A small scale ground effect test rig was used to study the ground plane flow field generated by a STOVL aircraft in hover. The objective of the research was to support NASA-Ames Research Center planning for the Large Scale Powered Model (LSPM) test for the ARPA-sponsored ASTOVL program. Specifically, small scale oil flow visualization studies were conducted to make a relative assessment of the aerodynamic interference of a proposed strut configuration and a wall configuration on the ground plane stagnation line. A simplified flat plate model representative of a generic jet-powered STOVL aircraft was used to simulate the LSPM. Cold air jets were used to simulate both the lift fan and the twin rear engines. Nozzle Pressure Ratios were used that closely represented those used on the LSPM tests. The flow visualization data clearly identified a shift in the stagnation line location for both the strut and the wall configuration. Considering the experimental uncertainty, it was concluded that either the strut configuration or the wall configuration caused only a minor aerodynamic interference. Distribution.

A small scale ground effect test rig was used to study the ground plane flow field generated by a STOVL aircraft in hover. The objective of the research was to support NASA-Ames Research Center planning for the Large Scale Powered Model (LSPM) test for the ARPA-sponsored ASTOVL program. Specifically, small scale oil flow visualization studies were conducted to make a relative assessment of the aerodynamic interference of a proposed strut configuration and a wall configuration on the ground plane stagnation line. A simplified flat plate model representative of a generic jet-powered STOVL aircraft was used to simulate the LSPM. Cold air jets were used to simulate both the lift fan and the twin rear engines. Nozzle Pressure Ratios were used that closely represented those used on the LSPM tests. The flow visualization data clearly identified a shift in the stagnation line location for both the strut and the wall configuration. Considering the experimental uncertainty, it was concluded that either the strut configuration or the wall configuration caused only a minor aerodynamic interference. Distribution.

Acquisition phase zero (Concept Exploration) of the Advanced Short Takeoff/ Vertical Land (ASTOYL) aircraft development includes, among other tests, evaluation of forces and moments on a large-scale powered model (LSPM) suspended in the Outdoor Aerodynamic Research Facility (OARF) at the NASA Ames Research Center. This investigation assessed the influence of the OARF support structure upon the flow field through LDV measurements in the vicinity of the struts and the wingtip of a generic flat-plate model mounted in the sub-scale NPS ground effects test rig. The model was a twin subcritical jet configuration with the nozzles arranged in tandem. The test environment was saturation seeded using a smoke generator and LDV measurements were made in the entrained flow. Non-coincident measurements were made to determine the three component mean velocities at points in the region of interest and the component mean and composite mean velocities compared for configurations with struts present and struts removed. Variations were discernible in the component mean velocities between samples both in the same strut configuration and between the struts-installed and struts-removed configurations, but were generally small enough to be considered negligible.