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Pressure Sensitive Paint (PSP) has been used for several years by the aircraft industry in transonic wind tunnel testing where the oxygen concentrations are low and the luminescence of the paint is easily recorded. Extending PSP to slower speeds where the oxygen concentrations are closer to atmospheric conditions is much more challenging. For the past few years, work has been underway at both Wright Patterson Air Force Base and Ford Motor Company to advance PSP techniques for testing at slower speeds. The CRADA (Cooperative Research and Development Agreement) provided a way for comparisons to be made of the different PSP systems that were being investigated. This paper will report on PSP tests conducted as part of the CRADA.

A discussion is given of the ongoing research related to laminar flow airfoils, nacelles, and wings where the laminar flow is maintained by a favorable pressure gradient, surface suction or a combination of the two. Design methologies for natural laminar flow airfoil sections and wings for both low and high speed applications are outlined. Tests of a 7-foot chord, 23° sweep laminar-flow-control-airfoil at high subsonic Mach numbers are described along with the associated stability theory used to design the suction system. The state-of-the-art of stability theory is simply stated and a typical calculation illustrated. In addition recent computer simulations of transition using the time dependent Navier-Stokes (N-S) equations are briefly described. Advances in wind tunnel capabilities and instrumentation will be reviewed followed by the presentation of a few results from both wind tunnels and flight. Finally, some suggestions for future work will complete the paper.

This paper discusses a project for adapting advanced technology, much of it borrowed from the jet transport, to general aviation design practice. The NASA funded portion of the work began in 1969 at the University of Kansas and resulted in a smaller, experimental wing with spoilers and powerful flap systems for a Cessna Cardinal airplane. The objective was to obtain increased cruise performance and improved ride quality while maintaining the take-off and landing speeds of the unmodified airplane. Some flight data and research pilot comments are presented. The project was expanded in 1972 to include a light twin-engine airplane. For the twin there was the added incentive of a potential increase in single-engine climb performance. The expanded project is a joint effort involving the University of Kansas, Piper Aircraft Company, Robertson Aircraft Company, and Wichita State University. The use of a new high-lift Whitcomb airfoil is planned for both the wing and the propellers.

An advanced analytical methodology has been developed for predicting the residual strength of stiffened thin-sheet riveted shell structures such as those used for the fuselage of a commercial transport aircraft. The crack-tip opening angle elastic-plastic fracture criterion has been coupled to a geometric and material nonlinear finite element shell code for analyzing complex structural behavior. An automated adaptive mesh refinement capability together with global-local analysis methods have been developed to predict the behavior of fuselage structure with long cracks. This methodology is currently being experimentally verified. Advanced nondestructive inspection technology has been developed that will provide airline operators with the capability to conduct reliable and economical broad-area inspections of aircraft structures.

This paper describes recent research in integrated aerodynamic-performance design optimization applied to a supersonic transport wing. The subsonic and supersonic aerodynamics are modeled with linear theory and the aircraft performance is evaluated by using a complete mission analysis. The goal of the optimization problem is to either maximize the aircraft range or minimize the take-off gross weight while constraining the total fuel load and approach speed. A major difficulty encountered during this study was the inability to obtain accurate derivatives of the aerodynamic models with respect to the planform shape. This work addresses this problem and provides one solution for the derivative difficulties. Additional optimization studies reveal the impact of camber design on the global optimization problem. In these studies, the plan-form optimization is first conducted on a flat plate wing and camber optimization is performed on the resulting planform.

The Aircraft Landing Dynamics Facility (ALDF), formerly called the Landing Loads Track, is described. The paper gives a historical overview of the original NASA Langley Research Center Landing Loads Track and discusses the unique features of this national test facility. Comparisions are made between the original track characteristics and the new capabilities of the Aircraft Landing Dynamics Facility following the recently completed facility update. Details of the new propulsion and arresting gear systems are presented along with the novel features of the new high-speed carriage. The data acquisition system is described and the paper concludes with a review of future test programs.

An experimental investigation of the flow over the rear end of a 0.16 scale notchback automobile configuration has been conducted in the NASA Langley Basic Aerodynamics Research Tunnel (BART). The objective of this work was to investigate the flow separation that occurs behind the backlight and obtain experimental data that can be used to understand the physics and time-averaged structure of the flow field. A three-component laser velocimeter was used to make non-intrusive, velocity measurements in the center plane and in a single cross-flow plane over the decklid. In addition to off-body measurements, flow conditions on the car surface were documented via surface flow visualization, boundary layer measurements, and surface pressures.

A research program is in progress to study the effects of the propeller slipstream on natural laminar flow. Flight and wind tunnel measurements of the wing boundary layer have been made using hot-film velocity sensor probes. The results show the boundary layer, at any given point, to alternate between laminar and turbulent states. This cyclic behavior is due to periodic external flow turbulence originating from the viscous wake of the propeller blades. Analytic studies show the cyclic laminar/turbulent boundary layer layer to result in a significantly lower wing section drag than a fully turbulent boundary layer. The application of natural laminar flow design philosophy yields drag reduction benefits in the slipstream affected regions of the airframe, as well as the unaffected regions.

Natural fliers demonstrate a diverse array of flight capabilities, many of which are poorly understood. NASA has established a research project to explore and exploit flight technologies inspired by biological systems. One part of this project focuses on dynamic modeling and control of micro aerial vehicles that incorporate flexible wing structures inspired by natural fliers such as insects, hummingbirds and bats. With a vast number of potential civil and military applications, micro aerial vehicles represent an emerging sector of the aerospace market. This paper describes an ongoing research activity in which mechanization and control concepts for biologically inspired micro aerial vehicles are being explored. Research activities focusing on a flexible fixed-wing micro aerial vehicle design and a flapping-based micro aerial vehicle concept are presented.

Preliminary braking, steering, and tread wear performance results from testing of 26 x 6.6 and 40 x 14 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, ongoing joint NASA/FAA/Industry Surface Traction And Radial Tire (START) Program involving these two different tire sizes as well as an H46 x 18-20 tire size which has not yet been evaluated. Both dry and wet surface conditions were evaluated on two different test surfaces - nongrooved Portland cement concrete and specially constructed, hexagonal-shaped concrete paver blocks. Use of paver blocks at airport facilities has been limited to ramp and taxiway areas and the industry needs a tire friction evaluation of this paving material prior to additional airport pavement installations.

Two major concerns have inhibited the use of natural laminar flow (NLF) for viscous drag reduction on production aircraft. These are the concerns of achieveability of NLF on practical airframe surfaces, and maintainability in operating environments. Previous research in this area left a mixture of positive and negative conclusions regarding these concerns. While early (pre-1950) airframe construction methods could not achieve NLF criteria for waviness, several modern construction methods (composites for example) can achieve the required smoothness. This paper presents flight experiment data on the achieveability and maintainability of NLF on a high-performance, single-propeller, composite airplane, the Bellanca Skyrocket II. The significant contribution of laminar flow to the performance of this airplane was measured. Observations of laminar flow in the propeller slipstream are discussed, as are the effects of insect contamination on the wing.

Brief flight evaluations of two different, light, composite constructed, canard and winglet configured airplanes were performed to assess their handling qualities; one airplane was a single engine, pusher design and the other a twin engine, push-pull configuration. An emphasis was placed on the slow speed/high angle of attack region for both airplanes and on the engine-out regime for the twin. Mission suitability assessment included cockpit and control layout, ground and airborne handling qualities, and turbulence response. Very limited performance data was taken. Stall/spin tests and the effects of laminar flow loss on performance and handling qualities were assessed on an extended range, single engine pusher design.

Over the past three decades, the application of simulation facilities to manned space flight projects has increased chances of successful mission completion by revealing the capabilities and limitations of both man and machine. The Space Station era, which implies on-orbit assembly, heightened system complexity, and great diversity of operations and equipment, will require increased dependence on simulation studies to validate the tools and techniques being proposed. For this reason the Society of Automotive Engineers (SAE) undertook a survey of both the facilities available for and the research requiring such simulations. This paper was written to provide LaRC input to the SAE survey of simulation needs and resources. The paper provides a brief historial sketch of early Langley Research Center simulators, and the circumstances are described which resulted in a de-emphasis of manned simulation in 1971.

The Federal Aviation Administration (FAA) and the National Aeronautics and Space Administration (NASA) have joined forces in a General Aviation Crashworthiness Program. This paper describes the research and development tasks of the program which are the responsibility of NASA. NASA is embarked upon research and development tasks aimed at providing the general aviation industry with a reliable crashworthy airframe design technology. The goals of the NASA program are: reliable analytical techniques for predicting the nonlinear behavior of structures; significant design improvements of airframes; and simulated full-scale crash test data. The analytical tools will include both simplified procedures for estimating energy absorption characteristics and more complex computer programs for analysis of general airframe structures under crash loading conditions.

A review is made of NASA aerodynamic research of interest to the designer of business aircraft. The results of wind-tunnel and flight studies of several current aircraft are summarized. The attainment of STOL performance is discussed and the effectiveness of several lift augmentation concepts is examined. Finally, the potentialities and problems of flight at and beyond the speed of sound are discussed.

Recent findings from NASA Langley tests to define effects of aircraft Type II chemical deicer depositions on aircraft tire friction performance are summarized. The Aircraft Landing Dynamics Facility (ALDF) is described together with the scope of the tire cornering and braking friction tests conducted up to 160 knots ground speed. Some lower speed 32-96 km/hr (20-60 mph) test run data obtained using an Instrumented Tire Test Vehicle (ITTV) to determine effects of tire bearing pressure and transverse grooving on cornering friction performance are also discussed. Recommendations are made concerning which parameters should be evaluated in future testing.

The ability to personalize air travel through the use of an on-demand, highly distributed air transportation system will provide the degree of freedom and control that Americans enjoy in other aspects of their life. This new capability, of traveling when, where, and how we want with greatly enhanced mobility, accessibility, and speed requires vehicle and airspace technologies to provide the equivalent of an internet PC ubiquity, to an air transportation system that now exists as a centralized hub and spoke mainframe NASA airspace related research in this new category of aviation has been conducted through the Small Aircraft Transportation (SATS) project, while the vehicle technology efforts have been conducted in the Personal Air Vehicle sector of the Vehicle Systems Program.

A two-dimensional, Navier-Stokes code developed by Imlay based on the implicit, finite-volume method of MacCormack has been applied to the prediction of the flow fields and performance of several nonaxisymmetric, convergent-divergent nozzles with and without thrust vectoring. Comparisons of predictions with experiment show that the Navier-Stokes code can accurately predict both the flow fields and performance for nonaxisymmetric nozzles where the flow is predominantly two-dimensional and at nozzle pressure ratios at or above the design values. Discrepancies between predictions and experiment are noted at lower nozzle pressure ratios where separation typically occurs in portions of the nozzle. The overall trends versus parameters such as nozzle pressure ratio, flap angle, and vector angle were generally predicted correctly.

The normal working and living areas of the astronaut are designed to provide an acceptable level of protection against the hazards of ionizing space radiation. Attempts to reduce the exposures require intervening shield materials to reduce the transmitted radiation. An unwelcome side effect of the shielding is the production of neutrons, which are themselves dangerous particles that can be (but are not always) more hazardous than the particles that produced them. This is especially true depending on the choice of shield materials. Although neutrons are not a normal part of the space environment, they can be a principle component of astronaut exposure in the massive spacecraft's required for human space travel and habitation near planetary surfaces or other large bodies of material in space.

Aerodynamic effects induced from vectoring an exhaust jet are investigated using a well established thin-layer Reynolds averaged Navier-Stokes code. This multiple block code has been modified to allow for the specification of jet properties at a block face. The applicability of the resulting code for thrust vectoring applications is verified by comparing numerically and experimentally determined pressure coefficient distributions for a jet-wing afterbody configuration with a thrust-vectoring 2-D nozzle. Induced effects on the body and nearby wing from thrust vectoring are graphically illustrated.