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Results for “LIFT-DRAG RATIO”

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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1958

Investigation of Minimum Drag and Maximum Lift-drag Ratios of Several Wing-body Combinations Including a Cambered Triangular Wing at Low Reynolds Numbers and at Supersonic Speeds

Theoretical and experimental data for wing-body combinations with wings of triangular, arrow, and diamond plan form are presented for Mach numbers of 1.62, 1.93, and 2.41 and a Reynolds number range of 1.4 x 10 to the 6th power to 0.7 x 10 to the 6th power. Included are two each of triangular and arrow plan-form wings cambered for approximately uniform load at m = 1.62 and lift coefficients of 0.08 and 0.20. Liquid-film studies of the flow over the various configurations are also presented.

Brown, Clinton E↗
NASA NTRS1934

The aerodynamic analysis of the gyroplane rotating-wing system

An aerodynamic analysis of the gyroplane rotating-wing system is presented herein. This system consists of a freely rotating rotor in which opposite blades are rigidly connected and allowed to rotate or feather freely about their span axis. Equations have been derived for the lift, the lift-drag ratio, the angle of attack, the feathering angles, and the rolling and pitching moments of a gyroplane rotor in terms of its basic parameters. Curves of lift-drag ratio against lift coefficient have been calculated for a typical case, showing the effect of varying the pitch angle, the solidarity, and the average blade-section drag coefficient. The analysis expresses satisfactorily the qualitative relations between the rotor characteristics and the rotor parameters. As disclosed by this investigation, the aerodynamic principles of the gyroplane are sound, and further research on this wing system is justified.

Wheatley, John B↗
NASA NTRS1954

Aerodynamic characteristics of two flat-bottomed bodies at Mach number of 3.12

The aerodynamic characteristics of two flat-bottomed bodies having a semicircular and a semielliptical cross section have been determined at a Mach number of 3.12 for a range of angles of attack from -10 degrees to 10 degrees and for Reynolds numbers of 8 x 10 (superscript)6 and 14 x 10 (superscript)6 (based on model length). A comparison of the flat-bottomed body characteristics with those previously determined for an equivalent cone-cylinder body of revolution shows that significant increases in lift and lift-drag ratio are obtained with a flat bottom. Additional improvement in lift and lift-drag ratio was achieved at positive angles of attack by expanding the plan form in the spanwise direction.

Jack, John R↗
NASA NTRS1939

Observations in Flight of the Region of Stalled Flow over the Blades of an Autogiro Rotor

The flow over the inner halves of the rotor blades on a Kellet YG-1B autogiro was investigated in flight by making camera records of the motion of silk streamers attached to the upper surfaces of the blades. These records were analyzed to determine the boundaries of the region within which the flow over the blade sections was stalled for various tip-speed ratios. For the sake of comparison, corresponding theoretical boundaries were obtained. Both the size of the stalled area and its rate of growth with increasing tip-speed ratio were found to be larger than the theory predicted, although experiment agreed with theory with regard to shape and general location of the stalled area. The stalled region may be an important factor in both the rotor lift-drag ratio and the blade flapping motion at the higher tip-speed ratios. The method of study used in this paper should be useful in further studies of the problem, including the reduction of the size of the region.

Bailey, F J , Jr↗
DOE OSTI2025

Leveraging interpolation models and error bounds for verifiable scientific machine learning

Effective verification and validation techniques for modern scientific machine learning workflows are challenging to devise. Statistical methods are abundant and easily deployed, but often rely on speculative assumptions about the data and methods involved. Error bounds for classical interpolation techniques can provide mathematically rigorous estimates of accuracy, but often are difficult or impractical to determine computationally. Here, in this work, we present a best-of-both-worlds approach to verifiable scientific machine learning by demonstrating that (1) multiple standard interpolation techniques have informative error bounds that can be computed or estimated efficiently; (2) comparative performance among distinct interpolants can aid in validation goals; (3) deploying interpolation methods on latent spaces generated by deep learning techniques enables some interpretability for black-box models. We present a detailed case study of our approach for predicting lift-drag ratios from airfoil images. Code developed for this work is available in a public Github repository.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS1947

Characteristics of a Configuration with a Large Angle of Sweepback

A brief discussion is given of some recent experimental results obtained on a supersonic transport-type airplane for a large range of Mach numbers. The theoretical arguments which led to the configuration of this airplane were brought out at the NACA Conference on Supersonic Aerodynamics at the Langley Laboratory, June 1940, 1947; hence, it will not be necessary to dwell on them herein. Briefly, our calculations showed that a reasonably good lift-drag ratio and, hence, reasonably good fuel economy, could be maintained up to a Mach number of 1.5. The configuration required would incorporate a long slender body and wings having a large angle of sweepback together with the highest practicable aspect ratio.

Jones, R. T.↗
NASA NTRS1934

The effects of full-span and partial-span split flaps on the aerodynamic characteristics of a tapered wing

The investigation was made to determine the effects of full-span and of partial-span split flaps on the aerodynamic characteristics of a tapered wing. Aerodynamic force tests were made in the N.A.C.A. 7 by 10 foot wind tunnel on a highly tapered Clark Y wing equipped with various split flaps. Two sizes of tapered-chord flaps were tested as full-span flaps, and a narrow tapered-chord flap was tested as a partial-span flap by cutting off portions first from the tip and then from the center. The investigation showed that with full-span split flaps the lift and drag characteristics of the tapered wing up to the stall are similar to those of a rectangular wing with flaps of comparable size, but that the stall of the tapered wing with full-span flaps occurs at progressively lower angles of attack with increasing flap deflection up to that for maximum lift. For partial-span tapered split flaps on a tapered wing it was found that the maximum lift is greater, and the lift-drag ratio at maximum lift is less, when the partial-span flap is located at the center of the wing than when it is located at the tip portion.

Wenzinger, Carl J↗
NASA NTRS1938

The effects of partial-span plain flaps on the aerodynamic characteristics of a rectangular and a tapered Clark Y wing

An investigation was made to determine the aerodynamic characteristics of tapered and rectangular wings with partial-span plain flaps. Two Clark Y airfoils equipped with center section and with tip-section flaps were tested. The results showed that the aerodynamic characteristics of partial-span plain flaps were, in general, similar to those of split flaps of the same span, but that the lift and the drag were less for the wing with plain flaps than for the wing with split flaps of comparable size. For the rectangular wing with center-section plain flaps, the maximum lift and the lift-drag ratio at maximum lift were greater and the drag at maximum lift was less than for the wing with tip-section plain flaps of the same size. The maximum lift of the tapered wing varied in the same manner as that of the rectangular wing but the drag and the lift-drag-ratio relationship were opposite.

House, R O↗
NASA NTRS1939

The effects of partial-span slotted flaps on the aerodynamic characteristics of a rectangular and a tapered N.A.C.A. 23012 wing

An investigation was made in the N.A.C.A. 7- by 10-foot wind tunnel to determine the aerodynamic characteristics of tapered and rectangular wings with partial-span slotted flaps. Two N.A.C.A. 23012 airfoils equipped with center-section and tip-section flaps were tested. The results showed that the changes in lift and drag due to changes in flap span for both rectangular and tapered wings having partial-span slotted flaps were similar to those for corresponding wings having partial-span split or plain flaps. For the two wings tested, higher values of maximum lift were obtained with center-section slotted flaps than with tip-section slotted flaps of the same size. The highest values of lift-drag ratio at maximum lift for the rectangular wing were obtained with center-section flaps and, for the tapered wing, with tip-section flaps. Center-section flaps on the tapered wing gave higher values of drag at maximum lift than tip-section flaps; no great difference in drag at maximum lift was apparent for either center-section or tip-section slotted flaps on the rectangular wing.

House, Rufus O↗
NASA NTRS1948

Aerodynamic Characteristics at Subsonic and Supersonic Mach Numbers of a Thin Triangular Wing of Aspect Ratio 2 II : Maximum Thickness at Midchord

The lift, drag, and pitching-moment characteristics of a triangular wing, having an aspect ratio of 2 and a symmetrical double-wedge profile of 5-percent-chord maximum thickness at midchord, have been evaluated from wind-tunnel tests at Mach numbers from 0.50 to 0.975 and from 1.09 to 1.49 and at Reynolds numbers ranging from 0.67 to 0.85 million. The lift, drag, and pitching-moment coefficients of the triangular wing with a leading-edge sweepback of approximately 63 degrees did not exhibit the irregular variations with Mach number at high subsonic and low supersonic Mach numbers that are characteristic of unswept wings. The lift-curve slope increased steadily with Mach number below unity and declined slowly beyond the Mach number of 1.13. A substantial rise in the minimum drag coefficient occurred between Mach numbers of 0.95 and 1.20 with an associated reduction in the maximum lift-drag ratio. The aerodynamic center shifted rearward toward the centroid of area of the wing with increasing Mach number below 0.975; whereas above 1.09 it coincided with the centroid.

Walker, Harold J↗