The Adaptive Performance Optimization project was designed to reduce the aerodynamic drag of large subsonic transport aircraft by varying the camber of the wing through real-time adjustment of flaps or ailerons in response to changing flight conditions. Reducing the drag will improve aircraft efficiency and performance, resulting in signifigant fuel savings for the nation's airlines worth hundreds of millions of dollars annually.
Flights for the NASA experiment were made over several years on the modified wide-bodied jetliner, with all flights flown out of Bakersfield's Meadows Field. The experiment is part of Dryden's Advanced Subsonic Transport Aircraft Research program.
Dryden conducted extensive wake vortice tests beginning in the 1970's. These wake vortices first became a serious concern when large jetliners were first introduced. The aircraft trailed vortices, created by any large-bodied aircraft, were powerful enough to cause problems for business jets and even other airliners.
Dryden became interested in vortex research both for safety and as a matter of aerodynamics. A wingtip vortex seriously reduces effiecency, causing drag, and therefore a consequent penalty in fuel consumption and performance.
The majority of the tests were conducted using spoilers on a Boeing 747-100, which NASA had just acquired for the Space Shuttle Approach and Landing (ALT) tests. With the two spoilers on the outer panels of each wing extended, the vortices were greatly reduced and the chase aircraft could safely fly five kilometers behind the large aircraft, compared to 15 kilometers with no spoilers.
Dryden's 747 wake vortex studies clearly indicated that the use of spoilers could reduce the severity of wake vortices. In July, 1977, the center began a brief series of tests on a Lockheed L-1011 Tristar to determine if the spoiler that worked so well on the 747 could be applied to other wide-body aircraft as well.
The test showed that while spoilers on the Tristar could reduce wake vortices, they were not as effective in doing so as the spoilers on the 747. NASA is continuing wake vortex studies to this day. These projects can be expected to improve the operational safety of many future aircraft.