Let's talk ground launching........

There are other risks than the glider hook hanging up. At North Weald,
we broke a child's leg when the drogue dropped into a group of young
football players and dragged one of them along the ground - the chopper
man decided not to pull the release but should have done. (Agreed there
were others things that should have avoided such accidents, but Sod's
law says that if something can go wrong it will if you keep trying long
enough.)

The requirement for a guillotine should not be dismissed lightly.

We also had a fatal accident on the ground - one end of the cable
snagged during retrieve, got very tight, and snapped back when a man at
the launch point went to release it, pulling him over, resulting in a
fractured skull. Tow truck driver didn't know there was a problem. The
victim forgot his training, to ensure the cable was slack before
releasing it from the truck. (If the chopper man had cut it when it
snagged, it would not have hurt anyone.)

Launch systems can bite, and will, if safety is not taken very
seriously.

Chris N.




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In message , Chris Nicholas
writes
Martin Gregorie wrote [snip] " . . .I think items 7 and 10 should be
swapped so the weak link is part of the wire strop assembly and item 4
should be selected so its colour matches the colour of the weak link."

Some clubs, including mine, do that - change the strop with weak link
attached, to suit the glider. Some have several weak links on the cable
and just switch the same strop from one to another. Some may just change
the weak link, with quick releases either side, so only one strop is
needed.

Fairly common practice that I have seen at all of the clubs I regularly
fly from (Cotswold, Mynd, Port Moak) go Tost Rings - shock rope - weak
link - quick change link.

The logic for this is that if you do break the weak link then you stand
a chance of finding the tost rings as they will have the shock rope that
is usually covered by a brightly coloured plastic pipe.

The shock rope length is about 6 to 10 feet long, port moak's is
shorter. Some clubs also choose coloured pipe to match the weak link
colour.

For What It's Worth. I fly from Cotswold and witnessed the last couple
of years of the reverse pulley system. It was simple to use but -

It was extremely tough on the vehicles with high maintenance costs and
effort;
The single strand wire broke very readily;
It was hard to get a good launch for heavier gliders;
The knots had to be cut out and re-made every morning before flying;
There was a significant dip in the launch just after rotation as the
truck gearbox changed gear.

We averaged 1,000 to 1,500 ft launches but did get to much higher on
occasion. (1 Mile Runway). We replaced the system with a Skylaunch
winch using stranded steel wire. This is much more repeatable and gets
launches between 1,400 and 1,800 feet with a much greater availability.

We fly gliders ranging from K8s to Duo Discus's and get good launches
with lots of good cross countries. We do have a tug on site which gets
used a fair amount but most people winch. One of our full cats managed
to get 30 mins with a T31 on Friday so it can't be that bad and he only
came down thinking that the owner (me) wanted it back.

Seriously, winching works well if you have a ridge within a straight
glide and if you have reasonable thermal sources around the airfield but
do get good instruction on it as it is easy to get into very bad habits
masked by the power of modern winches which will then bite you.

Hope this helps

Robin
Chris N.






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--
Robin Birch

On Sat, 03 Sep 2005 23:40:08 +0100, Robin Birch wrote:

We averaged 1,000 to 1,500 ft launches but did get to much higher on
occasion. (1 Mile Runway). We replaced the system with a Skylaunch winch
using stranded steel wire. This is much more repeatable and gets launches
between 1,400 and 1,800 feet with a much greater availability.

I was once winched in an SF-25 there. It was pretty calm
but we still made 1300 ft. The ride up was quite odd: climbing out
steeply with a stationary three-blader in front. We glided around for
400 feet before hitting the starter and flying back to Nympsfield.

--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

At 09:36 03 September 2005, Ian Johnston wrote: (snip)
Personally, I think it's time we stopped messing about
with spring
loaded cutters and went to explosive ones, but that's
incidental here!

Ian

Er.......you are kidding, right?