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Aviation Forum / General / Soaring / July 2009Spins, Spiral Dives and Training
Okay guys, here's your new thread. Please... Del asks "how well will pilots react if they unexpectedly get into a spin or a spiral dive? Normally you gird your loins up first before doing a deliberate spin!" Answer: this depends on the pilot, of course. By the time you are gaggle flying, thermaling up off ridges or flying in competition it damned well better be automatic, reflexive. The only point to doing deliberate spins by stalling straight ahead and kicking rudder is to get some sense of how the sailplane behaves and what it takes to recover from a fully developed spin. It might also help you develop some sense of spin entry feel, but unintentional spins normally come from some combination of turning, skidding flight, gusts, etc. Oh, there's also the famous pilot who transitioned from 15m to std class and early on charged into a gaggle, pulled up, reached for the "flap" handle and spun out of the gaggle with spoilers deployed. UH, hUH! But I won't mention any names :-). I love that story. What you should practice is realistic spin entries from thermaling turns and simulated pattern turns gone bad. Do 'em in all aircraft configurations. In flapped ships the behavior changes quite a lot. If you are fooling with CG location, check that out too. Your responses can and should become fast and accurate. You should do this until you aren't "girding your loins", you aren't tense. No panic. Aircraft departs controlled flight: so what, you deal with it, get it back. regards, Evan Ludeman / T8 > Okay guys, here's your new thread. Please... > [quoted text clipped - 29 lines] > > Evan Ludeman / T8 One of the scariest experiences I ever had was an inadvertant spin in a 2-place Fox. It's an aerobatic glider by design, with limited washout and anhedral, so it's not exactly typical of your modern racing gliders. The owner had asked me to fly with him to improve his thermalling skills. We went up on a booming day, and "I got it" at about 4,000. "Now, first thing we need to do is to slow it down a little bit ... like this... Then, we increase the bank a little bit like this.. Now, if we get a good bump we just wait for a one- Mississippi, then tighten up the turn using whatever it takes like th....... WOA, WHAT THE...." Sky and earth reversed and we're spinning like a top. Now, at that time I was flying about 130-150 hrs per year including instructing at least every weekend. I was just about as current and ready as you could be. Yet, it took me a good couple of seconds to sort things out. In the Swift, it's no big deal, since it has a VNE of something approaching Mach 1.0, but I'll tell you that it wasn't pretty. The owner (a very experienced aerobatic competitor) just sat there up front chuckling. The message here isn't about the Swift and it's nasty spinning habits. It's about the fact that we probably ALL get a little complacent from time to time. When we change some variables (in the case above, a new ship with very different handling characteristics), we probably don't realize how unprepared we are for the consequences. Whenever I fly my LS8, I'm always greatful for what a wonderful handling airplane it is. However, add some water, fly on a turbulent day, get a little too aggressive on thermal entry, and it will remind you fairly forcefully, that you've exceeded its limitations. I suspect that we all need to spend more time CONSCIOUSLY practicing flight at the edges of the controllable regime in various configurations on a much more frequent basis. Short wings without water. Short wings with water. Long wings without water. Divebrakes in. Divebrakes out. Flaps positive. Flaps negative. Whatever. In some regimes, our pussycats are more like a wildcat, and we need to be able to recognize the onset of bad behavior before it gets out of control. P3 http://news.bbc.co.uk/2/hi/uk_news/england/dorset/6905327.stm > Okay guys, here's your new thread. Please... > [quoted text clipped - 29 lines] > > Evan Ludeman / T8 Getting a glider to transition to spinning starting from normal flight with the airflow fully attached to the upper wing surface is difficult - it just doesn't want to spin. The trick in getting realistic spin departures is to set up an unstable flow with the glider already near a stall. The flow detachment/re-attachment phenomena can have some hysteresis effects where the flow will momentarily 'hang on' beyond the stalling AOA. Setting up a situation where the flow is just barely 'hanging on' can take a few tens of seconds. That's why I ask the student for a long 30 seconds plus of 'slow flight'. While the student is doing this, I'm watching for an increase in sink rate. If I can talk the student into this situation of flying very slowly with abnormally high sink rate, any attempt to turn will result in a sudden, and usually unexpected, spin departure. The key is timing. The turn has to begin before the airspeed increases again and the flow returns to stability. I actually think this is the real killer spin. The pilot gets distracted, perhaps the trim is still set for thermalling, the airspeed drifts lower and lower. The glider begins to mush in a semi- stalled state until the pilot attempts a sharp turn.... <snip> > I actually think this is the real killer spin. The pilot gets > distracted, perhaps the trim is still set for thermalling, the > airspeed drifts lower and lower. The glider begins to mush in a semi- > stalled state until the pilot attempts a sharp turn....- Hide quoted text - > > - Show quoted text - I think you have hit it here. I have see this many times when doing stalls with students and even some fairly experienced pilots. It is one thing to be on the trigger ready to recover from a spin. It is totally another to be wondering why the nose is dropping and the ailerons are not working for no apparent reason. I have even read an accident report where the pilot reported that he thought the ailerons have became disconnected becuase they were ineffective. I totally believe most stall spin accident soccur because the pilot is not thinking about a stall spin and is not on the hair trigger ready to recover, .i.e. they are distracted from this issue. Brian > I totally believe most stall spin accident soccur because the pilot is > not thinking about a stall spin and is not on the hair trigger ready > to recover, .i.e. they are distracted from this issue. I believe that many of the spin accidents in the UK occur because most pilots are trained ab initio in unspinnable gliders and, whatever their instructors say, end up believing deep down that spins have to be specially provoked in specially prepared or chosen aircraft. What glider has killed most pilots in spins? The K21. Ian That is a bit unfair on the K21!. The training glider that has killed the most pilots in spin related accidents in the UK is easily the Puchacz, latest count about 14 I believe. The K21 is a very safe glider in itself, but even that will do enough of a wing drop to have you into the ground off a poorly executed low final turn. My club still uses K13s as its basic trainer as it will just about drop wings and spin if you force it to, but it is still more docile than many single seaters. You are getting into the debate about whether deliberate spin training kills more people than accidental spins. I know from personal experience that an unexpected spin, e.g. in a rough thermal, can come as a bit of a shock, and it can take time to remember what to do about it. Derek Copeland >> I totally believe most stall spin accident soccur because the pilot is >> not thinking about a stall spin and is not on the hair trigger ready [quoted text clipped - 8 lines] > >Ian At 11:00 03 July 2009, Del C wrote: (Snip) > The training glider that has killed the >most pilots in spin related accidents in the UK is easily the Puchacz, >latest count about 14 I believe. And no positively identified cause, the conclusion has always been that the spin in was caused by an error of skill by the pilot but that is difficult to confirm. It could be that under certain loading conditions the Putchaz is irrecoverable from a spin, we may never know for certain. We do know that the Putchaz is a very dangerous glider, and has been involved in more than it's fair share of accidents. >You are getting into the debate about whether deliberate spin training >kills more people than accidental spins. There is no debate, more people are killed in deliberately induced spins than in accidental ones and yet people still deliberately spin at ridiculously low altitudes, and by that I mean below 2500ft. This despite the fact that knowing the spin recovery procedure would be unlikely to help in the most common spin, that off the final turn. The only thing that would help there is spotting the impending spin before it happened but little or no emphasis is placed on this in current training. We have the situation where the most life threatening situation is not addressed by proper training and an aspect, which gives an instructor the opportunity to scare his pupil witless, is very well covered. Current spin training is more about addressing the needs of the instructors than about addressing the need of their pupils. I would suggest that not commencing spin recovery procedure in a low spin, as off the final turn, would be more likely to save your life than getting part way through the recovery. More emphasis is needed on recognition of the lead up and prevention, if that was done properly then we might improve things. By all means teach it but rather than checking recovery every year check the ability to recognise and prevent. Less risk and the potential of greater benefit, it would also reduce the need for clubs to own the potentially lethal Putchaz as the recognition and prevention could be done in any two seater. > We do know that the Putchaz is a very dangerous glider, and has been > involved in more than it's fair share of accidents. That is a correlation, not a causation. Most Puchacz spin accidents occur with instructors on board: perhaps the problem lies with instructor training? > >You are getting into the debate about whether deliberate spin training > >kills more people than accidental spins. > > There is no debate, more people are killed in deliberately induced spins > than in accidental ones... That's meaningless unless we know how many deliberate and accidental spins there are, what proportion result in deaths, and how many deliberate spins those who die in accidental ones have done. And I'm still not sure I believe it. How many of the spins of a broken cable or at the final turn are deliberate. > Less risk and the potential of greater benefit, it would also > reduce the need for clubs to own the potentially lethal Putchaz as the > recognition and prevention could be done in any two seater. As long as there are spinnable single seaters out there, that's just asking for trouble. Ian Ian In one message you said: "Juniors have a complicated spin mode which is generally three turns nose down and recoverable, three flat and unrecoverable, rinse, repeat. If you don't recover in the first three turns (Turn 1: sh.t, better get the nose up. Turn 2: why didn't that work? Turn 3: What's spin recovery again?) you just have to sweat it out for a few hundred feet or your current altitude, whichever is less." and elsewhere "You are quite right - I should have said that the oscillation is at lighter weights / after CoGs." So a Junior behaves strangely with an aft CofG, and in your words is unrecoverable. My first point is the glider should not be flying and should certainly never have been certified under JAR if that is true, unless of course the CofG is aft of the permitted limit. What is really interesting is what you say about the Puchaz, which comes from the same design shop and that is: "That is a correlation, not a causation. Most Puchacz spin accidents occur with instructors on board: perhaps the problem lies with instructor training?" In fact I cannot recall an accident where a Puchacz has spun in solo. You are absolutely correct then when you say the accidents only occur with an instructor on board, or more correctly when the back seat is occupied. So we have a different loading situation in a glider which comes from the same design shop as another glider with known spin recovery problems if the CofG is moved aft. So is there the same problem with the Puchacz as with the Junior, and is that problem in fact worse to the extent that there is no recovery? We cannot know for sure but there is evidence that points that way. Does this not raise any concerns? I know we cannot prove that the Puchacz will not recover under certain loading conditions any more that we can prove that the spin ins have been caused by pilot error. The truth is that the Puchacz has been proved to be a glider that frequently kills people. I experienced a spin recovery in a Puchacz that was prolonged to an extent that I thought it was not going to recover. It did eventually. It is very easy to blame the unknown on pilot error but I suggest that we should at least consider the possibility that there is a major problem with the Puchacz, one which should mean that it is not intentionally spun as an absolute minimum. We are never going to have a pilot tell us "This glider was impossible to get out of a spin", because if that is the case he is dead and not saying much. My personal view is that there is sufficient evidence to show that the Puchacz is a dangerous glider, so dangerous in fact that it should never be flown again. > with the Junior, and is that problem in fact worse to the extent that > there is no recovery? We cannot know for sure but there is evidence that > points that way. Yes, we can and do know. The Puchacz as well as the Junior have been frequently flown in aerobatics contests. To my knowledge, no Puch nor Junior has been spun into the ground during a contest. So they do recover. More, they even do recover forseeably and precisely, otherwise they wouldn't be flown in contests. >> with the Junior, and is that problem in fact worse to the extent that >> there is no recovery? We cannot know for sure but there is evidence that [quoted text clipped - 5 lines] >recover. More, they even do recover forseeably and precisely, otherwise >they wouldn't be flown in contests. Yes, but are they flown in contests with the CofG aft and in the case of the Puchacz with the rear seat occupied with a heavier pilot? I doubt it. I am not saying that under all loading conditions that there is a problem. What I am suggesting is that under some loading conditions there may well be. What has been said in previous posts tends to indicate there might be. Evidence from pilots who recover is unhelpful, evidence from pilots who don't is not available. My one experience (in a Puchacz) showed me that there was a problem and I resolved from that day that I would never walk under one let alone fly in one again. I assume the instructor filed a report, at the time I was not involved with the BGA at all. > >> with the Junior, and is that problem in fact worse to the extent that > >> there is no recovery? We cannot know for sure but there is evidence [quoted text clipped - 19 lines] > one again. I assume the instructor filed a report, at the time I was not > involved with the BGA at all. I think the Puchacz spin characteristics are well explained in this report. http://www.tsb.gc.ca/eng/rapports-reports/aviation/2005/a05o0204/a05o0204.asp Note the paragraph where is states that after extensive testing they found that the only way a recovery could be prevented is by holding full back stick. It further states that the nose must be pushed to a very steep nose down attitude, which appears from the cockpit to be past the vertical, to get reliable recovery. They suggest that failed spin recoveries likely result from pilots unwilling to push the nose that far down. The Puchacz POH can be found here: http://soargbsc.com/members/manuals/puchacz.pdf It has two pages devoted to spins. It specifies that the ailerons MUST be held neutral, otherwise oscillations will result. It also says that with the CG aft of the mid point, the stick has to go forward of neutral elevator and to expect the spin may continue beyond one turn after anti- spin controls are applied. It also says rudder and elevator control forces are high during the spin recovery. It seems reasonable to say that Puchacz are spun in by pilots who are unfamiliar with its special spin recovery characteristics - perhaps by pilots who haven't bothered to read the POH and believe all they have to know is the "standard spin recovery" technique. The Puchacz is not a dangerous glider. There may be dangerous pilots who fly them, however. At 21:15 04 July 2009, bildan wrote: (snip) >The Puchacz is not a dangerous glider. There may be dangerous pilots >who fly them, however. How would you describe a glider in which so many people have been killed in spinning incidents? Unlucky? Challenging? or Misunderstood perhaps? I fully accept the reports of the pilots who tested the glider and found that it recovered, if it had not they would not have been able to report that it didn't. Of course no-one is going to design a glider that cannot recover from a spin, and of course no-one is going to design an airliner where the doors fall off either, causing major structural failure. I do not think that the level of expertise found at McDonnell-Douglas exists in a glider design facility. Design faults are found in aircraft after release to service and mostly something is done or at least restrictions are put in place to counteract the fault, not so with the Puchacz. The reason why no-one has reported that a Puchacz is impossible to recover is that if it has happened the pilots have not survived to do so. It is easy to blame someone when they are not around to challenge that finding and this is certainly what the Canadian report does. Is the best explanation that anyone can come up with is that the glider attracts more than it's fair share of dangerous pilots. I have little doubt that the Putchacz will go on killing people while it is permitted to continue to fly, it won't be me, I will never fly in one again. I have done quite a few flights in the Puchacz. It is a perfectly nice glider, albeit with a slightly greater tendency to spin than most West European designs. Ditto the Junior. They will both recover using the standard spin recovery, although you may have to get the stick well forward and hold it there until the spin stops. I personally prefer training gliders that spin properly and require a positive recovery. With the K13 for example, you are never quite sure whether it will go into a spin or a spiral dive, and it will usually recover from a spin as soon as the stick is moved off the backstop. not very realistic! Derek Copeland >At 21:15 04 July 2009, bildan wrote: (snip) > [quoted text clipped - 26 lines] >is permitted to continue to fly, it won't be me, I will never fly in one >again. > > with the Junior, and is that problem in fact worse to the extent that > > there is no recovery? We cannot know for sure but there is evidence that [quoted text clipped - 5 lines] > recover. More, they even do recover forseeably and precisely, otherwise > they wouldn't be flown in contests. I can cite more than one instance where an "experienced pilot" has spun a "well known" design, under "normal" circumstances resulting in "unexpected" characteristics. There are dozens, or more, variables involved and to assume that you have seen all the possibilities is shortsighted to say the least. You should not assume that you are doing everything the same way every time, with identical equipment. I've experienced such episodes and no longer will "explore" that part of a flight envelope. An appropriate phrase for such activity is "practice bleeding". > I've experienced such episodes and no longer will "explore" > that part of a flight envelope. An appropriate phrase for such > activity is "practice bleeding". Hey at least we can do RTSL aborts ok! It will be important for Soaring pilots to know whether the recent crashes were from a spinning or a spiraling ship..That most likely can be determined by the type of impact. Simply, every pilot should recognize and recover from an incipient spin. If he or she is not sure, one should be shown in a Blanik or similar spin happy ships. A glider in flight should really never come close to a spiral, since it is approaching red line fast. I feel the reason gliders get into spirals is not only the lack of spin recognition of the pilot, but poor flying technique. Yaw string, airspeeds, coordination. Of course all those problems can happen to a pilot becomming sick, passing out or similar. I have programmed myself to immidiately pull the trim all the way back and let go of the controls. Not sure if that would help, depends on the ship? soarski > It will be important for Soaring pilots to know whether the recent > crashes were from a spinning or a spiraling ship..That most likely can [quoted text clipped - 14 lines] > > soarski The programing myself, I meant If I had the time or the chance, to do so before getting incapasitated. In message <50ac5404-1870-4a2b-8e1f-85f1df0c2f78@v15g2000prn.googlegroups.com>, soarski <soarski@gmail.com> writes <snip> >A glider in flight should really never come close to a spiral, since >it is approaching red line fast. I feel the reason gliders get into >spirals is not only the lack of spin recognition of the pilot, but >poor flying technique. Yaw string, airspeeds, coordination. You could say exactly the same thing about spins. >Of course all those problems can happen to a pilot becomming sick, >passing out or similar. I have programmed myself to immidiately pull >the trim all the way back and let go of the controls. Not sure if >that would help, depends on the ship? > >soarski I suspect you are being very optimistic that you could do anything to avert disaster. You might pass out, or you might be in so much pain that you are totally incapacitated. I can't see what the point of trimming all the way back is, either.  SignatureSurfer! Email to: ramwater at uk2 dot net > I suspect you are being very optimistic that you could do anything to > avert disaster. You might pass out, or you might be in so much pain > that you are totally incapacitated. I can't see what the point of > trimming all the way back is, either. If you trim well back and add as much drag as possible using airbrakes, wheel down etc and get off the controls then you will probably get a fairly stable and low speed "benign spiral" which may even be survivable on contact with the ground depending on what you hit. Try it in your own ship at altitude and find out. > My personal view is that there is sufficient evidence to show that the > Puchacz is a dangerous glider, so dangerous in fact that it should never > be flown again. Detailed 'puchy' spin analysis found here: http://www.ssa.org/members/johnson/fileserve.asp?file=72-1994-06.pdf It's actually pronounced poo-hots BTW, but I'm not sure how it translates in plurality... regardless, it is odd how many have drilled into the ground with competent pilots and instructors onboard though. Of course there's the rudder pedal theory (rear pilot's feet obstructing mechanism's full travel...), but it's just that- a theory. -Paul >> My personal view is that there is sufficient evidence to show that the >> Puchacz is a dangerous glider, so dangerous in fact that it should never [quoted text clipped - 11 lines] > >-Paul The above document is only available to SSA members, it might be of some use to the wider gliding community > >Detailed 'puchy' spin analysis found here: > > >http://www.ssa.org/members/johnson/fileserve.asp?file=72-1994-06.pdf > The above document is only available to SSA members, it might be of some > use to the wider gliding community Sorry bout that... I can't figure out how to publicly post it yet, but I can email anyone that PM's me a copy of it if they like... -paul at eaglebrandproducts dot com Don, What height I am prepared to deliberate spin from when instructing very much depends on the type of glider I am flying. K13s as low as 800ft, Puchaczs (is the plural Puchi?) Grob 103s and DG1000s probably not below 2000ft. I don't see why spinning exercises are only 'addressing the needs of the instructor'. I would personally prefer not to be tumbling out of the sky, but pupils have to be taught that such things can happen, and how to recover from them. After every spin entry situation, I also demonstrate or talk them through how to avoid these situations, as do most other instructors trained or retrained in the last twenty years, so I don't agree with your premise that spin avoidance is not taught. Low level spins are easily avoidable by flying a bit faster and flying accurately, even in a Puch. If you spin off a final turn, it's game over, and just a case of whether you get killed or just seriously injured! You might just save yourself if you recognise the incipient stage in time and get the stick forward. Derek Copeland >snip >There is no debate, more people are killed in deliberately induced spins [quoted text clipped - 21 lines] >reduce the need for clubs to own the potentially lethal Putchaz as the >recognition and prevention could be done in any two seater. > That is a bit unfair on the K21!. The training glider that has killed the > most pilots in spin related accidents in the UK is easily the Puchacz, > latest count about 14 I believe. That is, if I may say so, the mistake too many people make. Sure, more people have died in the Puchacz, but I am quite sure that the K21 has killed a lot more indirectly. > I know from personal experience that an unexpected spin, e.g. in a rough > thermal, can come as a bit of a shock, and it can take time to remember > what to do about it. Don't we all? Ian In message <0572ec19-145f-4fc3-877e-65cad80cba7f@c36g2000yqn.googlegroups.com>, Ian <ian.groups@btinternet.com> writes >> I totally believe most stall spin accident soccur because the pilot is >> not thinking about a stall spin and is not on the hair trigger ready [quoted text clipped - 6 lines] > >What glider has killed most pilots in spins? The K21. However the two recent accidents both involved US pilots, presumably trained in the US. Is the K21 so ubiquitous over there? BTW have seen folks allowed to fly the K21 solo without spin training, but *not* the Juniors. SignatureSurfer! Email to: ramwater at uk2 dot net > In message > <0572ec19-145f-4fc3-877e-65cad80cb...@c36g2000yqn.googlegroups.com>, Ian [quoted text clipped - 20 lines] > Surfer! > Email to: ramwater at uk2 dot net Don't think the accidents had anything to do with training and certainly nothing to do with the K21 or whatever other ships they may have trained in. These were experienced competition pilots. -T8 > > In message > > <0572ec19-145f-4fc3-877e-65cad80cb...@c36g2000yqn.googlegroups.com>, Ian [quoted text clipped - 26 lines] > > -T8 The following has nothing to do with the UK which seems to exist in a parallel universe with different laws of physics - at least as Derek describes it. If the training isn't current, it really doesn't matter too much what it was. Without comment on the accidents still under investigation, many 'competition pilots' only fly at contests and haven't flown more than 20 flights a year in decades. I think we might eliminate a few 'contest accidents' by instituting a currency requirement for competitors. Angle of attack indicators are far more than stall warning devices. They provide extremely accurate and timely information about wing performance. However, they can also be the basis of a stall warning device. Since most glide computers already display height above terrain data, a stall warning could become louder and more insistent as the glider gets near the ground and/or the landing gear is extended. > BTW have seen folks allowed to fly the K21 solo without spin training, > but *not* the Juniors. Juniors have a complicated spin mode which is generally three turns nose down and recoverable, three flat and unrecoverable, rinse, repeat. If you don't recover in the first three turns (Turn 1: sh.t, better get the nose up. Turn 2: why didn't that work? Turn 3: What's spin recovery again?) you just have to sweat it out for a few hundred feet or your current altitude, whichever is less. Ian Hi Ian, I have spun our club's Junior and have never seen those different cycles. However, I weigh about 190 Lbs plus parachute. I'm sure the spin characteristics are very different at different weights. I thought the Junior spun aggressively, but I found it easy to exit the spin immediately after multiple (I don't recall how many - maybe 3 or 4) rotations. I love spinning gliders! Best Regards, Paul Remde >> BTW have seen folks allowed to fly the K21 solo without spin training, >> but *not* the Juniors. [quoted text clipped - 7 lines] > > Ian > I have spun our club's Junior and have never seen those different cycles. > However, I weigh about 190 Lbs plus parachute. I'm sure the spin > characteristics are very different at different weights. You are quite right - I should have said that the oscillation is at lighter weights / after CoGs. > I thought the > Junior spun aggressively, but I found it easy to exit the spin immediately > after multiple (I don't recall how many - maybe 3 or 4) rotations. I love > spinning gliders! Do you have Polish blood, by any chance? Ian I heard of one being test-flown by a gentleman who was certainly not too light. Apparently it recovered on it's own and he only had to pull out of the dive... >Hi Ian, > [quoted text clipped - 20 lines] >> >> Ian SignatureSurfer! Email to: ramwater at uk2 dot net We changed our spin training approach based on this thought. We now have the student enter a thermaling turn at slow speed with about 30 degrees of bank. Keep coaching them to get it slower, sometimes on their own they use a little too much inside rudder and zippity do dah.. spin entry. I had one Grob 103 check out, doing cross controlled stalls at about 15 degrees of bank and it got very slightly uncoordinated. The inside wing started to drop, and the student applied correcting aileron. I saw the nose starting to track to the inside of the very quickly and I just as quickly took the controls and applied spin recovery procedure. The student also saw it and asked if we could do that again... ahh... not intentionally and not this low. We were high enough per FAR for Stalls, but not above for my personal floor for spin recognition / recovery practice. BT > Okay guys, here's your new thread. Please... > [quoted text clipped - 29 lines] > > Evan Ludeman / T8 I personally am of the opinion that a lot of people thermal too slowly and put themselves in a position to have an inadvertent stall/spin accident. Most of us are aware that stall speed goes up in a banked turn. But the desire to fly slowly and stay in the thermal keeps us down in the "danger-zone", just above the stall speed. This is unnecessary and can actually be a big hinderance! Why? 1) There's no reason to fly below min-sink speed, as any good glider handbook will tell you. What they don't usually mention is that your min-sink speed is higher in a banked turn than straight-and-level flight! The same G-loading that affects your stall speed also affects your whole glide polar - just as added wing-loading does when you use water ballast. So in a thermal you should already be flying a bit faster than the POH indicates for min-sink. How much faster depends on your bank angle, and the same calculations for stall speed in a banked turn should be applicable to your aircraft. 2) The slower you go, the less control authority you have. This means upsets are tougher to avoid, recovery from an unusual attitude is harder to achieve, and control deflections have to be bigger in order to make normal corrections to maintain your bank & pitch angles. Remember - bigger control deflections equal more drag! 3) Remember that your airframe and wings start to experience localized areas of separated airflow long before you get down to true stall speed. _Any_ dirty or separated airflow is extra drag and can result in a slower overall climb-rate (as you burn some of your energy maintaining speed and countering the drag forces). You want the entire aircraft to be sliding through the air as cleanly as possible to maximize the lift in the thermal! 4) Thermals contain unstable air - turbulence and wind gusts and the shear around the edges of the thermal can all create assymetrical lift conditions across the wings; or cause airflow separation on parts of the wing (if the boundary layer is already close to seaparating). The closer you are to stall speed, the more likely this is to suddenly occur due to gusts or shear effects. (For those of you who are trying to fly fast, add in the effects of your water-ballast to all of this, too) Just some food for thought, --Noel > I personally am of the opinion that a lot of people thermal too slowly > and put themselves in a position to have an inadvertent stall/spin [quoted text clipped - 42 lines] > > --Noel For this reason and for safety is why I advocate an angle of attack indicator. The AOA indicator will help determine the exact airspeed for minimum sink for your wing loading and bank angle. Then, you can use either instrument as your guide. There's actually quite a large range of AOA between min sink and stall so flying min sink AOA will keep you a safe distance from a stall. I have to think that an AOA indicator 'might' have saved at least one life this summer. Our club's DG1000T has a stall warning device that sounds when a certain angle of attack is reached. However I find the thing a distaction, as it goes off every time you hit a gust (thermals tend to be gusty) and I can comfortably circle at a speed where it is sounding all the time. If Noel Wade came to visit the UK, he would probably not be able to climb at all in our often tiny little thermals using the techniques he suggests. The necessary skill is to be able to fly in accurate well banked turns at not more than about 5 knots over the turning stall speed. Otherwise he will be going round in the sink surrounding the thermal. However I agree that you should not fly so slowly that the glider is buffeting, as that is inefficient and dangerous. By the way, my favourite spin entry for annual checks on our members is out of a well banked turn. All you have to is slow the glider down in a typical thermalling turn until it is just starting to buffet and then feed in a bit of bottom rudder. The glider will depart instantly into a fully developed spin. This demonstrates the need for accurate flying and for not using too much rudder into the turn. If you put in a bit of top rudder it is almost impossible to make the glider spin, however slowly you fly it. Del Copeland >> I personally am of the opinion that a lot of people thermal too slowly >> and put themselves in a position to have an inadvertent stall/spin [quoted text clipped - 3 lines] >> the desire to fly slowly and stay in the thermal keeps us down in the >> "danger-zone", just above the stall speed. =A0This is unnecessary and >> can actually be a big hinderance! =A0Why? >> >> 1) There's no reason to fly below min-sink speed, as any good glider >> handbook will tell you. =A0What they don't usually mention is that your >> min-sink speed is higher in a banked turn than straight-and-level >> flight! =A0The same G-loading that affects your stall speed also affects >> your whole glide polar - just as added wing-loading does when you use >> water ballast. =A0So in a thermal you should already be flying a bit [quoted text clipped - 3 lines] >> >> 2) The slower you go, the less control authority you have. =A0This means >> upsets are tougher to avoid, recovery from an unusual attitude is >> harder to achieve, and control deflections have to be bigger in order [quoted text clipped - 4 lines] >> areas of separated airflow long before you get down to true stall >> speed. =A0_Any_ dirty or separated airflow is extra drag and can result >> in a slower overall climb-rate (as you burn some of your energy >> maintaining speed and countering the drag forces). =A0You want the [quoted text clipped - 5 lines] >> conditions across the wings; or cause airflow separation on parts of >> the wing (if the boundary layer is already close to seaparating). =A0The >> closer you are to stall speed, the more likely this is to suddenly >> occur due to gusts or shear effects. [quoted text clipped - 16 lines] >I have to think that an AOA indicator 'might' have saved at least one >life this summer. > If Noel Wade came to visit the UK, he would probably not be able to climb > at all in our often tiny little thermals using the techniques he suggests. > The necessary skill is to be able to fly in accurate well banked turns at > not more than about 5 knots over the turning stall speed. Otherwise he > will be going round in thesinksurrounding the thermal. Derek - Thanks for attacking my skills rather than arguing the point from a logical perspective... I trained and fly in places that have both weak lift and narrow lift, and I stay in them just fine - for the record. Now, to actually defend the point: If your argument is that you have to fly slowly in order to stay in a small thermal, you're ignoring an alternate solution: tighten your bank angle. It is true that a slower speed gives you a smaller turning radius at the same bank-angle, but it has a number of drawbacks (many of which I touched on with my post - you're closer to stall speed, you're possibly below min-sink - and therefore not flying the glider as cleanly or efficiently as you could be). If you simply keep your speed up and tighten your bank angle, you'll achieve a smaller turning radius and you won't be in danger of stalling. I urge you to do the math, as I have done (or at least look it up online, there are webpages that illustrate this - such as: http://www.soarns.ca/crclmotn.html)... Down around the speeds we're talking about, you will have a _smaller_ turn radius at a 45-degree bank-angle than at a 30-degree bank-angle, EVEN if you add 5 - 7 knots of speed in the higher bank-angle turn. AND the additional G-loading does not increase your sink rate by that much (around 20 ft/min in my DG-300). Even in a small 2-knot thermal you're really only giving up a small percentage of performance in order to be a lot safer. And there are plenty of ways that the average pilot can "make up" that performance, by flying more cleanly in other phases of flight. Finally, if you _have_ been flying below min-sink speed (for a given bank-angle), you may actually find _improved_ climb performance by keeping your speed up and tightening your bank-angle. Take care, --Noel Noel, It was not my intention to attack your flying skills, but just to state a fact of life about flying in UK conditions. The tighter you turn, the more the stalling speed increases, due to the extra g loading, and the more the sink rate increases. Our thermals can also be quite weak, so excessive angles of bank can increase the glider's sink rate enough to cancel out the thermal. 5 knots over the turning stall speed at a 35-40 degree angle of bank usually works well in the UK, and that puts you at about the effective min sink speed. I have flown in central France, where the thermals are normally huge and strong. In the UK you normally turn as soon as you encounter lift, but there you had to wait for maybe twenty seconds before you reached the core of the thermal. The French pilots seem to thermal at only about 15 degrees angle of bank. One holiday I had over there consisted of a whole fortnight of low inversion blue days, so somewhat UK like conditions with small weak thermals. My syndicate partner and I where able to do a number of 200-300k flights when most of the locals (with one exception, who was a world class competition pilot) couldn't stay up at all. Maybe that is why the UK has produced so many World Gliding Champions, although I am not quite in that league myself. Derek Copeland >> If Noel Wade came to visit the UK, he would probably not be able to >climb [quoted text clipped - 43 lines] > >--Noel yes.. but the idea is to train spin recognition and recovery.. and why it is not good to thermal too slowly.. but how if the pilot is not attentive to his speed.. he can get into trouble.. not fun in a thermal with others below BT >I personally am of the opinion that a lot of people thermal too slowly > and put themselves in a position to have an inadvertent stall/spin [quoted text clipped - 42 lines] > > --Noel If may, I would like to get off on a bit of a tangent, i.e. the original subject stated in the title of this thread. One of the problems that I have observed with students and a few high time pilots alike is the following: when presented with a spin or a spiral dive, mis-diagnosing the problem and applying the wrong recovery. To some who experience these maneuvers infrequently, they appear similar enough to bring about confusion and as you know, applying the wrong recovery can get grim. I believe airspeed, sound and G are the keys with the latter two very important. Some are so confused by the ground spinning around that they don't think about looking at the airspeed indicator. But they do seem to sense if it is relatively quiet or loud and if they are experiencing more than 1G. A thorough ground briefing on the differences and then demonstrating both on the same flight really helps. Then follow that with a lesson where they must make the diagnosis and apply the proper recovery. This has worked for me. I would enjoy hearing from others who have thoughts on this very important subject. Paul ZZ 8 wrote: > Okay guys, here's your new thread. Please... > [quoted text clipped - 29 lines] > > Evan Ludeman / T8 I have already been flamed once for bringing up this subject in the original Parowan accident thread, as being irrelevant to highly experienced competition pilots! However for those of them who are not also instructors, that experience consists of many hundreds or thousands of hours of either flying straight or circling in thermals! How well would they cope in the event of a sudden and unexpected upset? It is important to be able to differentiate between a spin and a spiral dive because the recovery actions are quite different. In a spin, the nose will often go well down, despite the fact you are stalled, the ground will rotate in front of you, and there will be very little build up of g. The ASI is likely to totally misread due to the amount of yaw present; it may even go back though zero and show a very high reading. In a spiral dive, the nose may remain fairly well up, despite the fact you are not stalled, and airspeed and g will build up rapidly and continue to do so. In many ways spiral dives are more dangerous as you risk going through Vne and breaking up the glider. Spins in themselves are not dangerous at all, at least as long as you recover before hitting the deck. Just a quick reminder of the standard recovery actions: Spin: 1) Centralise the ailerons 2) Apply full outspin rudder 3) Move the stick steadily and progressively forward until the spin stops 4) Centralise the rudder and ease out of the dive Spiral dive: 1) Keep the stick fairly well back and use the controls normally to reduce the angle of bank - a spiral dive is just a very overbanked turn. IMHO spins and spiral dives should be a part of periodic check flights. Derek Copeland (UK Gliding Instructor) >If may, I would like to get off on a bit of a tangent, i.e. the >original subject stated in the title of this thread. > >One of the problems that I have observed with students and a few high >time pilots alike is the following: when presented with a spin or a >spiral dive, mis-diagnosing the problem and applying the wrong recovery. >To some who experience these maneuvers infrequently, they appear similar >enough to bring about confusion and as you know, applying the wrong >recovery can get grim. > >I believe airspeed, sound and G are the keys with the latter two very >important. Some are so confused by the ground spinning around that they >don't think about looking at the airspeed indicator. But they do seem to >sense if it is relatively quiet or loud and if they are experiencing >more than 1G. A thorough ground briefing on the differences and then [quoted text clipped - 40 lines] >> >> Evan Ludeman / T8 > I have already been flamed once for bringing up this subject in the > original Parowan accident thread, as being irrelevant to highly [quoted text clipped - 98 lines] > > >> Evan Ludeman / T8 This is the "PARE" recovery technique published in the US a by NACA in 1936. However, that publication also stated that this technique was to be used only in the absence of a manufacturers recommended recovery method. If such a recommendation exists, it must be used instead. This remains the position of NACA's successor, NASA. All Pilots and Operators Handbooks (POH) supplied with certified (And most experimental) aircraft will have a spin recovery technique spelled out in the "Emergency" section of the handbook. It is often at variance to the PARE technique. The handbook may even state that spins are prohibited indicating that the spin or the recovery from it is hazardous, even unlikely. For an excellent source of spin information - and recovery technique see: http://en.wikipedia.org/wiki/Spin_%28flight%29 Nevertheless, if you get into an accidental spin, you have to make a recovery or die, whether or not the aircraft is certified for deliberate spinning. The only gliders I know of that may need special recovery techniques are some large span, flapped gliders such as the Nimbus 4. If you have flaps the first action should be to select neutral flap if you are already in a positive setting. This is to avoid exceeding the flap limiting speed in the recovery dive. Derek Copeland >This is the "PARE" recovery technique published in the US a by NACA in >1936. However, that publication also stated that this technique was [quoted text clipped - 12 lines] >see: >http://en.wikipedia.org/wiki/Spin_%28flight%29 >Nevertheless, if you get into an accidental spin, you have to make a >recovery or die, whether or not the aircraft is certified for deliberate >spinning. I have to take issue with that statement which nicely illustrates my point. Knowing any recovery technique is not going to help you at all if you spin from a low final turn, the only thing that will save you is recognising what is happening and stopping it happening. I would go further and say that recovery in such a situation should not be attempted. If you look at the video you see that the glider hit wingtip first, which is what wound up the rotational speed, and then the nose impacted, much of the impact was absorbed by this process and the crew survived. If you imagine the situation where the glider is just a little higher and recovery is attempted and part suceeds, what is the first thing that stops, the rotation so instead of impacting the ground and having some of the the impact energy absorbed the glider hits the ground, nose first, accelerating, known as tent pegging I believe. This is very bad news for the crew and yet we quite happily consider recovery from spinning of greater importance than recognition of the early signs and prevention. Knowing the spin recovery procedure would have been of no use whatsoever to the crew of the glider in the video. I am not very experianced or an instructor, but see this video, ... http://www.youtube.com/watch?v=jvK1ONl1CqE After being slow to recoginise the cable break, the glider is stalled and rotating, but the nose does not go down, so the crash is perhaps less painfull than going in nose first.? I hope I would have better recoginised/reacted to the break, but if not I would have still lowered the nose more to unstall the wing and hopefully flare the landing????? David. >>Nevertheless, if you get into an accidental spin, you have to make a >>recovery or die, whether or not the aircraft is certified for deliberate [quoted text clipped - 20 lines] >Knowing the spin recovery procedure would have been of no use whatsoever >to the crew of the glider in the video. Don, The German DG500 pilots escaped serious injury because, being so low, they didn't have that far to fall when the spin developed. Also DG gliders have crash resistant cockpits. Even so I bet that hurt! If you are in a full spin, you are decending at 50-60 knots or 5000ft/min+, which is probably enough to kill you. It certainly killed a former syndicate partner of mine who spun off a slow autotow launch at about 800ft and failed to make any sort of recovery. Once in a fully developed spin it probably matters not if you spin into the ground, or dive into it. If you have enough height to do so, it is better to recover because you then stand a very good chance of staying alive. I have already pointed out that you cannot afford to spin once down to circuit height, so you have to have to fly accurately at a safe airspeed. Derek Copeland >>Nevertheless, if you get into an accidental spin, you have to make a >>recovery or die, whether or not the aircraft is certified for deliberate [quoted text clipped - 20 lines] >Knowing the spin recovery procedure would have been of no use whatsoever >to the crew of the glider in the video. > All Pilots and Operators Handbooks (POH) supplied with certified (And > most experimental) aircraft will have a spin recovery technique > spelled out in the "Emergency" section of the handbook. It is often > at variance to the PARE technique. All JAR certified gliders, which means all European manufactured gliders certified after about 1970, *must* recover with the "standard method", which happens to be the same as what you call "pare". And they must do so with all allowed loadings, and even with asymmetric water ballast. > > All Pilots and Operators Handbooks (POH) supplied with certified (And > > most experimental) aircraft will have a spin recovery technique [quoted text clipped - 5 lines] > which happens to be the same as what you call "pare". And they must do > so with all allowed loadings, and even with asymmetric water ballast. I think the correct JAR 22 is standard recovery UNLESS the manufacturer specifies an alternative method. > I think the correct JAR 22 is standard recovery UNLESS the > manufacturer specifies an alternative method. Wrong. A glider *must* meet the standard recovery requirement to be certified. And it must recover with *all* allowed loading distributions and also with asymmetrical water ballast, and from a fully developed spin, defined as 5 turns (unless the spin converts to a spiral dive earlier). (Yes, 5. The FAR only ask for 3 turns.) Of course, manufactureres may define other recovery procedures which may work faster, but nevertheless the standard procedure *must* work. (E.g. the Cap 10 aerobatic airplane recovers much faster with the stick held fully back.) JAR 22 also asks that the spin must recover in less than something like 2 turns (I'm not entirely sure). Note that 2 turns will feel extremely long!!! E.g. the ASK 21 (with tail ballast) usually recovers in less than half a turn, but in certain circumstances (weight distribution, moment of recovery in the pitch oscillation rythm) may last up to 2 turns. If you are not aware of this, then it will frighten you to death and you will tell everybody that the ASK 21 is a potential killer, which it's not. > One of the problems that I have observed with students and a few high > time pilots alike is the following: when presented with a spin or a > spiral dive, mis-diagnosing the problem and applying the wrong recovery. > To some who experience these maneuvers infrequently, they appear similar I was still a fairly unexperienced pilot when I received my primary aerobatics training. My third or so spin (which means that I was really unexperieced) changed unexpectedly into a spiral dive after one rotation or so, something I had never experienced before. I needed about half a second to recognize the situation and apply the correct controls. Spin and spiral dive feel completely different. While I agree that practice recovering from "realistic entry" spins and/or spiral dives is highly desirable, there are real problems with trying to do so. For example, my LS8-18 POH specifically states "Aerobatic flight not approved". My club's Grob 103s are approved for spins, but the club insurance policy prohibits doing them. There is one nearby commercial operator who offers an introductory aerobatics course using a Blanik L-13AC, but as he wants to get out of the flying business that option won't be available much longer. -John For those of you who think spins can only be entered from almost straight flight in a nose height attitude with a bootful of rudder, have a look at the following video: http://www.youtube.com/watch?v=_xCct8cDtyk This was an attempted downwind landing after a winch launch cable break at 80 metres (260ft). Note that the glider is never in a nose high attitude. The pilot may have tried to rudder it round the low final turn, you can't really tell from the quality of the video, but there was a reasonable amount of bank on. What finally seems to have triggered the spin was opening the airbrakes half way round the final turn. Note also the amount of of rotational energy stored up once the spin developed, with the glider continuing to rotate even after it crashed into the ground. Reducing the rotation rate is the first action in recovering from a fully developed spin, i.e. full outspin rudder. At the wing drop or incipient stage, it is only necessary to move the stick forward to unstall the wings and prevent a full spin from developing. This will cost the minimum amount of height. The full spin recovery at this point may actually cause a flick in the opposite direction as well as delaying the recovery. So it's basically move the stick forward, maybe using the rudder as well to minimise any build up of yaw, and then sort out the bank and attitude by using the controls normally once the airflow is re-attached to the wings. Derek Copeland > For those of you who think spins can only be entered from almost > straight flight in a nose height attitude with a bootful of rudder, > have a look at the following video: > > http://www.youtube.com/watch?v=_xCct8cDtyk "This video or group may contain content that is inappropriate for some users, as flagged by YouTube's user community. To view this video or group, please verify you are 18 or older by signing in or signing up." Did it involve a fatality? > Did it involve a fatality? Listen to the text: The pilot suffered only slight injuries. >> Did it involve a fatality? > > Listen to the text: The pilot suffered only slight injuries. You elided the essential part where I pointed out that one can't view the video (and therefore "listen to the text") without first creating an account on Youtube and atesting that one is 18 or over. If it didn't involve a fatality, why is the video considered inappropriate for some viewers? > You elided the essential part where I pointed out that one can't view the I think this link works for all, it's the same video. http://www.youtube.com/watch?v=GUyVLshEMcs&feature=PlayList&p=95658D79FBDB28F6&p laynext=1&playnext_from=PL&index=2 >>> Did it involve a fatality? >> [quoted text clipped - 5 lines] > >If it didn't involve a fatality, why is the video considered inappropriate for some viewers? Possibly because of the rude word in German uttered by a lady witness that you can also hear in the soundtrack! Even if there were no fatalities or serious injuries, this video should be X or 18 rated, and not viewed by those of a nervous disposition. Fortunately such accidents are quite rare, at least in Europe, so this video should not put you off gliding or winch launching. Derek Copeland |
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