Prediction Techniques for Jet-Induced Effects in Hover on Stovl Aircraft

Prediction Techniques for Jet-Induced Effects in Hover on Stovl Aircraft
Author: National Aeronautics and Space Adm Nasa
Publisher:
Total Pages: 28
Release: 2018-10-18
Genre:
ISBN: 9781728932828

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Prediction techniques for jet induced lift effects during hover are available, relatively easy to use, and produce adequate results for preliminary design work. Although deficiencies of the current method were found, it is still currently the best way to estimate jet induced lift effects short of using computational fluid dynamics. Its use is summarized. The new summarized method, represents the first step toward the use of surface pressure data in an empirical method, as opposed to just balance data in the current method, for calculating jet induced effects. Although the new method is currently limited to flat plate configurations having two circular jets of equal thrust, it has the potential of more accurately predicting jet induced effects including a means for estimating the pitching moment in hover. As this method was developed from a very limited amount of data, broader applications of the method require the inclusion of new data on additional configurations. However, within this small data base, the new method does a better job in predicting jet induced effects in hover than the current method. Wardwell, Douglas A. and Kuhn, Richard E. Ames Research Center RTOP 505-68-71...

Jet-Induced Ground Effects on a Parametric Flat-Plate Model in Hover

Jet-Induced Ground Effects on a Parametric Flat-Plate Model in Hover
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
Total Pages: 308
Release: 2018-07-25
Genre:
ISBN: 9781724269133

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The jet-induced forces generated on short takeoff and vertical landing (STOVL) aircraft when in close proximity to the ground can have a significant effect on aircraft performance. Therefore, accurate predictions of these aerodynamic characteristics are highly desirable. Empirical procedures for estimating jet-induced forces during the vertical/short takeoff and landing (V/STOL) portions of the flight envelope are currently limited in accuracy. The jet-induced force data presented significantly add to the current STOVL configurations data base. Further development of empirical prediction methods for jet-induced forces, to provide more configuration diversity and improved overall accuracy, depends on the viability of this STOVL data base. The data base may also be used to validate computational fluid dynamics (CFD) analysis codes. The hover data obtained at the NASA Ames Jet Calibration and Hover Test (JCAHT) facility for a parametric flat-plate model is presented. The model tested was designed to allow variations in the planform aspect ratio, number of jets, nozzle shape, and jet location. There were 31 different planform/nozzle configurations tested. Each configuration had numerous pressure taps installed to measure the pressures on the undersurface of the model. All pressure data along with the balance jet-induced lift and pitching-moment increments are tabulated. For selected runs, pressure data are presented in the form of contour plots that show lines of constant pressure coefficient on the model undersurface. Nozzle-thrust calibrations and jet flow-pressure survey information are also provided. Wardwell, Douglas A. and Hange, Craig E. and Kuhn, Richard E. and Stewart, Vearl R. Ames Research Center NASA-TM-104001, A-93040, NAS 1.15:104001 RTOP 505-68-32...

Jet-induced Effects

Jet-induced Effects
Author: Richard E. Kuhn
Publisher: AIAA (American Institute of Aeronautics & Astronautics)
Total Pages: 226
Release: 2006
Genre: Technology & Engineering
ISBN:

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The unique characteristics of V/STOL flight bring with it unique aerodynamic challenges. Intended for the working professional or those in engineering graduate programs involved with V/STOL, this book provides information on the aerodynamic effects induced by the exiting flows of jet and fan powered V/STOL aircraft in hover and transition flight.

Multi Jet Induced Forces and Moments on VTOL Aircraft Hovering in and Out of Ground Effect

Multi Jet Induced Forces and Moments on VTOL Aircraft Hovering in and Out of Ground Effect
Author: Donald R. Kotansky
Publisher:
Total Pages: 161
Release: 1977
Genre:
ISBN:

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An engineering methodology has been developed for the prediction of propulsive lift system induced aerodynamic effects for multi-lift-jet VTOL aircraft operating in the hover mode in an out of ground effect. The developed methodology takes into account the effects of aircraft geometry, aircraft orientation (pitch, roll) and height above the ground plane, cross-flow, lift- jet vector directions with respect to the airframe, lift-jet exit flow conditions and noncircular nozzle exit geometry for low aspect ratio nozzles.