Development of a Telescoping Vaned Exhaust Nozzle for the ASTOVL LiftFan(Trademark) Application

A discussion on the development of a Telescoping, Vaned, Exhaust Nozzle (TEVEN) is presented. This nozzle was challenged to meet the thrust vectoring requirements of an Advanced Short Takeoff and Vertical Landing (ASTOVL) aircraft. The nozzle underwent a development process from concepts to detail design using computational flow analyses and from subscale performance verification tests to full-scale hardware design. The LiftFan(Trademark) nozzle is capable of providing a pitch vector range of about 80 degrees from up to 20 degrees forward to 60 degrees aft. In addition, a set of post exit yaw doors provide +/- 10 degrees yaw while maintaining a relatively high performance at all operating conditions. Further, the nozzle is axially compact, to be stowable in very short length (LJD less than 0.3), while efficiently converging the upstream nozzle flow from an annular cross section to a "D" shape at the nozzle exit. The discussion includes a review of various nozzle concepts, viscous flow analyses, and results from 1/3 scale nozzle model tests conducted at NASA LeRC Powered Lift Facility (PLF) in 1994