There was the project of a small, inflatable wing aircraft ( precursor to Microlights ) in I think the 1950's, for the use of 'spies in the field'.
It was flown, the Test Pilot ( Boscombe ? Can't find it for the moment but sure it's in the excellent 'Test Pilots' by Don Middleton ) commented he was uneasy relying on a PSI guage as a guide to structural integrity.
It was known as The Durex Delta.
Edit; a little searching reveals it as the Miles Utility, prototype XK776 first flown by Peter Twiss at Bedford, 23rd Aug 1956 before going to Boscombe in the hands of Fairey Test Pilots.
There were at least 2 prototypes, the 2nd being XK781, so the thing must have done a fair bit of flying.
Last edited by Double Zero; 18th Apr 2011 at 09:11.