Untersuchungen Ueber den Einfluss eines Geneigten Triebwerkstrahls auf die Aerodynamischen Eigenschaften eines Leitwerks (Investigations of the Influence of an Incline Propulsive Jet on the Aerodynamic Properties of the Tail Assembly)

Abstract : In a basic experimental study the change in lift of an 'isolated' tailplane induced by a cold circular jet is determined. With regard to the longitudinal stability of a VTOL aircraft in the transition speed range, a dominant parameter is the angle of the jet nozzle relative to the mainstream direction. As further parameters the jet-speed to mainstream-speed ratio, the diameter of the nozzle and its position relative to the tailplane, the incidence, the chord and the thickness of the tailplane are investigated. Systematic force and pressure measurements were carried out on several tailplane models (NACA 0010 section and flat plate with a rounded nose) of rectangular planforms and with sideplates. The results provide a survey on the magnitude of jet-induced tailplane contributions to changes in stability and may allow to estimate roughly engine-efflux effects in an early design stage of an aircraft. Some fluid-mechanical aspects of the spreading and interference of inclined jets are discussed. The testing installation and performance are briefly described. (Author)