NASA is working with CUBRC Inc. of Buffalo, NY to design, build, and test 2% scale models of the Space Launch System (SLS) propulsion system. Models include two five-segment solid rocket boosters and four core stage RS-25 engines, and a 2% scale model of the entire rocket. The models are fired for short durations of about 50-150 milliseconds per test.

A 2% scale model of the SLS core stage RS-25 engines (left), and a model of the SLS without the twin boosters. (NASA/MSFC)

Testing of the mini models will provide data on the convective heating environments the base of the rocket will experience upon ascent for both planned and unplanned flight conditions. Data from the test series will be used to verify flight hardware design environments and set specifications for the design of the rocket's base thermal protection system. The system keeps major hardware, wiring, and crews on future missions safe from the extreme heat the boosters and engines create while burning during ascent.

The full-stack configuration has 200 heat flux and pressure sensors within the aft section of the rocket to collect data on the base flow environment. More than 30 test cases have been performed, with about 85 total scheduled for the entire test series.

The test program uses new technology that wasn't available during past human spaceflight programs, such as high-speed visible light and infrared cameras, laser diagnostics and new designs of the model propulsion systems that more adequately simulate the SLS full-scale systems.