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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Cornering and wear characteristics of the Space Shuttle Orbiter nose-gear tire

Tests of the Space Shuttle Orbiter nose-gear tire have been completed at NASA Langley's Aircraft Landing Dynamics Facility. The purpose of these tests was to determine the cornering and wear characteristics of the Space Shuttle Orbiter nose-gear tire under realistic operating conditions. The tire was tested on a simulated Kennedy Space Center runway surface at speeds from 100 to 180 kts. The results of these tests defined the cornering characteristics which included side forces and associated side force friction coefficient over a range of yaw angles from 0 deg to 12 deg. Wear characteristics were defined by tire tread and cord wear over a yaw angle range of 0 deg to 4 deg under dry and wet runway conditions. Wear characteristics were also defined for a 15 kt crosswind landing with two blown right main-gear tires and nose-gear steering engaged.

Davis, Pamela A.↗
NASA NTRS1939

Flight Tests of N.A.C.A. Nose-slot Cowlings on the BFC-1 Airplane

The results of flight tests of four nose-slot cowling designs with several variations in each design are presented. The tests were made in the process of developing the nose-slot cowling. The results demonstrate that a nose-slot cowling may be successfully applied to an airplane and that it utilizes the increased slipstream velocity of low-speed operation to produce increased cooling pressure across the engine. A sample design calculation using results from wind-tunnel, flight, and ground tests is given in an appendix to illustrate the design procedure.

Stickle, George W↗
NASA NTRS1953

A low-speed experimental study of the directional characteristics of a sharp-nosed fuselage through a large angle-of-attack range at zero angle of sideslip

Static yawing moments and some instantaneous yawing moments are presented through a range of angle of attack at zero sideslip angle for a plain fuselage model having a sharp conical nose and for the fuselage with several nose modifications, one of which consisted of a ring located at different stations along the nose. Some circumferential pressure measurements at one station on the body at several angles of attack are also presented.

PROTUBERANCES-BODIES↗
NASA NTRS1952

Flow Separation from Rods Ahead of Blunt Noses at Mach Number 2.72

An experimental investigation in the Langley Gas Dynamics Laboratory has been made of the flow separation from slender rods mounted to extend forward along the axes of symmetry of blunt-nosed bodies. The mechanism of the separation and its governing criteria are discussed. Drag data at a Mach number of 2.72 for various rod lengths and nose radii at an angle of attack of zero degrees are presented. It was found that the drag coefficients of blunt noses could be appreciably reduced by the use of protruding rods. Criteria for rod length which gives lowest drag are given. (author)

Jones, Jim J↗
NASA NTRS1994

The reduction of takeoff ground roll by the application of a nose gear jump strut

A series of flight tests were conducted to evaluate the reduction of takeoff ground roll distance obtainable from a rapid extension of the nose gear strut. The NASA Quiet Short-haul Research Aircraft (QSRA) used for this investigation is a transport-size short take off and landing (STOL) research vehicle with a slightly swept wing that employs the upper surface blowing (USB) concept to attain the high lift levels required for its low-speed, short-field performance. Minor modifications to the conventional nose gear assembly and the addition of a high-pressure pneumatic system and a control system provided the extendable nose gear, or jump strut, capability. The limited flight test program explored the effects of thrust-to-weight ratio, wing loading, storage tank initial pressure, and control valve open time duration on the ground roll distance. The data show that a reduction of takeoff ground roll on the order of 10 percent was achieved with the use of the jump strut, as predicted. Takeoff performance with the jump strut was also found to be essentially independent of the pneumatic supply pressure and was only slightly affected by control valve open time within the range of the parameters examined.

Eppel, Joseph C.↗
NASA NTRS1994

Flight investigation of the use of a nose gear jump strut to reduce takeoff ground roll distance of STOL aircraft

A series of flight tests was conducted to evaluate the reduction of takeoff ground roll distance obtainable from a rapid extension of the nose gear strut. The NASA Quiet Short-haul Research Aircraft (QSRA) used for this investigation is a transport-size short takeoff and landing (STOL) research vehicle with a slightly swept wing that employs the upper surface blowing (USB) concept to attain the high lift levels required for its low speed, short-field performance. Minor modifications to the conventional nose gear assembly and the addition of a high pressure pneumatic system and a control system provided the extendible nose gear, or 'jump strut,' capability. The limited flight test program explored the effects of thrust-to-weight ratio, storage tank initial pressure, and control valve open time duration on the ground roll distance. The data show that the predicted reduction of takeoff ground roll on the order of 10 percent was achieved with the use of the jump strut. Takeoff performance with the jump strut was also found to be essentially independent of the pneumatic supply pressure and was only slightly affected by control valve open time within the range of the parameters examined.

Eppel, Joseph C.↗
NASA NTRS1993

Aircraft nose gear shimmy studies

An overview of previous studies involving aircraft nose gear shimmy behavior is given together with some test results identifying the influence of different factors inducing shimmy. A NASA Langley test program conducted at the Landing Loads Track (LLT) facility to evaluate shimmy characteristics of an actual Space Shuttle nose gear is described together with some of the test results. Based on results from these various evaluations, recommendations are made concerning nose gear design features, such as corotating wheels, to minimize the occurence of shimmy.

Yager, Thomas J.↗
NASA NTRS1996

Computational Methods for Frictional Contact With Applications to the Space Shuttle Orbiter Nose-Gear Tire

A computational procedure is presented for the solution of frictional contact problems for aircraft tires. A Space Shuttle nose-gear tire is modeled using a two-dimensional laminated anisotropic shell theory which includes the effects of variations in material and geometric parameters, transverse-shear deformation, and geometric nonlinearities. Contact conditions are incorporated into the formulation by using a perturbed Lagrangian approach with the fundamental unknowns consisting of the stress resultants, the generalized displacements, and the Lagrange multipliers associated with both contact and friction conditions. The contact-friction algorithm is based on a modified Coulomb friction law. A modified two-field, mixed-variational principle is used to obtain elemental arrays. This modification consists of augmenting the functional of that principle by two terms: the Lagrange multiplier vector associated with normal and tangential node contact-load intensities and a regularization term that is quadratic in the Lagrange multiplier vector. These capabilities and computational features are incorporated into an in-house computer code. Experimental measurements were taken to define the response of the Space Shuttle nose-gear tire to inflation-pressure loads and to inflation-pressure loads combined with normal static loads against a rigid flat plate. These experimental results describe the meridional growth of the tire cross section caused by inflation loading, the static load-deflection characteristics of the tire, the geometry of the tire footprint under static loading conditions, and the normal and tangential load-intensity distributions in the tire footprint for the various static vertical loading conditions. Numerical results were obtained for the Space Shuttle nose-gear tire subjected to inflation pressure loads and combined inflation pressure and contact loads against a rigid flat plate. The experimental measurements and the numerical results are compared.

Tanner, John A.↗
NASA NTRS1996

Computational methods for frictional contact with applications to the Space Shuttle orbiter nose-gear tire: Comparisons of experimental measurements and analytical predictions

A computational procedure is presented for the solution of frictional contact problems for aircraft tires. A Space Shuttle nose-gear tire is modeled using a two-dimensional laminated anisotropic shell theory which includes the effects of variations in material and geometric parameters, transverse-shear deformation, and geometric nonlinearities. Contact conditions are incorporated into the formulation by using a perturbed Lagrangian approach with the fundamental unknowns consisting of the stress resultants, the generalized displacements, and the Lagrange multipliers associated with both contact and friction conditions. The contact-friction algorithm is based on a modified Coulomb friction law. A modified two-field, mixed-variational principle is used to obtain elemental arrays. This modification consists of augmenting the functional of that principle by two terms: the Lagrange multiplier vector associated with normal and tangential node contact-load intensities and a regularization term that is quadratic in the Lagrange multiplier vector. These capabilities and computational features are incorporated into an in-house computer code. Experimental measurements were taken to define the response of the Space Shuttle nose-gear tire to inflation-pressure loads and to inflation-pressure loads combined with normal static loads against a rigid flat plate. These experimental results describe the meridional growth of the tire cross section caused by inflation loading, the static load-deflection characteristics of the tire, the geometry of the tire footprint under static loading conditions, and the normal and tangential load-intensity distributions in the tire footprint for the various static vertical-loading conditions. Numerical results were obtained for the Space Shuttle nose-gear tire subjected to inflation pressure loads and combined inflation pressure and contact loads against a rigid flat plate. The experimental measurements and the numerical results are compared.

Tanner, John A.↗
NASA NTRS1959

Review of Aircraft Altitude Errors Due to Static-Pressure Source and Description of Nose-Boom Installations for Aerodynamic Compensation of Error

A brief review of airplane altitude errors due to typical pressure installations at the fuselage nose, the wing tip, and the vertical fins is presented. A static-pressure tube designed to compensate for the position errors of fuselage-nose installations in the subsonic speed range is described. This type of tube has an ogival nose shape with the static-pressure orifices located in the low-pressure region near the tip. The results of wind-tunnel tests of these compensated tubes at two distances ahead of a model of an aircraft showed the position errors to be compensated to within 1/2 percent of the static pressure through a Mach number range up to about 1.0. This accuracy of sensing free-stream static pressure was extended up to a Mach number of about 1.15 by use of an orifice arrangement for producing approximate free-stream pressures at supersonic speeds and induced pressures for compensation of error at subsonic speeds.

Gracey, William↗
NASA NTRS1999

NDE Process Development Specification for SRB Composite Nose Cap

The Shuttle Upgrade program is a continuing improvement process to enable the Space Shuttle to be an effective space transportation vehicle for the next few decades. The Solid Rocket Booster (SRB), as a component of that system, is currently undergoing such an improvement. Advanced materials, such as composites, have given us a chance to improve performance and to reduce weight. The SRB Composite Nose Cap (CNC) program aims to replace the current aluminum nose cap, which is coated with a Thermal Protection System and poses a possible debris hazard, with a lighter, stronger, CNC. For the next 2 years, this program will evaluate the design, material selection, properties, and verification of the CNC. This particular process specification cites the methods and techniques for verifying the integrity of such a nose cap with nondestructive evaluation.

Suits, M.↗
NASA NTRS1961

Some Effects of Nose Bluntness and Fineness Ratio on the Static Longitudinal Aerodynamic Characteristics of Bodies of Revolution at Subsonic Speeds

. The effects of a systematic variation of nose shape and fineness ratio on the longitudinal aerodynamic characteristics of bodies of revolution have been qualitatively determined at subsonic speeds. Six nose shapes were investigated, representing five corner radii which varied from 0 to 50 percent of the body diameter and three face radii which varied from 50 percent of the model diameter to infinity. The complete models had fineness ratios of 0.50 to 2.00. In addition, effects of boattailing the afterbody and removing or varying the transitions trips which had been attached to initiate a turbulent boundary layer were noted. Results are presented for an angle-of-attack range from -4 deg to 24 deg for Mach numbers from 0.25 to 0.80, and indicate that small variations of the model nose can produce large variations in the static longitudinal aerodynamic characteristics of the body. These variations may in turn be moderated by an increase in the model fineness ratio .

Hayes, William C., Jr.↗
NASA NTRS1961

Free-Flight Skin-Temperature and Surface-Pressure Measurements on a Highly Polished Nose Having a 100 deg Total-Angle Cone and a 10 deg Half-Angle Conical Flare Section up to a Mach Number of 4.08

The skin temperature and surface pressure were measured on a large-scale, highly polished nose having a relatively sharp-tipped 100 deg total-angle cone followed by a conical flare section of 10 deg half-angle. The measurements were obtained in flight from a rocket-propelled model up to a peak Mach number of 4.08 and a peak Reynolds number of 22 x 10(exp 6) per foot. Temperature distributions indicated that the heating on the forward 3.5 inches of the 100 deg cone was lower than the heating on the rearward portion. Likewise, measured temperatures on the flare portion of the test nose were generally lower than the temperatures on the 100 deg cone portion. The data indicated that the local Reynolds numbers of transition, based on calculated boundary-layer momentum thicknesses, ranged from 530 to 940 for a Mach number range from 2.72 to 3.75. Comparison of measured cone pressures with theory for a sharp cone showed that theory overestimates the cone pressures. Pressure measurements on the flare portion of the nose showed that in the lower speed range the flow expands below atmospheric pressure in going from the cone to the flare; however, as the speed increased, the expansion diminished and for speeds greater than a Mach number of approximately 3.0 the flare pressure coefficients were at or near a value of zero.

Rashis, Bernard↗
NASA NTRS1992

Status of the Validation of High-Angle-Of-Attack Nose-Down Pitch Control Margin Design Guidelines

This paper presents a summary of results obtained to date in an ongoing cooperative research program between NASA and the U.S. Navy to develop design criteria for high-angle-of-attack nose- down pitch control for combat aircraft. A fundamental design consideration for aircraft incorporating relaxed static stability in pitch is the level of stability which achieves a proper balance between high- speed performance considerations and low-speed requirements for maneuvering at high angles of attack. A comprehensive data base of piloted simulation results was generated for parametric variations of critical parameters affecting nose-down control capability. The results showed a strong correlation of pilot rating to the short-term pitch response for nose-down commands applied at high- angle-of-attack conditions. Using these data, candidate design guidelines and flight demonstration requirements were defined. Full- scale flight testing to validate the research methodology and proposed guidelines is in progress, some preliminary results of which are reviewed.

Ogburn, Marilyn E.↗
NASA NTRS1946

Wind-Tunnel Investigation of the Stability of the Jettisonable Nose Section of the X-3 Airplane

Because previous work has indicated that jettisonable nose sections of airplanes may be inherently unstable, and thus may cause dangerous centripetal accelerations on a pilot after jettisoning during high-speed flight, an investigation has been conducted in the Langley 20-foot free-spinning tunnel to determine the behavior in descent of a model of the jettisonable nose section of the Douglas X-3 airplane. The effects of varying the center-of-gravity position, of attaching fins of various sizes, and of installing a stabilizing parachute were investigated. In the investigation the model descended with its front and trimmed 36 deg above the horizontal and rotated about a vertical wind axis while rolling about its longitudinal body axis. The nose section was made to descend in a stable front-down attitude when stabilizing fins were installed in conjunction with movement of the center of gravity forward or when a stable parachute was attached to the model.

Scher, Stanley H.↗
NASA NTRS1958

An Investigation of the Free-Spinning and Recovery Characteristics of a 1/24-Scale Model of the Grumman F11F-1 Airplane with Alternate Nose Configurations with and without Wing Fuel Tanks, TED No. NACA AD 395

A supplementary investigation has been conducted in the langley 20-foot free-spinning tunnel on a l/24-scale model of the Grumman F11F-1 airplane to determine the spin and recovery characteristics with alternate nose configurations, the production version and the elongated APS-67 version, with and without empty and full wing tanks. When spins were obtained with either alternate nose configuration, they were oscillatory and recovery characteristics were considered unsatisfactory on the basis of the fact that very slow recoveries were indicated to be possible. The simultaneous extension of canards near the nose of the model with rudder reversal was effective in rapidly terminating the spin. The addition of empty wing tanks had little effect on the developed spin and recovery characteristics. The model did not spin erect with full wing tanks. For optimum recovery from inverted spins, the rudder should be reversed to 22O against the spin and simultaneously the flaperons should be moved with the developed spin; the stick should be held at or moved to full forward longitudinally. The minimum size parachute required to insure satisfactory recoveries in an emergency was found to be 12 feet in diameter (laid out flat) with a drag coefficient of 0.64 (based on the laid-out-flat diameter) and a towline length of 32 feet.

Bowman, James S., Jr.↗
NASA NTRS2007

Effects of Nose Bluntness on Stability of Hypersonic Boundary Layers over Blunt Cone

Receptivity and stability of hypersonic boundary layers are numerically investigated for boundary layer flows over a 5-degree straight cone at a free-stream Mach number of 6.0. To compute the shock and the interaction of shock with the instability waves, we solve the Navier-Stokes equations in axisymmetric coordinates. The governing equations are solved using the 5th-order accurate weighted essentially non-oscillatory (WENO) scheme for space discretization and using third-order total-variation-diminishing (TVD) Runge-Kutta scheme for time integration. After the mean flow field is computed, disturbances are introduced at the upstream end of the computational domain. Generation of instability waves from leading edge region and receptivity of boundary layer to slow acoustic waves are investigated. Computations are performed for a cone with nose radii of 0.001, 0.05 and 0.10 inches that give Reynolds numbers based on the nose radii ranging from 650 to 130,000. The linear stability results showed that the bluntness has a strong stabilizing effect on the stability of axisymmetric boundary layers. The transition Reynolds number for a cone with the nose Reynolds number of 65,000 is increased by a factor of 1.82 compared to that for a sharp cone. The receptivity coefficient for a sharp cone is about 4.23 and it is very small, approx.10(exp -3), for large bluntness.

Kara, K.↗
NASA NTRS2008

Stability and Controls Analysis and Flight Test Results of a 24-Foot Telescoping Nose Boom on an F-15B Airplane

The Quiet Spike(TradeMark) F-15B flight research program investigated supersonic shock reduction using a 24-ft telescoping nose boom on an F-15B airplane. The program goal was to collect flight data for model validation up to 1.8 Mach. In the area of stability and controls, the primary concerns were to assess the potential destabilizing effect of the oversized nose boom on the stability, controllability, and handling qualities of the airplane and to ensure adequate stability margins across the entire research flight envelope. This paper reports on the stability and control analytical methods, flight envelope clearance approach, and flight test results of the F-15B telescoping nose boom configuration. Also discussed are brief pilot commentary on typical piloting tasks and refueling tasks.

Moua, Cheng M.↗