![]() |
If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
|
#1
|
|||
|
|||
![]()
Elevator power.
I may have missed the comment , but has anyone experienced insufficient pitch down authority with full forward stick? Our club had an incident in very rough conditions. A PIK20B , belly hook, flown by a very experienced pilot, was forced to release as a snatch caused an uncontrollable pitchup. CG position not known, but the pilot was not large. I did a calculation ( 30 years ago) to see if this was plausible and indeed, if the CG was is near the aft limit with a PIK 20, the transient pitchup couple in a snatch can probably overpower full nose down elevator, thus initiating kiting. There a re probably many other sailplanes susceptable to this near the aft CG limit. John firth At 14:46 22 February 2014, Chris Rollings wrote: At 14:28 22 February 2014, wrote: On Saturday, February 22, 2014 1:58:28 AM UTC-6, GC wrote: On 22/02/2014 16:17, Alan wrote: =20 =20 =20 ...You don't get kiting if you fly normal "high" tow behind the towplan= e, =20 if you remain in control. =20 =20 If you don't remain in control, starting from low tow is not going t= o =20 make a lot of difference. =20 =20 =20 Experience (tens of thousands of aerotows) shows there is a enormous=20 =20 difference. The inadequate control and time to go from high tow to=20 =20 kiting is orders of magnitude different from that required to g from=20 =20 low tow to kiting. In fact, I've never heard of that eve happening.=20 =20 Even with low time students. Kiting from high tow, however, is=20 =20 apparently so common as to need a whole new system of electronic=20 =20 whizzbangery and gallons of bandwidth to stop. =20 =20 =20 If the tug has just lifted off, being in low tow sounds a bit diffic= ult, =20 but that would be a particularly hazardous time. =20 =20 =20 Yes. Liftoff is a time to be wary and we train accordingly.=20 =20 Nevertheless, all I can say is that low tow has prevented kiting=20 =20 accidents for many years. But don't take my word for it, keep this=20 =20 ridiculous discussion going with another screwball idea fo pivoting,=20 =20 autoswivelling, pitch-sensing, stick-following nonsense. =20 =20 =20 If the issue is serious - as it was in Australia - flying low to will=20 =20 solve it. If it isn't - see my previous post. =20 =20 =20 GC =20 =20 =20 =20 =20 As for automatic methods to mitigate the problem, perhaps the soluti= on =20 is not to modify tow planes, but to modify gliders. If the glider is =20 in a very high pitch attitude on tow, it might be a good time to automa= tically =20 release. =20 =20 Another modification might be to attach the tow rope to the top of t= he glider. =20 This would cause the tow force to pitch the glider down. =20 =20 =20 Is this more of a problem when folks try to tow a slow glider like a= 2-33 at =20 high speeds? =20 =20 Alan =20 GC is making his point for low tows very convincingly - why is he immediate= ly being ripped, Chris? Preparing and steering into low tow at a safe alti= tude, say 300', If you wait 'till 300 feet the majority of the risk of a fatal kitin incident is already behind you, once past 400 feet there is just abou enough height for the tow pilot to recover. means to mentally and then practically pushing the stick fo= rward and then holding in the low tow position. That's the opposite maneuv= er of what's leading to kiting. Drifting upwards takes you into the prop w= ash and again, it takes forward stick pressure to move into the saf spot. = That feedback mechanism is correctly maintaining the intended safe spot wh= ile in the normal tow position only visual cues are being used. I think I'll give the low tow a try, if ever that polar vortex over Chicago= makes like tree... Herb I've been aware of the Australian preference for low tow and the reason for it for over 30 years. My own flight testing and experience lead me t believe that it does not significantly reduce the probability of a kitin accident. |
#3
|
|||
|
|||
![]()
Exactly right John, that's what causes the kiting event. That's exactly
what I found with a K8 on a C of G hook. At 22:14 22 February 2014, John Firth wrote: Elevator power. I may have missed the comment , but has anyone experienced insufficient pitch down authority with full forward stick? Our club had an incident in very rough conditions. A PIK20B , belly hook, flown by a very experienced pilot, was forced to release as a snatch caused an uncontrollable pitchup. CG position not known, but the pilot was not large. I did a calculation ( 30 years ago) to see if this was plausible and indeed, if the CG was is near the aft limit with a PIK 20, the transient pitchup couple in a snatch can probably overpower full nose down elevator, thus initiating kiting. There a re probably many other sailplanes susceptable to this near the aft CG limit. John firth At 14:46 22 February 2014, Chris Rollings wrote: At 14:28 22 February 2014, wrote: On Saturday, February 22, 2014 1:58:28 AM UTC-6, GC wrote: On 22/02/2014 16:17, Alan wrote: =20 =20 =20 ...You don't get kiting if you fly normal "high" tow behind the towplan= e, =20 if you remain in control. =20 =20 If you don't remain in control, starting from low tow is not going t= o =20 make a lot of difference. =20 =20 =20 Experience (tens of thousands of aerotows) shows there is a enormous=20 =20 difference. The inadequate control and time to go from high tow to=20 =20 kiting is orders of magnitude different from that required to g from=20 =20 low tow to kiting. In fact, I've never heard of that eve happening.=20 =20 Even with low time students. Kiting from high tow, however, is=20 =20 apparently so common as to need a whole new system of electronic=20 =20 whizzbangery and gallons of bandwidth to stop. =20 =20 =20 If the tug has just lifted off, being in low tow sounds a bit diffic= ult, =20 but that would be a particularly hazardous time. =20 =20 =20 Yes. Liftoff is a time to be wary and we train accordingly.=20 =20 Nevertheless, all I can say is that low tow has prevented kiting=20 =20 accidents for many years. But don't take my word for it, keep this=20 =20 ridiculous discussion going with another screwball idea fo pivoting,=20 =20 autoswivelling, pitch-sensing, stick-following nonsense. =20 =20 =20 If the issue is serious - as it was in Australia - flying low to will=20 =20 solve it. If it isn't - see my previous post. =20 =20 =20 GC =20 =20 =20 =20 =20 As for automatic methods to mitigate the problem, perhaps the soluti= on =20 is not to modify tow planes, but to modify gliders. If the glider is =20 in a very high pitch attitude on tow, it might be a good time to automa= tically =20 release. =20 =20 Another modification might be to attach the tow rope to the top of t= he glider. =20 This would cause the tow force to pitch the glider down. =20 =20 =20 Is this more of a problem when folks try to tow a slow glider like a= 2-33 at =20 high speeds? =20 =20 Alan =20 GC is making his point for low tows very convincingly - why is he immediate= ly being ripped, Chris? Preparing and steering into low tow at a safe alti= tude, say 300', If you wait 'till 300 feet the majority of the risk of a fatal kitin incident is already behind you, once past 400 feet there is just abou enough height for the tow pilot to recover. means to mentally and then practically pushing the stick fo= rward and then holding in the low tow position. That's the opposite maneuv= er of what's leading to kiting. Drifting upwards takes you into the prop w= ash and again, it takes forward stick pressure to move into the saf spot. = That feedback mechanism is correctly maintaining the intended safe spot wh= ile in the normal tow position only visual cues are being used. I think I'll give the low tow a try, if ever that polar vortex over Chicago= makes like tree... Herb I've been aware of the Australian preference for low tow and the reason for it for over 30 years. My own flight testing and experience lead me t believe that it does not significantly reduce the probability of a kitin accident. |
Thread Tools | |
Display Modes | |
|
|
![]() |
||||
Thread | Thread Starter | Forum | Replies | Last Post |
inReach website not updating track automatically | Eric Greenwell[_4_] | Soaring | 4 | September 23rd 13 09:59 PM |
Compare/Contrast: CG hook on aerotow vs. CG hook on winch | son_of_flubber | Soaring | 37 | June 4th 12 10:40 PM |
TOST E85 RELEASES | [email protected] | Soaring | 2 | March 6th 05 04:21 PM |
Cumulus releases version 1.2.1 | André Somers | Soaring | 0 | March 2nd 05 09:58 PM |
NSA releases EC-121 Liberty tapes: no smoking gun | Mike Weeks | Military Aviation | 0 | July 9th 03 05:06 AM |