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Accelerator : System X / Speed Zone
by Jérôme Daoust. Created 2001/4/24, revised
2002/12/11.
I
ordered mine from Snowdon
Gliders in the UK since I could not find a local reseller in the USA. With tax and shipping, it came to about 41 $US and I received it 6 days after placing the
order.
The
speedbar I received, differs slightly from the picture below.
I
set it up and added elastic lines running parallel to the lower accelerator
lines (both pass through the lower pulley), so that the speedbar always remains
close to the harness while kiting the wing or in flight. This does not add significant tension to the
accelerator lines, only about 2x the speedbar weight. In flight, there is about
2 inches (5 cm) of slack on the accelerator lines, and the bar is snug up to
the harness, thanks to the elastic lines. It is very easy to put my foot into
the lower (1st) step and I can keep looking ahead while doing so.
Fully pushing the 1st step, picks up the initial slack of my
accelerator lines and extends them such that the wing's airspeed rises to its
best glide (with respect to ground) with a 20 km/h headwind. Full range of acceleration is achieved with
the 2nd step.
Concerns :
I created several prototypes, which do not have the webbing link but instead have a continuous loop of tube. The problem with this idea is that the camming effect, when one pushes on the lower step, forces the top step into the back of your leg behind the knee. Not only is this annoying and distracting but the smooth-running of the system is hampered by the top bar having to slide along the underside of leg/flying suit. By retaining the webbing link the pressure on the back of the leg is reduced and the overall operation is smoother.
Even with my original speedbar getting deformed after about 200 hours of flying, and in need of a replacement, the cost was 0.21 $/hour, making it a low cost accessory.
Conclusion
·
A step
forward in speedbar design. What I
wanted is to perform the basics very well :
A two step speedbar system that activates without using the hands and is
out of the way while my feet are still on the ground. This has been achieved with an appealing simplicity.
·
I don't
need a "stirrup". Those
things should remain in the equestrian world.
Also, many of those limit the range of action for the accelerator lines.
·
I don't
care for a footrest. I have no problem
getting into my harness and I prefer to have my feet free to cross my legs in
flight as a complement to weight shifting.
·
Update
(2002/12/11) : The design is a good compromise
between cost, longevity and weight. I
would buy one again today if I had to.