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:* "opsw...@bigpond.net.au" <opsw...@bigpond.net.au>
*To:* Discussion of issues relating to Soaring in Australia.
<aus-soaring@lists.internode.on.net>
*Cc:* cub...@vic.chariot.net.au
*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
---- cub...@vic.chariot.net.au <mailto:cub...@vic.chariot.net.au> 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 <resand...@gmail.com
<mailto: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
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