Over the winter of 1944/1945 certain Allied POWs were imprisoned in
Colditz Castle (east of Chemnitz, Saxony). Some of the British prisoners
got desperate enough to build a glider in an attic. They never launched
because the war was effectively over by the time the machine was ready,
but in 1999, Britain's "Channel 4" TV channel commisioned a replica to
be built and flown.

It flew surprisingly well.


I've recently been working on a FDM for the Colditz Glider. If you'd
like to try it, I've put it up for comments on:

 ftp://tallyho.bc.nu/pub/steve/flightgear/colditz_20050518.tgz


I initially modelled the glider by entering the known physical
dimensions of the machine into aeromatic and claiming that it was a
"light aircraft with 0 engines" rather than a glider. It was, after all
built of floorboards and random junk covered with bedsheets doped with
porridge!

So, it's rather heavy for its size (110kg/240lb) and was expected to
carry two (70kg/160lb) men.

My FDM correctly models the stated stall speed of about 28 knots and 
sink rate of 240fpm. I have personal experience with slow-flying gliders
in the shape of early 1980's hang-gliders and so I've added modelling
for a fairly serious nose-dive on stalling the glider, plus an
entertaining amount of ground-effect to make landings resemble what I
recall from the hang-glider days.

All the photos and plans of the original Colditz glider show it to have
had almost no dihedral on its wings. The photos of the 1999 replica show
that this was the case for the copy too. My FDM has taken that into
account too, and indeed you'll find when flying it that it's pretty
unstable in roll.

                       **************

I would not have liked to have been the pilot who took this thing off
the chapel roof in Colditz, at night, on its maiden and only flight.
Stall it below 100m (300ft) from the ground and you're dead! It switches
from flying like a glider to flying like a piano almost instantly. Oh,
and 100m (300ft) is your launch height above the valley floor.....

The original glider had no instruments of course. For this model, I've
pinched the instruments panel from the Schweizer 2-33 that was already
in Flightgear. I did this to give me some idea of airspeed, to
compensate for not having the wind in my face whilst flying! I did
however re-scale the airspeed indicator to concentrate on the 10 - 90
knot range. ( I suspect that the Colditz glider would fall apart at much
higher velocities! )

Disclaimer:
This is a toy. It's fun, and probably isn't too far wrong from modelling
the real Colditz Glider. However, I've never even *seen* the Colditz
Glider replica (in the Imperial War Museum now, apparently) far less
flown it. So I don't know.

Please try it and if you have any suggestions, I'll be happy to take
them on board. I'm expecting complaints about the stall characteristics
which are probably too savage, but then, hang-gliders stall hard, so why
not this machine?

There's no 3D model, sorry. Suggestions for how to do one, or (better)
offers of help gratefully received!


Enjoy!
Steve Hosgood.


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