The destruction of a Titan 4 motor segment that burst into flames at Edwards Air Force Base in California dealt yet another setback to the aerospace contractor working to develop a more powerful booster for the rocket.
Hercules Aerospace was already a year or more behind schedule when its rocket motor fell from a crane and erupted Friday as it was being moved at a test laboratory at the base.While nearing the final phases of preparation for the first full-scale prototype test, Hercules lost the critical aft segment of the booster. The accident, which triggered a roaring propellant-fed fire, left one person dead and several others with minor injuries.
It was the third blow to the Hercules Titan 4 SRMU (solid-rocket motor upgrade) program in the past 18 months.
The 300,000-pound solid-rocket segment was swept over a hillside and ignited at Edwards when it dropped from the crane as it was being lifted out of a test stand.
Hercules officials have so far declined to discuss their theories on what happened. The Air Force is in the midst of its own investigation into the accident, but the results of the probe are not expected for some time.
However, several individuals with long experience in solid rocketry puzzled over why the unit ignited even after being dropped 70 feet.
Hercules spokesman Dave Nicponski said he could not talk about the accident's impact on his company's program or how long it would take to get the booster testing back on track.
Astronautics Laboratory, the base's testing facility, which dates back to the early days of the U.S. space program, also will be out of commission while the Air Force conducts its investigation.
A former Hercules engineer, who spoke on the condition of anonymity, said previous investigations of a 1974 motor that detonated at the Hercules plant in Magna have shown a motor that had been previously bumped could ignite under similar circumstances. He said those investigations revealed a bump could damage the motor's case bond and granulize the propellant, making it more sensitive to shock.
The 30-foot-long aft segment, loaded with a composite propellant similar to that used in space shuttle solid-rocket motors, was one of three needed to make up the SRMU test booster.
It was successfully cast late last year at the automated Hercules plant after the production line was shut down for several months by a $15 million fire that destroyed an 1,800-gallon propellant mixer.
But the second unit - a 28-foot center segment - had to be scrapped because of propellant-to-case bond failure.
Just prior to that incident, the Air Force Space Division at Los Angeles said Hercules was about a year behind in developing SRMU, but it had no outstanding technical concerns.
The Titan's prime contractor, Martin Marietta of Denver, was planning to get the first SRMU launch off sometime in 1991. Hercules considered the $500 million Titan 4 contract, awarded nearly three years ago, as the cornerstone of its strategy to move from military to space propulsion.
However, Hercules, headquartered in Wilmington, Del., was forced to take a $323 million charge against 1989 earnings because of Titan 4 and Delta 2 losses from schedule delays.