Longest static fire?

Question

What is the longest duration for a static fire of a complete rocket stage?

Initially I wanted to ask this for Falcon 9 and Falcon Heavy

I found a 10 second static fire for Falcon Heavy - https://spacenews.com/spacex-conducts-falcon-heavy-static-fire-test/

I am asking because the Starship static fire seems very short

Related question - Longest continuous burning chemical rocket engine? where this answer says:

In August 1988 an SSME (Space Shuttle Main Engine; RS-25) was fired on the ground for 2017 seconds; over 33 minutes.

Answer 1

The success rate of the Saturn V is attributed, among other factors, to the extensive testing, in particular testing beyond the design parameters. The three stages of the Saturn V had the nominal thrust durations:

• S-1C: 160-170 seconds
• S-II: 360-370 seconds
• S-IVB: 450-500 second (combined)

All stages were subjected to full-duration static firing tests, which would make the S-IVB a good candidate. A full-duration static firing test for the S-IVB used on AS-201 (Saturn 1B configuration) took 452 seconds. Before that, a test of S-IV-10, used on a Saturn 1, even lasted 480 seconds.

The engines were routinely fired beyond their nominal thrust durations, but I have not found any evidence that they did this with the stages too.

In March 2021 a full-duration test of the SLS lasted 499.6 seconds to take the record.

Hat tip to @IronEagle.

Answer 2

Longest Static Fire of a rocket engine:
With you showing interest in the SSME firing (which was probably not attached to a full stage), the Glen Research Center operated a xenon gas engine (0.236 N thrust) continuously from 2003 to 2009 (48,000 hours or 5.5 years).

Longest Static Fire of a complete solid-fuel stage:
(See other answer for longest liquid-fuel stage)
In terms of a complete stage, one avenue is solid-fuel stages, as those tend to be tested in full.

• The legendary AJ-260 (an alternative solid-fuel-only Saturn V first stage) had a burn time of 114 seconds, and three test firings were conducted in 1965-67.

• The first stage of the Ariane-6 is currently in development, a solid-rocket motor with test firings of 135-140 seconds.

• The second stage of the OmegA rocket will be the Castor-300, which had a test firing in 2020 which lasted for 139 seconds.

• The second stage of the Athena I and II rockets was the solid-fueled Orbus 21D, with a burn time of 152-156 seconds. A test firing of duration 145 seconds was conducted on 1979-03-16.