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Ron Sorry, rope is normally specified by circumference I think. It would be approx 10mm diameter. Average launch height with 1450ft of rope was around 1200ft. The highest I got was 1400ft. No chute used. Keep in mind that this sort of activity should only be carried out by current winch/auto tow pilots who have been properly briefed. Graham Ron Sanders wrote: 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 <grah...@arach.net.au>: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 <ctho...@bigpond.com>: 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: aus-soaring-boun...@lists.internode.on.net [mailto:aus-soaring-boun...@lists.internode.on.net] On Behalf Of cub...@vic.chariot.net.au 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 <resand...@gmail.com> 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 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 _______________________________________________ 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 _______________________________________________ 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 |
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