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At least 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Force and Moment Analysis for the High Reynolds Number Wind Tunnel Test of the Space Launch System at Ascent Conditions

A high Reynolds number test of the Space Launch System was performed at the NASA Langley National Transonic Facility (NTF). The objective of the test was to use the cryogenic testing capabilities of the NTF to acquire data over the largest range of Reynolds numbers possible with a specific focus on the Reynolds numbers closest to flight conditions. The test was performed at Mach numbers from 0.50 to 0.95 which corresponds to the ascent portion of flight for the SLS vehicle. Force and moment data showed that pitching and yawing moment were sensitive to Reynolds number effects over the full range of Mach and Reynolds numbers tested. Axial force also showed sensitivity to Reynolds number with the largest differences seen between Mach 0.50 to 0.90. Surface pressure data showed the highest sensitivity to Reynolds number in the vicinity of the solid rocket booster forward attach region.

Space Launch System↗
NASA NTRSDate not supplied

Force and Moment Analysis for the High Reynolds Number Wind Tunnel Test of the Space Launch System at Ascent Conditions

A high Reynolds number test of the Space Launch System was performed at the NASA Langley National Transonic Facility (NTF). The objective of the test was to use the cryogenic testing capabilities of the NTF to acquire data over the largest range of Reynolds numbers possible with a specific focus on the Reynolds numbers closest to flight conditions. The test was performed at Mach numbers from 0.50 to 0.95, which corresponds to the ascent portion of flight for the SLS vehicle. Force and moment data showed that pitching and yawing moment were sensitive to Reynolds number effects over the full range of Mach and Reynolds numbers tested. Axial force also showed sensitivity to Reynolds number with the largest differences seen between Mach 0.50 to 0.90. Surface pressure data showed the highest sensitivity to Reynolds number in the vicinity of the solid rocket booster forward attach region.

Space Launch System↗
NASA NTRSDate not supplied

Wind Tunnel Testing of Static Aerodynamic and Power Consumption Characteristics of an Octocopter

The introduction of multirotor unmanned aircraft systems (UAS) in low-altitude airspace poses significant safety challenges. Further development of advanced aviation systems is needed to realize the full potential of UAS applications, particularly for urban and beyond visual line-of-sight (BVLOS) operations. The NASA System Wide Safety (SWS) project is developing key technologies to mitigate future airspace safety risks involving autonomous aircraft operation in densely populated areas. An important part of these technologies requires flight dynamics and performance models to assess feasible trajectories, power consumption requirements, and operational envelope limitations. To support these efforts, this research seeks to improve the accuracy of multirotor aerodynamic models and investigate stability characteristics relevant to flight safety. This paper presents a recent study of an octocopter vehicle using the NASA Langley 12-Foot Low-Speed Tunnel (LST). Results from isolated-airframe (no propellers) and powered-airframe tests are presented. A one-factor-at-a-time (OFAT) approach was used to explore the effect of propeller advance ratio and vehicle angle of attack on vehicle forces, moments, and power consumption. The results show nonlinear aerodynamic behavior and indicate regions where aerodynamic interaction effects may be significant.

George V. Altamirano↗
NASA NTRSDate not supplied

Static and Forced Oscillation Wind Tunnel Tests of A Tandem Propeller Configuration

A series of static and forced oscillation tests were conducted using a tandem propeller configuration in the NASA Langley 12-Foot Low-Speed Tunnel. The primary objectives were to quantify the effect of aerodynamic interactions on propeller thrust and identify conditions where the effect is most significant. A secondary objective was to obtain a preliminary data set from dynamic testing to assess the impact of angular rate on thrust performance. This paper presents analysis of the experimental data, which includes propeller performance measurements and qualitative flow visualization. The static results show that the rear propeller in the tandem configuration can experience thrust degradations greater than 30%. The extent of the wake interaction is a function of the hub separation distance and the advance ratio of the front propeller. Forced oscillation results showed that the front propeller exhibited primarily linear behavior across the conditions tested, whereas the rear propeller exhibited dynamic nonlinearity in the region of significant thrust degradation. These results are intended to support high-fidelity modeling research, particularly for flight dynamics simulation development to aid trajectory prediction, control design, and identification of hazardous conditions for multirotor vehicles.

Aerodynamic Interactions↗
NASA NTRS1988

Porous wind tunnel corrections for counterrotation propeller testing

Wind tunnel interference corrections have direct impact on measured propeller efficiency. A systematic series of wind tunnel tests was done in the porous-wall NASA Lewis 8- by 6-Foot Wind Tunnel to determine the wind tunnel interference corrections to the NASA Lewis counterrotation propeller test data. The test results were compared with calculations from a potential flow code to determine the interference corrections. At a Mach number of 0.8, the interference corrections resulted in a -0.008 Mach number correction which reduced the counterrotation propeller net efficiency data by 0.46 percent at the reduced Mach number. Additional wind tunnel tests were done to measure the effect of propeller thrust on wind tunnel wall interference. No wall interference corrections due to propeller thrust were found necessary for the high speed counterrotation propeller data obtained in the porous wall NASA Lewis 8- by 6-Foot Wind Tunnel.

Stefko, George L.↗
NASA NTRS1988

Porous wind tunnel corrections for counterrotation propeller testing

Wind tunnel interference corrections have direct impact on measured propeller efficiency. A systematic series of wind tunnel tests was done in the porous-wall NASA Lewis 8- by 6-Foot Wind Tunnel to determine the wind tunnel interference corrections to the NASA Lewis counterrotation propeller test data. The test results were compared with calculations from a potential flow code to determine the interference corrections. At a Mach number of 0.8, the interference corrections resulted in a -0.008 Mach number correction which reduced the counterrotation propeller net efficiency data by 0.46 percent at the reduced Mach number. Additional wind tunnel tests were done to measure the effect of propeller thrust on wind tunnel wall interference. No wall interference corrections due to propeller thrust were found necessary for the high speed counterrotation propeller data obtained in the porous wall NASA Lewis 8- by 6-Foot Wind Tunnel.

Stefko, George L.↗
NASA NTRS1928

Characteristics of propeller sections tested in the variable density wind tunnel

Tests were carried out in the variable density wind tunnel of the National Advisory Committee for Aeronautics on six airfoil sections used by the Bureau of Aeronautics as propeller sections. The sections were tested at pressures of 1 and 20 atmospheres corresponding to Reynolds numbers of about 170,000 and 3,500,000. The results obtained, besides providing data for the design of propellers, should be of special interest because of the opportunity afforded for the study of scale effect on a family of airfoil sections having different thickness ratios. (author)

Jacobs, Eastman N↗
NASA NTRS1985

The UH-1H helicopter icing flight test program: An overview

An ongoing joint NASA/Army program to study the effects of ice accretion on unprotected helicopter rotor aerodynamic performance is discussed. This program integrates flight testing, wind tunnel testing, and analytical modeling. Results are discussed for helicopter flight testing in the Canadian NRC hover spray rig facility to measure rotor aero performance degradation and document rotor ice accretion characteristics. The results of dry wind tunnel testing of airfoil sections with artificial ice accretions and predictions of rotor performance degradation using available rotor performance codes and the wind tunnel data are presented. An alternative approach to conducting future helicopter icing flight programs is discussed.

Shaw, R. J.↗
NASA NTRS1985

The UH-1H helicopter icing flight test program - An overview

An ongoing joint NASA/Army program to study the effects of ice accretion on unprotected helicopter rotor aerodynamic performance is discussed. This program integrates flight testing, wind tunnel testing, and analytical modeling. Results are discussed for helicopter flight testing in the Canadian NRC hover spray rig facility to measure rotor aero performance degradation and document rotor ice accretion characteristics. The results of dry wind tunnel testing of airfoil sections with artificial ice accretions and predictions of rotor performance degradation using available rotor performance codes and the wind tunnel data are presented. An alternative approach to conducting future helicopter icing flight programs is discussed.

Shaw, R. J.↗