Temperature and Density Altitude Considerations for Design of Army Helicopters

摘要

The basic design criteria for the development of Army helicopters require that aircraft be capable of hovering out of ground effect at an altitude of 6,000 feet when the temperature is 95F. This requirement, commonly referred to as the Army Hot Day requirement, is more severe than the criteria in use for Air Force and Navy aircraft, and has been questioned by authorities familiar with helicopter operations. The 6,000 foot design temperature of the Air Force and Navy is 81F, requiring an air frame weight approximately one-half that necessary to meet the Army standard. The frequency of occurrence of high temperatures at elevations up to 6,500 feet in the warmer latitudes is presented in this study in order that the current Army hovering ceiling requirement can be evaluated. (Author)