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. 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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