AIR-TO-SURFACE TOWING WITH THE UH-2 HELICOPTER

• Main Authors: Motekaitis, P J, Gewehr, H W
• Format: Report
• Language: English
• Subjects: AERODYNAMIC LOADING; AIR TO SURFACE; AIRSPEED; ALTITUDE; ATTACHMENT; EXPERIMENTAL DATA; FEASIBILITY STUDIES; FLIGHT TESTING; FORCE(MECHANICS); H-2 AIRCRAFT; HELICOPTER ROTORS; Helicopters; NAVAL AIRCRAFT; PERFORMANCE(ENGINEERING); STABILITY; TIME; TOWING AIRCRAFT; TOWING CABLES; VIBRATION; WEIGHT; WIND

The influences of towing velocity, height-to-cable length, cable angle, relative wind, and sled weight, were elevated as they effect maximum towing capability, endurance, rotor loads, flying qualities and vibration. Cable load dynamics, including transient up to sudden cable failure, were investigated. The air-to-surface towing capability of the UH-2 helicopter was determined up to the limit of engine power available. Approximately 3400 pounds drawbar pull was attained at 15 knots vehicle velocity and 10 degrees cable angle. The recommended tow cable angle is between 10 and 20 degrees. At 10 degrees, with full engine power, the fuselage pitch attitude is 15 degrees nose down; lower cable angles produce greater nose down pitch attitudes and lower altitudes. Pitch attitudes greater than 20 degrees nose down are considered undesirable. Cable angles greater than 20 degrees reduce drawbar pull capability significantly. Three tow cable lengths were investigated; 100, 300 and 600 feet. Pilots preferred the higher towing altitude of the longer cable because of the 15 degree nose-down pitch attitude of the helicopter. (Author) Includes revision dated 15 Oct 65.