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#1
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spins from coordinated flight
Can you depart and spin from coordinated flight? Specifically a coordinated
climbing turn? Several weeks ago I chimed in on an otherwise awful thread suggesting that if the ball was in the center the airplane would not spin. One of the posters ) responded that the difference in relative wind between the inside/outside wing during a climbing turn would result in an assymetrical stall and wing drop even in coordinated flight. He had several Canadian/Australian citations to back it up. He posted summaries of them originally and my apologies for re-constructing them: Full power stalls in a balanced climbing turn tend to result in the outer wing stalling first, because of the higher aoa of the outer wing, with a fairly fast wing and nose drop (particularly so if the propeller torque effect is such that it reinforces the roll away from the original direction of turn and the aircraft is a high wing configuration) and likely to result in a stall/spin situation that any pilot lacking spin recovery experience may find difficult to deal with. If the climbing turn is being made with excessive bottom rudder then the lower wing might stall first with the consequent roll into the turn flicking the aircraft over. Recovery from a stall in a climbing turn is much the same as any other stall - ease the control column forward to about the neutral position, stop any yaw, level the wings and keep the power on. http://www.auf.asn.au/groundschool/u...ml#climb_turns When the aircraft stalls in a climbing turn, the high wing is at a greater angle of attack than the low wing and therefore stalls first, which results in a rolling motion toward the high wing, creating asymmetric lift and drag. The down-going wing will stall further as a result of less lift and more drag than the up-going wing. A deeper stall, generated by aft C of G, will aggravate these asymmetries, increasing aircraft rolling and yawing moments into the down-going wing. In addition, the aft C of G reduces the distance from the C of G to the centre of pressure of the vertical fin, thus reducing directional control authority, making recovery more difficult http://www.tsb.gc.ca/en/reports/air/...p?print_view=1 In a climbing turn, the outside or upgoing wing is meeting the relative wind at a slightly higher angle of attack than the lower wing. If we pull on the column to the stalling bite, then the upgoing wing will reach it first...The upgoing wing suddenly drops and the wing falls away from the original direction of turn. http://www.casa.gov.au/fsa/2000/sep/FSA34-35.pdf The Transport Canada Guidelines on Stall Training and Spin Awareness specifically requires demonstrations in coordinated climbing turns: http://www.tc.gc.ca/civilaviation/ge...stalltrain.htm I would have thought that the hamfisted chandelles I perform would have flirted with disaster if this were the case. However while I have had to demonstrate accellerated stalls from 20 degree banks, I cannot recall having to deliberately stall the airplane from a climbing turn. My question to uunet is; can you spin from coordinated flight? Regardless the previous dialog did get me thinking: The convergence of insufficient right rudder and a slipping turn, the left turning tendencies and the assymetrical stall could gang up on our hapless pilot resulting in a quick snap and spin during a climbing right turn away from obstacles in the departure path. Regards Todd -- "Instrument flying, I had concluded, is an unnatural act, probably punishable by God." --Gordon Baxter |
#2
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spins from coordinated flight
There is only one thing you have to know about spins. To enter one you
need 2 things to be present; stall and a yaw rate. All the rest is simply stating different ways to make these two things happen. You can spin a spin capable airplane from any flight condition, coordinated or uncoordinated, straight and level, a turn, a climbing turn, a descending turn; it doesn't matter. Just induce a stall either at 1g or accelerated above 1g, introduce a yaw rate at that stall, and you will have a spin. Don't get all bogged down in specifics trying to explain whether an airplane will spin from this or that. It simply confuses the issue. The answer to your question is simple aerodynamics. Yes, you can spin an airplane from coordinated flight and yes, you can spin an airplane from a climbing turn. All that is needed from ANY flight condition is to induce a stall and at that stall, induce a yaw rate. Todd W. Deckard wrote: Can you depart and spin from coordinated flight? Specifically a coordinated climbing turn? Several weeks ago I chimed in on an otherwise awful thread suggesting that if the ball was in the center the airplane would not spin. One of the posters ) responded that the difference in relative wind between the inside/outside wing during a climbing turn would result in an assymetrical stall and wing drop even in coordinated flight. He had several Canadian/Australian citations to back it up. He posted summaries of them originally and my apologies for re-constructing them: Full power stalls in a balanced climbing turn tend to result in the outer wing stalling first, because of the higher aoa of the outer wing, with a fairly fast wing and nose drop (particularly so if the propeller torque effect is such that it reinforces the roll away from the original direction of turn and the aircraft is a high wing configuration) and likely to result in a stall/spin situation that any pilot lacking spin recovery experience may find difficult to deal with. If the climbing turn is being made with excessive bottom rudder then the lower wing might stall first with the consequent roll into the turn flicking the aircraft over. Recovery from a stall in a climbing turn is much the same as any other stall - ease the control column forward to about the neutral position, stop any yaw, level the wings and keep the power on. http://www.auf.asn.au/groundschool/u...ml#climb_turns When the aircraft stalls in a climbing turn, the high wing is at a greater angle of attack than the low wing and therefore stalls first, which results in a rolling motion toward the high wing, creating asymmetric lift and drag. The down-going wing will stall further as a result of less lift and more drag than the up-going wing. A deeper stall, generated by aft C of G, will aggravate these asymmetries, increasing aircraft rolling and yawing moments into the down-going wing. In addition, the aft C of G reduces the distance from the C of G to the centre of pressure of the vertical fin, thus reducing directional control authority, making recovery more difficult http://www.tsb.gc.ca/en/reports/air/...p?print_view=1 In a climbing turn, the outside or upgoing wing is meeting the relative wind at a slightly higher angle of attack than the lower wing. If we pull on the column to the stalling bite, then the upgoing wing will reach it first...The upgoing wing suddenly drops and the wing falls away from the original direction of turn. http://www.casa.gov.au/fsa/2000/sep/FSA34-35.pdf The Transport Canada Guidelines on Stall Training and Spin Awareness specifically requires demonstrations in coordinated climbing turns: http://www.tc.gc.ca/civilaviation/ge...stalltrain.htm I would have thought that the hamfisted chandelles I perform would have flirted with disaster if this were the case. However while I have had to demonstrate accellerated stalls from 20 degree banks, I cannot recall having to deliberately stall the airplane from a climbing turn. My question to uunet is; can you spin from coordinated flight? Regardless the previous dialog did get me thinking: The convergence of insufficient right rudder and a slipping turn, the left turning tendencies and the assymetrical stall could gang up on our hapless pilot resulting in a quick snap and spin during a climbing right turn away from obstacles in the departure path. Regards Todd -- Dudley Henriques |
#3
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spins from coordinated flight
Dudley Henriques schrieb:
There is only one thing you have to know about spins. To enter one you need 2 things to be present; stall and a yaw rate. All the rest is simply stating different ways to make these two things happen. While I agree that this is a correct and simple recipe and therefore quite useful in practice, I don't agree that it helps to *understand* the situation, because *reason* for the spin is not the yaw rate. The reason for the spin is an asymmetric angle of attack, i.e. one wing is more stalled than the other. Of course this situation can only occur if there is some yaw, which leads us to the recipe given above. Recipe: As there is always some yaw in a coordinated turn (otherwise it wouldn't be coordinated), you can perfectly enter a spin from a coordinated turn. Aerodynamic reason: The inner wing has a higher angle of attack than the outer, so it stalls first or, if both wings stall, it is more stalled. Asymmetric stall condition - spin. |
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spins from coordinated flight
On Dec 27, 1:42 pm, "Todd W. Deckard" wrote:
Can you depart and spin from coordinated flight? Specifically a coordinated climbing turn? Well, yeah, prolly, but it'd have to be pretty tight. We used to spin some glider types "over the top" as you suggest, but it's kind of splitting hairs to suggest what you are suggesting. And courting disaster doing a chandelle? If you're going to do a commercial ticket you should be familair with spins intimately. An incipient spin shouldn't even make you break a sweat. BTW, stalls in a climbing turn are pretty much standard standard stuff even for Private pilots. Bertie |
#5
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spins from coordinated flight
Stefan wrote:
Dudley Henriques schrieb: There is only one thing you have to know about spins. To enter one you need 2 things to be present; stall and a yaw rate. All the rest is simply stating different ways to make these two things happen. While I agree that this is a correct and simple recipe and therefore quite useful in practice, I don't agree that it helps to *understand* the situation, because *reason* for the spin is not the yaw rate. The reason for the spin is an asymmetric angle of attack, i.e. one wing is more stalled than the other. Of course this situation can only occur if there is some yaw, which leads us to the recipe given above. Recipe: As there is always some yaw in a coordinated turn (otherwise it wouldn't be coordinated), you can perfectly enter a spin from a coordinated turn. Aerodynamic reason: The inner wing has a higher angle of attack than the outer, so it stalls first or, if both wings stall, it is more stalled. Asymmetric stall condition - spin. You can argue this until the cows come home but the answer is always the same. To spin an airplane you need stall and a yaw rate...period! All the rest of it, the difference in aoa, the dynamics of autorotation, the whole magilla, is nothing but explaining in aerodynamic terms what happens AFTER the stall and yaw rate are introduced. As you say, understanding these things is essential, but they are the EFFECT of what causes spin. Look at it this way. Without stall and without a yaw rate being introduced, you will have none of the things happening that you have mentioned. None will be present until stall occurs and a yaw rate introduced. They are relevant of course, but not the single answer a pilot needs to know when addressing the subject of spins. When I ask a student what causes a spin, I don't want that student to tell me what happens to each wing of the airplane as the spin is developing. If I get that answer I'm immediately going to ask that student how the airplane was placed in a position to cause these effects to happen. When someone asks what causes a spin, or whether or not an airplane can be spun from this flight position or that one, the correct answer is that stall and yaw rate must be present to produce a spin; and that spin can be entered from ANY flight condition. If you then ask a student to explain the aerodynamics in play as a spin develops, it's THEN you want the auto rotational aerodynamics. -- Dudley Henriques |
#6
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spins from coordinated flight
I have a limited exposure to spins (I've demonstrated spins or received spin
instruction in 5 different airplanes on six different occasions). I have a commercial certificate (although you wouldn't think so from my demonstration of a chandelle). Maybe I did have to demonstrate a power on stall while in a climbing 20 degree bank, once. As I recall, we survived it. I return to the original question: if the ball is in the middle will it spin? Becuase I believe snowmobile suits are for snowmobiling and not for flying I won't have a chance to explore it with an aerobatic instructor and an appropriate (but drafty) airplane for a few months -- so I thought I would put the question in a bottle and throw it in the ocean. Regards Todd "Bertie the Bunyip" wrote in message ... On Dec 27, 1:42 pm, "Todd W. Deckard" wrote: Can you depart and spin from coordinated flight? Specifically a coordinated climbing turn? And courting disaster doing a chandelle? If you're going to do a commercial ticket you should be familair with spins intimately. An incipient spin shouldn't even make you break a sweat. |
#7
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spins from coordinated flight
"Dudley Henriques" wrote in message ... There is only one thing you have to know about spins. To enter one you need 2 things to be present; stall and a yaw rate. So to corner your answer to my question: you cannot? spin from coordinated flight. The airplane must be yawed during the stall break (thus the inclinometer ball slips or skids to one side). My question is not to seek out practical advice in spins, or recoveries. It is to explore two academic debates: Can a certificated airplane depart if the ball is precisely in the middle and is there something telling in the emphasis from the foreign sources cited that exposes a gap in our US training practices and material. Thank you for your response. I'll be making a new years resolution to try it out in the neighboorhood Decathalon (with an appropriate chaperone) but as it is cold and snowy I thought I would put it to the uunet. Best regards, Todd |
#8
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spins from coordinated flight
Can a certificated airplane depart if the ball is
precisely in the middle[?] If the airplane is changing heading, then it is yawing, irrespective of the ball's position. Jose -- You can choose whom to befriend, but you cannot choose whom to love. for Email, make the obvious change in the address. |
#9
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spins from coordinated flight
Todd W. Deckard wrote:
I have a limited exposure to spins (I've demonstrated spins or received spin instruction in 5 different airplanes on six different occasions). I have a commercial certificate (although you wouldn't think so from my demonstration of a chandelle). Maybe I did have to demonstrate a power on stall while in a climbing 20 degree bank, once. As I recall, we survived it. I return to the original question: if the ball is in the middle will it spin? Becuase I believe snowmobile suits are for snowmobiling and not for flying I won't have a chance to explore it with an aerobatic instructor and an appropriate (but drafty) airplane for a few months -- so I thought I would put the question in a bottle and throw it in the ocean. Regards Todd "Bertie the Bunyip" wrote in message ... On Dec 27, 1:42 pm, "Todd W. Deckard" wrote: Can you depart and spin from coordinated flight? Specifically a coordinated climbing turn? And courting disaster doing a chandelle? If you're going to do a commercial ticket you should be familair with spins intimately. An incipient spin shouldn't even make you break a sweat. The answer to the ball question is no. It won't spin. A ball centered airplane in a climbing turn is compensated by rudder and is considered coordinated (in the classic sense). If you introduce a climbing turn stall with the ball centered, you might get a temporary wing drop at the break but unless you introduce a yaw rate as the stall breaks; no yaw rate...no spin! -- Dudley Henriques |
#10
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spins from coordinated flight
"Dudley Henriques" wrote in message ... Todd W. Deckard wrote: I have a limited exposure to spins (I've demonstrated spins or received spin instruction in 5 different airplanes on six different occasions). I have a commercial certificate (although you wouldn't think so from my demonstration of a chandelle). Maybe I did have to demonstrate a power on stall while in a climbing 20 degree bank, once. As I recall, we survived it. I return to the original question: if the ball is in the middle will it spin? Becuase I believe snowmobile suits are for snowmobiling and not for flying I won't have a chance to explore it with an aerobatic instructor and an appropriate (but drafty) airplane for a few months -- so I thought I would put the question in a bottle and throw it in the ocean. Regards Todd "Bertie the Bunyip" wrote in message ... On Dec 27, 1:42 pm, "Todd W. Deckard" wrote: Can you depart and spin from coordinated flight? Specifically a coordinated climbing turn? And courting disaster doing a chandelle? If you're going to do a commercial ticket you should be familair with spins intimately. An incipient spin shouldn't even make you break a sweat. The answer to the ball question is no. It won't spin. A ball centered airplane in a climbing turn is compensated by rudder and is considered coordinated (in the classic sense). If you introduce a climbing turn stall with the ball centered, you might get a temporary wing drop at the break but unless you introduce a yaw rate as the stall breaks; no yaw rate...no spin! My thought is that we're splitting hairs in this thread. If the airplane is in coordinated flight and stalls straight ahead (no wing drop), a spin can't happen. But on most aircraft, one wing will drop first even if the ball is centered. This wing drop creates a yaw, opening up the possibility for a spin. -- Dudley Henriques |
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