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At least 1,711 records · Page 95
All sourcesNASA NTRSDOE OSTI
NASA NTRS1930

Pressure distribution over a Douglas wing tip on a biplane in flight

This note presents the results obtained in pressure distribution tests on the right upper wing panel and tip of a Douglas M-3 airplane in flight. These tests are a part of a more extensive investigation of the effect of changes in tip shape on the load distribution, the tip reported herein being the first of a series of tip shapes being tested. The results are given in tables and curves in such form that the load distribution for any conditions may be determined easily. Tests were made at Langley Field by the NACA in the spring of 1930.

Rhode, Richard V↗
NASA NTRS1995

Navier-Stokes Aerodynamic Simulation of the V-22 Osprey on the Intel Paragon MPP

The paper will describe the Development of a general three-dimensional multiple grid zone Navier-Stokes flowfield simulation program (ENS3D-MPP) designed for efficient execution on the Intel Paragon Massively Parallel Processor (MPP) supercomputer, and the subsequent application of this method to the prediction of the viscous flowfield about the V-22 Osprey tiltrotor vehicle. The flowfield simulation code solves the thin Layer or full Navier-Stoke's equation - for viscous flow modeling, or the Euler equations for inviscid flow modeling on a structured multi-zone mesh. In the present paper only viscous simulations will be shown. The governing difference equations are solved using a time marching implicit approximate factorization method with either TVD upwind or central differencing used for the convective terms and central differencing used for the viscous diffusion terms. Steady state or Lime accurate solutions can be calculated. The present paper will focus on steady state applications, although time accurate solution analysis is the ultimate goal of this effort. Laminar viscosity is calculated using Sutherland's law and the Baldwin-Lomax two layer algebraic turbulence model is used to compute the eddy viscosity. The Simulation method uses an arbitrary block, curvilinear grid topology. An automatic grid adaption scheme is incorporated which concentrates grid points in high density gradient regions. A variety of user-specified boundary conditions are available. This paper will present the application of the scalable and superscalable versions to the steady state viscous flow analysis of the V-22 Osprey using a multiple zone global mesh. The mesh consists of a series of sheared cartesian grid blocks with polar grids embedded within to better simulate the wing tip mounted nacelle. MPP solutions will be shown in comparison to equivalent Cray C-90 results and also in comparison to experimental data. Discussions on meshing considerations, wall clock execution time, load balancing, and scalability will be provided.

Vadyak, Joseph↗
NASA NTRS2009

Ground/Flight Correlation of Aerodynamic Loads with Structural Response

United States Air Force Research Laboratory (AFRL) ground tests at the NASA Transonic Dynamics Tunnel (TDT) and NASA flight tests provide a basis and methodology for in-flight characterization of the aeroelastic performance through the monitoring of the fluid-structure interaction using surface flow sensors. NASA NF-15B flight tests provided a unique opportunity to test the correlation of aerodynamic loads with sectional flow attachment/detachment points, also known as flow bifurcation points (FBPs), as observed in previous wind tunnel tests. The NF-15B tail was instrumented with hot-film sensors and strain gages for measuring root-bending strains. These data were gathered via selected sideslip maneuvers performed at level flight and subsonic speeds. The aerodynamic loads generated by the sideslip maneuver resulted in root-bending strains and hot-film sensor signals near the stagnation region that were highly correlated. For the TDT tests, a flexible wing section developed under the AFRL SensorCraft program was instrumented with strain gages, accelerometers, and hot-film sensors at multiple span stations. The TDT tests provided data showing a gradual phase change between the FBP and the structural mode occurred during a resonant condition as the wings structural modes were excited by the tunnel-generated gusts.

Mangalam, Arun S.↗
NASA NTRS1951

Investigation to Determine the Effectiveness of a Split-Aileron Type Emergency Spin-Recovery Device for the Northrop XF-89 Airplane

The present paper presents the results of a brief investigation made to determine the effectiveness of a proposed emergency spin-recovery device to be used during demonstration spins of the Northrop XF -89 airplane. The proposed device makes use of split-type ailerons deflected +/-60deg on the outboard wing (left wing in a right spin). Tests made on a model which represented the airplane to a scale of 7 indicated that, if an uncontrollable spin is obtained in the design gross--weight loading, the device is not sufficiently effective to insure recovery,

Neihouse, A. I.↗
NASA NTRS2010

Process Improvement Through Tool Integration in Aero-Mechanical Design

Emerging capabilities in commercial design tools promise to significantly improve the multi-disciplinary and inter-disciplinary design and analysis coverage for aerospace mechanical engineers. This paper explores the analysis process for two example problems of a wing and flap mechanical drive system and an aircraft landing gear door panel. The examples begin with the design solid models and include various analysis disciplines such as structural stress and aerodynamic loads. Analytical methods include CFD, multi-body dynamics with flexible bodies and structural analysis. Elements of analysis data management, data visualization and collaboration are also included.

Integrated design and analysis↗
NASA NTRS1961

Aerodynamic Characteristics of a Large-Scale Model with a High Disk-Loading Lifting Fan Mounted in the Fuselage

An investigation was conducted to determine the longitudinal characteristics during low-speed flight of a large-scale VTOL airplane model with a direct lifting fan enclosed in the fuselage. The model had a shoulder-mounted unswept wing of aspect ratio 5. The effect on longitudinal characteristics of fan operation, propulsion by means of deflecting the fan efflux, trailing-edge flap deflection, and horizontal-tail height were studied.

Aoyagi, Kiyoshi↗
NASA NTRS1981

Effect of simulated in-flight thrust reversing on vertical-tail loads of F-18 and F-15 airplane models

Investigations were conducted in the Langley 16-Foot Transonic Tunnel to provide data on a 0.10-scale model of the prototype F-18 airplane and a 0.047-scale model of the F-15 three-surface configuration (canard, wing, and horizontal tails). Test data were obtained at static conditions and at Mach numbers from 0.6 to 1.2 over an angle-of-attack range from 2 deg to 15 deg. Nozzle pressure ratio was varied from jet off to about 8.0.

Bare, E. A.↗
NASA NTRS1976

Thermal effects during loading of vehicle-borne pressurizing gas tanks from reservoir tanks

Two theoretical methods of analyzing the process of filling vehicle-borne, high pressure gas tanks from gas reservoirs are presented. The first method assumes that a given weight of gas at ambient temperature and a specified pressure is required in the vehicle tank and selects a tank volume to exactly accommodate these conditions. The second method assumes the vehicle tank has a given volume and then predicts the temperature overshoot that results from loading a fixed weight of gas to a predetermined pressure and, thereafter, the final gas pressure after the vehicle tank and its contents have returned to ambient temperature. In addition, a means is presented for predicting to what pressure the vehicle tank must be loaded such that, after returning to ambient temperature, it will contain at least the desired weight of gas at the desired pressure.

Wing, L. D.↗
NASA NTRS1978

A brief survey of rotary wing induced-velocity theory

An attempt is made to summarize the state of rotary wing flow fields. The theory is traced from its origin as a momentum theory estimate of average interference, through simple vortex theory, to its present status where it is indispensible in calculating blade loads. A comparison of the theory with flow measurements are presented. The modern efforts toward using more detailed digital methods to obtain blade load distribution are described.

Heyson, H. H.↗
NASA NTRS1977

Quiet Clean Short-haul Experimental Engine (QCSEE) under-the-wing engine composite fan blade design report

A total of 38 quiet clean short haul experimental engine under the wing composite fan blades were manufactured for various component tests, process and tooling, checkout, and use in the QCSEE UTW engine. The component tests included frequency characterization, strain distribution, bench fatigue, platform static load, whirligig high cycle fatigue, whirligig low cycle fatigue, whirligig strain distribution, and whirligig over-speed. All tests were successfully completed. All blades planned for use in the engine were subjected to and passed a whirligig proof spin test.

Ravenhall, R.↗
NASA NTRS1982

Development of a nonlinear vortex method

Steady and unsteady Nonliner Hybrid Vortex (NHV) method, for low aspect ratio wings at large angles of attack, is developed. The method uses vortex panels with first-order vorticity distribution (equivalent to second-order doublet distribution) to calculate the induced velocity in the near field using closed form expressions. In the far field, the distributed vorticity is reduced to concentrated vortex lines and the simpler Biot-Savart's law is employed. The method is applied to rectangular wings in steady and unsteady flows without any restriction on the order of magnitude of the disturbances in the flow field. The numerical results show that the method accurately predicts the distributed aerodynamic loads and that it is of acceptable computational efficiency.

Kandil, O. A.↗
NASA NTRS1982

Steady and unsteady nonlinear hybrid vortex method for lifting surfaces at large angles of attack

Steady and unsteady Nonlinear Hybrid Vortex (NHV) method, for low aspect ratio wings at large angles of attack, is developed. The method uses vortex panels with first-order vorticity distribution (equivalent to second-order doublet distribution) to calculate the induced velocity in the near field using closed form expressions. In the far field, the distributed vorticity is reduced to concentrated vortex lines and the simpler Biot-Savart's law is employed. The method is applied to rectangular wings in steady and unsteady flows without any restriction on the order of magnitude of the disturbances in the flow field. The numerical results show that the method accurately predicts the distributed aerodynamic loads and that it is of acceptable computational efficiency.

Kandil, O. A.↗
NASA NTRS1984

Static and dynamic structural-sensitivity derivative calculations in the finite-element-based Engineering Analysis Language (EAL) system

The implementation of static and dynamic structural-sensitivity derivative calculations in a general purpose, finite-element computer program denoted the Engineering Analysis Language (EAL) System is described. Derivatives are calculated with respect to structural parameters, specifically, member sectional properties including thicknesses, cross-sectional areas, and moments of inertia. Derivatives are obtained for displacements, stresses, vibration frequencies and mode shapes, and buckling loads and mode shapes. Three methods for calculating derivatives are implemented (analytical, semianalytical, and finite differences), and comparisons of computer time and accuracy are made. Results are presented for four examples: a swept wing, a box beam, a stiffened cylinder with a cutout, and a space radiometer-antenna truss.

Camarda, C. J.↗
NASA NTRS1984

Numerical methods and a computer program for subsonic and supersonic aerodynamic design and analysis of wings with attainable thrust considerations

This paper describes methodology and an associated computer program for the design of wing lifting surfaces with attainable thrust taken into consideration. The approach is based on the determination of an optimum combination of a series of candidate surfaces rather than the more commonly used candidate loadings. Special leading-edge surfaces are selected to provide distributed leading-edge thrust forces which compensate for any failure to achieve the full theoretical leading-edge thrust, and a second series of general candidate surfaces is selected to minimize drag subject to constraints on the lift coefficient and, if desired, on the pitching moment coefficient. A primary purpose of the design approach is the introduction of attainable leading-edge thrust considerations so that relatively mild camber surfaces may be employed in the achievement of aerodynamic efficiencies comparable to those attainable if full theoretical leading-edge thrust could be achieved. The program provides an analysis as well as a design capability and is applicable to both subsonic and supersonic flow.

Carlson, H. W.↗
NASA NTRS1931

The pressure distribution over a modified elliptical wing tip on a biplane in flight

This note presents the results of flight pressure-distribution tests on the right upper wing panel of a Douglas M-3 airplane equipped with a modified elliptical tip having a slight amount of washout. The results are given in tables and curves in such form that the load distribution for any normal force coefficient within the usual range encountered in flight may be determined.

Lundquist, Eugene E↗