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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

In-flight measurements of wing ice shapes and wing section drag increases caused by natural icing conditions

Aircraft icing flight research was performed in natural icing conditions with a twin engine computer type STOL aircraft. In-flight measurements were made of the icing cloud environment, the shape of the ice accretion on the wing, and the corresponding increase in the wing section drag. Results are presented for three icing encounters. On one flight, the wing section drag coefficient increased 35 percent over the uniced baseline for cruise conditions while a 43 percent increase was observed at an aircraft angle of attack of 6.2 degrees.

Mikkelsen, K.↗
NASA NTRS1926

Model tests with a systematic series of 27 wing sections at full Reynolds number

A systematic series of 27 wing sections, characterized by a small travel of the center or pressure, have been investigated at 20 atmospheres pressure in the variable density wind tunnel of the National Advisory Committee for Aeronautics. The results are consistent with each other, and indicate that for such "stable" sections a small effective camber, a small effective S-shape and a thickness of 8 to 12 per cent lead to good aerodynamic properties.

Munk, Max M↗
NASA NTRS1939

Theory of two-dimensional potential flow about arbitrary wing sections

Three general theories treating the potential flow about an arbitrary wing section are discussed in this report. The first theory treats the method of conformal transformation as laid down by Theodorsen and Garrick; the second is a generalization of Birnbaum's theory for moderately thick airfoils; the third is a general investigation of the complex velocity function with particular reference to the relations first discussed by F. Weinig.

Gebelein, H↗
NASA NTRS1927

The aerodynamic characteristics of seven frequently used wing sections at full Reynolds number

This report contains the aerodynamic properties of the wing sections U.S.A. 5, U.S.A. 27, U.S.A. 35 A, U.S.A. 35 B, Clark Y, R.A.F. 15, and Gottingen 387, as determined at various Reynolds numbers up to an approximately full scale value in the variable density wind tunnel of the National Advisory Committee for Aeronautics. It is shown that the characteristics of the wings investigated are affected greatly and in a somewhat erratic manner by variation of the Reynolds number. In general there is a small increase in maximum lift and an appreciable decrease in drag at all lifts.

Munk, Max M↗
NASA NTRS1977

Supercritical wing sections III

The book describes recent computational flow research on the design and analysis of supercritical wing sections. The central object is a detailed description of a supercritical wing design code based on the concept of designing a shockless airfoil so that its pressure distribution very nearly takes on prescribed data. The accompanying two-dimensional analysis code with fast Poisson solver is also described. FORTRAN listings are included along with a users manual for the design code. Airfoils designed with the new code and data from analysis and experiment are provided. A brief description of the method of complex characteristics is also given.

Bauer, F.↗
NASA NTRS1923

General theory of thin wing sections

This report contains a new, simple method of calculating the air forces to which thin wings are subjected at small angles of attack, if their curvature is not too great. Two simple integrals are the result. They contain only the coordinates of the wing section. The first integral gives the angle of attack at which the lift of the wing is zero, the second integral gives the moment experienced by the wing when its angle is zero. The two constants thus obtained are sufficient to determine the lift and moment for any other angle of attack. This with the theory of the aerodynamical induction, and with our empirical knowledge of the drag due to friction, the results are valuable for actual wings also. A particular result obtained is the calculation of the elevator effect. (author)

Munk, Max M↗
NASA NTRS1975

Supercritical wing sections 2, volume 108

A mathematical theory for the design and analysis of supercritical wing sections was previously presented. Examples and computer programs showing how this method works were included. The work on transonics is presented in a more definitive form. For design, a better model of the trailing edge is introduced which should eliminate a loss of fifteen or twenty percent in lift experienced with previous heavily aft loaded models, which is attributed to boundary layer separation. How drag creep can be reduced at off-design conditions is indicated. A rotated finite difference scheme is presented that enables the application of Murman's method of analysis in more or less arbitrary curvilinear coordinate systems. This allows the use of supersonic as well as subsonic free stream Mach numbers and to capture shock waves as far back on an airfoil as desired. Moreover, it leads to an effective three dimensional program for the computation of transonic flow past an oblique wing. In the case of two dimensional flow, the method is extended to take into account the displacement thickness computed by a semi-empirical turbulent boundary layer correction.

Bauer, F.↗
NASA NTRS1948

Summary of Drag Characteristics of Practical-Construction Wing Sections

The effect of several parameters on the drag characteristics of practical-construction wing sections have been considered and evaluated. The effects considered were those of surface roughness, surface waviness, compressive load, and de-icers. The data were obtained from a number of tests in the Langley two-dimensional low-turbulence tunnels.

Quinn, John H , Jr↗
NASA NTRS1938

Correction of Profile-Drag Results from Variable-Density Tunnel and the Effect on the Choice of Wing-Section Thickness

Profile-drag coefficients published from tests in the N.A.C.A. variable-density tunnel (Technical Reports Nos. 460, 537, 586, and 610, references 1 to 4) have tended to appear high as compared with results from the N.A.C.A. full-scale tunnel (Technical Report No. 530, reference 5) and from foreign sources (references 6 to 8). Such discrepancies were considered in Technical Report No. 586, and corrections for turbulence and tip effects were derived that tended to reduce the profile-drag coefficients, particularly for the thicker airfoils. The corrected profile-drag coefficients, designated by the lower-case symbol cdo as contrasted with the older CDO, have been employed in the airfoil reports published since Technical Report No. 460, but even these corrected results continued to appear high, particularly for the thicker sections. The important practical result is that a smaller increase of drag with airfoil thickness is indicated, which may be of primary importance to the airplane designer in choosing the optimum airfoil sections for actual wings. Further investigations of this subject were, of course, undertaken, one of the most important being an investigation of three symmetrical sections N.A.C A. 0009, 0012, and 0018 under conditions of low turbulence in the full-scale tunnel. Preliminary results from this investigation also indicate a smaller increase in drag with airfoil thickness than the results from the variable-density tunnel. Furthermore, comparative tests made in the two tunnels by applying strings to the surface of the N.A.C.A. 0012 airfoil to move the transition point to a predetermined position indicated that the effective reynolds Number concept would account approximately for the drag as affected by the position of transition from laminar to turbulent flow in the boundary layer.

Jacobs, Eastman N.↗
NASA NTRS1937

Pressure Distribution on a Wing Section with Slotted Flap in Free Flight Tests

The pressure distribution was measured in flight on a wing section with a slotted flap for several flap deflections, and the results obtained are presented. The test apparatus and the procedure employed in obtaining the results are also described. A Fieseler type F 5 R airplane was used for the tests.

Kiel, Georg↗
NASA NTRS1934

General Potential Theory of Arbitrary Wing Section

This report gives the exact treatment of the problem of determining the 2-dimensional potential flow around wing sections of any type. The treatment is based directly on the solution of this problem as advanced by Theodorsen in NACA-TR-411. The problem condenses into the compact form of an integral equation capable of yielding numerical solutions by a direct process.

Theodorsen, T↗
NASA NTRS1923

Marcel Besson wing sections

Three different Marcel Besson airfoils are investigated in terms of maximum lift, maximum fineness, minimum required power, and wing section drag. Comparisons are then made between the three airfoils.

AIRFOILS - GOETTINGEN 430 (JOUKOWSKI) - CHAR & MOM↗
NASA NTRSDate not supplied

Additional Large-Drop Ice Accretion Test Results for a Large Scale Swept Wing Section from January 2022

In-flight icing is an important consideration that affects aircraft design, performance, certification and safety. Newer regulations combined with increasing demand to reduce fuel burn, emissions and noise are driving a need for improvements in icing simulation capability. To that end, this paper presents the results of additional ice accretion testing conducted in the NASA Icing Research Tunnel in January 2022 with a large swept wing section typical of a modern commercial transport. The model was based upon a section of the Common Research Model wing at the 64% semispan station with a streamwise chord length of 136 in. The test conditions were developed with an icing scaling analysis to generate similar conditions for a small median volumetric diameter (MVD) = 25 μm cloud and a large MVD = 110 μm cloud. A series of tests were conducted over a range of total temperature from -23.8 ˚C to -1.4 ˚C with all other conditions held constant. Another series of tests explored cloud MVD variations from 50 μm to 230 μm while holding constant certain scaling parameters. The variation in ice mass and scanned ice volume across repeat conditions was approximately 50% lower than the uncertainty in the cloud MVD and liquid water content. The measured ice mass and volume calculated from the 3D scans were used to compute the mass to volume ratio that is sometimes referred to as ice density or void fraction. When the ice volume based on the ice shape maximum combined cross section was used to determine this ratio, the resulting values were in the range of 240 to 455 kg/m 3 . This is consistent with analogous values previously reported in the literature. The ice shape mass and volume increased with MVD from 50 to 230 μm at fixed values of the scaling parameters. The ice mass to volume ratio was approximately constant for all of the cases which showed that the accreted mass and volume increased at approximately the same rate. These results demonstrate the significance of cloud MVD on ice shape mass and volume.

Ice accretion, Large drops, Wind tunnel↗
NASA NTRSDate not supplied

Additional Large-Drop Ice Accretion Test Results for a Large Scale Swept Wing Section from January 2022

In-flight icing is an important consideration that affects aircraft design, performance, certification and safety. Newer regulations combined with increasing demand to reduce fuel burn, emissions and noise are driving a need for improvements in icing simulation capability. To that end, this paper presents the results of additional ice accretion testing conducted in the NASA Icing Research Tunnel in January 2022 with a large swept wing section typical of a modern commercial transport. The model was based upon a section of the Common Research Model wing at the 64% semispan station with a streamwise chord length of 136 in. The test conditions were developed with an icing scaling analysis to generate similar conditions for a small median volumetric diameter (MVD) = 25 μm cloud and a large MVD = 110 μm cloud. A series of tests were conducted over a range of total temperature from -23.8 ˚C to -1.4 ˚C with all other conditions held constant. Another series of tests explored cloud MVD variations from 50 μm to 230 μm while holding constant certain scaling parameters. The variation in ice mass and scanned ice volume across repeat conditions was approximately 50% lower than the uncertainty in the cloud MVD and liquid water content. The measured ice mass and volume calculated from the 3D scans were used to compute the mass to volume ratio that is sometimes referred to as ice density or void fraction. When the ice volume based on the ice shape maximum combined cross section was used to determine this ratio, the resulting values were in the range of 240 to 455 kg/m3. This is consistent with analogous values previously reported in the literature. The ice shape mass and volume increased with MVD from 50 to 230 μm at fixed values of the scaling parameters. The ice mass to volume ratio was approximately constant for all of the cases which showed that the accreted mass and volume increased at approximately the same rate. These results demonstrate the significance of cloud MVD on ice shape mass and volume.

Ice accretion↗
NASA NTRS1925

Determination and classification of the aerodynamic properties of wing sections

The following note, prepared for the NACA, contains several remarks on the possible improvement of the experimental determination of the aerodynamic properties of wing sections. It shows how errors of observation can subsequently be partially eliminated, and how the computation of the maxima or minima of aerodynamic characteristics can be much improved.

Munk, Max M↗
NASA NTRS2001

About the Effect of Control on Flutter and Post-Flutter of a Supersonic/Hypersonic Cross-Sectional Wing

The control of the flutter instability and the conversion of the dangerous character of the flutter instability boundary into the undangerous one of a cross-sectional wing in a supersonic/hypersonic flow field is presented. The objective of this paper is twofold: i) to analyze the implications of nonlinear unsteady aerodynamics and physical nonlinearities on the character of the instability boundary in the presence of a control capability, and ii) to outline the effects played in the same respect by some important parameters of the aeroelastic system. As a by-product of this analysis, the implications of the active control on the linearized flutter behavior of the system are captured and emphasized. The bifurcation behavior of the open/closed loop aeroelastic system in the vicinity of the flutter boundary is studied via the use of a new methodology based on the Liapunov First Quantity. The expected outcome of this study is: a) to greatly enhance the scope and reliability of the aeroelastic analysis and design criteria of advanced supersonic/hypersonic flight vehicles and, b) provide a theoretical basis for the analysis of more complex nonlinear aeroelastic systems.

Silva, Walter A.↗
NASA NTRS2000

About the Effect of Control on Flutter and Post-Flutter of a Supersonic/Hypersonic Cross-Sectional Wing

The control of the flutter instability and the conversion of the dangerous character of the flutter instability boundary into the undangerous one of a cross-sectional wing in a supersonic/hypersonic flow field is presented. The objective of this paper is twofold: i) to analyze the implications of nonlinear unsteady aerodynamics and physical nonlinearities on the character of the instability boundary in the presence of a control capability, and ii) to outline the effects played in the same respect by some important parameters of the aeroelastic system. As a by-product of this analysis, the implications of the active control on the linearized flutter behavior of the system are captured and emphasized. The bifurcation behavior of the open/closed loop aeroelastic system in the vicinity of the flutter boundary is studied via the use of a new methodology based on the Liapunov First Quantity. The expected outcome of this study is: a) to greatly enhance the scope and reliability of the aeroelastic analysis and design criteria of advanced supersonic/hypersonic flight vehicles and, b) provide a theoretical basis for the analysis of more complex nonlinear aeroelastic systems.

Marzocca, Piergiovanni↗