Aeronautics and Space Report of the President FY 1995 Activities

Aeronautical Activities

Technological Developments

NASA managers accelerated their work on the High-Speed Research (HSR) program after awarding Phase II industry contracts in the fall of 1994 for the development of airframe, propulsion, and flight deck technologies. The objective of the HSR Phase II program is to conduct research and develop the high-leverage, high-risk technologies essential for an environmentally compatible and economically viable supersonic airliner or High-Speed Civil Transport (HSCT).

NASA and its industry partners completed wind tunnel testing and computer analyses and simulations to verify the ability of an HSCT to satisfy the Federal Aviation Regulation 36 Stage 3 noise standards. To assess noise and thrust performance, as well as to validate computer models, NASA conducted high-lift engine aeroacoustics technology tests in the 40- by 80-foot wind tunnel of the Ames Research Center (ARC). The results confirmed the computer predictions and increased NASA's confidence in the ability of the nozzle and high-lift concepts to meet stringent noise rules. In another noise-reduction effort, NASA continued its research and testing of advanced lightweight composite materials that could be used as liners for exhaust nozzles. NASA scientists and engineers measured the acoustic performance of several candidate materials in acoustic cells. The results indicated that a 3- to 4-decibel (dB) reduction in total jet noise is possible if designers used those materials as acoustic liners. Future plans include long-term testing in a high-temperature environment to assess the durability of these materials.

On the Russian Tu-144 project, NASA and its partners made significant progress in modifying this supersonic flying testbed, which will be used to conduct flight research and to validate high-speed research computer models and simulations. Technicians installed upgraded digital flight recorders, instrumentation, and engines.

The goal of NASA's fly-by-light/power-by-wire (FBL/PBW) program is to provide technology for lightweight, highly reliable, electromagnetically immune control and power management systems for advanced subsonic civil transport aircraft. Optical technologies are immune to electromagnetic interference and eliminate the threat of electrical sparking. PBW eliminates the need for centralized hydraulic and pneumatic systems, variable-engine-bleed air systems, and variable-speed constant-frequency drive systems found in secondary power systems in today's aircraft. The use of FBL/PBW results in significant weight savings, reduced maintenance, more efficient engine operation, and reduced complexity. The Boeing Commercial Aircraft Group completed the FBL system design and began a detailed design at the end of FY 1995. Additionally, managers selected the PBW-controlled power management and distribution system architecture from 10 prospective concepts.

In the area of aircraft noise, NASA established an objective of achieving a 10-dB noise reduction compared to 1992 levels, and a team of noise technology specialists from industry, academia, and Government began work to achieve that objective. During FY 1995, NASA, Pratt & Whitney, and Allison Engine conducted jet engine noise tests at the NASA Lewis Research Center (LeRC) aeroacoustic propulsion laboratory to explore engine air mixer designs that reduce noise on low and moderate bypass ratio engines. NASA obtained acoustic, aerodynamic, and structural data in tests performed at the LeRC 9- by 15-foot low-speed wind tunnel, using a research model of Pratt & Whitney's advanced ducted propulsor. Boeing performed a diagnostic fan test under joint LeRC/Langley Research Center (LaRC) sponsorship to identify the dominant noise sources from engine fans. There has been strong coordination among Government, industry, and academic groups in planning and transferring technologies within the noise reduction program.

The FAA participated with NASA in a series of joint noise reduction and emissions reduction research initiatives. The two agencies continued implementation of the joint subsonic airplane noise reduction technology research program and reported progress to Congress. The two agencies also jointly assessed the state of quiet aircraft technology for propeller-driven airplanes and rotorcraft. In the area of engine emissions, the FAA continued its participation in NASA's Atmospheric Effects of Aviation project to develop a scientific basis for assessing the impact of aircraft emissions on the environment, particularly on the ozone layer and global climate change. The two agencies also began a cooperative program for the development of engine exhaust emissions certification standards and procedures for future subsonic turbojet engine technology. In the area of aviation environmental assessment, the FAA released a significantly improved new computer model.

NASA worked with its industry partners on developing active noise control in aircraft engines. General Electric completed a test in the LeRC aeroacoustic propulsion lab, where it demonstrated an active noise control concept using a large, low-speed fan. In addition to experimental work, NASA performed several analyses to predict jet and fan noise and applied them to test hardware to validate the software code. Pratt & Whitney, on a contract to NASA, developed a new fan tone prediction code, called the Theoretical Fan Noise Prediction System. General Electric developed a fan broad-band noise prediction code and an improved version of a software code to predict jet noise.

Engineers at NASA's LaRC developed improved prediction codes for engine fan noise, an interior noise control concept using an active trim panel, and two new ducted fans, which incorporate active noise control. LaRC engineers used the prediction codes, which included nacelle effects, to develop noise control concepts that they will validate in a series of wind tunnel tests. NASA engineers also conducted a laboratory experiment using active devices to control interior aircraft noise in a model airplane fuselage in which control devices were attached to the interior trim panels. The results were encouraging. One ducted-fan model in which error microphones were installed demonstrated global far-field fan noise reduction. Researchers used the second duct-fan model, a high-power, high-fidelity engine simulator, in an experiment in LaRC's 14- by 22-foot wind tunnel to investigate the symmetry of radiated noise in the wind tunnel environment. Scientific investigators also conducted a one-fourth-scale model of the ARC flap edge experiment to develop acoustic and flow measurement techniques to be used in a 1996 follow-on, one-half-scale test to investigate the scaling of airframe noise. NASA personnel, in cooperation with their industry colleagues, performed a benchmark airframe noise test in the ARC 7- by 10-foot wind tunnel. The team employed microphone array technology to make successful acoustic measurements of a model semispan flap in a wind tunnel environment. Results of the test indicated that the flap edge is an important source of airframe noise. Researchers also conducted an airframe noise test in the 40- by 80-foot wind tunnel on a DC-10 model.

NASA's Advanced Composite Materials Technology program made significant progress in FY 1995 toward scaling up existing technology by designing, fabricating, and testing a full-scale wing section and fuselage panels under simulated flight loads. Specific program objectives are to verify composite fuselage and wing structure designs that will have an acquisition cost of 20 to 25 percent less (instead of the current twice as much) and weigh 30 to 50 percent less than the current aluminum aircraft with the same payload and mission. NASA tests of composite aircraft elements and panels indicated outstanding damage tolerance, durability, and weight savings compared to aluminum structures.

Engineers working on NASA's Advanced Subsonic Technology program, in cooperation with U.S. industry, developed propulsion technology that will help increase the competitiveness and market share of the U.S. propulsion industry and reduce the environmental impact of future commercial engines by reducing exhaust emissions. This program has helped protect the current base of highly skilled U.S. jobs and will seek to recover some of the 50,000 jobs recently lost from industry downsizing. NASA researchers have been developing new propulsion systems technology to reduce overall direct operating costs of future commercial transports by 3 percent, which represents the profit-and-loss margin for a U.S. airline. NASA started building a new and unique high-pressure and high-temperature combustor facility at LeRC to provide U.S. engine manufacturers the ability to test their new low-emission combustors.

Researchers working on NASA's civil tiltrotor program have been building the technological foundation for a vertical takeoff and landing commuter airliner of the future. In 1995, they conducted the fifth civil tiltrotor simulation experiment on the ARC Vertical Motion Simulator. The experiment investigated power requirements for a tiltrotor transport with one engine inoperative during terminal area operations. The aircraft required only a 600-foot paved "rollway" for takeoffs and landings, using simulated engine power that is typical of current designs. Using performance parameters typical of a higher rated engine made vertical operations possible from a much shorter paved surface and allowed the minimum visibility requirements to be reduced to a 100-foot ceiling.

During FY 1995, a general aviation task force subcommittee of the NASA Aeronautics Advisory Committee reviewed the status of the industry. The subcommittee recommended that NASA revitalize its general aviation program and make available to the community its "world-class tools," such as wind tunnels, computer simulations, engine test cells, and material property labs. In addition, the subcommittee recommended that NASA's technology programs for general aviation be balanced with respect to industry needs in the following four areas: aerodynamics; aeronautical systems; structure and materials; and propulsion, noise, and emissions. To those ends, NASA took the lead in an effort to revitalize the U.S. general aviation industry. NASA entered into Joint Sponsored Research Agreements that are managed and implemented primarily through industry-led consortia. An Advanced General Aviation Transport Experiments consortium was initiated to revitalize market growth for intercity transportation in small aircraft.

FAA personnel also cooperated with their NASA colleagues on general aviation programs of mutual interest, including innovative aircraft design, new cockpit display and control technologies, enhanced ground/cockpit information systems, noise reduction, advanced general aviation transport experiments, the Atlanta short-haul transportation system, the short-haul civil tiltrotor, situational awareness for safety, and advanced aeronautical decision making. FAA scientists continued their research with NASA's ARC on steep-angle approach profiles to reduce rotorcraft noise.

NASA and its industry partners also completed Phase I of the Atmospheric Effects of Stratospheric Aircraft flight campaign. Flights of the NASA ER-2 high-altitude aircraft, carrying as many as 16 instruments to measure reactive and inert trace gases, aerosols, temperature, pressure, winds, ultraviolet light, and temperature profiles, provided new observations to diagnose the chemistry, physics, and fluid motion of air in the lower stratosphere. These observations assessed the environmental effects of a fleet of HSCTs and will be used to support the development of emissions standards for the HSCT.

Managers working on the environmental assessment element of NASA's advanced subsonic technology program began establishing a scientific basis to assess the atmospheric chemistry and climatic impact of subsonic aircraft. A NASA/industry/university team has established experimental techniques for characterizing the trace chemistry of engine exhaust emissions. In FY 1995, the team studied a military engine in an altitude simulation chamber at the Air Force's Arnold Engineering Development Center. A ground-based laser radar (lidar) instrument was used at LaRC to study the interaction of engine exhaust and wing vortices from the NASA Boeing 737 Transport Systems Research Vehicle (TSRV) aircraft. NASA's Wallops Flight Facility T-39 aircraft gathered flight measurements of related chemical effects resulting from those interactions.

The joint X-31 enhanced fighter maneuverability cooperative effort, involving the Navy, Air Force, NASA, Rockwell International, the German Defense Ministry, and Daimler Benz Aerospace, was completed in FY 1995. These partners initiated the program to assess the impact of thrust vectoring during slow-speed, poststall maneuvering and later was expanded to investigate other key issues. In FY 1995, this two-aircraft program set a new X-plane productivity record by accumulating 580 total research flights. The final activity for this flight research program was a flight demonstration at the Paris Airshow in June 1995. Earlier in the year, researchers investigated aircraft controllability issues in low-speed flights to simulate Navy carrier landing operations using a "quasi-tailless" configuration on the X-31. This activity supported the requirements of the Joint Advanced Strike Technology (JAST) program office in DoD. In July 1995, the Smithsonian Institution announced that the X-31 International Test Organization was the winner of its 1995 Air and Space Museum Trophy for Current Achievement.

Joint X-31 Enhanced Fighter Maneuverability Program

The joint X-31 enhanced fighter maneuverability program involved the Navy, Air Force, NASA, Rockwell International, the German Defense Ministry, and Daimler Benz Aerospace. This two-aircraft program set a new X-plane productivity record and assessed the impact of thrust vectoring during slow-speed, poststall maneuvering.

Scientists involved with NASA's SR-71 aircraft testbed program conducted several flights in FY 1995 for aeronautical research to assist industry in developing an HSCT aircraft. NASA personnel successfully completed a research project to study the propagation of shock waves caused by the SR-71 sonic boom. Project personnel also investigated the effects of Mach number, altitude, and aircraft gross weight to validate analytic models and to investigate methods of softening sonic booms. The congressionally mandated Air Force SR-71 reconnaissance reactivation program began during FY 1995 and received extensive support from NASA's Dryden Flight Research Center (DFRC). The reactivation program included the training of Air Force pilots by NASA instructors.

Aircraft designers structured the F-18 high-alpha technology program to achieve an understanding of airplane aerodynamics at high angles of attack. The DoD/NASA program investigated the effects of thrust-vectoring and mechanical strakes on the air flowing around the aircraft. An inlet distortion data base was developed to validate inlet computational fluid dynamics codes and to develop design methods for engine inlets that are tolerant of high-alpha maneuvers. The researchers used flight research, wind tunnel research, and computational fluid dynamics modeling. The program used a highly instrumented F-18 aircraft specially outfitted with two new flight control concepts.

Designers created the F-18 systems research aircraft to help identify and flight-test advanced technological concepts. In FY 1995, technicians continued to flight-test and successfully operate a "smart actuator," installed as a replacement for a conventional aileron actuator. A second element of the program involved the installation of a self-contained electro-hydrostatic aileron actuator. Researchers continued to conduct flight tests in FY 1995 on the fiberoptic "fly-by-light" control systems programs. NASA personnel also flight-tested a structural integrity monitoring system and a flush-mounted air data system.

During FY 1995, NASA's flight research instrumentation and test techniques program acquired pressure data associated with the interaction of shock waves on the boundary layer. Researchers gathered the data using 12 special "kulite" pressure sensors capable of measuring 100,000 samples each per second. Scientists who performed other related experiments investigated special tape that is residue-free and resistant to high temperatures and technologies to attach heat gauges and thermocouples to the Russian Tu-144 supersonic transport aircraft.

The Environmental Research Aircraft and Sensor Technology alliance, established in September 1994, formed a new partnership among six companies in the remotely piloted aircraft industry and Government. The alliance identified two key missions as being critical to the collection, identification, and monitoring of environmental data. The first critical mission was to achieve 80,000 to 100,000 feet carrying an instrument payload of 500 pounds for a minimum of 2 hours. The second was to achieve 50,000 to 75,000 feet carrying a payload of 1,000 pounds for a minimum of 96 hours. Scientists in cooperation with ARC have proposed 10 environmental science sensor designs for future development. Scientists flew two remotely piloted aircraft this year at DFRC. One was the "Perseus A," which used an internal combustion engine and carried liquid oxygen to achieve an altitude of 50,000 feet. The second, known as "Pathfinder," was powered by electrically driven propellers and sported solar cells mounted atop its 100-foot-long wing to power the propellers. The "Pathfinder" began flight operations in the fourth quarter of FY 1995 and achieved a solar-powered world altitude record of 50,500 feet.

In a cooperative effort with the Orbital Sciences Corporation, researchers equipped an L-1011 transport aircraft with 1,000 "tufts" resembling small pieces of string or thread on top of the right wing. The aircraft will be used for research to optimize the deflection of wing flaps during cruise flight. In a separate flight research activity, investigators demonstrated Propulsion Controlled Aircraft (PCA) technology in-flight on an MD-11 airliner. The PCA system was developed to provide the pilot with a way to fly an aircraft if its normal flight controls were disabled by modulating engine thrust to control the flight path of an aircraft. Researchers continued to develop the PCA concept as a result of several airplane crashes in which the hydraulic systems, used to power the flight controls, became disabled.

The NASA Short Takeoff and Vertical Landing (STOVL) technology program was conducted in support of the DoD JAST program. The first element of the NASA program involved the Vertical/Short Takeoff and Landing (V/STOL) Systems Research Aircraft (VSRA) Harrier aircraft, equipped with an integrated flight propulsion control system, cockpit controls, and display systems. During FY 1995, investigators completed most of their research tests. NASA personnel enhanced technology transfer by inviting industry engineers and pilots to participate in the flight experiments and the ground-based simulations. A second major element of the STOVL program consisted of aerodynamic testing at NASA research facilities of the STOVL configurations and components. Researchers designed these tests to help the JAST program select two contractor teams for the next phase of the program.

The NASA High Performance Computing and Communications (HPCC) office's primary role in the Federal HPCC program includes leading the development of applications software and algorithms for scalable parallel computing systems, which will increase system performance to the sustained teraFLOPS (1012 floating point operations per second) level for NASA applications. NASA continued to develop and evaluate high-performance computing, communications, and information technologies and to effect the transfer of these technologies into use for national needs. NASA made progress toward solving its "grand challenge" research problems in areas such as aerospace vehicle design, remote communications, and Earth science. NASA HPCC personnel also continued their research in distributed high-performance computing using high-performance workstations. The objective of this research is to dramatically decrease the costs of many high-performance computing requirements while ensuring reliable performance on workstations in diverse geographic locations.

The Information Infrastructure Technology and Applications (IITA) component of the HPCC program continued to broaden the program's public outreach and furthered the development of a Global Information Infrastructure (GII) by supporting research and development in education, digital library technology, and access to Earth and space science data. The IITA efforts comprise the development of critical information technologies and the application of these technologies to the "national challenge" problems to which the application of HPCC technology can provide large benefits to all Americans. Accomplishments in IITA during FY 1995 include the opening of a new Internet World Wide Web site called "The Observatorium" to assist students, teachers, and researchers in accessing many of the applications, technologies, and data bases developed by NASA for use on the Internet in new and stimulating ways. Many of the new digital library technologies developed in the IITA efforts have begun to be demonstrated in new remote-sensing data base applications and have proven to be valuable to furthering GII development, especially for kindergarten through grade 12 education.

The Computational AeroSciences (CAS) component of the HPCC program supported the installation of sophisticated new computers at ARC. These new systems have augmented other scalable parallel computers to provide research platforms for systems software, virtual wind tunnels, and other aerospace and manufacturing projects. The success of these CAS projects has led to significant enhancements in design support and computer simulation of aerodynamic performance and, therefore, should lead to more efficient and cost-effective aircraft and spacecraft design.

The numerical aeronautics simulation facility at ARC continued its improvements during FY 1995 in support of advanced research requirements in the aeronautics community. Many aerospace industry leaders already have attributed major cost savings to breakthroughs in this facility, which is considered to be the Nation's model for future high-performance computer centers.

The Navy and the Marine Corps continued to develop the V-22 Osprey tiltrotor aircraft in FY 1995. Technicians successfully joined the first production-representative V-22 Osprey fuselage in August 1995, marking the validation of the Osprey's design and manufacturing techniques. By incorporating lessons learned in the V-22's full-scale development phase as well as new breakthroughs in manufacturing technology, this aircraft is more than 1,500 pounds lighter and almost 30 percent less costly than an earlier design.

During FY 1995, DoD continued to support the joint NASA/DoD/industry National Wind Tunnel Complex (NWTC) activity at NASA's LeRC. If pursued, the NWTC should provide the United States with high-productivity, high Reynolds number test facilities that will be the world's best in testing aeronautical systems.

The Darkstar unmanned aerial vehicle was unveiled at the contractor facility in Palmdale, California, in June 1995. The first project to be executed under new authority granted to the Advanced Research Projects Agency (ARPA) for unprecedented Government-industry collaboration, this vehicle is designed to be an affordable, low-observable tactical reconnaissance vehicle that can operate in the current military force structure. NASA's DFRC continued to provide flight evaluation support on the Darkstar program.

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Curator: Lillian Gipson
Last Updated: September 5, 1996
For more information contact Steve Garber, NASA History Office,