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Levin, A. D.

Publications and source records attributed to Levin, A. D..

16 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Evaluation of an electronic scanner of pressure (ESOP) module

An electronic scanner of pressure (ESOP) module, developed by NASA Ames Research Center, was installed in a wind tunnel and evaluated over a 5-month testing period. The solid-state ESOP module has 48 miniature pressure transducers and a heater circuit to maintain a constant module temperature. During the wind tunnel test, the module was subjected to an environmental temperature range from 60 F to 104 F, and to considerable module vibration. Zero drift was within + or - 0.5 percent of full-scale output for 37 of the transducers, and was greater than 5.0 percent for four transducers. Pressure measurements from 12 transducers were compared with Scanivalve modules. The agreement of these measurements was considered to be good.

Smeltzer, D. B.↗
NASA NTRS1983

Installed nacelle drag-improvement tests of an M = 0.8 turboprop transport configuration

An unpowered semispan model of a representative turboprop configuration was tested to determine the effect of configuration modifications on the the nonmetric body and wing juncture. It is indicated that the jet off nacelle-installation drag can be approximately 25% of the cruise drag. However, the losses can be reduced to 17% by changes to the wing leading edge and nacelle intersection. Comparison of test results from a semispan nonmetric fuselage model with those from a full span metric fuselage show differences in angles of attack produced the same lift. It is found that the constant lift drag rise of the semispan model is higher because of the increased angle of attack to achieve the same lift.

Levin, A. D.↗
NASA NTRS1982

Higher-Order Panel Method for Aerodynamic Flow Analysis

PANAIR uses high-order panel method to predict inviscid subsonic or supersonic flows about arbitrary configuration. Panel method solves linear partial differential equation numerically by approximating configuration surface with panels on which unknown "singularity strengths" are defined. PANAIR includes advanced software technology as well as advanced aerodynamic technology.

Erickson, L.↗
NASA NTRS1981

Propfan installation aerodynamics of a supercritical swept wing transport configuration

A semispan model with a powered propeller has been tested to provide data on the installation drag penalty of advanced propfan-powered transports designed to cruise at a Mach number of 0.8. These tests, conducted in 14-foot and 11-foot transonic wind tunnels, are a part of a NASA program to develop efficient, high-speed propellers for more fuel-efficient commercial transports for the 1990s and beyond. The model is instrumented for measuring propeller forces, wing/nacelle forces and moments, and pressure distributions over the wing and nacelle. The body in these tests was nonmetric, being connected to the wing by an RTV seal at the wing/body juncture. Tests were run at angles of attack from -3 to +5 deg over the Mach number range 0.6 to 0.85 at a Reynolds number of about 9,000,000. Results of these tests indicate that the nacelle interference drag can be quite large relative to an uninstalled nacelle. However, the losses due to the nacelle were reduced to acceptable levels by changes to the wing leading edge and nacelle intersection. The propeller slipstream causes substantial changes in the wing span load distribution indicating that twist modifications are needed to recover a more favorable span load distribution.

Smith, R. C.↗
NASA NTRS1978

High performance dash-on-warning air mobile missile system

Because fixed missile bases have become increasingly vulnerable to strategic nuclear attack, an air-mobile missile system is proposed, whereby ICBMs can be launched from the hold of large subsonic aircraft following a missile-assisted supersonic dash of the aircraft to a safe distance from their base (about 50 n mi). Three major categories of vehicle design are presented: staged, which employs vertical take-off and a single solid rocket booster similar to that used on the Space Shuttle; unstaged, which employs vertical take-off and four internally-carried reusable liquid rocket engines; and alternative concepts, some using horizontal take-off with duct-burning afterburners. Attention is given to the economics of maintaining 200 ICBMs airborne during an alert (about $600 million for each fleet alert, exclusive of acquisition costs). The chief advantages of the system lie in its reduced vulnerability to suprise attack, because it can be launched on warning, and in the possibility for recall of the aircraft if the warning proves to be a false alarm.

Hague, D. S.↗
NASA NTRS1975

High performance dash on warning air mobile, missile system

An aircraft-missile system which performs a high acceleration takeoff followed by a supersonic dash to a 'safe' distance from the launch site is presented. Topics considered are: (1) technological feasibility to the dash on warning concept; (2) aircraft and boost trajectory requirements; and (3) partial cost estimates for a fleet of aircraft which provide 200 missiles on airborne alert. Various aircraft boost propulsion systems were studied such as an unstaged cryogenic rocket, an unstaged storable liquid, and a solid rocket staged system. Various wing planforms were also studied. Vehicle gross weights are given. The results indicate that the dash on warning concept will meet expected performance criteria, and can be implemented using existing technology, such as all-aluminum aircraft and existing high-bypass-ratio turbofan engines.

Levin, A. D.↗
NASA NTRS1974

An experimental and theoretical study of low-aspect ration swept and oblique wings at Mach numbers between 0.6 and 1.4

Experimental forces and moments for two wing-body combinations having (a) a swept wing and (b) an oblique wing are compared. At all Mach numbers, the oblique wing (at its optimum sweep angle) had higher maximum lift-to-drag ratios than the fixed, swept wing. At high angles of attack, the direction of the pitching or rolling tendencies of the oblique wing was a function of the spanwise distribution of wing bend or washout for the two bends being investigated. At low angles of attack, linear theory gave satisfactory predictions of the subsonic lift-curve slope, the aerodynamic-center travel with Mach number, and the maximum lift-to-drag ratio.

Hopkins, E. J.↗