In response to tweets revealed by CEO Elon Musk on July 21st, SpaceX’s combined Starship and Super Heavy launch vehicle (BFR) might have as many as 41 Raptor engines at liftoff.
As with all different points of SpaceX’s next-technology rocket, it is a sign that issues stay in flux as the corporate near the end at which a specific design will need to be settled on for the first flight-ready prototype(s). With 6 Raptors on the higher stage (Starship) and 35 Raptors on the first stage/booster (Super Heavy), the rocket will – indisputably – be the most powerful launch vehicle ever developed when it attempts its inaugural launch.
Now anticipated to feature 35 Raptors in its final iteration, SpaceX’s Super Heavy booster can currently be anticipated to provide a minimum of ~70,000 kN (15.7M lbf) of thrust at full throttle, assuming that all 35 Raptors are the throttleable ~2000 kN variant. In keeping with Musk, SpaceX might also develop a simplified Raptor with minimal throttling that would produce upwards of ~2500 kN (550,000 lbf) of thrust.
If, say, 5 throttleable Raptors have been kept as the center cluster of engines used for landing, and necessary recovery-related burns, a Super Heavy booster with 30 uprated Raptors may produce upwards of 85,000 kN of thrust at launch. A Super Heavy booster anywhere within those rough bounds (70 MN to 85 MN) can be packing double the thrust of NASA’s Saturn V rocket and double the thrust of NASA’s in-development SLS rocket in its higher-thrust variants.
If all goes properly, Musk – likely telegraphing his old, wildly optimistic, “Musk-time” self – believes that the first Starship prototypes (one in Texas, one in Florida) might be ready for inaugural flight tests as early as September/October 2019.