Author Topic: Stage Testing  (Read 549 times)

Offline Obviousman

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Stage Testing
« on: January 04, 2021, 06:32:12 PM »
I was watching a documentary the other night and a senior NASA (Apollo-era) engineer said that the reason the N-1 failed was because they didn't have a facility to test (ground) fire the stages.

Is that right? I know that NASA had places like Huntsville and Michoud where stages could be test fired, and the 'all-up' testing promoted by people like Rocco Petrone was a major contributor to NASA meeting the 'end of the decade' deadline.

So was the first firing of a N-1 stage during a launch? No ground firing at all? Or did the Soviets have similar facilities and the gentleman's belief was perhaps unfair?

Offline smartcooky

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Re: Stage Testing
« Reply #1 on: January 04, 2021, 09:34:56 PM »
AIUI it was insufficient testing of the engine control system.

From Wikipedia https://en.wikipedia.org/wiki/N1_(rocket)
"Unlike Kennedy Space Center Launch Complex 39, the N1's Baikonur launch complex could not be reached by heavy barge. To allow transport by rail, all of the stages had to be shipped in pieces and assembled at the launch site. This led to difficulties in testing that contributed to the N1's lack of success."
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Offline Obviousman

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Re: Stage Testing
« Reply #2 on: January 05, 2021, 04:02:24 PM »
AIUI it was insufficient testing of the engine control system.

From Wikipedia https://en.wikipedia.org/wiki/N1_(rocket)
"Unlike Kennedy Space Center Launch Complex 39, the N1's Baikonur launch complex could not be reached by heavy barge. To allow transport by rail, all of the stages had to be shipped in pieces and assembled at the launch site. This led to difficulties in testing that contributed to the N1's lack of success."

So the Block A stage didn't get static fired whereas the remaining stages did.

The NK-15 engines had a number of valves that were activated by pyrotechnics rather than hydraulic or mechanical means, this being a weight-saving measure. Once shut, the valves could not be re-opened.[38] This meant that the engines for Block A were only test-fired individually and the entire cluster of 30 engines was never static test fired as a unit. Sergei Khrushchev stated that only two out of every batch of six engines were tested, and not the units actually intended for use in the booster. As a result, the complex and destructive vibrational modes (which ripped apart propellant lines and turbines), as well as exhaust plume and fluid dynamic problems (causing vehicle roll, vacuum cavitation, and other problems), in Block A were not discovered and worked out before flight.[39] Blocks B and V were static test fired as complete units.
« Last Edit: January 05, 2021, 04:10:50 PM by Obviousman »