 By the year 2000, the FAA will likely require further reductions in aircraft noise. More than a decade of research in development by the aeronautics industry has focused on compliance. After two years of wind tunnel tests, a model designed to meet that proposed FAA standard is crated and shipped for further testing. Designed by Pratt & Whitney, a division of United Technologies, the model was tested in two of the six wind tunnels at NASA Lewis Research Center in Cleveland, Ohio. The joint effort between NASA and this leading manufacturer of aircraft engines explored the acoustics, aerodynamic performance and the operability of the advanced ducted propeller known as the ADP. Initial indications are that from this new design, a quieter, better performing engine will emerge. The model scaled to one-sixth of the actual design was tested here in this tunnel, commonly called the 9x15, which are the dimensions of the wind chamber itself. This tunnel is nested in the return leg of the 8x6 tunnel. While the 8x6 has supersonic capabilities, only the subsonic speeds were used to test the ADP. For the Aeropropulsion Facilities and Experiments Division, this project began over three years ago. At that time, Lewis engineers started working closely with Pratt & Whitney to define the test parameters for the model. This preparation ensured that the wind tunnels and the model were ready for each other. The tunnel control room is the hub of ADP research. State-of-the-art equipment allows researchers to collect valuable data and monitor testing. At the close of this last day, an engineer reviews one of the nine test phases. Successful testing of any model requires the skills and talents of a number of people. Test day brings together those abilities in preparation for each experiment. And so begins the test. The tunnel operators control tunnel systems to obtain desired air speeds. The ADP was tested over a Mach number range from 0 to 0.85. The model operator controls RPMs by regulating the compressed air to the model's drive turbine. RPMs for the ADP ranged from windmill to 12,300. During testing, the model's safety is ensured by continuous monitoring of vibration and temperatures. The engineer who monitors stress ensures that the predetermined stress limits on blades, stator veins, and instrumentation are not exceeded. The primary researcher has lead responsibility for all aspects of ADP testing. Ongoing communications about the tunnel and model aid the Lewis researcher in making decisions about each test condition. The primary researcher is supported by a counterpart who helps monitor online test data. All these people depend on the electronics engineer who has complete responsibility for the electronics in the model, the hardware, the instrumentation, and the computer system. The ADP is a gear-driven fan with variable pitch, much like a turbo prop. However, a duct encircles the fan to suppress noise generated by the airfoil. Researchers discuss a primary focus of this ADP testing. Acoustics. Various inlet and spinner configurations were tested in the 8x6 to help determine aircraft noise affecting communities. Cabin noise affecting passengers is also a consideration. 12 microphones for these tests were mounted on a 1-inch thick aluminum plate and suspended above the model. They are calibrated daily to ensure accuracy. Pratt & Whitney is kept informed during each phase of testing. Pratt & Whitney's interest is supervised by Company Vice President William Webb. The testing here at Lewis is possible because of the wind tunnel facilities here at Lewis are capable of doing both performance testing and noise testing with one setup. Not many tunnels in the United States are capable of doing that. Lewis has developed what we call a rotating microphone that lets us measure noise and separate the things within the engine that create those noise. Such that if we have one component that's creating an offensive signal, we can then work on that one component and not have to waste our time struggling through all of the engine. That same focused approach characterized all of the acoustic testing, which included blade angles, inlets and spinners, stator vanes, and angles of attack. The other primary focus of ADP testing was aerodynamic performance. During the past two years, testing focused on four inlet spinner configurations and numerous blade angle settings. Mechanics were called on to make changes for each configuration. Hundreds of performance tests, including investigation of thrust and drag, resulted in thousands of test points. A sheet laser flow test provides an image of reverse thrust necessary during landing. The Laser Doppler Velocimeter, or LDV, is a non-intrusive measurement of velocity with light beams. It was used to map the reverse thrust velocity profile. To determine the operability of the ADP, the model was tested at various angles of attack, simulating takeoff and landing configurations. When modifications were necessary for a specific investigation, model changes, instrumentation and repairs were performed on-site by Lewis experts, minimizing any delays in the test program. NASA researchers are responsible for accurate gathering of the real-time data on the Escort D-plus computer system. The laborious process of analyzing and interpreting the information will continue for several months. Researchers map a trend within the test data and determine engine noise and performance. This helps to validate analytical codes, ultimately leading to improved technology and design codes for future industry use. Our technology readiness development program is scheduled to run through 1995. We anticipate that we could be ready to start the development of a commercial product in the 1994 to 1995 time period if the market is there that would support the cost of developing a new product. That would let us put an engine in service, that is, carrying revenue-generating passengers around the year 2000. NASA Lewis' leading role in long-range aeronautics research consistently places the center at the forefront of technology development. As flying on the ground for the model ends, the future for advanced ducted propulsion begins.