>>16742341
SSME (RS25) conducted an experiment of 60000 seconds in 1979. Only 8 engines were used, with 30000 seconds in the first half of the year and 135 engine starts. The average ignition time exceeds 200 seconds.
During SSME validation, the longest single machine experiment had a total duration of nearly 20000 seconds.
Raptor engine iterates faster than SSME?
Raptor 1 used at least 60 engines and verified for 30000 seconds, with a total of less than 600 starts. Then the entire engine stopped production and was dismantled and abandoned.
Then an estimated over 300 Raptor 2 engines were produced in one year, with the total number and duration of experiments unknown.
Two static ignition units malfunctioned, one unit did not start, and one unit shut down within 5 seconds. The total test is half thrust for 15 seconds.
SLS has conducted multiple 8-minute ignition tests.
During the first flight, the ignition of 3 units did not start, and about 30 seconds later, another unit exploded. At least 8-9 units shut down abnormally during the entire flight.
I respect SSME.