This system is now used extensively by UK pilots and is known as the
Kellerman Relief System which deposits either into a catheter bag, or
outside via relief tube installed in the glider.

Whilst flying at Jaca a few years ago, after a fellow pilot was
complaining about the supine position of modern gliders making it
difficult to use his funnel/cup device, we showed him the KRS and he
became very enthusiastic. So much so that we gave him a condom, tube and
bag to try it out.

I was intrigued to hear him on the radio landing back early, so once we
all got back, he explained exactly what had happened, we were
incapacitated for at least an hour, weeping with laughter. Here is his
story, imagine it being told in his soft scottish accent:

"I rigged up the relief system, took off and got about 100km down the
mountains when I felt it was time to use it. It all went well for the
first few seconds, but then I was aware of some 'back-pressure', the
condom was swelling up, but the bag was not filling up. Much to my
horror, I realised the tube had been trapped and squashed when I closed
the conopy down on it, so I was snookered.
Well it's very difficult to stop peeing, just like that, the condom
swelled to enormous proportions and then let go with a bang, covering all
of me and the cockpit.
So that is why I came back early, for a big clean-up operation!".

There, but for the grace of God, go many of us....

cheers Bill