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#11
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None of these big gliders are very good at diving. I don't believe there
is anything sinister about the N4DM. They're just not built for diving. Any time the nose is well below the horizon, they will pick up speed rapidly. Don't do that. Large span gliders will fly slowly and that means that there is a large airspeed difference across their span when circling - my "little" Nimbus 2C can develop a 15 knot difference. This, plus a thermal gust, can make them roll into a spiral dive. Recognizing this and taking prompt action when it happens is actually easy once you experience it a few times. Just allow the speed to increase a bit to increase control authority, then stop the turn and then recover normal airspeed. If the glider is allowed to progress into a full spiral dive, the options narrow considerably. Only very gentle and precise control inputs will save the day. Try not to apply large aileron and elevator inputs simultaneously - bending and twisting the wing at the same time can break it. Reading the Spanish report made it seem that the pilot did not have complete control of his glider. That's a shame when it's a two seater and there are a lot of experienced pilots who would have been willing to ride with him and help him master it. Bill Daniels "HL Falbaum" wrote in message ... Yes, indeed. If anything, the spiral dive recovery is more critical from a structural standpoint. A modern glider is more likely to progress to spiral dive anyway. The pilot, by his own admission, did the wrong recovery for either case. However, since the Spanish report refers heavily to the Minden report, with many similarities, I wonder if there is something peculiar about the Nimbus 4 DT. Both apparently departed into a stall and incipient spin in a strong thermal. This pilot had sufficient recent flight experience, and total time, to have developed good "survival" reflexes, including the "stick forward" manuver. He had little time in the Nimbus 4, but quite enough in the Nimbus 3 to know how to fly it. If it was purely the fault of very strong thermals, then the other gliders in common use at places like Minden would also have similar accidents. This does not seem to be the case. Obviously, I have never flown a Nimbus of any kind. I have a few hours in the Duo-Discus, but nothing larger. The Duo is certainly not malignant in any way. So my question is to those with Nimbus D experience. Is there some handling characteristic that will bite a fairly experinced and competent, but unsuspecting pilot? I am thinking that the (biennial USA) Flight Review should include spiral dive recovery routinely, in addition to the usual other "emergency" maneuvers. -- Hartley Falbaum CFIG USA "Stefan" wrote in message ... W.J. (Bill) Dean (U.K.). wrote: The Spanish report in English translation may be found at http://www.gliding.co.uk/accidents/r...s4dtreport.pdf (3MB). Thanks for the link. Very educational, indeed. I think this answers the question whether spins and spiral dives should be demonstrated and recovery should be regularly trained. Stefan |
#12
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At 13:24 21 June 2005, Stefan wrote:
Don Johnstone wrote: It is to be hoped that some of the above passage is the result of iffy translation, if not it is a very strange sequence of events. Perfectly correct translation. No strange sequence at all. The report conclusions do not help. I am no expert Yes, they do. Know your airplane, know the emergency procedures and particlarly know its behaviour in regading to spins. Practice spin recoveries, practice spiral dive recoveries. And any pilot who is even tempted to pull back the stick in a spin is not airworthy. I agree entirely. But was this glider ever spinning? The report does make the point that intentional spinning of the 4DM is prohibited. on the 4DM but is it possible to exceed VNe in a spin? Certainly not. But many gliders will not stay in the spin but go into a spiral dive. Which was obviously the case here. I don't see that as obvious. How did it get from spin to spiral dive. The action taken by the pilot would not have prevented the auto-rotation, in fact it should have ensured that it continued and that the glider remained stalled. Stall plus autorotation =spin. The question is was the glider ever in a spin. Reading Bill's post that is a pertinent question? My point about the conclusions not helping is that they say that the structural failure was from a 'spiral dive OR spin'. I have to accept that the recovery action taken by the pilot was incorrect but what was he trying to recover from? Stefan |
#13
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Don Johnstone wrote:
spiral dive. Which was obviously the case here. I don't see that as obvious. "Meanwhile, the glider quickly gathered speed until it exceeded Vne." (Page 2 of the report.) How did it get from spin to spiral dive. By itself. Just as many gliders do. The question is was the glider ever in a spin. I don't know (I'm tempted to say: nobody does) whether the glider was technically ever in a spin or started right into the spiral dive. The question is pretty pointless, pulling back the stick is a bad move in either case. Stefan |
#14
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During my experiments with the wrap-around ASI,
I too started with the controls in a clasic spin entry, and felt the stall, and then ended up in what I could not discern was a spin or a spiral. So I'd release the elevator pressure (assumed it was a spin) and recover from the dive. I did spins both before and after this in the Blanik (with a non-wrap ASI) and they seemed very easy to tell the difference from a spiral, and quite easy to sustain as a spin for 4 turns or whatever you wanted, with a subsequent quite well defined spin recovery. The spins in the other glider were at fairly forward CG, so after looking at it, I wasn't that surprised it didn't stay in a spin. I think Hartley was correct, that spins and spirals ought to be part of a flight review. From the report, however, it seems this pilot got spin entry training. In all of my spin entry training, this means crossed controls, and a full stall, with recovery by flaps/dive brakes/power to correct position, ailerons neutral, rudder opposite, stick pressure released or briefly forward to break the stall. I can see value in doing full 2 turn spins left and right, however, instead of just spin entries (which can be too mild, or not give a good sense of spin vs. spiral indications). I must think, however, that actually doing this in some gliders may be either prohibited or may damage the glider or actually cause structural failure. A slow reaction with flaps by the student might be a big problem. Likewise, practicing spins and recoveries with the engine extended in a motorglider might be prohibited or damaging, but this might be exactly the training needed to prevent a 180 turn back to the airport from becoiming a stall/spin for example. And how many instructors regularly spin a Nimbus or a DG1000 with extensions or the like? Honestly I don't know, since I generally fly 18m or less spans myself... What a shame to lose your own son though. Geesh, what a tragedy. At 13:24 21 June 2005, Stefan wrote: Don Johnstone wrote: It is to be hoped that some of the above passage is the result of iffy translation, if not it is a very strange sequence of events. Perfectly correct translation. No strange sequence at all. The report conclusions do not help. I am no expert Yes, they do. Know your airplane, know the emergency procedures and particlarly know its behaviour in regading to spins. Practice spin recoveries, practice spiral dive recoveries. And any pilot who is even tempted to pull back the stick in a spin is not airworthy. on the 4DM but is it possible to exceed VNe in a spin? Certainly not. But many gliders will not stay in the spin but go into a spiral dive. Which was obviously the case here. Stefan Mark J. Boyd |
#15
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M B wrote:
to be part of a flight review. From the report, however, it seems this pilot got spin entry training. In all Read it again. His last spin training was 20 years ago and he swore to never do it again. A pilot who panics when he hears the S-word is not airworthy. (Respect, yes. Panic, no.) of my spin entry training, this means crossed controls, Then improve your spin training. Spin doesn't necessairily mean crossed controls. I can see value in doing full 2 turn spins left and right, however, instead of just spin entries (which can be too mild, or not give a good sense of spin vs. spiral indications). Which it doesn't need. At this early stage, recovery actions are the same. A slow reaction with flaps by the student might be a big problem. Then the student needs more training. Likewise, practicing spins and recoveries with the engine extended in a motorglider might be prohibited or damaging, but this might be exactly the training needed to prevent a 180 turn back to the airport from becoiming a stall/spin for example. You never explored how your glider drops the wing with the engine extended/running? Gee, I wouldn't let my son be your student. Stefan |
#16
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M B wrote:
To verify this, I replicated the same situation twice more on the same flight. It was surprising how little onformation I could get through windspeed noise. I was relying on the ASI, and it was ambiguously reading either 30kts or 100kts. Don't the controls feel differently at 30 knots and 100 knots? That should be a good clue as you begin the spin recovery. -- Change "netto" to "net" to email me directly Eric Greenwell Washington State USA |
#17
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At 17:12 21 June 2005, Stefan wrote:
M B wrote: to be part of a flight review. From the report, however, it seems this pilot got spin entry training. In all Read it again. His last spin training was 20 years ago Three months before the accident 'the pilot had carried out some flights with the test pilot (including diving at Vne and the start of spins.' 20 years ago may have been the last time he did fully developed spins, but 'start of spins' sounds like 'spin entries' to me. If your point was that his training was inadequate, or that perhaps the spin entries were demonstrated rather than trained, these are both possibilities, and I would agree. I recently had a student do some spin training with me and was happy to see him seek it out before flying a very tautly spinning single-seater. I recommended another aerobatic glider instructor for further aerobatics if he wanted more interesting training. Some exposure to aerobatics every so often seems to be good for pilots. I can see value in doing full 2 turn spins left and right, however, instead of just spin entries (which can be too mild, or not give a good sense of spin vs. spiral indications). Which it doesn't need. At this early stage, recovery actions are the same. I might have this out of context. Please elucidate. Spiral and spin recovery actions are quite differently spelled out in our US manuals. I've also found that students 'get it' after doing some 2-turn or more spins, but don't necessarily 'get it' after only spin entry recoveries. Likewise, practicing spins and recoveries with the engine extended in a motorglider might be prohibited or damaging, but this might be exactly the training needed to prevent a 180 turn back to the airport from becoiming a stall/spin for example. You never explored how your glider drops the wing with the engine extended/running? Gee, I wouldn't let my son be your student. I do not plan to teach spins with the engine extended in contravention to a flight manual, such as the DG500MB, paragraph 2.9 I know you weren't suggesting teaching spins in contravention to the flight manual. I certainly agree with exploring non-prohibited edges of the performance envelope to get a feel for the aircraft (including the control stiffness felt at higher speeds). But why don't you do this with your son yourself, Stephan, aren't you an instructor? Stefan Mark J. Boyd |
#18
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AFTER I did it, yes I thought back and yes, the
control pressure was definitely more than expected at low airspeeds. But WHEN I did it, I think the surprise of looking at an ASI and having it tell me... ambiguous garbage... distracted my keenness to listen for airflow or feel for control pressures. The controls on this glider were quite light to begin with. The airflow sound was actually easier to detect for me than control pressures in this (fairly noisy) glider. I just distinctly remember it was the very first time I had ever looked at an ASI where it was impossible to read as a stand-alone indication of airspeed. That was very, very strange for me. Before that, I'd never flown any aircraft with a wrap-around ASI and done intentional spins. Part of why I'm writing this now is because the was quite fascinating. I had to do it many times and study the ASI to really believe I was in a spiral and recovery and not a spin. The ASI needle whipped around in a flash. I tried spins later with further aft CG and was able to sustain spins, with the expected noise and control feel indications. At 17:24 21 June 2005, Eric Greenwell wrote: M B wrote: To verify this, I replicated the same situation twice more on the same flight. It was surprising how little onformation I could get through windspeed noise. I was relying on the ASI, and it was ambiguously reading either 30kts or 100kts. Don't the controls feel differently at 30 knots and 100 knots? That should be a good clue as you begin the spin recovery. -- Change 'netto' to 'net' to email me directly Eric Greenwell Washington State USA Mark J. Boyd |
#19
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M B wrote:
I recently had a student do some spin training with me and was happy to see him seek it out before flying a very tautly spinning single-seater. We ask it from ours before transitioning them to the first single seater. I might have this out of context. Please elucidate. Spiral and spin recovery actions are quite differently spelled out in our US manuals. Luckily, gliders cannot read. :-) Recovering from a developed spin is certainly different from recovering from a developed spiral dive. But at the early stage, when the glider just drops a wing and pitches forward, your neither in a spiral nor in a spin yet. At this early stage, corrective action is quite simple: Immediately stick forward and opposite rudder. In most cases, this will do the trick just fine, and you won't even know whether it would have developed into a spiral or a spin. If a spin or spiral develops, you're in a different situation, of course. I do not plan to teach spins with the engine extended in contravention to a flight manual, such as the DG500MB, paragraph 2.9 Dropping a wing with the engine extended is part of our "club syllabus" for transitioning to the DG505M/22m. If you have never done it, it's a real eye opener how aggessively the wing will drop. Of course, we don't let the spin develop but take immediate action. (The glider will recover after about a quarter of a turn.) Try it! You don't need to cross the controls, just pitch up with the engine running until the glider ceases to fly. It *will* drop a wing then, you have no chance to hold it with the rudder. As I said, an eye opener. Stefan |
#20
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M B wrote:
But WHEN I did it, I think the surprise of looking at an ASI and having it tell me... ambiguous garbage... I find it even more surprizing that somebody in this situation would look at the ASI at all... I tried spins later with further aft CG and was able to sustain spins, with the expected noise and control feel indications. See? You *can* tell a spin from a dive if you have familiarisized (?) yourself with the glider. Which you should (must, according to the legislation where I live and fly) in your first couple of flights, anyway. Stefan |
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