Talk:NK-33
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This may be a stupid question, but can information be added to the article on whether the technical drawings and documents necessary to make more NK-33s still exist? From the paragraph "When the N-1 program was shut down, all work on the project was ordered destroyed. A bureaucrat instead took the engines, worth millions of dollars each, and stored them in a warehouse." it is not clear whether anything other than the physical engines themselves was preserved.
[edit] Thrust/weight
The source says 136:1. An anonymous editor has twice replaced this with 120:1, on the grounds that back pressure reduces the thrust at sea level.
I disagree with, and have removed this, on two grounds:
- doing so is OR (it disagrees with the quoted source)
- vehicle performance is usually relatively modestly affected by sea level thrust/weight ratio, but more strongly affected by burnout mass (which typically occurs in near vacuum conditions) and the average Isp.
- (User) WolfKeeper (Talk) 14:57, 4 January 2008 (UTC)
- "sea level thrust/weight is far less relevant, since it is the burnout weight that mostly determines the mass fraction"
You don't even realize why this is off, do you?
N1 stage construction was ridiculously beefy- discarded N1 tanks currently survive as small buildings. The weight of engines- particularly these advanced ones- is much less of a factor.
In the more general case, a "classic" first stage is used to generate altitude, not velocity. The vehicle should not attempt drastic acceleration until reaching the upper atmosphere; this minimizes drag loss and aerodynamic heating. Thus, the relevant equation is not so much Tsiolkovsky's, but more Newton's second.
More modern first stages still have significant non-engine masses. First stages are loaded with reserve propellant. This covers performance shortfalls, as virtually all engines do not reach the point of mass production to guarantee high levels of quality. In addition, reserve propellant prevents a rough MECO, and high loads which may damage the payload. MECO is typically the first- or second-most violent design load. In earlier decades, lower-than-expected orbits and rough rides had to be tolerated. Now, especially for commercial flights but also for precision instruments on scientific missions, the launch provider is expected to guarantee a minimum altitude, and take at least reasonable steps to limit maximum stresses.
And then there's pressurant. First stages are often pressurized with nitrogen, not helium. As burnout altitude and speed are not that high, the weight of a tankful (or two) of nitrogen is higher, but considered acceptable. Meanwhile nitrogen reduces costs significantly. For a good-sized stage, the weight of pressurant gas at burnout can reach into four digits.
That's the difference between book knowledge and working knowledge. May 4, 2008 —Preceding unsigned comment added by 128.8.238.186 (talk) 19:41, 4 May 2008 (UTC)
