>I certainly hope no-one has let their speed drop that far and remained >on the wire.
They probably didn't remain on the wire. They probably stall/spinned off it :-( The BGA says this: A glider with a 1g stalling speed of 34kt is likely to stall during rotation at about 50kt if the rotation rate is 20º per second. The suggested 5 seconds for rotation to a 35º climb angle implies an average of around 7º per second and a maximum of perhaps 10º per second. At this rotation rate the stall speed will be about 44kt. I assume these numbers are done for a K13. If you do the same things for many more modern gliders with stall speeds of 38 - 42 knots where some have a max winch speed of 65 or so knots, they are very close to stalling on any fast rotated take-off. This is why the BGA state: There is no case of an airworthy glider being damaged by excessive airspeed on a winch launch which is why it is not listed as a hazard. The placarded maximum winch launch speed may safely be exceeded during the early part of the launch. However, that contradicts the placarded speed on the glider, so we are not allowed to talk about it in Australia. For once, I agree with Mike B. There's no belly hook on my glider. D On 28/05/2010, Mike Borgelt <mborg...@borgeltinstruments.com> wrote: > At 01:29 PM 28/05/2010, you wrote: >>Thanks Michael, particularly with respect to the speed and lowering >>the nose. If only ever this lesson was learned, then >>accidents/incidents would drop dramatically. >> >>At Harry's suggestion I cruised the BGA Safe Winch Site and looked >>at the simulations >><http://www.gliding.co.uk/bgainfo/safety/winch-safety.htm>http://www.gliding.co.uk/bgainfo/safety/winch-safety.htm >> >>I don't know about the flick roll, but the spin and wing drop would >>definitely feature in our accident stats. >> >>Dave > > Stalling has nothing to do with speed and everything to do with angle > of attack which is controlled by the pilot by where he puts the stick > in the fore and aft sense. > When that sinks in to everyone including instructors we might get somewhere. > > Next time you are at a safe altitude while local soaring get yourself > a little extra speed, nose up and when stabilised at 45 degrees nose > up hold the stick in that position and see what happens. Report back > on your findings. You won't stall. The glider may go over the top of > the parabola at lower than the 1g stalling speed but won't stall > unless you pull the stick back. > > It takes very little time to go from a non stalling AoA to a stalled > AoA as the glider doesn't have a high moment of inertia about the > spanwise axis and the elevator control is usually quite powerful. > Having the trim jump out of the full forward detent to full aft or > close to it while holding back pressure on the stick will probably do > nicely to initiate a flick roll, particularly for the inexperienced. > > My personal opinion on winching is that it is a cheap and nasty way > to get airborne with emphasis on the nasty. The only reason it is > tolerated is because it is cheap. > > Mike > Borgelt Instruments - manufacturers of quality soaring instruments since > 1978 > phone Int'l + 61 746 355784 > fax Int'l + 61 746 358796 > cellphone Int'l + 61 428 355784 > > email: mborg...@borgeltinstruments.com > website: www.borgeltinstruments.com > > _______________________________________________ > Aus-soaring mailing list > Aus-soaring@lists.internode.on.net > To check or change subscription details, visit: > http://lists.internode.on.net/mailman/listinfo/aus-soaring > _______________________________________________ Aus-soaring mailing list Aus-soaring@lists.internode.on.net To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring
