After successfully assembling the last one of its first orbital-class Starship’s six Raptor engines over the weekend, SpaceX is preparing the prototype for one or more record-breaking tests later this week.
The next test on Starship 20’s (S20) docket is tentatively slated for as early as 10 a.m. to 6 p.m. CDT on Monday and Tuesday, November 1st and 2nd, and will most likely be the ship’s third static fire in eleven days.
In addition to completing its first Raptor-involved test – known as a preburner test – on October 19th, Ship 20 also successfully executed two back-to-back static burns the following day, one using one Raptor and the other involving two Raptors – on October 21st.
Installing Raptors and watching the sunset. This is #Starbase.
— Nic Ansuini (@NicAnsuini) October 29, 2021
The Starship’s two missing Raptor Center (RC) engines (of a total of three) were successfully installed by Friday morning, October 22nd, less than 36 hours after they went missing.
No testing was completed the following week for unclear reasons, and it took SpaceX another six and a half days to transfer the last two missing engines to the pad for installation on S20, bringing the total time to nine and a half weeks.
Regardless, both of the missing Raptor Vacuum engines were installed by 2 a.m. CDT on Saturday, October 30th, making this the second time that all six Raptors had been placed on a Starship prototype.
It is possible that this is the second time SpaceX has put six Raptors on a Starship, but it is most likely the first time that six engines have been properly integrated with Ship 20’s propellant tanks, gas supply system, and avionics system.
Although it is unclear how SpaceX intends to proceed, it is likely that Starship S20’s next static fire test campaign will involve the simultaneous ignition of at least four of its six Raptor engines, setting a new record for the largest number of Raptors ever ignited in a single static fire test campaign.
Ship 20’s next campaign, on the other hand, is more than likely to conclude with the simultaneous ignition of all six Raptors, which would (ideally) complete the first real orbital-class Starship static fire in history.
The use of flight-proven Starships may eventually allow SpaceX to eliminate the need for pre-flight static fire tests. However, it is virtually certain that SpaceX will continue to proof test Starship and Super Heavy before flights until the ships, boosters, and Raptors have stable designs and substantial flight experience, as the company has only recently begun to do with Falcon boosters.
Those static fires will always have to validate all of the installed engines in order to assure complete fidelity testing. This includes Starship, which is planned to burn both its sea-level and vacuum-optimized Raptors from the time of booster separation until the time of orbital entry.
At maximum throttle, and depending on the efficiency of its three RVacs at sea level, the six Raptor V1.0 engines aboard Starship S20 may generate around 1100 tonnes (2.4 million lbf) of thrust.
According to SpaceX, its workhorse Falcon 9 rocket produces approximately 760 tonnes (1.7 million lbf) of thrust at liftoff, indicating that Starship will likely become the most powerful single-core rocket the company has ever tested, even if it never throttles above about 70% of its maximum performance.
Following the recent two-engine test, there is a good chance that SpaceX will begin the next round of tests on Ship 20 by firing both sets of three Raptor Center and Vacuum engines separately, or by conducting a mixed three- or four-engine test following the latest two-engine test.
Another option is for SpaceX to follow the most iterative method possible and test three, four, and five engines at a time before doing the final six-engine test. It doesn’t matter how you look at it, practically every static fire test that Ship 20 is now prepared to do will be a programme “first” of some type. Keep an eye out for updates on the first of those tests, which might begin as early as 10 a.m. CDT (15:00 UTC) on November 1st and 2nd, depending on the weather.