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At least 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Thermal enclosures for electronically scanned pressure modules operating in cryogenic environments

Specific guidelines to design, construct, and test ESP thermal enclosures for applications at cryogenic temperatures are given. The enclosures maintain the ESP modules at a constant temperature (10 C plus or minus 1 C) to minimize thermal zero and sensitivity shifts, to minimize the frequency of expensive on-line calibrations, and to avoid adverse effects on tunnel and model boundary layers. The enclosures are constructed of a rigid closed-cell foam and are capable of withstanding the stagnation pressures to 932kPa (135 psia) without reduction in thermal insulation properties. This construction procedure has been used to construct several thermal packages which have been successfully used in National Transonic Facility.

Mitchell, Michael↗
NASA NTRS1988

Navier-Stokes simulation of wind-tunnel flow using LU-ADI factorization algorithm

The three dimensional Navier-Stokes solution code using the LU-ADI factorization algorithm was employed to simulate the workshop test cases of transonic flow past a wing model in a wind tunnel and in free air. The effect of the tunnel walls is well demonstrated by the present simulations. An Amdahl 1200 supercomputer having 128 Mbytes main memory was used for these computations.

Obayashi, Shigeru↗
NASA NTRS1990

Thermal/structural analysis of the shaft-disk region of a fan drive system

In January 1989, a mishap occurred in the National Transonic Facility wind tunnel at NASA-Langley. It is believed that the failure of an insulation retainer holding foam insulation around the exterior of the fan drive shaft resulted in the subsequent damage to other components in the tunnel. The effect was determined of removing the external thermal insulation on the shaft would have on the stresses on the shaft, disk and bolts holding the two together. To accomplish this, a detailed thermal/structural finite element analysis of the shaft-disk interface was performed. The maximum stresses on the three components were determined for several configurations and conditions with and without the external thermal insulation, and then these results were compared to the original analyses to access the effect of removing the external thermal insulation on the proposed future operation of the shaft/disk structures of the fan drive system. Although the stresses were higher without the external insulation, the stresses did meet all stress criteria. In addition, all stresses were within the infinite life regime of the Modified Goodman diagram. Therefore, it was determined that the structural integrity of the shaft-disk region is not compromised if the external insulation is removed.

Gregory, Peyton B.↗
NASA NTRS1989

Smart tunnel: Docking mechanism

A docking mechanism is presented for the docking of a space vehicle to a space station comprising a flexible tunnel frame structure which is deployable from the space station. The tunnel structure comprises a plurality of series connected frame sections, one end section of which is attached to the space station and the other end attached to a docking module of a configuration adapted for docking in the payload bay of the space vehicle. The docking module is provided with trunnions, adapted for latching engagement with latches installed in the vehicle payload bay and with hatch means connectable to a hatch of the crew cabin of the space vehicle. Each frame section comprises a pair of spaced ring members, interconnected by actuator-attenuator devices which are individually controllable by an automatic control means to impart relative movement of one ring member to the other in six degrees of freedom of motion. The control means includes computer logic responsive to sensor signals of range and attitude information, capture latch condition, structural loads, and actuator stroke for generating commands to the onboard flight control system and the individual actuator-attenuators to deploy the tunnel to effect a coupling with the space vehicle and space station after coupling. A tubular fluid-impervious liner, preferably fabric, is disposed through the frame sections of a size sufficient to accommodate the passage of personnel and cargo.

Schliesing, John A.↗
NASA NTRS1992

Numerical methods for the simulation of complex multi-body flows with applications for the integrated Space Shuttle vehicle

This project forms part of the long term computational effort to simulate the time dependent flow over the integrated Space Shuttle vehicle (orbiter, solid rocket boosters (SRB's), external tank (ET), and attach hardware) during its ascent mode for various nominal and abort flight conditions. Due to the limitations of experimental data such as wind tunnel wall effects and the difficulty of safely obtaining valid flight data, numerical simulations are undertaken to supplement the existing data base. This data can then be used to predict the aerodynamic behavior over a wide range of flight conditions. Existing computational results show relatively good overall comparison with experiments but further refinement is required to reduce numerical errors and to obtain finer agreements over a larger parameter space. One of the important goals of this project is to obtain better comparisons between numerical simulations and experiments. In the simulations performed so far, the geometry has been simplified in various ways to reduce the complexity so that useful results can be obtained in a reasonable time frame due to limitations in computer resources. In this project, the finer details of the major components of the Space Shuttle are modeled better by including more complexity in the geometry definition. Smaller components not included in early Space Shuttle simulations will now be modeled and gridded.

Chan, William M.↗
NASA NTRS1992

A low-noise 492 GHz SIS waveguide receiver

The design and performance are described of an SIS waveguide receiver which provides low noise performance from 375 to 510 GHz. At its design frequency of 492 GHz the receiver has a double-sideband noise temperature of about 172 K. By using embedded magnetic-field concentrators Josephson pair tunneling is effectively suppressed. Techniques for improving receiver performance are discussed.

Walker, C. K.↗
NASA NTRS1992

Particle diagnostics and turbulence measurements in a confined isothermal liquid spray

An experimental study of the behavior and structure of a liquid spray immersed in a strong swirling field is reported. In order to simulate some of the aerodynamic conditions experienced by a spray in a model combustor, an experimental setup using an acrylic chamber, a vane-type swirler, and separate air supplies for both the secondary air and swirl air were integrated to perform the experiments in the wind tunnel. The effect of the swirling flow on the original spray cone is to widen it substantially, and to provide a vortex core where intense mixing results in large changes in particle size distribution and in particle number density. Outside the recirculation region, both the D32 and N sub d attain more uniform values. Inside the recirculation region, the mean axial velocity averaged over all the drop sizes has larger values than the mean air velocity. Outside the recirculation region, both the particles and the air exhibit virtually the same velocities. The turbulence measurements showed regions of high turbulence intensity in the boundaries of the recirculation region.

Brena De La Rosa, A.↗
NASA NTRS1938

Interference of Wing and Fuselage from Tests of the 18 Combinations in the N.A.C.A. Variable-density Tunnel - Combination with Split Flaps

As part of the wing-fuselage interference investigation in progress in the N.A.C.A. variable density wind tunnel, the effects of various split-flap arrangements applied to wing-fuselage combinations were determined. Split flaps were found to exert their influence independently of the interference, and their effects on the aerodynamic characteristics of rectangular-airfoil combinations appeared to be more or less proportional to their exposed span lengths. The interference, moreover, showed the same character with the split flaps as without them.

Sherman, Albert↗
NASA NTRS1946

Free-spinning-tunnel Tests of a 1/26th Scale Model of the Douglas XTB2D-1 Airplane

A spin-tunnel investigation of a 1/26 scale model of the Douglas XTB2D-1 airplane has been conducted in the Langley 20-foot free-spinning tunnel. The effects of control settings and movements upon the erect- and inverted-spin and recovery characteristics of the model were determined for various loading conditions. Tests were also performed to determine the effects of various tail modifications. The investigation included emergency spin-recovery parachute tests as well as crew-escape and rudder- and elevator-force tests. All tests were performed at an equivalent spin altitute of 20,000 feet. The recovery characteristics of the model in the original design were found to be unsatisfactory. Installation of a large ventral fin, installation of tip fins on the horizontal tail, or installation of a small ventral fin in combination with antispan fillets and a spanwise extension of the horizontal-tail surfaces satisfactorily improved the recovery characteristics of the model.

Stone, Ralph W↗
NASA NTRS1994

The nu(sub 6), nu(sub 7), nu(sub 8), and nu(sub 10) Bands of HO2NO2

Two new fundamental vibration-rotation bands have been observed for HO2NO2 and assigned. They are nu(sub 7) at 648 1/cm and nu(sub 8) at 466 1/cm. On the basis of these assignments the previously observed bands at 722, 801.5, and 919 1/cm are assigned to nu(sub 10), nu(sub 7) + nu(sub 12), and 2 nu(sub 8), respectively. A partial rotational analysis of the atmospherically relevant nu(sub 6) band has been carried out, and the effects of tunneling, Coriolis interactions, and hot bands on the rotational structure have been characterized.The band origin derived from this analvsisis 8O2.54(sub 3) 1/cm.

Friedl, Randall R.↗
NASA NTRS1959

Longitudinal Aerodynamic Characteristics of a Wing-Body-Tail Model Having a Highly Tapered, Cambered 45 degree Swept Wing of Aspect Ratio 4 at Transonic Speeds

The longitudinal aerodynamic characteristics of a wing-body-horizontal-tail configuration designed for efficient performance at transonic speeds has been investigated at Mach numbers from 0.80 to 1.03 in the Langley 16-foot transonic tunnel. The effect of adding an outboard leading-edge chord-extension to the highly tapered 45 deg. swept wing was also obtained. The average Reynolds number for this investigation was 6.7 x 10(exp 6) based on the wing mean aerodynamic chord. The relatively low tail placement as well as the addition of a chord-extension achieved some alleviation of the pitchup tendencies of the wing-fuselage configuration. The maximum trimmed lift-drag ratio was 16.5 up to a Mach number of 0.9, with the moment center located at the quarter-chord point of the mean aerodynamic chord. For the untrimmed case, the maximum lift-drag ratio was approximately 19.5 up to a Mach number of 0.9.

West, F. E., Jr.↗
NASA NTRS1947

Free-Spinning-Tunnel Tests of a 1/16-Scale Model of the Chance Vought XF5U-1 Airplane, TED No. NACA 2349

Spin tests of a 1/16-scale model of the Chance Vought XF5U-1 airplane have been performed in the Langley 20-foot free-spinning tunnel. The effect of control position and movement upon the erect and inverted spin and recovery characteristics ae well as the effects of propellers, of stability flaps, and of various revisions to the design configuration have been determined for the normal fighter loading. The investigation also included spin recovery parachute, tumbling, and pilot-escape tests. For the original design configuration, with or without windmilling propellers, the recovery characteristics of the model were considered unsatisfactory. Increasing the maximum upward deflection of the ailavators from 45 deg to 65 deg resulted in greatly improved recovery characteristics. Dimensional revisions to the original airplane configuration, which satisfactorily improved the general spin and recovery characteristics of the model, consisted of: (1) a supplementary vertical tail 34 inches by 59 inches (full-scale) attached to a boom 80 inches aft of the trailing edge of the airplane in the plane of symmetry, (2) a large semispan undersurface spoiler placed along the airplane quarter-chord line and opened on the outboard side in a spin, or (3) two additional vertical tails 64 inches by 52 inches (full-scale) located at the tips of the ailavators. A satisfactory parachute arrangement for emergency spin recovery from demonstration spins was found to be an arrangement consisting of a 13.3-foot parachute attached by a 30-foot towline to the arresting gear mast on the airplane and opened simultaneously with an 8-foot parachute on the outboard end of the wing attached by a 3-foot towline. Tests indicated that pilot escape from a spin would be extremely hazardous unless the pilot is mechanically ejected from the cockpit. Model tumbling tests indicated that the airplane would not tumble.

White, Richard P.↗
NASA NTRS1947

Free-Spinning-Tunnel Tests of a 1/24-Scale Model of the McDonnell XP-88 Airplane with a Conventional Tail

An investigation of the spin and recovery characteristics of a 1/24-scale model of the McDonnell XP-88 airplane has been conducted in the Langley 20-foot free-spinning tunnel. The effects of control settings and movements on the erect and inverted spin and recovery characteristics of the model in the normal loading were determined. Tests of the model in the long-range loading also were made. The investigation included tail-modification, spin-recovery parachute, pilot-escape, and rudder-pedal-force tests. Recoveries were generally satisfactory for spins in the normal loading provided the ailerons were not held against the spin. Satisfactory recoveries were obtained regardless of the aileron setting when the leading-edge flaps were deflected and normal recovery technique was used or when the horizontal tail was raised 70 inches, full scale. Recoveries were rapid from all inverted spins obtained. In the long-range loading with tanks on, it may be necessary to jettison the tanks in order to obtain recovery. A 12.0-foot spin-recovery parachute at the tail or a 4.0-foot parachute opened on the outer wing tip (drag coefficient of 0.66) was found to be effective for recoveries from demonstration spins. Test results showed that in an emergency the pilot should attempt to escape from the outboard side of the spinning airplane. The rudder-pedal forces in a spin were indicated to be within the capabilities of the pilot.

Berman, Theodore↗
NASA NTRS1948

Free-Spinning-Tunnel Tests of a 1/24-Scale Model of the Grumman XF9F-2 Airplane, TED No. NACA DE 317

An investigation of the spin and recovery characteristics of a scale model of the Grumman XF9F-2 airplane has been conducted in the Langley 20-foot free-spinning tunnel. The effects of control settings and movements on the erect and inverted spin and recovery characteristics of the model in the flight loading were determined. The investigation also included spin-recovery-parachute, pilot-escape, and rudder-pedal- . force tests. The recovery characteristics of the model were satisfactory for all configurations tested. Spins for the normal control configuration were oscillatory in roll and yaw. Deflecting the leading-edge flaps or the dive brakes did not change the spin and recovery characteristics of the model noticeably. A 10.0-foot tail parachute or a 6.0-foot wing-tip parachute (drag coefficient of 0.75) was found to be effective for recoveries from demonstration spins. The rudder forces in the spin appeared to be within the capabilities of the pilot.

Berman, Theodore↗
NASA NTRS1948

Free-Spinning-Tunnel Tests of a 0.057-Scale Model of the Chance Vought XF7U-1 Airplane

An investigation of the spin and recovery characteristics of a 0.057-scale model of the Chance Vought XF7U-1 airplane has been conducted in the Langley 20-foot free-spinning tunnel. The effects of control settings and movements on the erect and inverted spin and recovery characteristics were determined, as were also the effects of extending the wing slats, of center-of-gravity movement, and-of variation in the mass distribution. The investigation also included wing-tip spin-recovery-parachute tests, pilot-escape tests, and rudder-control-force tests. The investigation indicated that the spin and recovery characteristics of the airplane will be satisfactory for all conditions. It was found that a single 4.24-foot (full-scale) parachute when opened alone from the outboard wing tip or two 8.77-foot (full-scale) parachutes when opened simultaneously, one from each wing tip, would effect satisfactory emergency recoveries (the drag coefficients of the parachutes, based on the surface area of the parachute, were 0.83 and 0.70 for the 4.24- and 8.77-foot parachutes, respectively). The towline length in both cases was 25 feet (full scale). Tests results showed that, if the pilot should have to leave the airplane during a spin, he should jump from the outboard side (left side in a right spin) of the cockpit. The rudder-control force necessary for recovery from a spin was found to be rather high but appeared to be within the upper limits of a pilot's capabilities.

Daughtridge, Lee T., Jr.↗
NASA NTRS1950

Free-Spinning-Tunnel Investigation of a 1/24-Scale Model of the Grumman AF-2S, -2W Airplane

An investigation of the spin and recovery characteristics of a 1/24-scale model of the Grumman AF-2S, -2W airplane was conducted in the Langley 20-foot free-spinning tunnel. The effects of controls on the erect and inverted spin and recovery characteristics for a range of possible loadings of the.airplane were determined. The effect of a revised-tail installation (small dual fins added to the stabilizer of the original tail and the vertical-tail height of the original tail increased) and the effect of various ventral-fin and antispin-fillet installations were determined. The investigation also included spin-recovery parachute tests.

Klinar, Walter J.↗