Re: Depressing
"It's not that the NK33 was particularly unreliable as an individual unit, just that they were used in a configuration where the failure of one, or a small number, had a grossly disproportionate impact on the rocket as whole."
Yep. Having lots of high-strung, new-model engines together gives a lot of chances for something to go wrong.
It's one reason I'm wary of SpaceX's 9-engine approach on the Falcon 9, and the planned 27-engine approach for its 3-core heavy design. More engines make you more likely to survive the failure of 1 (as happened with the Falcon 9), or 2 (as happened with the Saturn V), or even 3-4 (as happened with 747s) but every extra engine is another opportunity for failure. There's a point where extra engines begin increasing your risk, not lowering it. (I don't know what that number is - it is probably engine- and chassis-specific.)