Thanks Graham that is what I wanted to know! The swivel bit is interesting and important I guess to ensure that nothing gets fouled up at the glider release end. The pause at 150 feet and the smoothness is exactly how I remember it. 1 & 1/8 inch rope sounds pretty hefty to me?? That thick??
Ron 2009/11/25 Graham Watts <[email protected]>: > Ron > > During 1970 I did about 100 reflex launches at the Exmouth GC as assistant > instructor to the late Basil Cazalet. We were using a Blanik and a Holden > wagon as the tow car. Rope, according to my log book was 1 1/8" > polypropylene (twisted, not plait) 1450 feet long. We had a normal set of > rings attached to a swivel fitting which would have normally seen service > with the sailing fraternity. I am thinking that we used the nose release as > the swivel would get up to high rpm when the load came on the rope. Take off > distance was about 15 or 20 metres followed by an initial climb to 150-200ft > not unlGke a normal winch launch. At this point care was needed to keep a > safe speed while waiting for the rope to load up again. The rest of the > launch was as per a normal winch launch. The whole launch was nice and > smooth without the vibrations and other stuff you get with a hard wire. > > >From the towing end, enough slack was left in the rope so that the car > could attain about 35mph before the slack was out. The car was then > accelerated to about 45mph (sorry about the units.. say 75 kph). This speed > was maintained until near the top of the launch then slowly backed off until > the glider released. > > The rope lasted about 60 launches off a gravel strip. I never had a rope > break in the air. If the rope broke it was always before the glider moved. > > In 1970 the rope cost $60 so worked out at $1 a launch. We sold old ropes to > cray fishermen for their pots. > > Abinitio pilots were trained on this system and I know one bloke who went > solo without ever experiencing any other launch system. > > Graham > > > Ron Sanders wrote: > > Thanks Chris, > the information about the rope was of interest to me not whether it > was in accordance with the MOSP or not at this stageon, > > Ron > > 2009/11/25 Christopher Thorpe <[email protected]>: > > > Firstly, MOSP 2 Section 23.4 states that reflex launching is no longer > considered a satisfactory launch method and permission for such launching > may not be granted. > > As I recall the rope we used was 12mm ployprop that had a stretch of around > 1.4 times. The problem with his type of launch, apart from the nose high > attitude at the start and low speed as Terry describes, gliders that sit on > the nose skid need to have the tail held down to prevent the tail skid > banging hard into the ground. The car we used was a short wheel base Toyota > 4WD. The rope was snaked out at the glider end and the car started near the > glider. The car was driven to 80kph and the rope hissed as it was dragged > out. Once the rope was tight, the glider was launched immediately into the > air with no ground run. I did a few launches in both a K13 and Zephyrus. > With both the tail skid hit the ground with great force and the glider was > airborne. We eventually managed to have someone hold the tail of the K13 > down but you couldn't do this for Zephyrus. One had to closely monitor the > speed and ensure you released if it got below safe. It seemed to take an > eternity for the "power to come on. I would not like to do one of these > launches in a slippery machine. > > It should also be pointed out that this method was being trialled, not as a > normal method of launching, but so that a glider could be launched off a > beach to slope soar the sand dunes down Anglesea way. Terry can tell you > how successful this venture was! > > Chris > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of > [email protected] > Sent: Wednesday, 25 November 2009 9:05 AM > To: Discussion of issues relating to Soaring in Australia. > Subject: Re: [Aus-soaring] Reflex car launching > > Hi Ron, > we did some reflex launching at Bacchus a while back (10-15 years?) and it > was good fun. We > used aerotow rope, approx 1000 feet if my memory is correct - the stretch > meant that you could > actually get (slightly) greater altitude than that. I can't remember the car > speed as it took off > down the runway, but 60-70kph sound familiar. You'll just have to try that > one. The speed was > certainly a lot less than people think it needs to be. > > The really exciting part is after you leave the ground and due to the > reduction in drag the rope > starts to shrink (un-stretch) which gives you the same feeling as a cable > break or loss of power > with a winch lanch. If you keep the nose down the rope continues to shrink > and you have a major > problem, so the solution is to trust in some greater being and just keep > pulling back and hope that > the rope really hasn't broken - not a good feeling and goes against all of > your training. If you pull > back the rope (eventually) goes tight again and you have a lovely launch. > > We did it for a while but then fear took over and we resorted to normal auto > tow, with heights > achieved not much less than the reflex. > > Terry > > > On Wed, Nov 25th, 2009 at 12:07 AM, Ron Sanders <[email protected]> wrote: > > > > Does anybody remember the old "reflex launch" I am not sure if it > was > ever legal but at Cunderdin I can remember sitting in a Kooka and > upon > the ready advice the car took off straight down the runway at full > bore with no uptake of the slack or anything---the shock was > absorbed > by a flexible (nylon??) rope section which somewhat later after its > rapid extension would give back all that energy after which you then > did a "normal" auto tow. I am after approximate lengths of rope and > stretch part that people might have used in those days if anyone > remembers. > > Might do it again for a laugh one day!!!!!! > > Ron > _______________________________________________ > Aus-soaring mailing list > [email protected] > To check or change subscription details, visit: > http://lists.internode.on.net/mailman/listinfo/aus-soaring > > > > > > _______________________________________________ > Aus-soaring mailing list > [email protected] > To check or change subscription details, visit: > http://lists.internode.on.net/mailman/listinfo/aus-soaring > > _______________________________________________ > Aus-soaring mailing list > [email protected] > To check or change subscription details, visit: > http://lists.internode.on.net/mailman/listinfo/aus-soaring > > > > _______________________________________________ > Aus-soaring mailing list > [email protected] > To check or change subscription details, visit: > http://lists.internode.on.net/mailman/listinfo/aus-soaring > > > > > _______________________________________________ > Aus-soaring mailing list > [email protected] > To check or change subscription details, visit: > http://lists.internode.on.net/mailman/listinfo/aus-soaring > _______________________________________________ Aus-soaring mailing list [email protected] To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring
