The full-scale demonstrator engines will be too large to test in a facility that can simulate high altitude conditions. Although sea-level tests will be an important milestone in the development of new supersonic engines, some important questions will remain unanswered. Flight demonstrations are needed to determine propulsion system responses to atmospheric conditions and disturbances, including turbulence and wind gusts. A full-scale technology demonstration aircraft will also be needed to verify critical angles for engine unstart to investigate the impact of engine unstart on the aircraft and its occupants.

Similarly, flight demonstration would verify the ability of the integrated airframe and propulsion systems to meet noise and emissions goals. For example, as part of the AESA project, NASA has made in-flight measurements of emissions from the Concorde. However, an HSCT engine is likely to have a very different thermodynamic cycle from the Concorde's Olympus engines, and NO_x emissions from an HSCT engine are expected to be considerably different (NRC, 1997).

NASA (National Aeronautics and Space Administration). 1995a. 1995 Scientific Assessment of the Atmospheric Effects of Stratospheric Aircraft. NASA Reference Publication 1381. Washington, D.C.: National Aeronautics and Space Administration.

NASA. 1995b. The Atmospheric Effects of Stratospheric Aircraft, A Fourth Program Report. NASA Reference Publication 1359. Washington, D.C.: National Aeronautics and Space Administration.

NRC (National Research Council). 1997. An Interim Assessment of AEAP's Emissions Characterization and Near-Field Interactions Elements. Washington, D.C.: National Academy Press.

FRONT MATTER (R1-R10)

EXECUTIVE SUMMARY (1-10)

1 INTRODUCTION (11-25)

2 REQUIREMENTS ANALYSIS (26-45)

3 PROPULSION (46-60)

4 AIRFRAME (61-90)

5 INTEGRATED AIRCRAFT (91-109)

6 SUMMARY OF PROGRAM PLANNING ISSUES (110-126)

A LIST OF FINDINGS AND RECOMMENDATIONS (127-141)

B BIOGRAPHICAL SKETCHES OF COMMITTEE MEMBERS (142-146)

C STATEMENT OF TASK (147-147)

D PARTICIPANTS IN COMMITTEE MEETINGS (148-149)

ACRONYMS (150-151)