Rocket engines of the future

Rocket engines of the future

Keywords: Rocket engines, Space technology, Mechanical engineering

A new rocket propulsion technology demonstration has marked an important milestone, achieving “mainstage” or constant full-power performance for the first time. Called the Integrated Powerhead Demonstration, or IPD, this development project combines the very latest in rocket engine propulsion technologies. To date, the IPD has conducted 21 of 26 tests and accumulated 300 seconds of operation, up to 100 percent power level at NASA's Stennis Space Center (SSC) in Mississippi.

The IPD is being developed through the combined efforts of Pratt &Whitney Rocketdyne (PWR), a business unit of United Technologies Corp., Aerojet,and NASA's SSC, under program direction by the Air Force Research Laboratory(AFRL) and technical direction of NASA's Marshall Space Flight Center (MSFC). Its technologies are directed at achieving the goals of the Integrated High Payoff Rocket Propulsion Technology program and NASA's Exploration Technology Development Program.

Capable of generating about 250,000 pounds of thrust, the demonstrator uses liquid oxygen and liquid hydrogen in a first US demonstration of a full-flow,staged-combustion (FFSC) cycle. The FFSC cycle uses a fuel-rich pre-burner to drive the fuel turbopump, and an oxidiser-rich pre-burner to drive the oxygen turbopump. Because all of the propellants in the pre-burners are burned, more mass flow is available to drive the turbines than in a conventional staged combustion cycle.

This additional power enables lower turbine temperatures, which translates into longer turbine life, a key factor in reusable engine life. Also, the use of oxidiser-rich gas in the oxidiser turbine and fuel-rich gas in the fuel turbine eliminates the need for a complex propellant seal for the pumps, and means lower risk of leaking liquid fuel into a fuel-rich gas or liquid oxygen into an oxidiser-rich gas, thus increasing engine system reliability. The turbopumps also employ hydrostatic bearings, eliminating wear and enabling high reusability.

Stephen Hanna, Air Force Research Laboratory's (AFRL) IPD program manager,commented about the technological success and its team. “I can't tell people how excited I am about this program. Our team, composed of engineers and managers from AFRL, the NASA MSFC, the NASA SSC, Pratt & Whitney Rocketdyne,and Aerojet, is incredibly talented and the best that the industry and government have to offer. The partnership that we have forged among AFRL, NASA and industry is second to none. We continue to pave new technological ground each day, currently developing and test firing the first new liquid rocket engine cycle in the last 35 years. That dates back to the early development days of the Space Shuttle's Staged-Combustion Main Engine.”

“Our intent is to validate new propulsion technologies that can be used in a new generation of rocket engines,” said Don McAlister, PWR IPD program manager. “The IPD itself will not be flown, but its technologies will find their way into future rocket engines and will be especially valuable for NASA's Vision for Space Exploration.”

Added PWR President Byron Wood, “The IPD is a critical program that clearly demonstrates how effective NASA, the Air Force and industry can be when they work together for a common objective. That will be increasingly important as we continue to build on America's leadership in space.”

“Reaching 100 percent power level is a major milestone in testing the IPD engine,” said SSC Director Rick Gilbrech. “Technologies developed through the IPD could benefit the Vision for Space Exploration –to return humans to the moon, Mars and beyond. I congratulate the entire IPD team led by the Air Force Research Lab and NASA's MSFC and am proud of the Stennis test team for enabling this significant achievement.”

The IPD program is managed out of the AFRL at Edwards AFB, California, with technical support from NASA's MSFC. PWR is the systems integrator and also provides the fuel and oxidiser turbopumps, the main injector, the main combustion chamber, the demonstrator control system and other systems components. Aerojet provides the fuel and oxidiser pre-burners, nozzle, and fuel pre-mixer. Test operations and facilities are provided by NASA SSC.

NEXT propulsion system

Another exciting new development in rocket engines is reported by Aerojet, a GenCorp Inc., company, it has delivered the first of a new generation of propulsion thrusters to NASA's Glenn Research Center in Cleveland, Ohio, for NASA's Evolutionary Xenon Thruster (NEXT) project. The NEXT propulsion system could provide breakthrough improvements in propulsion capabilities that will now enable NASA's most ambitious robotic exploration missions.

Using highly advanced “electric propulsion” technology, the new engine emits an iridescent glow rather than the smoke and flame of a traditional chemical rocket making George Lucas' movie portrayals seem not as farfetched after all. It's not just the appearance of the new system during operation that has caused excitement, it's the performance.

Aerojet's NEXT ion thruster is capable of operating continuously in excess of 30,000 hours to provide the large total energy (or impulse) needed for NASA's outer planetary exploration missions. The NEXT thrust level is three times higher than the state-of-the- art NASA Solar Electric Propulsion Technology Application Readiness (NSTAR) ion thruster used on the Deep Space One mission. Fuel efficiency, or specific impulse, is 30 percent higher than the NSTAR ion thruster and is a ten-fold increase over today's chemical rocket engines. Spacecraft using NEXT propulsion will use just 10 percent of the propellant of conventional chemical rocket propelled spacecraft, enabling more ambitious NASA missions with greater science return.

Initial acceptance testing of the NEXT engine by NASA Glenn demonstrated that the thruster met or exceeded performance specifications “right out of the box.” Acceptance testing is complete and the thruster was sent to the Jet Propulsion Lab, Pasadena, California, for environmental testing. Aerojet will also fabricate and deliver a second prototype model thruster for NEXT system integration and long duration testing.

“Delivery of the NEXT engine to NASA continues Aerojet's long history of delivering advanced new propulsion technologies in support of our nation's needs,” said Aerojet Vice President of Space Programs Julie Van Kleeck.“The NEXT project could enable NASA to go places and do missions that could not be done before.”

The NEXT project is a joint technology and engineering development program led by NASA Glenn since 2002 to develop a next generation electric propulsion system, including power processing, propellant management and digital controller. The NEXT project is being conducted under the In-Space Propulsion Technology Program, managed by NASA's Science Mission Directorate in Washington DC and implemented by the MSFC, Huntsville, Alabama.

In a paper published in this issue of Aircraft Engineering and Aerospace Technology, Professor Alexander Bolonkin suggests a revolutionary new electrostatic engine. He puts forward the theory that this engine can be used as a linear engine (accelerator), a strong space launcher, a high speed delivery system for space elevator, Earth-Moon, Earth-Mars, electrostatic train,levitation, conventional high voltage rotating engine, electrostatic electric generator, weapon, and so on. The author develops the theory of this engine application and outlines its powerful possibilities in space, transport and military industry. The projects are computed to show the potential of this new concept.