Polypropylene (code 5 plastic) hinges for rotor blades. How thick should these be? 40 thou seems too stiff for a rotor of 4 feet diameter or less, is 25 thou OK? Unless the blade can freely flap the aircraft will surely tip over. Seems to me the thinnest sheet polypropylene possible is required, but of course it must have adequate strength to do the job.
Colin Duthie