Stall Warning
Join Date: Sep 2006
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Ultralights and Spam Cans - as above!!!
Modern designed high speed aircraft - not so much.
Angle of attack indicators, airspeed, and outside air temp fed to computer.
Approaching stall = stick shaker - this is the warning system.
Approaching stall by a lesser margin = stick pusher - this is stall prevention system.
Have tested many of them as the aircraft is trimmed nose up - power back - and watch the airplane do it all by itself. Nice gentle oscillations.
On the other end of the spectrum is the mach trim system. When aircraft speed build up to sensed critical point - before mach tuck will occur - the stick pull will gently cause the aircraft to climb and bleed off speed. Again all by itself. Nice gentle oscillations as the speed bleeds down and the stick pull releases - then aircraft speeds up etc.
So a correctly functioning computer system can actually prevent stalls from taking place if the crew lets it.
Source of information - Bombardier Lear 31 maintenance training manual that I am currently revising my training notes for. One of many aircraft with the above 2 systems.
Mx
Modern designed high speed aircraft - not so much.
Angle of attack indicators, airspeed, and outside air temp fed to computer.
Approaching stall = stick shaker - this is the warning system.
Approaching stall by a lesser margin = stick pusher - this is stall prevention system.
Have tested many of them as the aircraft is trimmed nose up - power back - and watch the airplane do it all by itself. Nice gentle oscillations.
On the other end of the spectrum is the mach trim system. When aircraft speed build up to sensed critical point - before mach tuck will occur - the stick pull will gently cause the aircraft to climb and bleed off speed. Again all by itself. Nice gentle oscillations as the speed bleeds down and the stick pull releases - then aircraft speeds up etc.
So a correctly functioning computer system can actually prevent stalls from taking place if the crew lets it.
Source of information - Bombardier Lear 31 maintenance training manual that I am currently revising my training notes for. One of many aircraft with the above 2 systems.
Mx
Ultralights,
It's called a dynamic stall. You can stall at any speed if you wish to test Darwin's theory of natural selection.
Wally,
You are completely incorrect re the airbus and normal law. You can easily stall the aircraft in normal law. Alpha floor isn't going to save you.
The inflight protections are there to protect the average aviator having a bad day. There will always be a situation that the aeronautical engineer couldn't fathom.
Next time you're in the sim and have a spare 15 mins reposition to 34 plus at a high gross weight for the level. Introduce an overspeed close to coffin corner. Follow the QRH procedure including speed brake full.
Always an interesting conversation waiting for them to stand down 25 seconds after you watched the gator coming to bite you from below.
Airbus protections are not infallible.
It's called a dynamic stall. You can stall at any speed if you wish to test Darwin's theory of natural selection.
Wally,
You are completely incorrect re the airbus and normal law. You can easily stall the aircraft in normal law. Alpha floor isn't going to save you.
The inflight protections are there to protect the average aviator having a bad day. There will always be a situation that the aeronautical engineer couldn't fathom.
Next time you're in the sim and have a spare 15 mins reposition to 34 plus at a high gross weight for the level. Introduce an overspeed close to coffin corner. Follow the QRH procedure including speed brake full.
Always an interesting conversation waiting for them to stand down 25 seconds after you watched the gator coming to bite you from below.
Airbus protections are not infallible.
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All you need to remember is when you push the stick forward the houses get bigger, when you pull the stick back half way the houses get smaller, and when you pull the stick all the way back the houses get bigger again.. 
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maybe (at least in the case of Cessna 100 series(and no not all!!!!)) it is placed on the left wing because
1 In testing this was the most reliable place to give an indication. (outboard of the slipstream and prior to the ailerons or outboard sections due to washout.)
It was probably also found that in varying a/c configurations and operating conditions (flap,slat,gear,speed,loading and bank) that the pressure envelope over that portion of the wing stayed adequately consistent with regards to its migration at varying angles of attack thus providing the most reliable information.
2 its a reed type warning and placed such that a pilot flying without a headset (as some used to and still do) has the best chance of hearing the warning.
vane types don't have this concern
3 the weight and plumbing of the warning, pitot tube and fuel vent are on the left to offset the weight of the flap motor on the right. (lets not chicken or egg that one)
4 cause that's where they effing stuck it...... You know how, why, where and when it works.........put some time and thought into preventing it being correct.
Its already been said though COST, WEIGHT, FUNCTIONALITY what more do you need to know for crying out loud.
PS number one is the most likely reason for the position of stall warnings
1 In testing this was the most reliable place to give an indication. (outboard of the slipstream and prior to the ailerons or outboard sections due to washout.)
It was probably also found that in varying a/c configurations and operating conditions (flap,slat,gear,speed,loading and bank) that the pressure envelope over that portion of the wing stayed adequately consistent with regards to its migration at varying angles of attack thus providing the most reliable information.
2 its a reed type warning and placed such that a pilot flying without a headset (as some used to and still do) has the best chance of hearing the warning.
vane types don't have this concern
3 the weight and plumbing of the warning, pitot tube and fuel vent are on the left to offset the weight of the flap motor on the right. (lets not chicken or egg that one)
4 cause that's where they effing stuck it...... You know how, why, where and when it works.........put some time and thought into preventing it being correct.
Its already been said though COST, WEIGHT, FUNCTIONALITY what more do you need to know for crying out loud.
PS number one is the most likely reason for the position of stall warnings
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You can stall at any speed if you wish to test Darwin's theory of natural selection.
actually, an asymmetric stall while rolling off the top can actually help complete the manoeuvre and score you full points!
interesting stalling while inverted and ending up upright! the hard bit is recovering from the stall when upright and not lose height (actually, recovering from stall and not losing height is the easy bit)
Last edited by Ultralights; 16th Oct 2013 at 09:30.
I do not fear the stall mr ultralight after years of aerobatic flight in my earlier career.
I was merely pointing out you can stall at any speed, if you want to test natural selection. I.e excess g loads, wings breaking off etc etc.
At least you won't be able to report your own crash on pprune!
I was merely pointing out you can stall at any speed, if you want to test natural selection. I.e excess g loads, wings breaking off etc etc.
At least you won't be able to report your own crash on pprune!
Simple questions
Post number 50 in this thread. Who woulda thought.
Yep it is, but show me an AoA indicator in a 152 or pretty much any light trainer?
The stall speed is generally tested and decided for a particular AC at MTOW, most forward CoG,ISA, Power at idle etc and as someone else mentioned, the aircraft is usually brand new.So older aircraft are generallt less predictable. That fella had obviously flown some of the heaps of sh1t I have.
The stall can occur at any speed, if approx 16º AoA is exceeded (you could be pointing at the sky or the ground and exceed this critical angle). Thats why Ultralights can get the stall warning to go off at high speed (remind me not to fly with you after a spag bol.)
Heres another coupla simple questions for the gallery:
1-Why does CoG effect stall speed.
2-Why does the stall speed increase so much in a steep turn?
3 Why is there a difference in the buffet (when it happens) between high and low wing.
Stall is irrelevant to speed.
The stall speed is generally tested and decided for a particular AC at MTOW, most forward CoG,ISA, Power at idle etc and as someone else mentioned, the aircraft is usually brand new.So older aircraft are generallt less predictable. That fella had obviously flown some of the heaps of sh1t I have.
The stall can occur at any speed, if approx 16º AoA is exceeded (you could be pointing at the sky or the ground and exceed this critical angle). Thats why Ultralights can get the stall warning to go off at high speed (remind me not to fly with you after a spag bol.)
Heres another coupla simple questions for the gallery:
1-Why does CoG effect stall speed.
2-Why does the stall speed increase so much in a steep turn?
3 Why is there a difference in the buffet (when it happens) between high and low wing.
Last edited by Homesick-Angel; 16th Oct 2013 at 11:49.
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Angle of attack
Angle of attack is only measurable during refuelling operations. A slightly high angle results in a dribble. There is no need to report this to either your colleagues or on your Maintenance Release. However, too much angle results in significant spillage. CASA Penalty for large angle of attack: One round of refuelling for all pilots within your direct and peripheral vision.
The term can also refer to operations after refuelling. After significant refuelling operations you may involuntarily experience psychsomatic symptoms. To counteract this, most pilots involuntarily deploy their an otherwise ineffective protective device called beer goggles. Such pilots may think that their angle of attack is impressive but they are typically subject to visual illusions, especially if operating night VFR (some even attempt this IFR). From time-to-time, after-refuelling angle of attack can, surprisingly, operate within the designated operational envelope. A recently published CAAP recommends that you if you are in this operational envelope you should open it, especially if there is a French communication within.
Stall warning
Related to the refuelling operations above, it can either mean: a) A failure in the use of radio communication to attract someone previously positively radar identified through the "beer goggles"; or b) An imminent pump failure. You may need to initiate the boost pump and/or add additional type certified lubricant to rectify this situation.
A CASA-approved alternative means of compliance is also available in this situation. You should disregard the angle (of attack) of the dangle and ensure that the motion of ocean has been calibrated through non-destructive testing.
Angle of attack is only measurable during refuelling operations. A slightly high angle results in a dribble. There is no need to report this to either your colleagues or on your Maintenance Release. However, too much angle results in significant spillage. CASA Penalty for large angle of attack: One round of refuelling for all pilots within your direct and peripheral vision.
The term can also refer to operations after refuelling. After significant refuelling operations you may involuntarily experience psychsomatic symptoms. To counteract this, most pilots involuntarily deploy their an otherwise ineffective protective device called beer goggles. Such pilots may think that their angle of attack is impressive but they are typically subject to visual illusions, especially if operating night VFR (some even attempt this IFR). From time-to-time, after-refuelling angle of attack can, surprisingly, operate within the designated operational envelope. A recently published CAAP recommends that you if you are in this operational envelope you should open it, especially if there is a French communication within.
Stall warning
Related to the refuelling operations above, it can either mean: a) A failure in the use of radio communication to attract someone previously positively radar identified through the "beer goggles"; or b) An imminent pump failure. You may need to initiate the boost pump and/or add additional type certified lubricant to rectify this situation.
A CASA-approved alternative means of compliance is also available in this situation. You should disregard the angle (of attack) of the dangle and ensure that the motion of ocean has been calibrated through non-destructive testing.
Heres another coupla simple questions for the gallery:
1-Why does CoG effect stall speed.
2-Why does the stall speed increase so much in a steep turn?
3 Why is there a difference in the buffet (when it happens) between high and low wing.
1-Why does CoG effect stall speed.
2-Why does the stall speed increase so much in a steep turn?
3 Why is there a difference in the buffet (when it happens) between high and low wing.
2. Stall speed increases in a steep turn due to an increase in load factor, this increased load factor is caused by the need to generate more lift due to the lift vector not acting in the directly opposite direction to the weight vector (therefore increasing the aircraft's effective weight). The formula for calculating the effect of load factor on stall speed is "New Vs = Old Vs x Square Root of the Load Factor". A 60°AoB turn results in a 2g load factor which translates to a 41.4% increase in the straight and level flight stall speed.
3. Buffet occurs due to the disturbed/turbulent airflow seperating from the main wing and traveling over the tail plane whilst approaching and during the stall. Buffet tends to occur earlier and be more pronunced on low wing aircraft than high wing aircraft because this airflow seperation tends to miss the tail section on high wing aircraft.
T28 it is only a waste of time for those smart enough to already know everything about stalling (and that's not me - I did get some new info out of it).
The OP is clearly a newbie who was asked a question but could not find an answer. Now, if he has been paying attention, he has quite a few credible answers to offer to his inquisitor. And hopefully enough knowledge to set his inquisitor right if he is full of sh!t. As are so many instructors, it seems.
Unfortunately, some wise-guys here proffered light-hearted (at least I hope it was) comment about the left wing being closer to the ground in a stall and how that must be avoided at all costs, how the down-going wing always stalls first (really?), cows getting bigger then smaller then bigger etc.
When justified, I am all for taking the p!ss, but spare genuine newbies with legitimate questions, please.
The OP is clearly a newbie who was asked a question but could not find an answer. Now, if he has been paying attention, he has quite a few credible answers to offer to his inquisitor. And hopefully enough knowledge to set his inquisitor right if he is full of sh!t. As are so many instructors, it seems.
Unfortunately, some wise-guys here proffered light-hearted (at least I hope it was) comment about the left wing being closer to the ground in a stall and how that must be avoided at all costs, how the down-going wing always stalls first (really?), cows getting bigger then smaller then bigger etc.
When justified, I am all for taking the p!ss, but spare genuine newbies with legitimate questions, please.
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I've seen lots of vids of doods who don't fear the stall plowing in........from a stall. I did a loop in an aircraft, 280knots over the back and felt the stick shake, we were doing more than twice the 'stall speed'
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Surely if a newbie was under instruction the person to answer the question would be his/her instructor.
That way the nonsense about wing position would be avoided and the whole issue around A of A would be answered properly not nonsense about left wings and left hand circuits, spare me !!!!!!!!!
That way the nonsense about wing position would be avoided and the whole issue around A of A would be answered properly not nonsense about left wings and left hand circuits, spare me !!!!!!!!!
