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#51
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I would question the 99% but surely theproblem is that
the 1% tend to be spectacular, and stings a bit. At 02:06 24 June 2005, Andreas Maurer wrote: On 23 Jun 2005 21:27:25 GMT, Don Johnstone wrote: Now here's a question. Given the answer above why when the wing drops at the start of a take off run (winch or aero-tow) does everyone almost without exception try and lift the downgoing wing with aileron? .... because it works in 99 percent of the cases? Bye Andreas |
#52
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At 22:24 23 June 2005, Ian Johnston wrote:
snip OK, so how would you described the difference. How far does the wing have to drop before /you/ use spin recovery rather than stall recovery? I'm genuinely interested: it's not supposed to be a trick question in any way. Ian Its not about how far the wing has dropped, its about whether the glider has started to rotate about the dropped wing. A wing drop stall has a lot of roll, some pitch but not much yaw so your first action is to unstall the wings by moving the stick forward. If you've been slow to intiate the recovery, the glider will start to yaw/rotate around the dropped wing and once this has happened, your first action should be full opposite rudder. Ed |
#53
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Edward Lockhart writes
Its not about how far the wing has dropped, its about whether the glider has started to rotate about the dropped wing. I think //that's// the answer the question was looking for. If you've been slow to intiate the recovery, the glider will start to yaw/rotate around the dropped wing and once this has happened, your first action should be full opposite rudder. Or the nose drop self-corrects the stall and the glider develops into a spiral dive, in which case centring the controls and kicking in a boot-full of opposite rudder is only going to delay recovery in the face of a now rapidly approaching Vne. Despite knowing the difference, being practised and familiar with the characteristics, recovery and differences of both, it's the prospect of mistaking a spiral dive for a spin in the adrenaline rush of the moment that actually still scares me, despite the fact that I quite enjoy being upside down in a glider -- Bill Gribble http://www.scapegoatsanon.demon.co.uk - Learn from the mistakes of others. - You won't live long enough to make all of them yourself. |
#54
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A careful read of the Minden accident report will reveal what two very
experinced pilots did. The owner P1 was a famous glider pilot, and P2 was a WW II trained Naval Aviator, also famous. Eyewitness reports (in the NTSB report) stated that the rotation had stopped, the glider nosed down, then the wings bent up to about 45 deg, then failed. The spoilers were found actuated. The wings broke just outboard of the spoiler. The report refers to an interconnction between the flaps and the spoiler, full spoiler also produces full flap. The report also states time for the glider to accelerate to Vne and Vd, indicating quite rapid acceration. Further in the report it is indicated that the N4DM was certified by JAR with exceptions for stall/spin behavior. The implication is that the pilot(s) stopped the yaw, the glider dropped it's nose and started accelerating as expected, and then at or above Vd, spoilers were actuated, and the wings broke. Neither pilot got out. The Spanish accident reports notes that the spoilers were found in the locked position. So, in summary, one pilot pulled the stick and broke the aircraft, and one pilot pulled the spoilers and broke the aircraft. Faced with going through Vd and breaking the aircraft, or trying to recover and breaking the aircraft--maybe the best chioce is to jump while it's still intact? -- Hartley Falbaum "Robert William" wrote in message ... At 02:06 24 June 2005, Andreas Maurer wrote: On Thu, 23 Jun 2005 16:34:41 -0500, Bob Johnson wrote: Frankly spoken, pulling the stick back hard enough to break off the wings shows that the pilot was lacking the most basic skills to fly that bird. well, possibly, but having got to the position where you could either go through Vd or pull back what would YOU do? |
#55
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"Ian Johnston" wrote in message news:dzZo7CxomoOm-pn2-QjvLCM11RPHz@localhost... On Thu, 23 Jun 2005 21:27:25 UTC, Don Johnstone wrote: The answer is again simple and goes to recognition. A stall with wing drop is just that and provided action is taken to solve that problem, unstall the wing, the a spin will be prevented. A spin is the result of failure at the first step for whatever reason. Everyone properly trained will know the difference. OK, so how would you described the difference. How far does the wing have to drop before /you/ use spin recovery rather than stall recovery? I'm genuinely interested: it's not supposed to be a trick question in any way. Ian What do we think about picking up the wing with rudder when in a stall with wing drop? It's not the BGA method and I'm troubled by someone who recommends it. Stephen |
#56
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Hmmm,
disagree in practice if not in principle. Bending and twisting moments are much greater with increasing span. And a certain degree of symmetry is assumed in measuring load limits. Contol inputs will significanly change the lift distribution across the span (the squatcheloid). So will twist in the wing. Al Blackburn's point, and I take it to heart, is that design requirements don't look at failure modes under a variety of assymetric lift distributions. Consider the deployment of one spoiler cap during the spiral dive recovery with deflected ailerons to recover from a steep bank. The lesson I take away is to be very thoughful in applying the controls under high load. |
#57
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HL Falbaum wrote:
Further in the report it is indicated that the N4DM was certified by JAR with exceptions for stall/spin behavior. How so? You cannot get a glider certificated without adhering to all JAR 22 requirements. So, in summary, one pilot pulled the stick and broke the aircraft, and one pilot pulled the spoilers and broke the aircraft. Wrong. Neither of the two would have done any damage. They broke the glider by doing both things at the same time. Stefan |
#58
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Most important is recognition of prestall and initial departure. Since
the spin is a product of yaw moment at departure, you can prevent a spin with coordinated controls alone. IE, modern aircraft must be "helped" into the spin. (Put another way, the vertical stabilizer creates enough yaw dampening to prevent autorotaion at stall so long no pro spin control imputs are made. Since there are two yaw controls, that would mean pro rudder or anti stick.) Thus, any prestall or initial departure that is met with a release of back pressure and use of coordinated controls to level the wings will produce the desired effect before a spin or spiral dive can develop. Even if you choose not to release back pressure, you shouldn't spin. Instead, you might find yourself in a secondary stall. The longer it takes to apply these simple actions, the less likely that it will produce an immediate remedy, as the aircraft will continue into either a spin or spiral dive. |
#59
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That would be sasquatcheloid assymetry, typically only encountered in
the high Sierra during the winter. It would be much more manageable (if not entirely polite), if they hitched their rides in pairs. |
#60
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Stephen ] writes
What do we think about picking up the wing with rudder when in a stall with wing drop? It's not the BGA method and I'm troubled by someone who recommends it. I'm not sure I understand what you mean. Say, right wing drops in a stall so this "method" would advocate kicking in left rudder as you move the stick forwards to alleviate the stall? Personally, the last thing I'd do when the aircraft was in a stalled state, whether or not a wing drop was involved, would be to intentionally use the rudder in an uncoordinated fashion. That is, unless I actually wanted to spin. -- Bill Gribble http://www.scapegoatsanon.demon.co.uk - Learn from the mistakes of others. - You won't live long enough to make all of them yourself. |
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