December 03, 2012
Credit: Credit: Missile Defense Agency
Guy Norris Los Angeles
Within the defense aerospace community, the intense choreography involved in guiding one missile to intercept another is widely viewed as one of the toughest tasks in the business.
Figuring out how to test, and ultimately fix problems in such a system is therefore one of the more extreme challenges facing Boeing as it works to restart tests of the Ground-based Midcourse Defense (GMD) system in the wake of intercept failures in 2010. The company, which won a $3.48 billion sustainment and development contract for the GMD missile defense system in late 2011, is focusing test efforts on a suspected vibratory anomaly related to the guidance system, which played a role in one of these intercept attempts.
Boeing Test & Evaluation has developed a high-frequency testbed (HFTE), details of which it revealed to Aviation Week as it closes in on the resumption of flight tests. Development of the testbed, which began at Boeing's Huntington Beach, Calif., facility about 10 months before contract award, is a key element of the company's work with the U.S. Missile Defense Agency (MDA) to restart GMD flights.
These were targeted for year-end, and although contractors are thought to be ready, the first test is being pushed to late January under the cautious approach being taken by the MDA. The flight, designated CTV-01, will be a “fly-out” mission with no intercept.
The electromechanical testbed, developed by teams led by Boeing Environmental Lab technical lead engineer Pat Rogers and Boeing GMD lead mechanical systems engineer Ali Mandvi, simulates the high-frequency vibration noted by the GMD navigation unit. “In 2010, we had an issue with a test which was traced to a high-frequency event that was generated during the flight,” says Mandvi. Although some mission assurance experts suggested that replicating the rocket thruster's high-energy, high-frequency vibration was impossible, he added, “we came up with a concept, and brought it to the lab and started to develop it.”
“Normally a system tests to 2,000 or 3,000 hertz, but with this we create a tremendous amount of energy up to 80,000 hertz,” says Rogers. The system, which has been adapted to run vibration tests on deliverable flight hardware, can rapidly evaluate a part through more than 50 test conditions. “Before, it would take a couple of hours to get through all the frequencies and tones, and with the new system we can do it in just 3 sec.,” says Mandvi. The HFTE generates a high-frequency shock by focusing the sound energy from 3,000-watt amplifiers. “We put complex waveforms through the speakers to produce a lot of energy,” explains Rogers.
The upcoming flight test of the ground-based interceptor will “aim to validate what we've seen here,” rather than evaluate a specific fix, says Mandvi. The interceptor consists of a three-stage booster supplied by Orbital Sciences, and a Raytheon-developed Exoatmospheric Kill Vehicle (EKV). The EKV is configured with an infrared seeker to detect an incoming warhead, which it destroys using the kinetic force of a direct collision. To close on the target, the EKV is equipped with its own propulsion, communications link, discrimination algorithms, guidance and control system and computers.