Engineering topics

Eshleman, James E.

Publications and source records attributed to Eshleman, James E..

2 records

NASA NTRS1988

Ground vortex flow field investigation

Flow field investigations were conducted at the NASA Ames-Dryden Flow Visualization Facility (water tunnel) to investigate the ground effect produced by the impingement of jets from aircraft nozzles on a ground board in a STOL operation. Effects on the overall flow field with both a stationary and a moving ground board were photographed and compared with similar data found in other references. Nozzle jet impingement angles, nozzle and inlet interaction, side-by-side nozzles, nozzles in tandem, and nozzles and inlets mounted on a flat plate model were investigated. Results show that the wall jet that generates the ground effect is unsteady and the boundary between the ground vortex flow field and the free-stream flow is unsteady. Additionally, the forward projection of the ground vortex flow field with a moving ground board is one-third less than that measured over a fixed ground board. Results also showed that inlets did not alter the ground vortex flow field.

Kuhn, Richard E.↗

NASA NTRS1986

Full-scale ground effects of twin impinging jets beneath a subsonic tactical V/STOL aircraft

This paper presents a summary of an analysis of flow field characteristics about a large scale twin-tilt-nacelle V/STOL aircraft in close proximity to the ground. The analysis uses experimental data in the form of measurements of pressure distributions on the ground beneath the aircraft and on the undersurface of the aircraft's fuselage. The integrals of these distributions are compared with forces measured directly, for both the total model and isolated nacelles, (i.e., net thrust). The handling qualities of the vehicle were found to be influenced by flow field characteristic features, not present in simpler models. Lift increases and significant degradation in roll control occur at low heights for fuselage strake deflections of 30 degrees or more. Reductions in control effectiveness about the other axes were also observed.

Dudley, Michael R.↗