Imagine a desert environment that is just right for good flying weather, on the average of 345 days a year. That ideal situation, and the absence of large population centers, makes the high desert locale of the Dryden Flight Research Center a premier installation for aeronautical flight research. Dryden is NASA's center of excellence for atmospheric flight operations. The center's charter is to develop, verify, and transfer advanced aeronautics, space and related technologies.

Located at Edwards, California, on the western edge of the Mojave Desert, Dryden's history dates back to September 1946. Preparations were then underway to fly the X-1, the first aircraft to fly faster than the speed of sound. That work was partly sponsored by the National Advisory Committee for Aeronautics (NACA), the predecessor organization to NASA.

Since those early days, many milestones in aviation have taken place at Dryden--from supersonic and hypersonic flight, and wingless lifting bodies, to forward- swept wing testing and space shuttle air drops.

Dryden continues to pioneer programs for new aircraft and spacecraft. The center is also aiding the U.S. general aviation community in global economic competition, increasing safety for the flying public.

Just like its past, Dryden remains at the forefront of flight research. One such indicator is Dryden's use of a highly modified F-15 research aircraft. The F-15 is tasked to the Advanced Control Technology for Integrated

Vehicles--or ACTIVE--program. This multi-year flight research effort is improving the performance and maneuverability of future civil and military aircraft flying at subsonic and supersonic speeds. For this program, advanced flight control systems and the ability to thrust vector engine exhaust were integrated into the aircraft.

Other NASA centers have also made use of the ACTIVE F-15 as a flying test bed for experiments. NASA's Lewis Research Center, for instance, is evaluating a computerized system that can sense and respond to high levels of engine inlet airflow distortion or turbulence. This computer system can prevent sudden in-flight engine compressor stalls, potential engine failures, and will also lead to reduced fuel consumption.

High-speed research acoustics is another use of the ACTIVE aircraft. NASA's Langley Research Center used the advanced engine control systems to calibrate engine noise predictions. Such experiments are critical for minimizing noise impact during takeoffs and landings of 21st century High Speed Civil Transport, a second-generation American supersonic jetliner.

The ACTIVE F-15 program is being equipped to assist in the development of advanced "neural network" flight control computer technology. Sponsored by the NASA Ames Research Center, this experiment would allow aircraft control systems to adapt to unforeseen changes in aircraft operating conditions, such as sudden equipment failure.

In 1997, the first flight tests of a "Smart Skin" antenna system took place aboard Dryden's F/A-18 Systems Research Aircraft (SRA). This antenna system may well revolutionize airborne communications. The idea was jointly developed by Northrop-Grumman Corporation and TRW's Avionics Systems Division using internally-generated company funds. The Smart Skin antenna was embedded in a specially-built tip, mounted on the SRA's right vertical stabilizer. Flights of Dryden's F/A-18 substantiated a five-fold increase in voice communication range and a major improvement in the quality of radio transmissions from the aircraft when compared with transmissions from the F/A-18's standard blade antenna.

A Smart Skin antenna has the potential to greatly improve the range and quality of air-to-air and air-to-ground communications. It could also result in improved maintainability and reduced aerodynamic drag. Smart Skin antenna systems could also lead to a 65 percent reduction in airframe structural cutouts for external antennas and a weight savings of 250 to 1,000 pounds per aircraft. Potential application to military needs looks promising, as does use in commercial aircraft. Furthermore, the antenna could be applied to "smart" automobiles and other forms of transportation requiring high-efficiency communications capabilities.

Dryden's F/A-18 SRA was also tasked in 1997 to carry the Advanced L-probe Air Data Integration (ALADIN) experiment. The revolutionary air data probe, designed by Rosemount Aerospace, could result in some informational "magic" for pilots of high-performance aircraft. The new L-probe gives two parameters that standard air data probes do not provide: angle-of-attack (vertical angle of an aircraft's wings and fuselage relative to its actual flight path) and sideslip information (the lateral angle between the aircraft and its actual flight path). The L-probe offers the prospect that the number of probes or vanes needed on a plane can be reduced.

In another milestone, engineers at Dryden completed tests on a device that paves the way for developing future all-electric airplanes that could be safer and more fuel efficient than today's aircraft. Called the Electro-Hydrostatic Actuator, the device eliminates or minimizes airborne dependence on pneumatic, hydraulic, and mechanical systems. Flawless performance of the actuator on the left aileron of the F/A-18 SRA was achieved, without using the aircraft's central hydraulics. The actuator and related electrical systems could lead to a five to nine percent fuel savings on an all-electric passenger plane, a thirty to fifty percent reduction in ground equipment, and a reduction in the vulnerability of military aircraft in combat situations.

Other major projects being pioneered at Dryden include the Environmental Research Aircraft and Sensor Technology (ERAST) program. This NASA/industry alliance is expected to lead to a family of unpiloted aircraft that would carry out scientific and environmental missions at heights of up to 100,000 feet. Moreover, such flights can last up to several days or more. ERAST involves a seven-year evaluation program at Dryden that concludes in 2000, designed to rate propulsion, aerodynamics, structures, materials, avionics, and sensor technology used in the remotely controlled aircraft.

A propulsion push into the future is being provided by a Dryden SR-71 aircraft. This high-speed, high-altitude plane has been outfitted with a test model of the Linear Aerospike Rocket Engine. Aerospike engine technology is being refined and developed for space propulsion, and is part of the Lockheed Martin X-33 advanced technology demonstrator for a next generation reusable launch vehicle.

A multi-year hypersonic flight-test program is also underway at the center called Hyper-X. This joint project between Dryden and NASA Langley Research Center is to make use of four unpiloted research aircraft that can fly up to ten times the speed of sound.

Dryden research aircraft are pushing the envelope and providing critical data for NASA's Aeronautics and Space Transportation Enterprise. This work is a commitment to expand human activity and space-based commerce in the frontiers of air and space.