Soviet Moonshot need more delta V?

[sevenperforce]

7 hours ago, kerbiloid said:

N-1 was equipped with NK-15.
NK-33 is its further modification.

Good catch.

7 hours ago, kerbiloid said:

8 hours ago, sevenperforce said:

their inability to be test-fired

in a pack 30 at once.

Poor rocket design + unfinished engine.

The NK-15 couldn't be test-fired at all. Once it had fired once, it was melted inside and useless.

You could certainly test it, but once you tested it, you couldn't use it again. In fact, that is how the test system ran. They would pick one engine out of the production run to test-fire and hope the rest of the engines in that production run also worked.

Could they have static-fired the N-1? Sure! They would have had to load all 30 engines onto the first stage, fill up the N-1, start up, shut down, and then replace all 30 engines.

[wumpus]

1 hour ago, sevenperforce said:

Could they have static-fired the N-1? Sure! They would have had to load all 30 engines onto the first stage, fill up the N-1, start up, shut down, and then replace all 30 engines.

I'm convinced they had to.  I suspect the engineers in the program knew this as well and also knew what it would do to the schedule (and budget) so it never happened.  There's no point in understanding how to build it right after you've blown the budget (and schedule) and you can't build it afterwards anyway.  All they could do was launch and hope the problems were small enough to fix on the fly (they weren't).  They at least got to test all the other systems at once.

I'm sure the engineers were also kicking themselves for not making the N-15 sufficiently similar to a non-slagging rocket that could act as a stand-in to test the control circuitry.  The requirements for those controls are mind boggling (think 90s Cisco gear in the 60s) and needed testing much more than the engines themselves.

In engineering, often the steps (which aren't often obvious) in between "off" and "working" are harder to get right than getting the working state to work right.  In large projects, this means that each little step has to be possible (note that I have no idea if the Nova could have met the pre-1970 schedule had Gemini not proven that lunar rendezvous was a reasonable choice.  This was merely an obvious individual step that needed to be done).

[IncongruousGoat]

11 hours ago, wumpus said:

I'm sure the engineers were also kicking themselves for not making the N-15 sufficiently similar to a non-slagging rocket that could act as a stand-in to test the control circuitry.  The requirements for those controls are mind boggling (think 90s Cisco gear in the 60s) and needed testing much more than the engines themselves.

Not only that, but Soviet avionics were notoriously poor. U.S. computing hardware was barely up to the task of what it was used for during Project Apollo, and it was on the bleeding edge of computing technology when it was designed. Soviet hardware was nowhere near as sophisticated. The Soviet design bureaus also had an unfortunate tendency towards over-complicated designs that tried to automate as much as possible, sacrificing redundancy and robustness along the way.

12 hours ago, sevenperforce said:

Good catch.

The NK-15 couldn't be test-fired at all. Once it had fired once, it was melted inside and useless.

You could certainly test it, but once you tested it, you couldn't use it again. In fact, that is how the test system ran. They would pick one engine out of the production run to test-fire and hope the rest of the engines in that production run also worked.

Could they have static-fired the N-1? Sure! They would have had to load all 30 engines onto the first stage, fill up the N-1, start up, shut down, and then replace all 30 engines.

There's another reason why the N1 couldn't test-fired - no hold-down mechanism. The booster just kinda sat on top of the flame trench, and lifted off the moment the TWR exceeded 1.0. They had no way to hold the booster down on the pad for a launch, and insufficient means to build a dedicated test site. The Soviet space program was in pretty dire financial (insofar as that term applies to the Soviet economy) straits at the time.

[sevenperforce]

11 hours ago, IncongruousGoat said:

Not only that, but Soviet avionics were notoriously poor. U.S. computing hardware was barely up to the task of what it was used for during Project Apollo, and it was on the bleeding edge of computing technology when it was designed. Soviet hardware was nowhere near as sophisticated. The Soviet design bureaus also had an unfortunate tendency towards over-complicated designs that tried to automate as much as possible, sacrificing redundancy and robustness along the way.

There's another reason why the N1 couldn't test-fired - no hold-down mechanism. The booster just kinda sat on top of the flame trench, and lifted off the moment the TWR exceeded 1.0. They had no way to hold the booster down on the pad for a launch, and insufficient means to build a dedicated test site. The Soviet space program was in pretty dire financial (insofar as that term applies to the Soviet economy) straits at the time.

I'm not entirely sure why the N-1 elected to use grid fins on its S1, but that might speak to overall lacks, too.