the rotor system to continue to rotate in the event of engine failure, allowing the R22 to enter autorotation and land in a controlled manner. Because the main rotor has very little mass and inertia, autorotation in an R22 requires careful and proper execution to assure a successful outcome. Much time is spent in training practicing various types of autorotation. Target speed in an autorotation is and the glide ratio is approximately 4:1 in maximum-glide configuration. Transport The two-bladed rotor and the small size of the R22 make transporting the helicopter without blade folding or dismantling tasks possible. Transporting the R22 requires securing the tail boom and rotor blades to a truck or trailer bed, which must be torsionally rigid to prevent motion and stresses being applied to the helicopter during transportation. Take off and landing directly onto a trailer is possible. Variants R22 The initial production version, it is powered by a Lycoming O-320-A2B or A2C piston engine. R22 HP A higher-powered version, it has a 160 bhp Lycoming O-320-B2C piston engine. R22 Alpha This improved version, certified in 1983, is powered by a Lycoming O-320-B2C piston engine. Fitted with a more powerful engine, it is powered by a Lycoming O-320-B2C piston engine. R22 Beta II Fitted with a more powerful engine, it is powered by a Lycoming O-360-J2A piston engine. R22 Beta II Police This police patrol version is equipped with a searchlight and loudspeaker. R22 Mariner Designed for off-shore work, it is fitted with floats and a Lycoming O-320-B2C piston engine, and is limited to daylight operations when fitted with floats. R22 Mariner II Designed for off-shore work, it is fitted with floats and a Lycoming O-360-J2A piston engine, andis limited to daylight operations when fitted with floats. R22 Police Police version R22 IFR Designed for IFR training, it has a larger, 10-hole panel to accommodate additional instruments. It is not IFR certified, so training must be done with a safety pilot in VFR conditions. Maverick UAV Unmanned military version marketed by Boeing Renegade UAV Unmanned R&D version built for DARPA Unmanned derivatives The R22 is the basis for Boeing's Maverick military unmanned aerial vehicle helicopter, and its Renegade version. In 1999, Frontier Systems developed a remotely piloted R22, the Maverick. This aircraft, along with the company, was later acquired by Boeing Phantom Works. In 2003, the United States Navy purchased four aircraft, equipped with Wescam electro-optical/infrared