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#11
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Basic Training Gliders, K21 tail ballast.
There are two approved methods of adding rear ballast to the K21 to move the
C. of G. aft. It is possible to fit a lead ballast block in the rear fuselage just aft of the fin spar, this is not intended to be fitted or removed between flights, and of course the machine must be re-weighed.. It is also possible to have a hole through the fin to take a bar to carry external ballast in the form of up to 10 x 1kg lead weights, which is intended to be adjusted or removed between flights as required. See "optional extras" on the specification sheet at http://www.as-segelflugzeuge.de/englisch/e_main.htm , "Your Sailplane", "ASK 21", at the bottom of the page "Download Info:", "Specification ASK 21 (english)". Both schemes are described in the owners' handbook. See also the Schleicher AD and Technical notes http://www.as-segelflugzeuge.de/englisch/e_main.htm "TN/LTA", "ASK 21" in particular TN-No 4 &4a, see also "further TN/AD see overview (PDF)". Note also that in common with all German gliders (as far as I know) the minimum front cockpit weight is always shown as 70 kg (154 lbs). However if the glider is carefully weighed it may be found that the minimum front cockpit load calculated by moments when flown solo is less than this. Of course the minimum front cockpit load calculated by moments will always be reduced when there is a rear seat pilot, by an amount which increases as the rear cockpit load is increased. The importance of all this is that the glider will not hold a stable spin unless the C. of G. is close to the aft limit (the numbers are in the handbook), but you will be in trouble if you fly it with the C. of G. aft of the aft limit. Don't even think of trying for a full spin, or flying with the C. of G. well aft unless you have read the pilots' manual AMENDED BY TN 23. The TN itself is on the Schleicher web-site but the page amendments are not. W.J. (Bill) Dean (U.K.). Remove "ic" to reply. "Markus Gayda" wrote in message ... For the ASK-21 is a "spin-weight" available which can be installed on the rudder. Of course you have to weigh the pilots before deciding which weights to add to the glider. But then you have a very nice trainer with which you can also train spins. CU Markus |
#12
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Basic Training Gliders
Derek Copeland wrote:
While a headrest may be an important safety item in a car to protect you from whiplash in a rear end shunt, I am still trying to work out in what circumstances a glider might get rammed from behind?!!!!!! Stupid F***ing Bureaucrats! Perhaps the "Stupid F***ing Bureaucrat" saw the same video I saw at an SSA convention: it showed the pilot dummy movement during a test crash of a glider, with violent whiplash occurring. I then asked Gerhard Waibel about the safety value of the headrest in Schleicher gliders, and he told me it was very important. So, I retrieved the headrest for my ASH 26 E from the basement and put it back in the glider! -- Change "netto" to "net" to email me directly Eric Greenwell Washington State USA |
#13
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Basic Training Gliders
At 20:42 04 December 2005, Eric Greenwell wrote:
Derek Copeland wrote: While a headrest may be an important safety item in a car to protect you from whiplash in a rear end shunt, I am still trying to work out in what circumstances a glider might get rammed from behind?!!!!!! Stupid F***ing Bureaucrats! Perhaps the 'Stupid F***ing Bureaucrat' saw the same video I saw at an SSA convention: it showed the pilot dummy movement during a test crash of a glider, with violent whiplash occurring. I then asked Gerhard Waibel about the safety value of the headrest in Schleicher gliders, and he told me it was very important. So, I retrieved the headrest for my ASH 26 E from the basement and put it back in the glider! So what do you have to do to achieve the whiplash - Tailslide backwards into the ground? I did once injure my neck as a result of a student's very heavy landing. Basically my head went forwards and down and I got what is called an 'acute flexion injury' which is the reverse of the usual whiplash injury where the head initially goes backwards. I don't believe that a headrest would have helped. I had to wear a surgical collar for several weeks after this, but luckily no permanent damage was done. On the subject of making K21s spin, there is a privately owned K21 at Lasham that spins and recovers very nicely (unlike our club owned one), even with a slightly heavy pilot like myself on board. This was rebuilt after a crash several years ago, before which it had been a perfectly normal K21 with the usual reluctance to spin. I don't know whether the tail got heavier or the angle of incidence of the tailplane was changed during the repairs, to account for this change in spinning characteristics. Perhaps Schleichers should take a look at this particular glider and incorporate any changes from the standard specification into their production models? Derek Copeland |
#14
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Basic Training Gliders
At 21:48 04 December 2005, Derek Copeland wrote:
At 20:42 04 December 2005, Eric Greenwell wrote: Derek Copeland wrote: While a headrest may be an important safety item in a car to protect you from whiplash in a rear end shunt, I am still trying to work out in what circumstances a glider might get rammed from behind?!!!!!! Stupid F***ing Bureaucrats! Perhaps the 'Stupid F***ing Bureaucrat' saw the same video I saw at an SSA convention: it showed the pilot dummy movement during a test crash of a glider, with violent whiplash occurring. I then asked Gerhard Waibel about the safety value of the headrest in Schleicher gliders, and he told me it was very important. So, I retrieved the headrest for my ASH 26 E from the basement and put it back in the glider! So what do you have to do to achieve the whiplash - Tailslide backwards into the ground? I did once injure my neck as a result of a student's very heavy landing. Basically my head went forwards and down and I got what is called an 'acute flexion injury' which is the reverse of the usual whiplash injury where the head initially goes backwards. I don't believe that a headrest would have helped. I had to wear a surgical collar for several weeks after this, but luckily no permanent damage was done. On the subject of making K21s spin, there is a privately owned K21 at Lasham that spins and recovers very nicely (unlike our club owned one), even with a slightly heavy pilot like myself on board. This was rebuilt after a crash several years ago, before which it had been a perfectly normal K21 with the usual reluctance to spin. I don't know whether the tail got heavier or the angle of incidence of the tailplane was changed during the repairs, to account for this change in spinning characteristics. Perhaps Schleichers should take a look at this particular glider and incorporate any changes from the standard specification into their production models? Derek Copeland The answer to the whiplash question is very simple and whiplash describes the action which causes the injury. When a car, or glider decelerates very rapidly, the head, which is unrestrained and has a fairly high mass continues to move forward until it is stopped at full body extension. It then whips back and if there is nothing to stop it extends backwards, that is what causes the injury. It is correct that a headrest prevents injury in a rear shunt but that is not the primary cause of 'whiplash' injuries. It is the whipping action following a sudden deceleration. I suppose if an impact in a glider is severe enough to cause the whiplash then that injury may be the least of your problems as you are much closer to the crash in a glider that you are in a car. |
#15
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Basic Training Gliders
Derek Copeland wrote:
The front cockpit has a largish headrest that almost completely blocks the forward view from the rear cockpit. In Europe, because the DG1000 is certified by EASA, we are not even allowed to remove it, as it is specified in the type certificate! While a headrest may be an important safety item in a car to protect you from whiplash in a rear end shunt, I am still trying to work out in what circumstances a glider might get rammed from behind? Perhaps a ground loop? Jack |
#16
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Basic Training Gliders - head rests
At 23:18 04 December 2005, Jack wrote:
Derek Copeland wrote: The front cockpit has a largish headrest that almost completely blocks the forward view from the rear cockpit. In Europe, because the DG1000 is certified by EASA, we are not even allowed to remove it, as it is specified in the type certificate! While a headrest may be an important safety item in a car to protect you from whiplash in a rear end shunt, I am still trying to work out in what circumstances a glider might get rammed from behind? Derek Perhaps you should try to understand whiplash. When the glider/car or whatever is carrying a body is stopped suddenly the head goes forwards. When restrained by the seatbelts the remainder of the body cannot follow it. Hence in cars we now have airbags. Unfortunately for the poor neck, the shoulders and head eventually whip back (in reality a fraction of a second). The shear forces on the neck as it goes backwards from the top of the seat are enormous hence in cars, the head restraint is fitted. It is not a head rest. Perhaps for gliders we should insist on airbags and head restraints for both seats? Having flown from the rear of many two seaters the head gear and hairstyle of the front seat passenger causes more problems than a well designed head retraint. IMHO the worst thing the front seat passenger can wear is a white hat or an have affro/permed hairstyle. Dave |
#17
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Basic Training Gliders
At 22:42 04 December 2005, Don Johnstone wrote:
The answer to the whiplash question is very simple and whiplash describes the action which causes the injury. When a car, or glider decelerates very rapidly, the head, which is unrestrained and has a fairly high mass continues to move forward until it is stopped at full body extension. It then whips back and if there is nothing to stop it extends backwards, that is what causes the injury. It is correct that a headrest prevents injury in a rear shunt but that is not the primary cause of 'whiplash' injuries. It is the whipping action following a sudden deceleration. I suppose if an impact in a glider is severe enough to cause the whiplash then that injury may be the least of your problems as you are much closer to the crash in a glider than you are in a car. -------------------------------------- I actually did an instructional flight in the back seat of a DG1000 today, and was reminded how poor the forward visibility from the rear cockpit is. You have to peer though a small semi-circular gap between the canopy hoop, the front headrest and the student's head. The forward view is far worse than in a K13 with its one piece canopy, and not helped by the fact that you sit fairly low down in the cockpit. I think that I will make a point of only flying this type with well switched on students who keep a good look out! I suppose that it's a case of what is the greater risk. Whiplash in the event of a crash or heavy landing, or a head on mid-air collision with another aircraft because you can't see ahead? BTW I don't dislike the DG1000. It handles and performs beautifully, it has good airbrakes (unlike the Duo Discus), it is fully aerobatic in 18 metre mode (unlike the Duo) and you can operate the undercarriage from both cockpits (unlike the Duo). BUT, I don't like the restricted view from the rear cockpit, the difficult and heavy ground handling, getting in and out of the thing, and the trigger type trimmer mounted on the stick that doesn't seem to work. You end up trimming with the trimmer tell-tale knob on the side of the cockpit wall, so why bother with the trigger in the first place? Good try for the ideal trainer DG, but no cigar yet! Derek Copeland P.S. The r.a.s. black hole seems to re-appeared. this is my third attempt at posting this! |
#18
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Basic Training Gliders
"Derek Copeland" wrote in message ... At 22:42 04 December 2005, Don Johnstone wrote: The answer to the whiplash question is very simple and whiplash describes the action which causes the injury. When a car, or glider decelerates very rapidly, the head, which is unrestrained and has a fairly high mass continues to move forward until it is stopped at full body extension. It then whips back and if there is nothing to stop it extends backwards, that is what causes the injury. It is correct that a headrest prevents injury in a rear shunt but that is not the primary cause of 'whiplash' injuries. It is the whipping action following a sudden deceleration. I suppose if an impact in a glider is severe enough to cause the whiplash then that injury may be the least of your problems as you are much closer to the crash in a glider than you are in a car. -------------------------------------- I actually did an instructional flight in the back seat of a DG1000 today, and was reminded how poor the forward visibility from the rear cockpit is. You have to peer though a small semi-circular gap between the canopy hoop, the front headrest and the student's head. The forward view is far worse than in a K13 with its one piece canopy, and not helped by the fact that you sit fairly low down in the cockpit. I think that I will make a point of only flying this type with well switched on students who keep a good look out! I suppose that it's a case of what is the greater risk. Whiplash in the event of a crash or heavy landing, or a head on mid-air collision with another aircraft because you can't see ahead? BTW I don't dislike the DG1000. It handles and performs beautifully, it has good airbrakes (unlike the Duo Discus), it is fully aerobatic in 18 metre mode (unlike the Duo) and you can operate the undercarriage from both cockpits (unlike the Duo). BUT, I don't like the restricted view from the rear cockpit, the difficult and heavy ground handling, getting in and out of the thing, and the trigger type trimmer mounted on the stick that doesn't seem to work. You end up trimming with the trimmer tell-tale knob on the side of the cockpit wall, so why bother with the trigger in the first place? Good try for the ideal trainer DG, but no cigar yet! Derek Copeland P.S. The r.a.s. black hole seems to re-appeared. this is my third attempt at posting this! It does seem like the cockpits just keep getting worse. Maybe someone should just try to improve the old Grob 103. Putting everything else aside, the cockpit was nice. Maybe the perfect trainer will be the Stemme S2 - if they ever build it. Bill Daniels |
#19
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Basic Training Gliders
Derek Copeland wrote in
: BUT, I don't like the restricted view from the rear cockpit, the difficult and heavy ground handling, getting in and out of the thing, and the trigger type trimmer mounted on the stick that doesn't seem to work. You end up trimming with the trimmer tell-tale knob on the side of the cockpit wall, so why bother with the trigger in the first place? Good try for the ideal trainer DG, but no cigar yet! Derek Copeland Yes, the DG trimmer control is cr@p, in all the DG's I have flown. Also the very stiff aileron control in the 1000 -- takes both hands on the stick to enter a thermal. The front seat of the 1000 is quite comfortable, but the back seat is like sitting on a toilet. The Duo has a few minor faults, but the visibility is superb from both cockpits and the handling is light and well balanced, nore like a single seater. -Bob Korves |
#20
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Basic Training Gliders - head rests
Dave Martin wrote in
: (snip) Perhaps for gliders we should insist on airbags and head restraints for both seats? Having flown from the rear of many two seaters the head gear and hairstyle of the front seat passenger causes more problems than a well designed head retraint. IMHO the worst thing the front seat passenger can wear is a white hat or an have affro/permed hairstyle. Dave No glider air bags for me. Most of my landings would set them off! When I fly our Duo I insist on the front seat person wearing a dark colored hat. Otherwise all the rear seater sees in the canopy is reflections of white hat. -Bob Korves |
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