Research & Development

CSULB/GSC Team Conducts First Powered Liquid Propellant Aerospike Flight Test, Sept. 20, 2003

(Updated 10/07/03 after detailed post-flight vehicle analysis)

A joint academic / industry team conducted the first known flight test of a powered liquid-propellant aerospike engine this past Saturday, 20 September 2003. California State University, Long Beach (CSULB) and Garvey Spacecraft Corporation, Huntington Beach, CA, principal partners in the California Launch Vehicle Education Initiative (CALVEIN), successfully launched their Prospector 2 (P-2) research vehicle using a 1,000 lbf LOX/ethanol aerospike engine designed and developed by CSULB students.

After the successful static fire test conducted in June, the team met its primary objective: get the vehicle into the air using the liquid-propellant aerospike engine. This success represents a small but important step in validating such engine technology for future reusable launch systems. From a broader perspective, this kind of hardware-based research and development, which has depended heavily on student contributions, is essential for preparing tomorrow's aerospace engineers who will be developing such vehicles.

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P-2 takes off powered by the 1000 lbf aerospike engine

P-2 takes off powered by the 1000 lbf aerospike engine (Photo by Tony Richards)

Aerospike engine mounted to P-2

Aerospike engine mounted to P-2 (Photo by Kim Garvey)

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The CALVEIN and Cerritos High School team (Photo by Kim Garvey)

The aerospike flight test took place in the early afternoon under excellent weather conditions at the Mojave Test Area, site owned and operated by the non-profit Reaction Research Society. After a smooth countdown and nominal engine ignition, the thirteen-foot long P-2 quickly accelerated up a 60-ft launch rail and entered stable flight. Rapidly however, the thrust was reduced and vectored. Post flight engine analysis showed that a significant amount of flow went around the graphite outer ring and burnt the back of the chamber, leading to several secondary plumes. These are already visible when the rocket leaves the rail but have, at that time, little impact on thrust. They become more apparent as the flight progresses. Eventually, these secondary plumes led to asymmetric thrust and sent the vehicle out of control until it went into a ballistic terminal descent. These large regions of secondary flows occurred in flight but not during the static fire test conducted in June because of a slight difference in the seal quality at the back of the combustion chamber. Here, a slightly wider gap existed at the exhaust, and this gap turned out to be sufficient to lead to a downward movement of the graphite outer ring.

P-2 in flight - Gasses flow around the throat outer ring

P-2 in flight - Gasses flow around the throat outer ring (Photo by Tony Richards)

solid model of the engine

Aerospike engine cross-section. The graphite outer ring (blue) was not perfectly sealed with the bottom of the chamber (grey) and moved ownward very slightly. This opened several gas paths between the ring and the ablative material (beige) which then melted the back of the chamber and led to thrust vectoring. This phenomenon did not occur during the static fire test.

The subsequent impact with the desert floor destroyed student payloads provided by a USC/JPL team and another from Cerritos High School, but the aft section with the aerospike survived relatively intact. The payload provided by the USC/JPL team was a MEMS propulsion device being flown for tests under the stressful launch environment (very stressful here!). Cerritos High School students also provided a small digital camera payload which was to be activated upon ejection from the rocket using a new payload deployment system developed by the CALVEIN team. The payload, however, was not ejected and was crushed on rocket impact. Another CSULB payload was a GPS receiver with downlink to the ground using wireless network technologies. Data collected during flight will be analyzed in the next few days.

It should be noted that the failure of the recovery system to work properly was independent of the engine malfunction during flight. Rather, due to new regulations, the team had moved from a pyro-based recovery system deployment to a pneumatic system. Post flight analysis showed that the altimeter did trigger the deployment, but that too large an amount of grease put in during integration prevented the release pin to fully retract. This system had been tested successfully several times in the lab, but without the grease.

Cerritos High School students

Cerritos High School students perform a last minute check of their camera system payload. The payload was not ejected and was crushed on impact.

This mission was actually the second for the Prospector 2, which first flew in February 2002 with a standard bell-shaped ablative engine chamber, and fourth overall for the CALVEIN team. John Garvey of Garvey Spacecraft Corporation notes that "We have already identified several areas for improving the basic aerospike engine design. At the post-flight data review we will collect any other lessons-learned from the flight test and then will update our near-term flight test plans. As always, the real challenge will be balancing what we would like to do with the available resources. We could either run more static fire tests to characterize the engine better or adapt the new Prospector 4 to carry an updated aerospike. We will know more once we have had a chance to open up the P-2 engine and take a look inside."

Special Thanks

In addition to Garvey Spacecraft Corporation, other corporate contributors to the Prospector 2 flight test include Advanced Composite Products and Technologies (ACPT) for the graphite epoxy aeroshell and Electro-Tech Machining (ETM) which provided the graphite engine components.

In addition to the "regulars" (John Engberg, Dave McCue, Mike Novratil and Mark Holthaus), the CSULB team would also like to recognize the following individuals who, through their support, made this flight a success. First, Tom Mueller who was instrumental in mentoring the students during the design process, Richard Ornellas for providing the LOX and Dave Crisalli, President of the RRS, for giving the CALVEIN team access to the MTA and overseeing launch operations.

For additional information about either the CALVEIN project and/or the cooperative program between CSULB and Garvey Spacecraft Corporation, please contact the following project representatives:

  • Dr. Eric Besnard
  • Mechanical and Aerospace Engineering Dept.
  • California State University, Long Beach
  • 1250 Bellflower Blvd Long Beach, CA 90840
  • Tel:(562) 985-5442
  • Fax:(562) 985-1669
  • Email:besnarde@csulb.edu
  • John Garvey
  • Garvey Spacecraft Corporation
  • 389 Haines Avenue
  • Long Beach, CA 90840-1841
  • Tel:(562)-498-2984
  • Email: info@garvspace.com