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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 667 records · Page 37
All sourcesNASA NTRSDOE OSTI
NASA NTRS1933

Wind-tunnel tests of a Clark Y wing with a narrow auxiliary airfoil in different positions

Aerodynamic force tests were made on a combination of a Clark Y wing and a narrow auxiliary airfoil to find the best location of the auxiliary airfoil with respect to the main wing. The auxiliary was a highly cambered airfoil of medium thickness having a chord 14.5 per cent that of the main wing. It was tested in 141 different positions ahead of, above, and behind the nose portion of the main wing, the range of the test points being extended until the best aerodynamic conditions were covered. A range of positions was found in which the combination of main wing and auxiliary gave substantially greater aerodynamic efficiency and higher maximum lift coefficients (based on total area) than the main Clark Y wing alone. In the optimum position tested, considering both the maximum lift and the speed-range ratio, the combination of main wing and auxiliary gave an increase in the maximum lift coefficient of 32 per cent together with an increase in the ratio of 21 per cent of the respective values for the main Clark Y wing alone.

Weick, Fred E↗
NASA NTRS1935

The Influence of Tip Shape on the Wing Load Distribution as Determined by Flight Tests

Pressure measurements were made in flight on the right upper wing of an M-3 airplane. The effects of tip plan form, washout, and transverse camber were investigated with eight tip forms in unyawed conditions through the range of positive lift coefficients from zero lift to the stall. The conclusion is that the tip plan form does not influence the span distribution of the coefficients of normal force and moment. It is shown inferentially that temperature, humidity, and the aging of the wood and fabric wing structure used on the M-3 airplane have an appreciable influence on the load distribution.

Rhode, Richard V↗
NASA NTRS1936

Characteristics of the NACA 23012 Airfoil from Tests in the Full-Scale and Variable-Density Tunnels

This report gives the results of tests in the NACA full-scale and variable-density tunnels of a new wing section, the NACA 23012, which is one of the more promising of an extended series of related airfoils recently developed. The tests were made at several values of the Reynolds number between 1,000,000 and 8,000,000. The new airfoil develops a reasonably high maximum lift and a low profile drag, which results in an unusually high value of the speed-range index. In addition, the pitching-moment coefficient is very small. The superiority of the new section over well-known and commonly used sections of small camber and moderate thickness is indicated by making a direct comparison with variable-density tests of the NACA 2212, the well-known NACA family airfoil that most nearly resembles it. The superiority is further indicated by comparing the characteristics with those obtained from full-scale-tunnel tests of the Clark y airfoil.

Jacobs, Eastman N↗
NASA NTRS1939

The Aerodynamic Characteristics of Six Full-Scale Propellers Having Different Airfoil Sections

Wind-tunnel tests are reported of six 3-blade 10-foot propellers operated in front of a liquid-cooled engine nacelle. The propellers were identical except for blade airfoil sections, which were: Clark y, R.A.F. 6, NACA 4400, NACA 2400-34, NACA 2rsub200, and NACA 6400. The range of blade angles investigated extended for 15 degrees to 40 degrees for all propellers except the Clark y, for which it extended to 45 degrees. The results showed that the range in maximum efficiency between the highest and lowest values was about 3 percent. The highest efficiencies were for the low-camber sections.

Biermann, David↗
NASA NTRS1940

Design charts relating to the stalling of tapered wings

An aid in airplane design, charts have been prepared to show the effects of wing taper, thickness ratio, and Reynolds number on the spanwise location of the initial stalling point. Means of improving poor stalling characteristics resulting from certain combinations of the variables have also been considered; additional figures illustrate the influence of camber increase to the wing tips, washout, central sharp leading edges, and wing-tip slots on the stalling characteristics. Data are included from which the drag increases resulting from the use of these means can be computed. The application of the data to a specific problem is illustrated by an example.

Soule, H A↗
NASA NTRS1942

Wind-tunnel investigation of an NACA 23012 airfoil with 30 percent-chord venetian-blind flaps

Report presents the results of an investigation made in the NACA 7 by 10-foot wind tunnel of a NACA 23012 airfoil with 30-percent-chord venetian-blind flaps having one, two, three, and four slats of Clark y section. The three-slat arrangements was aerodynamically the best of those tested but showed practically no improvement over the comparable arrangement used in the preliminary tests published in NACA Technical Report No. 689. The multiple-slat flaps gave slightly higher lift coefficients than the one-slat (Fowler) flap but gave considerably greater pitching-moment coefficients. An analysis of test data indicates that substitution of a thicker and more cambered section for the Clark y slats should improve the aerodynamic and the structural characteristics of the venetian-blind flap.

Rogallo, F M↗
NASA NTRS1944

Wall interference in a two-dimensional-flow wind tunnel, with consideration of the effect of compressibility

Theoretical tunnel-wall corrections are derived for an airfoil of finite thickness and camber in a two-dimensional-flow wind tunnel. The theory takes account of the effects of the wake of the airfoil and of the compressibility of the fluid, and is based upon the assumption that the chord of the airfoil is small in comparison with the height of the tunnel. Consideration is given to the phenomenon of choking at high speeds and its relation to the tunnel-wall corrections. The theoretical results are compared with the small amount of low-speed experimental data available and the agreement is seen to be satisfactory, even for relatively large values of the chord-height ratio.

Allen, H Julian↗
NASA NTRS1945

General theory of airfoil sections having arbitrary shape or pressure distribution

In this report a theory of thin airfoils of small camber is developed which permits either the velocity distribution corresponding to a given airfoil shape, or the airfoil shape corresponding to a given velocity distribution to be calculated. The procedures to be employed in these calculations are outlined and illustrated with suitable examples.

Allen, H Julian↗
NASA NTRS1948

Theoretical and experimental data for a number of NACA 6A-series airfoil sections

The NACA 6a-series airfoil sections were designed to eliminate the trailing-edge cusp which is characteristic of the NACA 6a-series sections. Theoretical data are presented for NACA 6a-series basic thickness forms having the position of minimum pressure of 30, 40, and 50 percent chord and with thickness ratios varying from 6 percent to 15 percent. Also presented are data for a mean line designed to maintain straight sides on the cambered sections.

Loftin, Laurence K , Jr↗
NASA NTRS1950

The effects of variations in Reynolds number between 3.0 x 10sub6 and 25.0 x 10sub6 upon the aerodynamic characteristics of a number of NACA 6-series airfoil sections

Results are presented of an investigation made to determine the two-dimensional lift and drag characteristics of nine NACA 6-series airfoil section at Reynolds numbers of 15.0 x 10sub6, 20.0 x 10sub6, and 25.0 x 10sub6. Also presented are data from NACA Technical Report 824 for the same airfoils at Reynolds numbers of 3.0 x 10sub6, 6.0 x 10sub6, and 9.0 x 10sub6. The airfoils selected represent sections having variations in the airfoil thickness, thickness form, and camber. The characteristics of an airfoil with a split flap were determined in one instance, as was the effect of surface roughness. Qualitative explanations in terms of flow behavior are advanced for the observed types of scale effect.

Loftin, Laurence K, Jr↗
NASA NTRS1947

Systematic investigations of the influence of the shape of the profile upon the position of the transition point.

The position of the beginning of transition laminar/turbulent as a function of the thickness and the camber of the profile at various Reynolds numbers and lift coefficients was investigated for a series of Joukowsky profiles. The calculation of the boundary layer was carried out according to the Pohlhausen method which may be continued by a simplified stability calculation according to H. Schlichting. A list of tables is given which permits the reading off of the position of the transition point on suction and pressure side for each Joukowsky profile.

Bussmann, K↗
NASA NTRS1954

Investigation of the Effects of Leading-edge Chord-extensions and Fences in Combination with Leading-edge Flaps on the Aerodynamic Characteristics at Mach Numbers from 0.40 to 0.93 of a 45 Degree Sweptback Wing of Aspect Ratio 4

This investigation was made to determine the effects of 6 degree full-spoan and 3 degree partial-span leading-edge flaps in combination with chord-extensions or fences on the aerodynamic characteristics of a wing-fuselage configuration with a 45 degree sweptback wing of aspect ratio 4, taper ratio 0.3, and NACA 65A006 airfoil sections. The investigation was made in the Langley high-speed 7- by 10-foot tunnel over a Mach number range of 0.40 to 0.93 and an angle-of-attack range of about -2 degrees to 24 degrees. Lift, drag, and pitching-moment data were obtained for all configurations. From overall considerations of stability and performance it appears that with the model of this investigation the 6 degree full-span leading-edge flaps in combination with the chord-extension over the outboard 35 percent of the span, with or without leading-edge camber, would be the most desirable configuration.

Spreeman, Kenneth P↗
NASA NTRS1958

Design and experimental investigation of a single-stage turbine with a rotor entering relative Mach number of 2

The design and experimental investigation of a single-stage supersonic turbine are presented herein. The turbine was designed for a rotor entering relative Mach number of 2. The maximum equivalent specific work output of the turbine at design speed and approximately design over-all pressure ratio was 32.9 BTU per pound at a static efficiency of 0.414. This static efficiency gave good verification to an independent reference that indicated theoretical static efficiencies for similar single-stage turbines within the range 0.40 to 0.45. An experimental ratio of effective rotor blade momentum thickness to mean camber length was determined to be 0.0014, which compares favorably with the results obtained from several transonic and subsonic turbines. The design procedure for this turbine would have been improved by allowing for more rotor losses by assuming a value of this momentum parameter comparable with those obtained from transonic turbines. Removing a large portion of the rotor suction surface enabled a lower static pressure to be felt at the stator exit, at the expense of higher rotor losses. The net result was an improvement in turbine work output of about 3 percent at design setting conditions. No problems associated with supersonic starting were encountered even under the worst conditions of turbine operation with respect to this problem.

Moffitt, Thomas P↗
NASA NTRS1936

Flow phenomena on plates and airfoils of short span

Investigations on the flow phenomena at plates and cambered models were carried out with the aid of force measurements, some pressure distribution measurements, and photographic observation. The experimental methods are described and the results given. Section III of this work gives a comprehensive account of the results and enables us to see how nearly the lift line and lift surface theories agree with the experimental results.

Winter, H↗
NASA NTRS1932

Reduction of wing lift by the drag

Drag and loss of lift of a wing are attributable to the same cause, wake formation, thus indicating that there is some relation between both. The analysis of measurements on Joukowsky sections revealed a typical course of curves for the interdependence between drag and loss of lift. The shape of the curves apparently depends quite regularly on the mean camber and on the thickness of the profile.

Betz, A↗
NASA NTRS1931

Development of a Non-autorotative Airplane Capable of Steep Landing

In the following we develop a non-autorotating monoplane wing. The conditions imposed on such a wing, aside from its freedom from autorotation,with respect to its polars and its construction, are taken into account as far as possible. It is indicated that the autorotation characteristics of a wing are dependent upon the speed of air flow as well as on the angle of yaw. This report postulates the knowledge of the behavior of certain conventional wings of different chords and cambers with respect to their air loads at large angles of attack.

Schmidt, Wilhelm↗
NASA NTRS1993

Aerodynamic configuration design using response surface methodology analysis

An investigation has been conducted to determine a set of optimal design parameters for a single-stage-to-orbit reentry vehicle. Several configuration geometry parameters which had a large impact on the entry vehicle flying characteristics were selected as design variables: the fuselage fineness ratio, the nose to body length ratio, the nose camber value, the wing planform area scale factor, and the wing location. The optimal geometry parameter values were chosen using a response surface methodology (RSM) technique which allowed for a minimum dry weight configuration design that met a set of aerodynamic performance constraints on the landing speed, and on the subsonic, supersonic, and hypersonic trim and stability levels. The RSM technique utilized, specifically the central composite design method, is presented, along with the general vehicle conceptual design process. Results are presented for an optimized configuration along with several design trade cases.

Engelund, Walter C.↗
NASA NTRS1994

On the use of controls for subsonic transport performance improvement: Overview and future directions

Increasing competition among airline manufacturers and operators has highlighted the issue of aircraft efficiency. Fewer aircraft orders have led to an all-out efficiency improvement effort among the manufacturers to maintain if not increase their share of the shrinking number of aircraft sales. Aircraft efficiency is important in airline profitability and is key if fuel prices increase from their current low. In a continuing effort to improve aircraft efficiency and develop an optimal performance technology base, NASA Dryden Flight Research Center developed and flight tested an adaptive performance seeking control system to optimize the quasi-steady-state performance of the F-15 aircraft. The demonstrated technology is equally applicable to transport aircraft although with less improvement. NASA Dryden, in transitioning this technology to transport aircraft, is specifically exploring the feasibility of applying adaptive optimal control techniques to performance optimization of redundant control effectors. A simulation evaluation of a preliminary control law optimizes wing-aileron camber for minimum net aircraft drag. Two submodes are evaluated: one to minimize fuel and the other to maximize velocity. This paper covers the status of performance optimization of the current fleet of subsonic transports. Available integrated controls technologies are reviewed to define approaches using active controls. A candidate control law for adaptive performance optimization is presented along with examples of algorithm operation.

Gilyard, Glenn↗