Engineering topics
Publications and source records attributed to Montoya, E. J..
The objectives of the NASA Advanced Medium STOL Transport Experiments Program are discussed and several of the NASA experiments currently implemented and conducted on the YC-14 and YC-15 prototype aircraft are described. Emphasis is placed on experiments related to powered lift aerodynamics and acoustics.
Description of the requirements for a comprehensive flight and wind-tunnel propulsion research program to examine the predictability of inlet performance, evaluate the effects of high-frequency pressure phenomena on inlets, and investigate improved control concepts in order to cope with airframe interactions. This program is unique in that it requires precise similarity of the geometry of the flight vehicle and tunnel modes; the test conditions, including local flow at the inlet; and instrumentation. Although few wind-tunnel instrumentation problems exist, many problems emerge during flight tests because of the thermal environment. Mach 3 flight temperatures create unique problems with transducers, connectors, and wires. All must be capable of withstanding continuous 1000 F temperatures, as well as the mechanical stresses imposed by vibration and thermal cycling.
The flow field at the left inlet spike tip of a YF-12A airplane was examined using at 26 deg included angle conical flow sensor to obtain measurements at free-stream Mach numbers from 1.6 to 3.0. Local flow angularity, Mach number, impact pressure, and mass flow were determined and compared with free-stream values. Local flow changes occurred at the same time as free-stream changes. The local flow usually approached the spike centerline from the upper outboard side because of spike cant and toe-in. Free-stream Mach number influenced the local flow angularity; as Mach number increased above 2.2, local angle of attack increased and local sideslip angle decreased. Local Mach number was generally 3 percent less than free-stream Mach number. Impact-pressure ratio and mass flow ratio increased as free-stream Mach number increased above 2.2, indicating a beneficial forebody compression effect. No degradation of the spike tip instrumentation was observed after more than 40 flights in the high-speed thermal environment encountered by the airplane. The sensor is rugged, simple, and sensitive to small flow changes. It can provide accurate imputs necessary to control an inlet.
Wind-tunnel tests were conducted with three different fixed pressure-measuring hemispherical head sensor configurations which were strut-mounted on a nose boom. The tests were performed at free-stream Mach numbers from 0.2 to 3.6. The boom-angle-of-attack range was -6 to 15 deg, and the angle-of-sideslip range was -6 to 6 deg. The test Reynolds numbers were from 3.28 million to 65.6 million per meter. The results were used to obtain angle-of-attack and angle-of-sideslip calibration curves for the configurations. Signal outputs from the hemispherical head sensor had to be specially processed to obtain accurate real-time angle-of-attack and angle-of-sideslip measurements for pilot displays or aircraft systems. Use of the fixed sensors in flight showed them to be rugged and reliable and suitable for use in a high temperature environment.
Wind tunnel force and pressure tests of rocket engine nozzle extensions on X-15-2 model at supersonic and hypersonic speeds
Wind tunnel study of flow field beneath X-15 aircraft fuselage at supersonic to hypersonic speeds
Stratosphere and mesosphere density-height profiles obtained with X-15 aircraft