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R. Lavi

Bio: R. Lavi is an academic researcher from Northrop Corporation. The author has contributed to research in topics: Inlet & Thrust-to-weight ratio. The author has an hindex of 1, co-authored 2 publications receiving 6 citations.

Papers
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Journal ArticleDOI
R. Lavi1
TL;DR: In this paper, the performance of plain inlets and inlets with scoop-type doors were evaluated in the NASA Anies 40-by-80-ft wind tunnel using the Ames Lift Engine Pod containing five YJ85 engines.
Abstract: Tests of VTOL lift-engine plain inlets and inlets with scoop-type doors were conducted in the NASA Anies 40- by 80-ft wind tunnel using the Ames Lift Engine Pod containing five YJ85 engines. The objectives were to determine inlet/door performance characteristics during lift-engine operation and to establish engine start and acceleration characteristics during transition. Over-all inlet pressure distortion levels were, in general, lower than the nominal acceptable level of 10%. Acceptable inlet total pressure recoveries were achieved, and considerable improvement in engine windmilling characteristics was observed with the inlet doors. Results also showed the feasibility of windmill starting of lift engines equipped with scoop-type inlet doors at landing transition speeds between 200 and 240 knots.

6 citations

Journal ArticleDOI
TL;DR: A large-scale boiler plate VTOL test bed was designed and fabricated around the Ames Lift Engine Pod and ground proximity tests were conducted in cooperation with Ames Research Center at the Ames VTOL Test facility as discussed by the authors.
Abstract: A large-scale boiler plate VTOL test bed was designed and fabricated around the Ames Lift Engine Pod. Ground proximity tests were conducted in cooperation with Ames Research Center at the Ames VTOL test facility. Program objectives were to establish VTOL aircraft environmental characteristics during near-ground operation and to determine the degree of hot gas ingestion and induced lift effects experienced by a number of potential VTOL fighter configurations. The results showed, as expected, that both ingestion and induced lift effects are strongly configuration-dependent, and for some configurations the degree of ingestion experienced cannot be tolerated in an operational aircraft. Rapid inlet temperature rise with a high temperature distortion at the compressor face generally resulted in engine stall. For certain engine groupings, wing, and lift/cruise inlet locations, hot gas ingestion was greatly minimized. Results also showed that transient measurements with rapid-response thermocouple and recording equipment are needed for realistic assessment of the VTOL environment and for inlet temperature rise caused by ingestion.

Cited by
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Proceedings ArticleDOI
01 Jan 1968
TL;DR: Exhaust gas reingestion and inlet flow distortion in V/STOL lift engines, discussed static and wind tunnel testing using fighter configuration models, were discussed in this article.
Abstract: Exhaust gas reingestion and inlet flow distortion in V/STOL lift engines, discussing static and wind tunnel testing using fighter configuration models

12 citations

Journal ArticleDOI
TL;DR: In this paper, an investigation was conducted to determine the force and moment contribution of V/STOL lift-jet and lift-fan inlets in transition based on momentum theory, which provided total inlet force, inlet lift, and drag force, as well as inlet lip force and inlet pitching moment.
Abstract: An investigation was conducted to determine the force and moment contribution of V/STOL lift-jet and lift-fan inlets in transition based on momentum theory. A lift-jet or lift-fan inlet with its axis perpendicular to the freestream develops strong forces that contribute to positive pitching moments at low forward speeds. The analysis is based on the addition of freestream flow with the static-induced flow at the inlet, which is represented by a sink flow over a hemispherical control surface. The results of the analysis, which provide total inlet force, inlet lift, and drag force, as well as inlet lip force and inlet pitching moment, agree reasonably well with a limited amount of published inlet test data. It is shown that the lift-fan inlet develops significantly greater lift, drag, and moment than the lift-jet inlet at comparable thrust and forward speed. Other comparisons are presented which show the close agreement between inlet drag and total incremental jet-induced drag developed by lift fan-in-fuselage and lift fan-in-wing configurations in transition flight. Nomenclature Ai — inlet area in plane of inlet D = drag Di = inlet momentum drag AD = interference drag increment due to freestream velocity di = inlet diameter F = force L = lift Li = inlet momentum lift AL = interference lift increment due to freestream velocity m = mass flow M = moment Mi = inlet moment of momentum AM = interference moment increment due to freestream velocity p = pressure r = inlet duct radius T = thrust V = velocity v = static inlet velocity y = moment arm of resultant inlet lift J3 = angle of resultant lip force measured from horizontal 6 = coordinate angle = coordinate angle p = air density

7 citations

01 Jan 1971
TL;DR: In this article, the authors present results of a study of the lift-fan inlet problem and include a comprehensive survey of the existing experimental data and analytical methods, an analysis of the potential flow, and a boundary layer analysis for liftfan inlets Numerical solutions for potential flows associated with inlet ducts set in an infinite plane with and without a centerbody simulating the hub of the fan.
Abstract: : The report presents results of a study of the lift-fan inlet problem and includes a comprehensive survey of the existing experimental data and analytical methods, an analysis of the potential flow, and a boundary layer analysis for lift-fan inlets Numerical solutions are presented for potential flows associated with inlet ducts set in an infinite plane with and without a centerbody simulating the hub of the fan The effects of the cross flow to mean inlet velocity ratio, of the inlet and hub lip radii to duct width ratio, of the inclination of the duct axis to the plane, and of the position of the hub relative to the plane on the flow in and near the inlet ducts are discussed utilizing a two dimensional potential flow analysis (Modified author abstract)

4 citations

Journal ArticleDOI
TL;DR: Exhaust gas reingestion and inlet flow distortion in V/STOL lift engines, discussed static and wind tunnel testing using fighter configuration models, were discussed in this paper.
Abstract: Exhaust gas reingestion and inlet flow distortion in V/STOL lift engines, discussing static and wind tunnel testing using fighter configuration models

4 citations

Journal ArticleDOI
TL;DR: In this article, an experimental investigation of lift engine inlet total pressure recovery and total and static pressure distortion during simulated hover and transitional flight has been conducted on a full-scale XV-4B model.
Abstract: An experimental investigation of lift engine inlet total pressure recovery and total and static pressure distortion during simulated hover and transitional flight has been conducted on a full-scale XV-4B model. The objectives were to develop fixed-geometry inlets for the four vertical-mounted lift engines that were independent of inlet closure door considerations and to provide satisfactory inlet pressure conditions for all modes of VTOL flight. The results indicate that satisfactory inlet pressures can be achieved with a design having single fixed auxiliary lips only in the forward inlets. Engine stalls, surges, and critical vibration levels were absent throughout the test program, which included numerous starts and accelerations at 200 knots relative wind speed. The total pressure recovery at static hover conditions was optimum, while total and static pressure distortions were always less than 13% and generally less than 10% in the VTOL transitional flight regimes for the final inlet configuration. A compact and flexible method of correlating inlet performance data is presented.

3 citations