The Adams-Wilson Choppy single-seat helicopter is undoubtedly the best known and most popular homebuilt helicopter ever developed. Also known as the Flying Triumph or Hobbycopter, this design was the inspiration for a number of other successful homebuilts, including the Scorpion I and the Skytwister.

CONFIGURATION: Single seat. Two-bladed single main rotor. Anti-torque tail rotor. Bolted aluminum-tube airframe. CONTROL: Main rotor: full cyclic and collective pitch, incorporating a swash plate system. Tail rotor pitch: bellcrank operated. Autorotation accomplished by manual-disengagement lever at cyclic stick. POWER PLANT (Prototype): Triumph motorcycle engine rated at 52 hp., 650cc, vertical twin cylinder O.H.V., magneto ignition, dry sump lubrication, kick lever starting, fuel 100 octane, fuel consumption approximately 4.2 gals. (U.S.) per hour at sea level. Virtually any aircraft, motorcycle, marine, etc. engine of 450cc to 1100cc, or 45 hp or more may be substituted.

*Please note: when powered by a lightweight two-cycle engine, the Choppy may have an empty weight of under 254 pounds and qualify as a license-free ultralight aircraft. **The Gross Weight may be increased when more powerful engines are used.