As per my recent posts, our friendly competitors at Aerostar Raven seem to have beaten it as early as the sixties. By all means, don't post from work--like I do! :<) Best regards, IndyJones.
WW is right--spherical balloons or flexible envelopes are the key. Small size is also a possible answer--which brings us back to looking at EWA or Valtronic for miniaturization. Good discussion IMO. Thanks to you guys! With appreciation, IndyJonesOhio