On Richard's birthday, the team were hosted by the RAF Centre of Aviation Medicine at RAF Henlow for a ride in one of their state-of-the-art hypobaric chambers to 25,000 ft.
Richard had of course done this before in the Italian airforce chamber at Practica di Mare back in 2004, and on that occasion right up to 43,000 ft but it was nevertheless a very useful exercise and one or two issues which weren't fully understood on that first occasion were clearly answered at the briefing this time.
Unfortunately, under RAF rules David was deemed too much of a veteran to be allowed into the chamber and could only watch us through a porthole from the outside. Mark and Richard were given a thorough medical inspection and then issued with the Royal Airforce type masks which are, if anything, even more uncomfortable than the American ones we use in the microlight. Mark had an intermittent sticky exhaust valve problem with his and had to change it during the 30 min pre-breathing exercise to leech out excess nitrogen in the blood which can cause the 'bends' when you go up at a military speed of several thousand feet per minute. Of course even one breath of air would mean starting again so he had to hold his breath during the changeover. His eyeballs were definitely rolling by the time it was clipped onto his helmet and all connected up.
Eventually the heavy metal doors were pulled shut and we were off. Once at 25,000 ft both Mark and Richard were told to remove their masks and do some simple puzzles on a sheet of paper. For Richard, initially it all went rather well (see fig 1) but as time went on he was asked to check the options: 'Flushed', 'Warm', 'Dizzy', 'Tingly', 'Tired', 'Clumsy', 'Sick', 'Euphoric', 'Anxious', 'Vision blurred' whenever they became apparent. At one stage he checked 'Dizzy' but looking at the sheet afterwards, he should have perhaps also checked 'Clumsy' which despite trying to concentrate like mad was a good description of the last exercise he did just before the 5 minutes were up! (see fig 2).
Thankyou to Wing Commander Donald Ross and the staff of RAF Henlow who looked after us (and kept us alive).