Mi-28N Helicopter - Most Essential Design Features Providing Its Flight Performance

The paper is devoted to development of the night version of the MI-28 attack helicopter including design changes and experimental activities, which have been carried out to ensure flight performance of the aircraft. Some aspects of wind tunnel tests of the airframe shape modifications, incorporating the mast-mounted radar, have been analyzed. The results obtained from the tests involved in improving the main rotor efficiency by using anhedral and swept blade tips are presented. The paper describes the design of the horizontal stabilizer whose angle changes with airspeed and aircraft angle of attack due to its flexible attachment to the airframe. The logic used in the selection of the flexibly mounted horizontal stabilizer parameters is given. The results of the helicopter dynamics simulation and flight tests carried out on the flying test bed are presented. The results of the tests performed in investigating the main rotor characteristics at low airspeeds and the effect of the main rotor wake on the horizontal stabilizer in these flight conditions are given. Design features provided to ensure flight safety and to eliminate the possibility of the main rotor blades to come too close to the helicopter structural members are described. The logic used in the selection of the parameters of the movable stops in the cyclic control stick depending on air speed with due account of the main rotor collective pitch is given.