Soviet Moonshot need more delta V?

[Jestersage]

While testing my UR-700 clone, I realize one thing that Saturn V does not really need to account as much: the inclination.

Kennedy Space Center is very close to the equator, so it's close to parallel to 0. Thus, the inclination change is not that high. Compare to launch from Baikonaur, they will need to do more inclination change -- one to close to 0 and one to Moon's inclination?

So does this also contribute to the failure for the Soviets to reach the moon -- because they need to expand more delta V (in addition to in fighting, N1 30 rockets / the need for efficent asparagus staging of UR-700)?

[sevenperforce]

4 minutes ago, Jestersage said:

While testing my UR-700 clone, I realize one thing that Saturn V does not really need to account as much: the inclination.

Kennedy Space Center is very close to the equator, so it's close to parallel to 0. Thus, the inclination change is not that high. Compare to launch from Baikonaur, they will need to do more inclination change -- one to close to 0 and one to Moon's inclination?

So does this also contribute to the failure for the Soviets to reach the moon -- because they need to expand more delta V (in addition to in fighting, N1 30 rockets / the need for efficent asparagus staging of UR-700)?

Good question. However, inclination change in cislunar space is really really cheap, dv-wise. So this probably wasn't the big deal.

[Bill Phil]

Not so much. It just adds another limitation to launch windows. You do get a slight reduction in performance, but it's not too much of an issue.

[Jestersage]

1 minute ago, sevenperforce said:

Good question. However, inclination change in cislunar space is really really cheap, dv-wise. So this probably wasn't the big deal.

Okay. So in theory, how would you launch from Woomerang to KSP's Mun? They are both at 45 degree North...

[Bill Phil]

7 minutes ago, Jestersage said:

Okay. So in theory, how would you launch from Woomerang to KSP's Mun? They are both at 45 degree North...

You launch into LEO and wait until you can transfer to the Mun. It's much easier in KSP since the Mun orbits above the equator of Kerbin. In real life, the Moon's orbit is not directly above the equator.

And the KSC isn't all that close to the equator. Closer than Baikonur, but still.

[VaPaL]

25 minutes ago, Jestersage said:

Okay. So in theory, how would you launch from Woomerang to KSP's Mun? They are both at 45 degree North...

If you have MJ to help you, do you Hohmann burn first, you won't get an encounter at first, than do an inclination change burn somewhere along the way (use "Fine tune closest approach" to 10km, for instance, on MJ). Nomally, for Minmus from an equatorail orbit, the inclination burn is about 60 or 70m/s.

If you wait for a better launch window, your inclination relative to your target (Mun/Minmus) will be lower, so will be the DV needed.

32 minutes ago, Bill Phil said:

And the KSC isn't all that close to the equator. Closer than Baikonur, but still.

No, but for a Moon launch is almost ideal, the Moon orbit inclination to the equator is 28°36'.

Baikonur Cosmodrome: 46°N
Kennedy Space Center: 27°28'N
Guiana Space Center: 5°N
Alcantara Launch Center: 2º18'S

[YNM]

You want your Moon (or Mün) encounter to be right at the ascending/descending node wrt the Moon (or Mün) orbit. This is why we have launch windows.

[sevenperforce]

35 minutes ago, YNM said:

You want your Moon (or Mün) encounter to be right at the ascending/descending node wrt the Moon (or Mün) orbit. This is why we have launch windows.

You don't need a launch window if you can hang out waiting for an alignment indefinitely.

2 hours ago, Jestersage said:

Okay. So in theory, how would you launch from Woomerang to KSP's Mun? They are both at 45 degree North...

Launch from Woomerang east-south-east, so that you'll reach the equator roughly as you reach initial apoapsis, then circularize until you get a nice high orbit. Wait there until you get a transfer window line up, then burn the rest of the way.

[NSEP]

2 hours ago, Jestersage said:

So does this also contribute to the failure for the Soviets to reach the moon -- because they need to expand more delta V

The amount of Delta-V needed for a Baikunur launch to the Moon isn't much larger than that of a Florida launch, so i doubt was a major problem. The Soviets had their succesfull unmanned Moon Landings, wich had these same problems, obviously got around the inclination problem. The failed unmanned attempts of the Soviets had nothing to do with inclination.

[sevenperforce]

5 minutes ago, NSEP said:

The amount of Delta-V needed for a Baikunur launch to the Moon isn't much larger than that of a Florida launch, so i doubt was a major problem. The Soviets had their succesfull unmanned Moon Landings, wich had these same problems, obviously got around the inclination problem. The failed unmanned attempts of the Soviets had nothing to do with inclination.

The Soviet moonshot failed because the N-1 failed, and the N-1 failed because the N-1's first stage failed, and the N-1's first stage failed (over and over and over again) because it was a rush job with untestable engines and a poor control computer.

[Jestersage]

Quote

The Soviet moonshot failed because the N-1 failed, 

More like the N-1 failed because N-1 is a poor design, chosen because of in fighting. UR-700 is a proper design. UR-700A is even better.

Edited June 5, 2018 by Jestersage

[KSK]

10 hours ago, Jestersage said:

More like the N-1 failed because N-1 is a poor design, chosen because of in fighting. UR-700 is a proper design. UR-700A is even better.

From a quick bit of reading up on this, UR-700 was an ambitious design in its own right. The RD-270 engine intended to power it was complex (full flow staged combustion), it was apparently going to use propellant cross-feed and it used hypergolic propellants with their relatively poorer specific impulse. That all adds up to a big rocket, with plenty to go wrong and the exciting prospect of spreading large quantities of UDMH and N₂O₂ across the landscape if anything did go wrong. I'm not sure if it would have been as nasty as the R-16 explosion  (bigger rocket vs slightly less nasty oxidiser) but it wouldn't have been any kind of picnic either.

Both rockets had advantages and disadvantages. I'm not sure I agree that either was necessarily better than the other, or that the UR-700 wouldn't have failed just as spectacularly (and more poisonously) as the N1.

Edited June 6, 2018 by KSK

[YNM]

3 hours ago, KSK said:

The RD-270 engine intended to power it was complex (full flow staged combustion), it was apparently going to use propellant cross-feed and it used hypergolic propellants with their relatively poorer specific impulse.

You nailed down the F-1 and the M-1, I'm pretty sure their headhonchos would nail down the same with whatever is it they came up with.

[KSK]

50 minutes ago, YNM said:

You nailed down the F-1 and the M-1, I'm pretty sure their headhonchos would nail down the same with whatever is it they came up with.

The F1 was a relatively simple engine design with a relatively low chamber pressure - it was just very big. Granted, that bigness (for want of a better word) caused all sorts of problems along the way, most notably with combustion instability. I'm not sure about the M1 - Wikipedia tells me it was designed and component tested but I don't know whether an actual complete engine was tested.

The RD-270 had performance comparable to the F1 (6,300 KN thrust at sea level vs 6,700 KN or thereabouts) but used a much higher chamber pressure (26.1 MPa vs 7MPa) and a more complicated cycle (full flow staged combustion vs gas generator). All numbers pulled from Wikipedia again, in case anyone has any counter-sources.

The Soviets built some amazing rocket engines, so I'm sure they could have got the RD-270 to work. However, I think they would have had all the scale-up problems that the F1 faced plus a whole bunch of other problems on top.

Which is why I'm disagreeing that the UR-700 was necessarily a better solution than the N1.

 

[kerbiloid]

33 minutes ago, KSK said:

I'm sure they could have got the RD-270 to work

http://www.astronautix.com/r/rd-270.html

40 fire tests have been done, with several units.

P.S.
But you can like this one. Powered by kerolox engines.

Edited June 6, 2018 by kerbiloid

[YNM]

43 minutes ago, KSK said:

Which is why I'm disagreeing that the UR-700 was necessarily a better solution than the N1.

N1's flaws are far more apparent. But I'm not an actual rocket engineer so I can't comment on the truth of that statement, it might well be blatantly wrong.

[sevenperforce]

16 hours ago, Jestersage said:

More like the N-1 failed because N-1 is a poor design, chosen because of in fighting. UR-700 is a proper design. UR-700A is even better.

All rocket failures (excluding sabotage) are due to poor design.

[wumpus]

22 minutes ago, sevenperforce said:

All rocket failures (excluding sabotage) are due to poor design.

All rocket failures are human failures.  Most fail due to errors in design.  Challenger was a program management failure.  Spaceship One was a combination design and pilot error.

16 hours ago, sevenperforce said:

The Soviet moonshot failed because the N-1 failed, and the N-1 failed because the N-1's first stage failed, and the N-1's first stage failed (over and over and over again) because it was a rush job with untestable engines and a poor control computer.

I'm curious why the rockets were so untestable.  Presumably you had to test them vertically, keep them above anything that burns/melts when rocket flame present (i.e. everything), and restrain them with more force than the weight of an N-1 rocket.  I have to get back to reading "Rockets and People", but while the US may have snatched up all the V-2 rocket scientists, the Soviets managed to grab any test rigs in sight (and were happy to get them).  I'd assume that such test equipment would still have a high priority in building the N-1.

I can only assume that such a rig was possible, but by the time the necessity of such was obvious it couldn't be built remotely before Apollo landed on the Moon.  I'm guessing that the difficulty of strapping that many engines together wasn't obvious (I still can't imagine the control circuitry, it sounds like it is up there with the CDC6600*), and there may have been bureaucratic issues (see the "it wouldn't explode, since Glushko's engines were reliable and didn't fail" defense of the RD-270).

* the CDC6600 was a super computer designed by Seymour Cray and shipped at the end of the 1960s.  It lead to a famous memo by an IBM executive that their high profile "stretch" computer was beaten by "34 guys and a janitor" (which was certainly an exaggeration, but do you really think IBM would deal with a manager whose status report would read "[yearly status report: 1/6 way of building the world's fastest computer]"?).  Even more to the point, one of the lead engineers (Throton) wrote a book on the design "Design of a Computer", and I think it is still available free as an e-book. http://ed-thelen.org/comp-hist/DesignOfAComputer_CDC6600.pdf

Edited June 6, 2018 by wumpus

[sevenperforce]

39 minutes ago, wumpus said:

All rocket failures are human failures.  Most fail due to errors in design.  Challenger was a program management failure.  Spaceship One was a combination design and pilot error.

Challenger and Columbia and SpaceShip One all trace to design problems. If it's designed properly, later human error is accommodated for.

39 minutes ago, wumpus said:

I'm curious why the rockets were so untestable.  Presumably you had to test them vertically, keep them above anything that burns/melts when rocket flame present (i.e. everything), and restrain them with more force than the weight of an N-1 rocket.  I have to get back to reading "Rockets and People", but while the US may have snatched up all the V-2 rocket scientists, the Soviets managed to grab any test rigs in sight (and were happy to get them).  I'd assume that such test equipment would still have a high priority in building the N-1.

The NK-33 uses ORSC (oxy-rich staged combustion) that melts turbopumps like butter. As a result, it's cooled ablatively. You can't fire the engine more than once because it ablates away the structure.

[KSK]

2 hours ago, kerbiloid said:

http://www.astronautix.com/r/rd-270.html

40 fire tests have been done, with several units.

Cool. Taken from that same article though:

 “Authorised  for development in the 1962-1971 period, the RD-270 was Glushko's answer to the US F-1 rocket engine and was the largest rocket engine ever built in the Soviet Union. It was to be used on Chelomei's UR-700 lunar vehicle or Yangel's R-56 monster rocket. The UR-700 would have used 6 RD-270 in the first stage. No design bureau would attempt anything like it today. It was the maximum possible power from the design: gas and gas mixture in the combustion chamber; two gas generators in the combustion chamber; one oxidizer rich and one fuel rich; closed cycle; staged burning; very high pressure in the combustion chamber (266 bar compared to about 80 bar in many today, except the SSME). Thrust was 640,000 kgf. Hot fire tests had started (with 40 done) and some units had been proved. Engine head testing had started. The peak of problems had almost been surmounted when all the N-1 lunar program was closed down and efforts had to stop. It never was used on a flight vehicle and funding ran out before combustion instability problems could be solved. Wet Mass: 5603 kg wet. Engine Cycle: closed staged. Feed Method: turbo-pump.”

Emphasis added. It seems they got a lot of testing done, proved a lot of the components but didn’t have a reliably working engine before funding was pulled. In other words, pretty much what I said. They might have been able to get it to work but were facing some of the same problems as the F1 team.

The UR-700 might  have been a better choice than the N1. We’ll probably never know. But I stand by my original opinion that it wasn’t the obviously better choice that @Jestersage implied. 

Edit. Sorry about the text size - posting from my phone.

Edited June 6, 2018 by KSK

[Jim DiGriz]

You don't need to match inclinations with the Moon.  You can launch into a polar orbit and transfer to the moon just fine.   The timing of the launch becomes more of an issue in order to select  a plane where the transfer orbit will be cheap.

[wumpus]

7 hours ago, sevenperforce said:

The NK-33 uses ORSC (oxy-rich staged combustion) that melts turbopumps like butter. As a result, it's cooled ablatively. You can't fire the engine more than once because it ablates away the structure.

I have a hard time believing you would get better telemetry from a launch than a test jig (at least for the stage the rocket was in when they canceled).  Perhaps it worked when fixed in a test jig, but kept needing to be shut down as attached to a rocket?  I have to admit that knowing this makes my impression of the decision to use these (specific engines) in the Antares rocket much less a good idea.

[mikegarrison]

For any prograde orbit doesn't KSC get some free V compared to Baikonaur just because it's got a bigger lever arm from the axis of rotation?

[sevenperforce]

5 hours ago, wumpus said:

I have a hard time believing you would get better telemetry from a launch than a test jig (at least for the stage the rocket was in when they canceled).  Perhaps it worked when fixed in a test jig, but kept needing to be shut down as attached to a rocket?  I have to admit that knowing this makes my impression of the decision to use these (specific engines) in the Antares rocket much less a good idea.

The NK-33s were not unreliable engines (although N-1's second failure did originate in one of the LOX turbopumps due to burn-through, probably the result of a manufacturing defect); with that one exception, all 119 other NK-33s launched in the N-1 test program performed perfectly, as far as the individual engines are concerned. The problems all came from firing all thirty engines together. The NK-33s couldn't be test-fired, so they couldn't do a brief test fire (like a Falcon 9 and Falcon Heavy) with the whole stack. Issues like pogo and wiring interactions popped up only in a full stack.

So while the engines themselves are fairly reliable (given their cutting-edge design), their inability to be test-fired doomed the N-1's first stage from the kind of testing it would have needed to perform properly.

4 hours ago, mikegarrison said:

For any prograde orbit doesn't KSC get some free V compared to Baikonaur just because it's got a bigger lever arm from the axis of rotation?

Yes, but not a lot. Advantage of a lower-latitude launch is more about needing less dV for inclination matching than about needing less dV for getting orbital.

Edited June 7, 2018 by sevenperforce

[kerbiloid]

1 hour ago, sevenperforce said:

The NK-33s were not unreliable engines

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

1 hour ago, sevenperforce said:

their inability to be test-fired

in a pack 30 at once.

Poor rocket design + unfinished engine.

Edited June 7, 2018 by kerbiloid