Flight Test Results from the Rake Airflow Gage Experiment on the F-15B

Abstract

The Rake Airflow Gage Experiment involves a flow-field survey rake that was flown on the Propulsion Flight Test Fixture at the NASA Dryden Flight Research Center using the Dryden F-15B research test bed airplane. The objective of this flight test was to ascertain the flow-field angularity, local Mach number profile, total pressure distortion, and dynamic pressure at the aerodynamic interface plane of the Channeled Centerbody Inlet Experiment. This new mixed-compression, supersonic inlet is planned for flight test in the near term. Knowledge of the flow-field characteristics at this location underneath the airplane is essential to flight test planning and computational modeling of the new inlet, and it is also applicable for future propulsion systems research that may use the Propulsion Flight Test Fixture. This report describes the flight test preparation and execution, and the local flowfield properties calculated from pressure measurements of the rake. Data from the two Rake Airflow Gage Experiment research flights demonstrate that the F-15B airplane, flying at a free-stream Mach number of 1.65 and a pressure altitude of 40,000 ft, would achieve the desired local Mach number for the future inlet flight test. Interface plane distortion levels of 2 percent and a local angle of attack of-2° were observed at this condition. Alternative flight conditions for future testing and an exploration of certain anomalous data also are provided.

Proposed Flight Research of a Dual-Bell Rocket Nozzle Using the NASA F-15 Airplane

“…15,16 Although several measurements in this region have been taken, measurements near the aft end of a simulated rocket forebody (such as the CDE) are still required during Phase I, since this is near the placement of the nozzle exit plane for the proposed experiments. As noted earlier, the external flow field of the dual-bell nozzle is expected to have a significant effect on the nozzle plume behavior, including the dual-bell nozzle plume mode transition.…”

“…17 Although the PFTF is capable of flights up to 60,000 ft, flights higher than 50,000 ft with the F-15 airplane will require additional life support systems. Figure 14 shows the PFTF flight envelope, 16 which is a subset of the F-15 flight envelope. This flight envelope provides an ample range capability in which to test the dual-bell nozzle in a relevant flight environment at numerous flight-test conditions of interest.…”