New NASA rocket programme
Keywords: NASA, Rockets
Engineers at the Marshall Space Flight Centre in Huntsville, Alabama, are combining air-breathing and rocket propulsion in a single flow path under a NASA programme for Advanced Reusable Technologies. The Rocket-Based Combined Cycle project may one day help decrease how much pressurised oxygen spacecraft need to lug along on their way into orbit.
The combined cycle engines, which are currently undergoing wind-tunnel testing at General Applied Sciences Laboratories in Ronkonkoma, New York, are designed to launch as air-augmented rockets, then switch to ramjet propulsion as flights near Mach 3. A transition from subsonic to supersonic combustion takes place around Mach 6, when the engines begin operating as scramjets. At Mach 10,the rocket engines restart, propelling the vehicles out of the air-breathing corridor and into orbit. In the corridor, the vehicle flies at a constant dynamic pressure of 1,500 pounds per square foot.
Testing so far has centred around what are called ''flow path simulation''. The engines run in the wind tunnel for intervals that typically last for 30 seconds. During such brief periods, engineers have been able to dynamically simulate the transition from air-augmented rocket to, ramjet and from ramjet to scramjet. They have also been able to change the Mach number and enthalpy of wind-tunnel air.
Marshall, the NASA Glenn Research Centre in Cleveland and the Langley Research Centre in Hampton, Virginia, along with industry partners Aerojet Corp of Sacrarnento, Rocketdyne of Canoga Park, California, Astrox Corp of Rockville,Maryland and Pennsylvania State University will continue wind-tunnel testing. The next step will likely entail building a complete engine system with flight-type hardware.
NASA is sponsoring research into a variety of technologies designed to reduce the costs of space missions. Within 25 years NASA wants to bring launch costs down from today's $10,000 a pound to a mere hundreds of dollars per pound.
The space agency's interest in combined cycle engines stems partly from a dusting off of research that the nation had conducted into air-breathing propulsion in the 1960s and 1970s.
