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Whitcomb, R. T.

Publications and source records attributed to Whitcomb, R. T..

17 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Transonic Airfoil Development

This lecture consists of three parts, in which discussions are presented of the current state of development of transonic or supercritical airfoils designed for fully turbulent boundary layers on the surfaces, previous research on subcritical airfoils designed to achieve laminar boundary layers on all or parts of the surfaces, and current research on supercritical airfoils designed to achieve laminar boundary layers. In the first part the use of available two dimensional computer codes in the development of supercritical airfoils and the general trends in the design of such airfoils with turbulent boundary layers are discussed. The second part provides the necessary background on laminar boundary layer phenomena. The last part, which constitutes the major portion of the lecture, covers research by NASA on supercritical airfoils utilizing both decreasing pressure gradients and surface suction for stabilizing the laminar boundary layer. An investigation of the former has been recently conducted in fight using gloves on the wing panels of the U.S. Air Force F111 TACT airplane, research on the later is currently being conducted in a transonic wind tunnel which has been modified to greatly reduce the stream turbulence and noise levels in the tests section.

Whitcomb, R. T.↗
NASA NTRS1983

Transonic empirical configuration design process

This lecture describes some of the experimental research pertaining to transonic configuration development conducted by the Transonic Aerodynamics Branch of the NASA Langley Research Center. Discussions are presented of the following: use of florescent oil films for the study of surface boundary layer flows; the severe effect of wind tunnel wall interference on the measured configuration drag rise near the speed of sound as determined by a comparison between wind tunnel and free air results; the development of a near sonic transport configuration incorporating a supercritical wing and an indented fuselage, designed on the basis of the area rule with a modification to account for the presence of local supersonic flow above the wing; a device for improving the transonic pitch up of swept wings with very little added drag at the cruise condition; a means for reducing the large transonic aerodynamic interference between the wing, fuselage, nacelle and pylon for a for a fuselage mounted nacelle having the inlet above the wing; and methods for reducing the transonic interference between flows over a winglet and the wing.

Whitcomb, R. T.↗
NASA NTRS1979

NASA low- and medium-speed airfoil development

The status of NASA low and medium speed airfoil research is discussed. Effects of airfoil thickness-chord ratios varying from 9 percent to 21 percent on the section characteristics for a design lift coefficient of 0.40 are presented for the initial low speed family of airfoils. Also, modifications to the 17-percent low-speed airfoil to reduce the pitching-moment coefficient and to the 21-percent low speed airfoil results are shown for two new medium speed airfoils with thickness ratios of 13 percent and 17 percent and design-lift coefficients of 0.30. Applications of NASA-developed airfoils to general aviation aircraft are summarized.

Mcghee, R. J.↗
NASA NTRS1976

A design approach and selected wind tunnel results at high subsonic speeds for wing-tip mounted winglets

Winglets, which are small, nearly vertical, winglike surfaces, substantially reduce drag coefficients at lifting conditions. The primary winglet surfaces are rearward above the wing tips; secondary surfaces are forward below the wing tips. This report presents a discussion of the considerations involved in the design of the winglets; measured effects of these surfaces on the aerodynamic forces, moments, and loads for a representative first generation, narrow body jet transport wing; and a comparison of these effects with those for a wing tip extension which results in approximately the same increase in bending moment at the wing-fuselage juncture as did the addition of the winglets.

Whitcomb, R. T.↗
NASA NTRS1976

A high subsonic speed wind tunnel investigation of winglets on a representative second-generation jet transport wing

The effects of winglets on the aerodynamic forces and moments, loads, and crossflow velocities behind the wing tip are discussed. The results of the investigation indicate that winglets significantly reduce the drag coefficient at lifting conditions. The experiments were conducted in an 8-foot transonic pressure tunnel at Mach numbers from 0.70 to 0.83 and over a lift coefficient range up to 0.65. A semispan model was used.

Flechner, S. G.↗
NASA NTRS1976

Airfoil shape for flight at subsonic speeds

An airfoil is examined that has an upper surface shaped to control flow accelerations and pressure distribution over the upper surface and to prevent separation of the boundary layer due to shock wave formulation at high subsonic speeds well above the critical Mach number. A highly cambered trailing edge section improves overall airfoil lifting efficiency. Diagrams illustrating supersonic flow and shock waves over the airfoil are shown.

Whitcomb, R. T.↗
NASA NTRS1976

Advanced Transonic Aerodynamic Technology

Supercritical airfoils and their applications to wings for various types of aircraft are studied. The various wings discussed were designed for a subsonic jet transport with increased speed, a variable sweep fighter with greater transonic maneuverability, a high subsonic speed STOL jet transport with improved low speed characteristics, and a subsonic jet transport with substantially improved aerodynamic efficiency. Results of wind tunnel and flight demonstration investigations are described. Also discussed are refinements of the transonic area rule concept and methods for reducing the aerodynamic interference between engine nacelles and wings at high subsonic speeds.

Whitcomb, R. T.↗
NASA NTRS1974

Review of NASA supercritical airfoils

NASA supercritical airfoils are characterized by a substantially reduced curvature of the midcord region of the upper surface together with increased camber near the trailing edge. The basic aerodynamic phenomena associated with the airfoils and representative wind tunnel results are discussed. The results indicate that the drag rise Mach numbers for NASA supercritical airfoils are 0.1 higher than for comparable NACA 6-series airfoils. A recent analytic method for predicting the aerodynamic characteristics of supercritical airfoils is described. The flight demonstration programs of three applications of supercritical airfoils utilizing the F-8, T-2C and F-111 as test beds are summarized.

Whitcomb, R. T.↗