Top 15 Technologies
5.
A NASA SR-71 completes first test flight of LASRE program
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A NASA (www.nasa.gov) SR-71, used for the NASA/Rocketdyne/Lockheed Martin (www.lockheedmartin.com) Linear Aerospike SR-71 Experiment (LASRE), has completed its first test flight at Dryden Flight Research Center. It flew for 1 hr 50 min and traveled at a maximum speed of Mach 1.2 before landing at Edwards Air Force Base.
Linear Aerospike rocket engines, which are going to power the X-33 Advanced Technology Demonstrator, have been laboratory- and ground-tested over the past 30 years, but never flown. These experiments were designed to gather data on the engine's exhaust plume during transonic flight.
LASRE, a one-tenth-scale, half-span model of the X-33, contains eight thrust cells of an aerospike engine and is mounted on a housing known as the "canoe," which contains gaseous hydrogen, helium, and instrumentation gear. The entire "pod," which is the engine and canoe together, is 41 ft long and weighs 14,300 lb.
This flight, which is the first in a series of ground-based and in-flight qualification tests, might be followed by either data-collection flights or ground testing at the USAF Research Laboratory Propulsion Directorate. The data-collection flights will begin with the in-flight refueling of the SR-71 and it climbing to 20,000-80,000 ft with the piggyback LASRE pod. Upon reaching testing altitude, the aerospike engine will be fired and in-flight engine performance data collected. This will last for approximately 2-3 s due to the limited fuel capacity of the LASRE pod.
The aerospike's performance will be measured from subsonic speeds up to Mach 3 with the important flight tests being conducted in the transonic region (Mach 0.8-1.2). The purpose of these flight research missions will be to gather accurate information on the interaction between the X-33 model's airflow and the exhaust plume of the linear aerospike engine. The aerospike is expected to provide approximately 7000 lb of thrust to the X-33.
More than 30 years ago, Rocketdyne, now Boeing North American-Rocketdyne, developed the Propulsion Directorate's concept of both the linear and annular aerospike engines in the mid-1960s with ground testing continuing through the 1970s. Since being turned down by the Space Shuttle program because of its lack of development, Rocketdyne's linear aerospike engine has accomplished 73 laboratory and ground-test firings and over 4000 s of operation. Rocketdyne has invested over $500 million in the aerospike technology, and with recent funding by the USAF, has improved the manufacturing of the aerospike engine thrust cells, while modern performance sensors and monitoring controls enable split-second engine control.
Similar to conventional rocket engines in their plumbing, accessories, and use of similar components such as turbopumps, linear aerospike engines differ in their use of the atmosphere as part of the nozzle, with the surrounding airflow containing the rocket's exhaust plume. This enables the engine to operate at peak performance and efficiency along the entire trajectory of ascent into orbit. Traditional rockets, with their bell-shaped nozzles, cannot compensate for atmospheric changes and are designed for a particular performance range.
Another advantage of linear aerospike engines is they are 75% smaller than conventional rocket engines of comparable thrust. This means less engine weight and support structure, which allows for a lighter spacecraft and lower launch costs.
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