1
$\begingroup$

When a rocket engine is loaded into a test stand is it tested once before removal or is it allowed to cool and then tested again. Is every liquid-fueled rocket motor that flies to space first tested in a test stand, or do they test each design in the test stand and put fresh ones onto the space flying rocket? Are sea level rocket motors damaged or worn out by firing?

Clearly, solid fueled rockets and any rocket with ablative cooling is not going to survive multiple tests. I am happy with answers that cover liquid fueled rockets with effective cooling.

$\endgroup$
1
$\begingroup$

This is probably going to be different for every engine.

For the early days of the Space Shuttle Main Engine (SSME), it went like this

Every engine that went on the orbiter was acceptance tested. Unless there was a rebuild, which would trigger the need for a new acceptance or green run test, testing was done once for each engine. If the engine passed, it was put into the flight pool. Engine 2005, earmarked for the first orbital flight of the SSP, was the first of the three-engine cluster to be delivered to SSC, in April 1979, for acceptance testing. Engines 2006 and 2007 followed. The acceptance test protocol at this point in the program included a 1.5-second start verification, a 100-second calibration firing, and a 520-second flight demonstration test. Engine 2007 was the first to complete the acceptance test requirements, and to qualify as the first flight engine for the SSP. Following successful completion of the test series, the three engines were shipped to KSC for installation on Columbia.

(emphasis mine)

Source SPACE TRANSPORTATION SYSTEM HAER No. TX-116

The shuttle program also infrequently conducted a "Flight Readiness Firing" using a vehicle stacked for flight, during which all three SSMEs were briefly ignited and then shut down on the pad. This was only done after delivery of a new Orbiter or if there was some compelling circumstance.

Test firing the engine accumulated "wear and tear" on it just like running it on the vehicle did.

$\endgroup$
2
  • 2
    $\begingroup$ A couple more data points: SpaceX not only does test fires of their engines, they routinely do static fires of their boosters before launch. And some engines can't be tested, since they use burst disks or pyrotechnic devices. The NK-15 engines used in the Soviet N1 rocket could only be fired once, and testing was limited to firing a subset of engines from each production batch. $\endgroup$ – Christopher James Huff Dec 29 '20 at 17:21
  • $\begingroup$ Shuttle also - rarely - did a "Flight Readiness Firing" on the launch pad where all 3 installed engines were fired. I should probably put that in the answer too. Thanks for the reminder. $\endgroup$ – Organic Marble Dec 29 '20 at 17:22
2
$\begingroup$

A footnote on page 82 of Pellegrino and Stoff's Chariots for Apollo reads "Lynn Radcliffe explains: The Teflon seals and other materials in the [lunar-module ascent] engine were good for only forty days after exposure to live propellants, so if you test-fired it or let live propellants get anywhere near the seals, you had to do you mission with forty days or throw the engine away. No test firings, which meant we had to make it right, make it reliable, so that when it was first fired in the vicinity of the moon, it would work...."

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.