Environmentally Responsible Aviation Project Status of Airframe Technology Subproject Integrated Technology Demonstrations
No abstract available
Davis, Pamela A.↗
Engineering topics
Davis, Pamela A.
Publications and source records attributed to Davis, Pamela A..
Damage Arresting Composites
Under NASA's Environmentally Responsible Aviation Project (ERA) the most promising vehicle concepts and technologies that can simultaneously reduce aircraft fuel use, community noise, and emissions are being evaluated. Two key factors to accomplishing these goals are reducing structural weight and moving away from the traditional tube and wing aircraft configuration to a shape that has improved lift and less drag. The hybrid wing body (HWB) configuration produces more lift and less drag by smoothly joining the wings to the center fuselage section so it provides aerodynamic advantages. This shape, however, presents structural challenges with its pressurized, non-circular cabin subjected to aerodynamic flight loads. In the HWB, the structure of the center section where the passenger cabin would be located must support large in-plane loads as well as internal pressure on nearly-flat panels and right-angle joints. This structural arrangement does not lend itself to simple, efficient designs. Traditional aluminum and even state-of-the-art composites do not provide a solution to this challenge.
Jegley, Dawn C.↗
Quasi-Static and Dynamic Response Characteristics of F-4 Bias-Ply and Radial-Belted Main Gear Tires
An investigation was conducted at Langley Research Center to determine the quasi-static and dynamic response characteristics of F-4 military fighter 30x11.5-14.5/26PR bias-ply and radial-belted main gear tires. Tire properties were measured by the application of vertical, lateral, and fore-and-aft loads. Mass moment-of-inertia data were also obtained. The results of the study include quasi-static load-deflection curves, free-vibration time-history plots, energy loss associated with hysteresis, stiffness and damping characteristics, footprint geometry, and inertia properties of each type of tire. The difference between bias-ply and radial-belted tire construction is given, as well as the advantages and disadvantages of each tire design. Three simple damping models representing viscous, structural, and Coulomb friction are presented and compared with the experimental data. The conclusions discussed contain a summary of test observations.
Davis, Pamela A.↗
Studies of Shuttle orbiter arrestment system
Scale model studies of the Shuttle Orbiter Arrestment System (AS) were completed with a 1/27.5-scale model at the NASA Langley Research Center. The purpose of these studies was to determine the proper configuration for a net arrestment system to bring the orbiter to a safe stop with minimal damage in the event of a runway overrun. Tests were conducted for runway on-centerline and off-centerline engagements at simulated speeds up to approximately 100 knots (full scale). The results of these tests defined the interaction of the net and the orbiter, the dynamics of off-centerline engagements, and the maximum number of vertical net straps that may become entangled with the nose gear. In addition to these tests, a test program with a 1/8-scale model was conducted by the arrestment system contractor, and the results are presented in the appendix.
Davis, Pamela A.↗
NASA Langley's Aircraft Landing Dynamics Facility
The Aircraft Landing Dynamics Facility (ALDF) is a unique facility with the ability to test aircraft landing gear systems on actual runway surfaces at operational ground speeds and loading conditions. A brief historical overview of the original Landing Loads Track (LLT) is given, followed by a detailed description of the new ALDF systems and operational capabilities.
Davis, Pamela A.↗
Comparison of 30x11.5 - 14.5 bias-ply and radial-belted tire characteristics
An investigation at NASA Langley Research Center was conducted to determine the static and dynamic mechanical characteristics of 30x11.5-14.5, Type VIII, bias-ply and radial-belted aircraft tires. The tire characteristics were determined by application of vertical and fore-and-aft loads. The results of the study are presented to show static load deflection curves, hysteresis losses, and stiffness and damping characteristics of each tire type tested. The advantages and disadvantages of each type of tire are also given.
Davis, Pamela A.↗
Braking, steering, and wear performance of radial-belted and bias-ply aircraft tires
Preliminary steering, braking, and tread wear performance results from testing of radial-belted and bias-ply aircraft tires at NASA Langley are described. An overview of the joint NASA/FAA/industry START program is presented. Attention is given to the Langley Test Facility, equipment and future activities.
Yager, Thomas J.↗
Langley Aircraft Landing Dynamics Facility
NASA Reference Publication reports on NASA Langley Research Center's recent upgrading of Landing Loads Track (LLT) to improve capability of low-cost testing of conventional and advanced landing-gear systems. Features include ability to test aircraft landing-gear systems on actual runway surfaces at operational ground speeds and loading conditions. Historical overview of original LLT given, followed by detailed description of systems and operational capabilities of new ALDF.
Davis, Pamela A.↗
26 x 6.6 radial-belted aircraft tire performance
Preliminary results from testing of 26 x 6.6 radial-belted and bias-ply aircraft tires at NASA Langley's Aircraft Landing Dynamics Facility (ALDF) are reviewed. The 26 x 6.6 tire size evaluation includes cornering performance tests throughout the aircraft ground operational speed range for both dry and wet runway surfaces. Static test results to define 26 x 6.6 tire vertical stiffness properties are also presented and discussed.
Davis, Pamela A.↗
Aircraft radial-belted tire evaluation
An overview is given of the ongoing joint NASA/FAA/Industry Surface Traction And Radial Tire (START) Program being conducted at NASA Langley's Aircraft Landing Dynamics Facility (ALDF). The START Program involves tests using three different tire sizes to evaluate tire rolling resistance, braking, and cornering performance throughout the aircraft ground operational speed range for both dry and wet runway surfaces. Preliminary results from recent 40 x 14 size bias-ply, radial-belted, and H-type aircraft tire tests are discussed. The paper concludes with a summary of the current program status and planned ALDF test schedule.
Yager, Thomas J.↗
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.↗
Fore-and-aft stiffness and damping characteristics of 30 x 11.5-14.5, Type VIII, bias-ply and radial-belted aircraft tires
Measurements of footprint geometrical properties and fore and aft stiffness and damping characteristics were obtained on 30 x 11.5-14.5 bias-ply and radial-belted aircraft tires. Significant differences in stiffness and damping characteristics were found between the two design types. The results show that footprint aspect ratio effects may interfere with the improved hydroplaning potential associated with the radial-belted tire operating at higher inflation pressures.
Lopez, Mercedes C.↗
Shuttle Orbiter arrestment system studies
Scale model studies of the Shuttle Orbiter arrestment system were conducted to determine the proper net arrestment system configuration to bring the Orbiter to a safe stop in the event of a runway overshoot. Areas of interest include the effect of various net geometries on net engagement of the nose gear and main gear; and whether or not the top bundle contacts the crew cabin window. The model tests indicated that the net arrestment system was properly designed to bring the Orbiter to a safe stop with minimal amount of damage. The test procedures and data are presented.
Davis, Pamela A.↗
Static mechanical properties of 30 x 11.5 - 14.5, type 8 aircraft tires of bias-ply and radial-belted design
An investigation was conducted to determine the static mechanical properties of a 30 x 11.5 to 14.5, Type 8, bias-ply and radial-belted aircraft tire. The properties measured were the spring rate and damping characteristics of each tire from vertical- and lateral-loading hysteresis loops. Mass moment of inertia tests were also conducted. The results of the study are presented along with a discussion of the advantages and disadvantages of each type of tire.
Davis, Pamela A.↗
Oscillation pressure device for dynamic calibration of pressure transducers
Method and apparatus for obtaining dynamic calibrations of pressure transducers. A calibration head (15), a flexible tubing (23) and a bellows (20) enclose a volume of air at atmospheric pressure with a transducer (11) to be calibrated subject to the pressure inside the volume. All of the other apparatus in the drawing apply oscillations to bellows (20) causing the volume to change thereby applying oscillating pressures to transducer (11) whereby transducer (11) can be calibrated.
Hess, Robert W.↗
Langley Aircraft Landing Dynamics Facility
The Langley Research Center has recently upgraded the Landing Loads Track (LLT) to improve the capability of low-cost testing of conventional and advanced landing gear systems. The unique feature of the Langley Aircraft Landing Dynamics Facility (ALDF) is the ability to test aircraft landing gear systems on actual runway surfaces at operational ground speeds and loading conditions. A historical overview of the original LLT is given, followed by a detailed description of the new ALDF systems and operational capabilities.
Davis, Pamela A.↗
Static mechanical properties of 30 x 11.5-14.5, type VII, aircraft tires of bias-ply and radial-belted design
An investigation was conducted to determine the static mechanical characteristics of 30 x 115-14.5 bias-ply and radial aircraft tires. The tires were subjected to vertical and lateral loads and mass moment of inertia tests were conducted. Static load deflection curves, spring rates, hysteresis losses, and inertia data are presented along with a discussion of the advantages and disadvantages of one tire over the other.
Davis, Pamela A.↗