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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. These tire tests are part of a larger, on going joint NASA/FAA/Industry Surface Traction and Radial Tire (START) Program involving three different tire sizes. 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.

Tests with specially instrumented NASA B-737 and B-727 aircraft together with several different ground friction measuring devices have been conducted for a variety of runway surface types and wetness conditions. This effort is part of the Joint FAA/NASA Aircraft/Ground Vehicle Runway Friction Program aimed at obtaining a better understanding of aircraft ground handling performance under adverse weather conditions and defining relationships between aircraft and ground vehicle tire friction measurements. Aircraft braking performance on dry, wet, snow-, and ice-covered runway conditions is discussed together with ground vehicle friction data obtained under similar runway conditions. For a given contaminated runway surface condition, the relationship between ground vehicles and aircraft friction data is identified. The influence of major test parameters on friction measurements such as speed, test tire characteristics, and surface contaminant type are discussed.

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.

Results are presented of an experimental and analytical study of the dynamic response to crash loadings of five different load-limiting subfloors for general aviation aircraft. These subfloors provide a high-strength structural floor platform to retain the seats and a crush-able zone to absorb energy and limit vertical loads. Experimental static load-deflection data and dynamic deceleration response data for the five subfloors indicated that the high-strength floor platform performed well in that structural integrity and residual strength was maintained throughout the loading cycle. The data also indicated that some of the subfloor crush zones were more effective than others in providing nearly constant load for a range of displacement. The analytical data was generated by characterizing the nonlinear crush zones of the subfloor with static load-deflection data and using the DYCAST nonlinear finite element computer program.

Computational experiments have been performed for a few configurations in order to investigate the effects of external flow disturbances on the extent of laminar flow and wake drag. Theoretical results have been compared with experimental data for the AEDC cone, for Mach numbers from subsonic to supersonic, and for both free flight and wind tunnel environments. The comparisons have been found to be very satisfactory, thus establishing the utility of the present method for the design and development of “laminar flow” configurations and for the assessment of wind tunnel data. In addition, the present paper presents results of calculations concerning the effects of unit Reynolds numbers on transition. This phenomenon has been observed by a few experimental investigators but has been analyzed in detail for the first time in the present paper with the aid of the theoretical predictions.

Emerging advanced controls technology will allow future generation fighter aircraft to aggressively maneuver at high angles-of-attack. Currently there is a need to develop flight-validated design methodologies and guidelines to effectively integrate this technology into future aircraft. As part of the NASA High-Alpha Technology Program (HATP), advanced controls technology is being developed in ground-based research and demonstrated using the High-Alpha Research Vehicle (HARV) as a flying testbed. Efforts are in progress to develop flight validated control law design methodologies and design guidelines which could be used to effectively exploit the capabilities provided by advanced controls at high angles of attack. This paper outlines this research effort and summarizes the design process and preliminary methodologies and guidelines developed to date.

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° to 12°. Wear characteristics were defined by tire tread and cord wear over a yaw angle range of 0° to 4° 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.

Seventeen Environmental Control and Life Support System technology options to provide metabolic oxygen and water to sustain a multiperson crew on Space Station missions have been evaluated. The options included state-of-the-art technologies as well as advanced technologies that offer the potential for improvements in Environmental Control and Life Support Systems performance. The methodology for candidate technology recommendations was based upon specific assessment criteria as functions of prelaunch development activities and postlaunch operational considerations. The electrochemical depolarized cell option for carbon dioxide concentration, the sabatier option for carbon dioxide reduction, the static feed water electrolysis option for metabolic oxygen recovery, and vapor compression distillation and multifiltration options for waste water recovery were recommended.

Message exchange for air traffic control (ATC) purposes via data link offers the potential benefits of increasing the airspace system safety and efficiency. This is accomplished by reducing communication errors and relieving the overloaded ATC radio frequencies, which hamper efficient message exchanges during peak traffic periods in many busy terminal areas. However, the many uses and advantages of data link create additional questions concerning the interface among the human-users and the cockpit and ground systems. A flight test was conducted in the NASA Langley B-737 airplane to contrast flight operations using current voice communications with the use of data link for transmitting both strategic and tactical ATC clearances during a typical commercial airline flight from takeoff to landing. Commercial airplane pilots were used as test subjects.

An investigation was conducted to determine the fore and aft elastic response characteristics and footprint geometrical properties of 30 × 11.5 −14.5, Type VIII, bias-ply and radial-belted aircraft tires. Stiffness and damping characteristics of each tire were obtained from load-deflection curves generated from static tests. Tire footprints were obtained for various vertical loads, and geometrical measurements were obtained from the resulting silhouettes. Results of this investigation show considerable differences in stiffness and damping characteristics between the bias-ply and radial-belted tire designs. Footprint geometrical data indicate that footprint aspect ratio effects may interfere with improved hydroplaning potential associated with the radial-belted tire operating at higher inflation pressures. Tire-wheel slippage problems encountered when testing the radial-belted tire design required special attention.

The design and analysis of the National Aerospace Plane (NASP) depends heavily on developing critical technology areas through the Technology Maturation Program (TMP). The TMP is being completed almost entirely in government laboratories with technology dissemination to all prime NASP contractors immediately upon completion of any portion of the technology development. These critical technology areas span the entire engineering design of the vehicle; included are structures, materials, propulsion systems, propellants, propulsion/airframe integration, controls, subsystems, and aerodynamics areas. There is currently a heavy dependence on Computational Fluid Dynamics (CFD) for verification of many of the classical engineering tools. Quite often the design of an aircraft uses wind tunnel tests for much of this verification, but for NASP, this task is almost impossible from a practical standpoint.

A flight test investigation was conducted to evaluate an infrared (IR) imaging technique to visualize off-surface flow phenomena. A single-engine, general-aviation airplane was equipped with an IR imaging system that viewed the region around the left wingtip. Vortical flow at the wingtip was seeded with sulfur hexafluoride, a gas with strong infrared absorbing and emitting characteristics. Different terrain and sky backgrounds were evaluated for their effect on IR images of vortical flow. The best IR images were obtained with a clear sky background. The results of the investigation indicate that IR flow visualization compliments existing smoke generator methods for off-surface flow visualization.

Airplane flight tests have been conducted to determine the effects of wing leading-edge modifications and a ventral fin addition on the spin resistance of a typical high-wing, single-engine, general aviation airplane. Drooped wing leading-edge modifications which improve lateral stability at high angles of attack were tested in combination with a ventral fin that improves directional stability. Each modification was evaluated using spin resistance criteria which have been proposed for incorporation into the Federal Aviation Regulations for certification of light aircraft. The best configuration tested, a combination of outboard wing leading-edge droop and a ventral fin, provided a very significant increase in overall airplane spin resistance, but was not sufficient to satisfy all requirements of the spin resistance criteria.

Large space structures will be a key element of our future space activities. They will include spacecraft such as the planned Space Station and large antenna/reflector structures for communications and observations. These large structures will exceed 100 m in length or 30 m in diameter. Concepts for construction of these spacecraft on orbit and their materials of construction provide some unique research challenges. This paper will provide an overview of our research in space construction of large structures including erectable and deployable concepts. Also, an approach to automated, on-orbit construction will be presented. Materials research for space applications focuses on high stiffness, low expansion composite materials that provide adequate durability in the space environment. The status of these materials research activities will be discussed.

Discontinuous wing leading-edge droop designs have been evaluated as a means of modifying wing autorotative characteristics and thus improving airplane spin resistance. Addition of a discontinuous outboard wing leading-edge droop to three typical light airplanes having NACA 6-series wing sections produced significant improvements in stall characteristics and spin resistance. Wind tunnel tests of two wings having advanced natural laminar flow airfoil sections indicated that a discontinuous leading-edge droop can delay the onset of autorotation at high angles of attack without adversely affecting the development of laminar flow at cruise angles of attack.

A description is given of a computer program developed at the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) for the assessment of manned space station environmental control and life support systems (ECLSS) technology. The program methodology along with the data base and mission model variables are given for 17 candidate technologies that show potential for supplying metabolic oxygen and water on manned space missions. The data base includes metabolic design loads associated with crew activity, engineering design parameters for each technology option, and cost data required for candidate life cycle cost comparisons. The method for ranking the candidate options in order to provide recommendations for space station application or subsequent development is presented.

A future requirements and advanced market evaluation study indicates derivatives of current wide-body aircraft, using 1980 advanced technology, would be economically attractive through 2008, but new dedicated airfreighters incorporating 1990 technology, would offer little or no economic incentive. They would be economically attractive for all payload sizes, however, if RD and T costs could be shared in a joint civil/military arrangement. For the 1994-2008 cargo market, option studies indicate Mach 0.7 propfans would be economically attractive in trip cost, aircraft price and airline ROI. Spanloaders would have an even lower price and higher ROI but would have a relatively high trip cost because of aerodynamic inefficiencies. Dedicated airfreighters using propfans at Mach 0.8 cruise, laminar flow control, or cryofuels, would not provide any great economic benefits.

On December 1, 1984, the National Aeronautics and Space Administration (NASA) and the Federal Aviation Administration (FAA) conducted the first remotely-piloted air-to-ground crash test of a transport category aircraft. The Full-Scale Transport Controlled Impact Demonstration (CID) was the culmination of four years of effort by the two agencies. NASA and the FAA had many objectives during the joint planning and conduct of the Controlled Impact Demonstration. NASA's interest was primarily structural crashworthiness. The FAA's primary interest was the demonstration of an antimisting fuel additive's performance. Demonstration of improved crashworthy design features was a secondary objective for the FAA. This paper is a report on the NASA experiments conducted during the CID. A portion of the preliminary structural loads data was released to the public at a Government/Industry CID Workshop held April 10, 1985, at Langley Research Center, Hampton, Virginia.

This paper represents a first step in developing the criteria for pilot interaction with advanced controls and displays in a single pilot IFR (SPIFR) environment. The research program presented herein is comprised of an analytical phase and an experimental phase. The analytical phase consisted of a review of fundamental considerations for pilot workload taking into account existing data, and using that data to develop a SPIFR pilot workload model. The rationale behind developing such a model was based on the concept that it is necessary to identify and quantify the most important components of pilot workload to guide the experimental phase of the research which consisted of an abbreviated flight test program. The purpose of the flight tests was to evaluate the workload associated with certain combinations of controls and displays in a flight environment. This was accomplished as a first step in building a data base for single pilot IFR controls and displays.

The effectiveness of a proposed concept for shielding a manned Mars vehicle using a confined magnetic field configuration is evaluated by computing estimated crew radiation exposures resulting from galactic cosmic rays and a large solar flare event. In the study the incident radiation spectra are transported through the spacecraft structure/magnetic shield using the deterministic space radiation transport computer codes developed at Langley Research Center. The calculated exposures unequivocally demonstrate that magnetic shielding could provide an effective barrier against solar flare protons but is virtually transparent to the more energetic galactic cosmic rays. It is then demonstrated that through proper selection of materials and shield configuration, adequate and reliable bulk material shielding can be provided for the same total mass as needed to generate and support the more risky magnetic field configuration.