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#41
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spins from coordinated flight
Flight is an art based on a science.
"Stefan" wrote in message ... | Jim Macklin schrieb: | | I don't know of any autopilot that could be programmed to fly an aerobatic | maneuver based on predicted actions. Yet an autopilot can be designed to | observe and respond to the observed dynamic actions of the airplane. | | I don't know of any autopilot that could be programmed to perform | rolling circles, either. But where's the relevance? |
#42
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spins from coordinated flight
Stefan wrote:
Different approach. You, as a military pilot (as I think to have understood), believe in the behavioristic approach. Me, as a scientist (and amateur pilot) follow the cognitive approach. Your approach yields pilots who exactly know what to do in this or that situation, but probably without really understanding the deeper reasons. Well...I could say that your comment above is a deep personal insult (which it is BTW :-) but in this case I will respect the fact that you simply don't know anything at all about me since you have assumed I am a military pilot which as half the world knows couldn't be further from the truth. I am in fact simply a civilian pilot who has flown military airplanes. It's as simple as that really....oh yes...there is one more thing....I've spent about 50 odd years directly involved with the flight training community as both a CFI and an adviser and consultant at levels ranging from primary training to teaching people to fly the highest performance airplanes in the world. If you surmise that the people I have taught to spin airplanes "probably don't understand the deeper reasons" involved that YOU as a scientist can provide, or that the pilots I have trained don't know thoroughly the complete aerodynamics involved with spins, I fear you are in for a deep disappointment :-)) We just present these things when it is correct to present them and not when another explanation is the right explanation :-) -- Dudley Henriques |
#43
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spins from coordinated flight
Stefan wrote:
Dudley Henriques schrieb: Yaw should only be present in the turn dynamic during the entry into the turn and exit from the turn. Once stabilized in the turn, there should be no yaw present. I don't agree. A coordinated turn is *always* a turn around all three axes. (The only exception is a turn with a 90 degrees bank.) You can easily demonstrate this by "hand-flying" a toy airplane. Axis isn't really used in this way. You will notice if you move your toy airplane that the axis system remains in place and moves with the aircraft centered on the aircraft's cg. To define turn using axis reference is not the best way to explain turn since once established in a stable turn there should be no movement on the airplane's axis system. The axis system references the lines crossing through the aircraft's Cg and are used to define movement and moment on each axis. The axis system moves in place with the aircraft and never deviates from it's center point through the cg. There is movement on the longitudinal axis in roll as the airplane is rolled into and out of the turn, and movement as well on the lateral axis in pitch as angle of attack is increased to compensate for the split in the lift vector. There is movement on the Vertical axis as rudder is used to compensate for adverse yaw both during and exiting the turn, but once established in a coordinated turn, (I'm using medium banked turn here for easy reference as under bank and over bank in shallow and steep turns cause in turn axis changes complicating the situation a bit) all movement on the aircraft's axis should be stable. The proper way to define turn as relates to change in direction is to define the change in the velocity vector as relates to heading change not as a change on or around the axis of the aircraft. -- Dudley Henriques |
#44
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spins from coordinated flight
Recently, Todd W. Deckard posted:
That is to say "stall reocover while turning and climbing is not mandatory" Any item in the PTS is "required", and can be part of the test. Perhaps you should re-read item #5 under both power-on and power-off stalls so as not to be surprised during your check ride. Neil |
#45
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spins from coordinated flight
To define turn using axis reference is not the best way to explain turn since once established in a stable turn there should be no movement on the airplane's axis system.
I am not sure I'm getting this. We'll ignore translation (straight line motion). The axis system is (as I have been using it) fixed to the aircraft, and the axis system moves whenever the aircraft rotates (around any point). It has nothing to do with the actual earth's horizon. Then, as I understand it, rotation of the aircraft involves a rotation around one or more of the axes. Yaw involves rotation (=of= the longitudinal axis, and thus the airplane) =about= the (airplane) vertical axis, =in= the plane (roughly described by the wing tips and tail) of the (airplane) horizontal axes. In a turn, slipping, skidding, or coordinated, the nose of the airplane (dragging the longitudinal axis with it) is changing its direction. The airplane is changing heading. If this happens at a constant rate (say, 3 degrees per second), I would say the aircraft is yawing at a steady angular velocity, and undergoing no acceleration in yaw. To =enter= or =leave= this state would require an =acceleration= of yaw in one direction or another. Where do our understandings and vocabulary diverge? Jose -- You can choose whom to befriend, but you cannot choose whom to love. for Email, make the obvious change in the address. |
#46
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spins from coordinated flight
Jose wrote:
To define turn using axis reference is not the best way to explain turn since once established in a stable turn there should be no movement on the airplane's axis system. I am not sure I'm getting this. We'll ignore translation (straight line motion). The axis system is (as I have been using it) fixed to the aircraft, and the axis system moves whenever the aircraft rotates (around any point). It has nothing to do with the actual earth's horizon. Then, as I understand it, rotation of the aircraft involves a rotation around one or more of the axes. Yaw involves rotation (=of= the longitudinal axis, and thus the airplane) =about= the (airplane) vertical axis, =in= the plane (roughly described by the wing tips and tail) of the (airplane) horizontal axes. In a turn, slipping, skidding, or coordinated, the nose of the airplane (dragging the longitudinal axis with it) is changing its direction. The airplane is changing heading. If this happens at a constant rate (say, 3 degrees per second), I would say the aircraft is yawing at a steady angular velocity, and undergoing no acceleration in yaw. To =enter= or =leave= this state would require an =acceleration= of yaw in one direction or another. Where do our understandings and vocabulary diverge? Jose Jose; Do some research on the aircraft axis system and what each axis represents, then research forces in turns. It should become clearer then. Thank you -- Dudley Henriques |
#47
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spins from coordinated flight
Todd W. Deckard wrote:
Can you depart and spin from coordinated flight? Specifically a coordinated climbing turn? During training and several BFR's I have done stalling turns with a CFI present. I have never spun. Your Mileage May Vary. |
#48
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spins from coordinated flight
On Dec 27, 10:07 am, Dudley Henriques wrote:
Todd W. Deckard wrote: But the links that Dan_Thomas sent me indicated that the airplane would not stall "straight ahead" if you were in a climbing turn. The outside wing has a higher AoA which diverges even further as it initially drops. Dan isn't wrong. Climbing turn stalls are a bit complicated to nail down to a strict behavioral pattern as each airplane and indeed each stall entered in a specific airplane will probably be exhibiting slightly different stall behavior due to varying control inputs by the pilot. The result of this is that climbing turn stalls can produce different results depending on what the pilot is doing with the airplane up to and at the instant of the stall break. Basically, if you are (as we say) coordinated, the top wing will stall first and the airplane will roll off in that direction. The reason for this is that as the stall is approached both wings start losing lift causing the airplane to mush into a slip. The highest wing gets interference from the fuselage and usually quits first. If you watch the ball as this happens, as you get near to stall, you'll probably notice that if you can't hold it centered, and a slip develops, that high wing will usually be the one to go first. This doesn't always happen however :-)) and if you skid the airplane, the bottom wing can break first. The bottom line is that in most climbing turn stalls, you will get a roll off as the stall breaks, but remember, this is a ROLL OFF, not a yaw rate!! Just reduce the angle of attack and use aileron to raise the lowering wing and no pro spin forces are present. -- Dudley Henriques But we've had full-blown spins develop from the climbing-turn stall. If the pilot isn't expecting it, it will roll off the high side and start yawing in that direction, and if full power is still on it can get violent. It'll spin readily, as this re-quoted excerpt states: "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." By "balanced" I presume these Aussies mean "coordinated." And if the stall is fully developed the aileron won't help and might aggravate things. Of course if the pilot gets the nose down quick, and uses rudder rather than aileron, it will recover OK. But he has to understand immediately what's happening. Dan |
#49
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spins from coordinated flight
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#50
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spins from coordinated flight
For my conclusion I am fixed in the stall + yaw = spin (where I was to start
with). I appreciate the references to the Transport Canada material as the tendency for the airplane to "go over the top" when snapping over from a climbing turn was a very needed reminder and I intend to experiment with it aggressively next year with the appropriate equipment and circumstances. At Mr. Henriques suggestion I solicited an explaination from Rich Stowell: He is the evangelist for the P-A-R-E recovery acronymn. Power (to idle) Ailerons (to neutral) Rudder (against the spin) Elevator (briskly forward to break the stall). I must say he drafted a very thoughtful response to me in a direct email. The only conclusion I can offer to this essay is to point to his web site, and his book(s): http://www.richstowell.com/ He articulately explained that the inclinometer is not a precise indication of coordinated flight and that some form of yaw is a necessary ingredient to the spin. With this I'll sign off, thanks for the responses. Todd Deckard |
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