Press Release

  This press release is issued by NASDA.


Test Results of the H-IIA Rocket Solid Fuel Rocket Booster (SRB-A) Qualified-Type Motor Ground Propulsion Test (QM2)

June 5, 2000 (JST)

National Space Development Agency of Japan

The National Space Development Agency of Japan (NASDA) performed an SRB-A ground propulsion test at the Ground Combustion Test Facilities for Solid Rocket of the Takesaki launch site at the Tanegashima Space Center at 11:00 a.m. on Friday, Jun. 2 , 2000.

The test concluded with gathering the expected data. The test was confirmed that the problems with the nozzle had been solved by the change in plan this time. The nozzle had produced much more erosion than NASDA had expected.

After the test, fragments of CFRP (Carbon Fiber Reinforced Plastic), which made up the nozzle was scattered. For that reason, NASDA analyzed SRB-A and scrutinized an image of propulsion test closely.

-- Throat Insert fell into the motor case.
-- Parts of the upstream side Radiation Shielder (made of CFRP) and the Liner Insert (made of CFRP) at the rear of the Throat Insert were damaged. These parts matched with the scattered CFRP.
-- At the end of propulsion, red-hot material was scattered from the nozzle.

From the above circumstances, the following phenomena have been inferred:

    1. Just as the propulsion ended, the Throat Insert moved to the upstream side of the nozzle (*).
    That caused damage to a portion of the Radiation Shielder, which broke into pieces and was discharged from the nozzle.

    (*) The propulsion pressure maintaining the Throat Insert declines when propulsion is completed. In some cases, the Throat Insert is pushed to the upstream side by the balance of the gas pressure that the Liner Insert develops and the binding power of the Radiation Shielder.

    It had been anticipated that this could happen, the Throat Insert to the upstream side had also moved in previous propulsion tests.

    2. Because the Throat Insert detached from the nozzle, the rear of the Liner Insert was exposed and fell off.

Approximately the same amount of erosion on the Radiation Shielder (including scattered CFRP) was seen in previous tests. In the future, more in-depth mechanism investigations shall be conducted on these phenomena.