Aircraft manufacturers of several nations are developing technology to position themselves for the next plateau of international aviation competition: the long range, economical, environmentally acceptable second generation supersonic passenger transport, which could be flying before 2010.
Market experts predict that a projected quadrupling of traffic to and from the nations of the Pacific Rim, together with more moderate increases in demand for long range passenger transporta- tion in other areas of the world, will create a need for some 500 next generation supersonic transports worth an estimated $200 billion and 140,000 jobs.
Capturing a major share of that market is vitally important to a U.S. aerospace industry that is transitioning from a traditionally defense- oriented product line to a commercially-driven manufacturing activity. To help boost the industry's competitiveness, NASA is conducting a High Speed Research (HSR) program that addresses the highest priority, highest risk technologies needed for a High Speed Civil Transport (HSCT). The HSR program is intended to demonstrate the technical feasibility of the vehicle; the decision to proceed with full scale development will be up to industry and will hinge primarily on market, financial and other business considerations.
The 21st century HSCT will probably be only moderately faster than the Anglo - French Concorde now in airline service, because studies indicate that the most promising speed-considering propulsion, structural and aerodynamic requirements - is Mach 2.4, or about 1600 miles per hour. However, it will most likely have almost double the Concorde's range and will carry three times as many passengers. Like the Concorde, the HSCT will fly supersonically only over water, but research suggests that it can be economically viable in subsonic flight over land.
The HSR program is being conducted as a national team effort with shared government/industry funding and responsibilities. The team includes NASA's Langley, Lewis and Ames Research Centers and Dryden Flight Research Center; engine manufacturers GE Aircraft Engines and Pratt & Whitney division of United Technologies; airframe manufacturers The Boeing Company and McDonnell Douglas Corporation; other manufacturers, materials suppliers and academic institutions.
The team has established a baseline design concept, known as Reference H, which serves as a common configuration for HSR investigations. Shown being readied for a wind tunnel run at left is a 19-foot model of the Reference H design; at right, a smaller model is being flown in Langley Research Center's National Transonic Facility. A full-size airplane of this type would be capable of accommodating 300 passengers and flying route segments as long as 5,000 nautical miles.
Phase I of the HSR program, which focuses on environmental challenges - engine emission effects on the atmosphere, airport noise and sonic boom - got under way in 1990 and will continue through 1995. A most critical technology need is an advanced combustion concept to reduce the nitrogen oxide (NOx) emissions expelled in jetliner exhaust, because NOx can cause an ozone - depleting chemical reaction in the atmosphere. The HSR team has established a NOx index goal that is some 90 percent below current emission levels; if that goal can be attained, the stratospheric effect of emissions by a whole fleet of HSCTs would be almost negligible.
The goal for aircraft noise levels is to make the HSCT as quiet as the newest subsonic transports; that goal, though demanding, appears achievable. Similarly, the team has identified promising approaches toward alleviating the sonic boom; current research seeks to determine how much the boom can be softened without significantly compromising aircraft performance. Generally speaking, although Phase I is still ongoing, NASA officials say there is "growing confidence" that environmental concerns can be satisfied.
Phase II of the HSR program, initiated in 1994, is running concurrently with Phase I; it focuses on the technology advances needed for economic viability, principally weight reductions in every aspect of the baseline configuration because weight affects not only the aircraft's performance but its acquisition cost, operating costs, and environmental compatibility.
One target area is airframe materials and structures; the HSR team is developing, analyzing and verifying the technology for trimming the baseline airframe by 30-40 percent. In aerodynamic research, a major goal is to minimize drag to enable a substantial increase in HSCT range; Phase 11 incudes computational and wind tunnel analyses of the baseline HSCT and alternative designs over the entire speed range. Propulsion research looks for environment related and general efficiency improvements in critical engine components, such as inlet systems, combustors and nozzles. Other research involves ground and flight simulations aimed at development of advanced control systems and flight deck - or technology for optimal supersonic flying quality.
The HSR program will move beyond laboratory investigations into the actual supersonic flight realm through a NASA agreement with the Russian Tupolev design bureau. Under this agreement, Tupolev will modify a TU-144 supersonic transport for use as a flying laboratory gathering aerodynamic structural and environmental data. First flight is targeted for early 1996.
Overall, the HSR program seeks technology advances that would make a 2005 HSCT almost 50 percent lighter than the baseline HSCT established in 1990 and enable attainment of the economic and environmental goals.