In March NASA is planning to test the massive solid rocket booster for the agency’s Space Launch System rocket. The engineers are exploring an advanced composite that might be used in the future to create even more powerful boosters.
To understand how well these materials would behave under the immense strains of a launch, the engineers ran a test that involved pressurising a booster structure made of composite materials to the breaking point to see how it stacks up with the metallic cases currently in use.
In the tests, a booster case 25 feet long and 92 inches in diameter was subjected to 3,000 pounds per square inch of pressure – well beyond what would be encountered in flight conditions – to verify exactly what loads the composite material could withstand.
Angie Jackman, of the SLS Spacecraft/Payload Integration and Evolution (SPIE) office at NASA’s Marshall Space Flight Centre in Huntsville, Alabama, where the SLS Program is managed for the agency said;
The test is very dramatic, when composites fail, it’s the glue or the resin that fails first – not the fibre that fails. There’s a big boom, and it’s all spaghetti.
Before the test, damage was purposefully caused at multiple points on the case to study what effect it would have on how the case fared. Even so, the damaged case performed as well as an intact case, demonstrating not only the composite case could withstand the rigors of launch, but that it could do so even in a damaged condition.
During the test, the case failed within 1% of pretest estimates, validating the models for strength of the composites. Over one hundred channels of instrumentation provided data on the case failure. The rocket motor case test is part of an effort to optimise a composite case design that may be stronger, lighter, yet more affordable than traditional steel cases. In turn, this would provide increased payload performance due to reduced weight inherent in composite materials.
After the initial flights of SLS, the rocket will be upgraded from a configuration capable of delivering 77 tonnes to low-Earth orbit to an evolved configuration that will launch 143 tonnes. To reach its full capability, SLS will use more powerful boosters.