For the first time, SpaceX has static fired a Starship booster at its South Texas orbital launch pad, marking important milestones for both.
After months of cautious testing and multiple rounds of repairs, Super Heavy Booster 7 made it through its first Raptor tests (without causing an explosion) on August 8th, completing a pair of “spin-prime” tests with one Raptor engine. Booster 7 began testing in early April, more than four months ago. As previously discussed on Teslarati, the massive 69-meter-tall (~227 ft) rocket has had an exceptionally rocky journey to its current test campaign.
“Booster 7 first headed to the pad on March 31st and successfully completed two major cryogenic proof tests, but was severely damaged during a subsequent structural stress test. After a few weeks of repairs back at the factory, B7 rolled out to the pad a second time, completed a third cryoproof test, and returned to the factory again on May 14th, where it stayed until June 23rd.”
Teslarati.com – June 24th, 2022
After several halting, minimal tests in late June and early July, Booster 7 – partially loaded with either propellant or a combination of more neutral cryogenic fluids – attempted a spin-prime test with all 33 of its Raptor 2 engines on July 11th. The mixture of gas that testing created found an unintended ignition source and violently exploded, significantly damaging parts of Super Heavy’s aft section. For the third time, SpaceX returned Booster 7 to its Starbase factory and spent another three weeks removing the rocket’s just-installed Raptor engines and repairing the damage.
On August 6th, Booster 7 rolled to the pad for the fourth time, revealing that SpaceX had only reinstalled 20 of the rocket’s maximum 33 Raptor engines. On August 8th, clearly indicative of a much more cautious second attempt at engine testing, SpaceX ‘primed’ just one of those 20 Raptors by flowing high-pressure gas through the engine to spin up its turbopumps without igniting its preburners (used to generate the gas that powers the turbopumps) or main combustion chamber.
Less than 24 hours later, SpaceX successfully kicked off another round of testing and ignited the same spin-primed engine on the first try. Super Heavy B7 survived the test without visible issue and was safely depressurized and detanked soon after. The lone Raptor engine also appeared to perform perfectly and shut down cleanly after a stable three or four-second burn.
Booster 7’s first static fire – also the second static fire test of a Super Heavy – was the first test of an upgraded Raptor 2 engine on any rocket prototype. At the cost of slightly less efficient combustion, Raptor 2 is designed to produce up to 230 tons (~510,000 lbf) of thrust – almost 25% more than Raptor 1 (185 tons or ~410,000 lbf).
With about four hours left in August 9th’s test window, which closes at 10 pm CDT (03:00 UTC), SpaceX still has time to test Starship S24, which also completed Raptor spin-prime tests on August 8th. SpaceX has an additional 10am-10pm road closure scheduled on Wednesday, August 10th.