JIM, SCOTT IS CORRECT THAT YOU READ FAR 103 FOR ALL THE DEFINATIVE ANSWERS YOUR SEEKING. I HOLD A B.F.I. EXEMPTION FOR ULTRALIGHTS AND I CAN GIVE YOU THE BASIC NUMBERS. BASICALLY THE ULTRALIGHTS AND TRAINERS HAVE TO MEET LIMITS ON WEIGHT, FUEL CAPICITY AND AIRSPEED. ULTRALIGHT - SINGLE PLACE, 254 LBS "EMPTY WEIGHT", AIRSPEED NOT TO EXCEED 55 KNOTS AND POWER OFF STALL AIRSPEED OF NOT MORE THAN 24 KNOTS. FUEL TANK OF NOT MORE THAN 5 U.S. GAL. TRAINER - TWO PLACE, 496 LBS "EMPTY WEIGHT", AIRSPEED NOT TO EXCEED 75 KNOTS AND POWER OFF STALL SPEED OF NOT MORE THAN 35 KNOTS. MAX FUEL IS 10 U.S. GAL. TRAINER MUST BE MARKED 'FOR INSTRUCTIONAL USE ONLY'. YOU CAN'T FLY IT RECREATIONALLY FOR YOURSELF EXCEPT FOR TEST FLYING AFTER SCEDULED MAINTAINCE OR FERRYING IT TO AN INSTRUCTIONAL SITE. YOU MUST ALSO HOLD A WAVIER FROM THE FAA THROUGH EITHER THE EAA, USUA OR ASC ORGANIZATIONS. HOPE THAT THIS HELPS. (OBVIOUSLY, I DON'T FLY MY "FLYBABY" AS AN ULTRALIGHT! N89VK). SEE WWW.USUA.COM FOR MORE DETAILED FAA RULES