The glider drops the rope - there is no parachute - and it falls in a straight
line behind the launch vehicle. Very little lay-off is required. Since there is
a pulley under the launch vehicle the rope (going towards the fixed pulley)
continues to feed through the fixed pulley and the launch vehicle pulley. The
rope then comes off the fixed pulley (as the vehicle continues to drive) and is
then only attached to the launch vehicle pulley and the end fixed point (which
is at the fixed pulley) . The launch vehicle continues to the launch point.
Slightly after the launch point the end of the rope and rings are drawn through
the vehicle pulley and are then free. Sounds confusing, but works well in
practice.
Dave
________________________________
From: Peter Stephenson <[email protected]>
To: Discussion of issues relating to Soaring in Australia.
<[email protected]>
Sent: Wed, 25 November, 2009 12:26:14 PM
Subject: Re: [Aus-soaring] Reflex car launching
Dave Donald wrote:
>
>At Boonah we use an Auto-tow system with a 2-to-1 reduction and
>rope. The rope goes from the glider, around a fixed pulley (fixed in
>the ground but spins), under the F250 which has a pulley mounted
>horizontally and then back to a fixed point (the bottom of the fixed
>pulley) and attached by a shackle that can rotate. The launch vehicle
>is an F250 v8 that does the launch effortlessly. The rope is 10mm poly
>and absorbs any surges/thermals and provides a very smooth launch. The
>good thing about this system is that the launch vehicle actually heads
>towards the glider (from the other end of the strip) as part of the
>launch. The glider is always visible during the launch. When the glider
>releases the launch vehicle continues on and lays the rope at the
>launch point for the next launch.
After the glider release, presumably the rope attached to the vehicle
pulley is taken off the pulley on the vehicle and allowed to run free
back to the fixed end?
PeterS
The impact on the surface of the strip (grass) due to the rope
>is minimal as are the sand tyres on the F250. While not as strictly
>'reflex' launching as requested, it is still a very useful way of
>getting aircraft in the air (for $8).
>
>>Regards,
>
>>Dave
>
>
>
>
________________________________
From: "[email protected]" <[email protected]>
>To: Discussion of
>issues relating to Soaring in Australia.
><[email protected]>
>Cc: [email protected]
>Sent: Wed, 25
>November, 2009 8:38:59 AM
>Subject: Re:
>[Aus-soaring] Reflex car launching
>
>>Ron,
>
>>I'm doing some work with synthetic helicopter long lines that have zero
>stretch so there is no stored energy in case they break.
>
>>Will ask some questions about the rope suitability. it is far better
>than steel cables.
>
>>Was looked at as an alternate for aerotow at a couple of nsw clubs. I
>did a lot of work with Eric Sweet at one site using a pully system to
>keep the vehicle speed down and using the mechanical advantage.
>
>>There was some postings or pictures on a chat site, possibly this one
>in the early days showing pulley systems and synthetic rope.
>
>>Cheers
>
>>Peter Heath
>
>
>
>>---- [email protected] >wrote:
>>> 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
>>> > _______________________________________________
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>>> >
>>> >
>>> >
>>>
>>>
>>>
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