be stalled! Note an aircraft has two stall stick positions, a positive and a negative stall stick position, but with the Cherokee we won't worry about the negative stall stick position. (BTW please don't try this above Va as you might just exceed the design limits of the aircraft structure
.)So the ONLY way the cherokee could not be stalled at this apparent slow speed (and we all seem to agree that it "flops" onto the ground and so has very little energy - read airspeed) would be if the stabilator was not fully deflected and the stick forward of the stall stick position. As it is fully deflected then the aircraft has to be stalled.
I reckon that during most pilots ab-initio training, we have all "dropped in" a landing from 5 or so feet (maybe even higher) and this appears to happen here, you can see that the tail and MLG touch at the same time and then due to the deceleration on the gound, inertia causes the nose to come down rather smartly!
Cheers
CB
OK well you say potato, I say the other thing. In the context of the incident we are talking about, you yourself said "from my comfy chair he just had a high sink rate as he ran out of energy extending the glide", so you clearly agree that he was running out of energy. The point on which we differ is whether he stalled or whether he somehow developed a high sink rate for some other reason. As there is no evidence that I can see that there is any reason for a high sink rate to develop, I'm going to go for the stall scenario as it seems a lot more likely. Neither of us are ever going to to know for sure. The main point is that he did run out of energy (and control) before he flopped it on.
In terms of what we see he exchanges Airspeed for angle of attack trying to stretch the glide and gets the cherokee on the back of the drag curve. Due to the increased drag and increased lift in this configuration he develops a high sink rate and bangs it on the ground.
Cloud Basher
You're on the money, the only thing I don't agree with is the aeroplane being stalled, if he raised the nose anymore then I believe he could have very easily. Don't forget he did not have any flap lowered and as such can have a much higher nose attitude without the subsequent stall.
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Good to see they at least taught you a sense of humour
You have to have a sense of humour when explaining aviation to Ozmates, otherwise you go mad...
Good to see they at least taught you a sense of humour
You have to have a sense of humour when explaining
aviation to Ozmates, otherwise you go mad...
