Balloon envelope (the gas bag)

https://www.google.com/search?rlz=1CDGOYI_enUS805US805&hl=en-US&ei=0NXqW_DANaXZjwTWwLqwDw&ins=false&q=raven+aerostar+roundrock&oq=raven+aerostar+roundrock&gs_l=mobile-gws-wiz-serp.3..33i299l2j33i160l2.2426.5905..6240...0.0..0.162.1399.0j10…0…1…0j0i71j0i20i263j0i22i30.Q-TPPnM6CKA

  • Winzen more stuff

https://www.google.com/search?rlz=1CDGOYI_enUS805US805&hl=en-US&ei=p1bqW7iGIuGwjwSV0I-AAQ&ins=false&q=winzen+engineering+super+pressure&oq=winzen+engineering+super+pressure&gs_l=mobile-gws-wiz-serp.3...63666.67095..67247...0.0..0.257.2117.0j14j1…0…1…0i22i30j33i160j33i299.K0_PgTH15Pk