Robinson R22 design evolution

1979 - R22 - 1300 lbs gross  - 150 hp - impulse magnetos - small panel - battery front - light blades - some had fixed dual controls

1981 - R22 Hp - 1300 lbs gross - 160 hp - shower of sparks ignition - bigger panel - repositioned clutch switch - heavy blades

1983 - R22 Alpha - same as Hp plus: 1370 lbs gross -  bigger panel and IFR trainer version - battery shift to Center Line - higher rear vertical component of the engine chrome molly frame - different Tail Rotor Gear Box casting to set the horizontal stabilizer at a different angle

1985 - R22 Beta - same as Alpha plus: bigger panel - plastic switches - bigger oil cooler - remarked MAP gauge - up rated power for 5 minutes @ takeoff (131 BHP)

1996 - R22 Beta 2 - same as Beta plus: 0-360 engine - carb heat assist - bigger inlet system - high capacity cooling fan – up rated frame and mechanical components for the extra engine torque - modified pilot grip  - vernier mixture control.

The Beta was later modified to reduce engine issues and fan cracking by fitment of a smaller carburetor and the removal of the vernier mixture control