Author Topic: Was N1's failure due to the number of engines? (seeking clarification)  (Read 11471 times)

Offline Pipcard

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With the recent reveal of SpaceX's plans for a 42-engine heavy-lift rocket, some people are worried that this would be N1 all over again. But what actually caused its failure? Did it have to do with having 30 engines and complex plumbing? Or was it about not being able to do proper test fires?
« Last Edit: 10/12/2016 05:50 PM by Pipcard »

Offline Kansan52

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You'll likely receive posts that each of the items you mention are suspect.

The failure of the same engines on the test stand here and on Orbital's Antares points to the engines (IMHO).

Offline teetlebomb

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Knowing more about the N1 failures is something I would like to know.

In my perspective (as a systems (although not rocketry) programmer), the failure came down to improper or insufficient testing in the KORD control system. From what I understand, KORD could not react properly (or in-time) to handle all the situations that were input to it by the high number of engines.

With modern day rocket control technologies, I don't think controlling 42 engines will be a major problem.

Offline edkyle99

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In my mind, the first key problem was that none of the first stages were ever test fired on a test stand!  The Soviets chose to skip that step and it cost them. 

The second key problem was the reliability of the engines, but that wasn't as big a problem as the system engineering problems that caused most of the failures.  Those problems might have been solved during an extensive series of test stand firings.

 - Ed Kyle
« Last Edit: 10/12/2016 06:31 PM by edkyle99 »

Online Space Ghost 1962

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N1 flew with NK-15/15V's not NK33/43.  N1-8 had them but was unflown/scrapped. See Soviet Moon rocket plunges to the ground after a minute in flight for the "blow by blow" on this.

NK33 flew as reworked with AJ gimbals as AJ26 flew 4 engines on two flights successfully. Twice with a four nozzled steering engine (NK-33 was fixed) on single engined Soyuz 2.1v.

There have been at least two test stand failures prior to flights. One did extensive damage to the test stand.

It is hard to examine the NK33 results due to the gap in time and also the nature of how they were stored and "re-qualified" for flight - these and the elapsed time (many decades) may have played a significant role in all failures.

Irrespective of design, consolidation of manufacturing decision led to not restarting production, thus discontinuing NK-33 use. So we'll never know.
 
As to the OP, suggest that the question can't be answered as stated, because too much of the program had so many flaws, that attempting to answer it might do a disservice.

A better answer is to examine Falcon 9 (and perhaps eventually Falcon Heavy) because there is more flight history, it is a better run program that has more accountability and transparency, not to mention is also current with current technology.

Know that's not the answer you want, but that's what you have.

IMHO N1 could have been successful given other conditions than it experienced. Saturn V program had vastly more advantages as a program to start with, which allowed it less program risk, which meant that it arrived ahead of schedule with a better measure of confidence. N1 program's lack of those advantages meant that the program risk exceeded it's designers/builders/operators capabilities to "bring in the program" fast enough to garner a success. Which was a "common mode" for other like programs between both.

As an eye to ITS, its "how" you execute on a program as much as the design that matters.

In my mind, the first key problem was that none of the first stages were ever test fired on a test stand!  The Soviets chose to skip that step and it cost them.

Nor did they, like Antares and unlike Saturn S1C, test fire the entire stage independently.

Quote
The second key problem was the reliability of the engines, but that wasn't as big a problem as the system engineering problems that caused most of the failures.  Those problems might have been solved during an extensive series of test stand firings.
The general thought was that they'd accept the fact that the first ones WOULD BLOW UP, and they'd be smart enough to figure out why and fix before they exhausted the program. And that the "speed"/"cost" advantage they'd gain by NOT doing the testing/etc would mean they'd outmaneuver rivals, as sometimes (but not this time) they did.

Which is why it's a BAD IDEA(TM) to use N1 as a reference case for "too many engines" ...

Online Space Ghost 1962

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Knowing more about the N1 failures is something I would like to know.
See above, read all the flight history.

Quote
In my perspective (as a systems (although not rocketry) programmer), the failure came down to improper or insufficient testing in the KORD control system. From what I understand, KORD could not react properly (or in-time) to handle all the situations that were input to it by the high number of engines.
Not the root cause.

Quote
With modern day rocket control technologies, I don't think controlling 42 engines will be a major problem.

Unproven either way with N1. Nor F9. However, N < 12 is adequately proved, so the need for a single engine per stage (as with Ariane 5/6, Atlas V, DIV, others) is no longer the "gold standard".

The alternative of huge, lower pressure, less efficient combustion chamber engines (as with F1) however is not in doubt. They are obsolete and not coming back.

Offline Hobbes-22

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The general thought was that they'd accept the fact that the first ones WOULD BLOW UP, and they'd be smart enough to figure out why and fix before they exhausted the program. And that the "speed"/"cost" advantage they'd gain by NOT doing the testing/etc would mean they'd outmaneuver rivals, as sometimes (but not this time) they did.

Which is why it's a BAD IDEA(TM) to use N1 as a reference case for "too many engines" ...

They were counting on having ~14 test flights before the first manned mission, and losing a large fraction of them. Cost was a major factor, ISTR they skipped the first stage test stand because it'd tie up too much of the available concrete production capacity at the time (but I haven't been able to find a reference for that anywhere).

They ran several hundred engine tests, so there was little doubt about the individual engines.

Offline Michel Van

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There Were several reason were N1 failed

1. Sergei Korolev who envision the N1 died during the program in 1966.

2. his successor Vasily Mishin had to make modifications to N1 to increase it payload
installment of 6 additional NK-15 engines in center, increase complexity of feed lines in rocket.
Super cooling of Liquid Oxygen and Kerosine to get more fuel into tanks
i have the suspicion that Mishin not change the steel of feed lines for Liquid oxygen
and that was to brittle for super cool Liquid oxygen


3. the installed NK-15 were not tested, just one of two from production taken and fired
the rest were build into rocket, after N1 destroy it's launch pad
they start to check all NK-15 and find allot bad welding and metal shaving inside the engines
A turbopump sucking in metal shaving can rupture and explode

4. Flight computer KORD was junk
it never work properly on first launches, as they discover that engines produce a vibration
in same frequency as KORD clock frequency !
later version of KORD work on another clock frequency and covert in asbestos protection against fire.

5. a Shoe string Budget
in contrast to NASA, the MoM had Not vast money reserve for Lunar program
so there were no Test Stand for stages of N1 rocket
while NASA tested there Saturn V stages bevor assembly at cape,
hope Vasily Mishin to do 12 to 14 test flight until N1 was ready

6. forget Dallas or Dynasty, the real drama is in Soviet Moon program
the Soviet Space Program is full of Intrigue worthy for a play by  William Shakespeare.
instead to combine there best effort, the major Chief Designers  fight each other in
Chelomei proposed UR-500 and UR-700 rocket with Lk-1 and LK-700 lander
Valentin Glushko refused to build the N1 rocket engines, if not use NTO/UMHD fuel
so the Kuznetsov Design Bureau inexperienced in Rocket engine had to build them.
as in end Valentin Glushko replaced Mishin, instead to get last bugs out the N1.
He order end of program and total destruction of N1 hardware...

and start new program called "Vulcan" what became Energia/Buran in 1976
« Last Edit: 10/12/2016 08:15 PM by Michel Van »

Offline whitelancer64

With the recent reveal of SpaceX's plans for a 42-engine heavy-lift rocket, some people are worried that this would be N1 all over again. But what actually caused its failure? Did it have to do with having 30 engines and complex plumbing? Or was it about not being able to do proper test fires?

Wikipedia has an excellent N-1 entry, which includes a section with the 4-flight history. I suggest that be read, but to summarize:

Flight 1 - Very early in flight, the rocket's control system shut down two engines in error due to a short circuit. The shutdowns caused POGO oscillations which ruptured a LOX line. Further oscillations ruptured an RP-1 line some 20 seconds later, which resulted in a fire. The fire burned through the wires of the flight control system, which caused it to shut down the entire rocket, including the 2nd and 3rd stages, at 68 seconds into the flight. The rocket subsequently fell to the ground. On the plus side, the launch escape system on the boilerplate spacecraft on top worked perfectly.

Basically the cause of failure was bad wiring of instrumentation and poor programming of the rocket's computers that ran the control system. POGO oscillations and vibrations contributed to the failure as well.

Flight 2 - The most well known failure, a few seconds after liftoff all of the rocket's engines - except for one - shut down and it crashed back on the launch site, exploding and destroying the launch pad. On the plus side, once again, the launch escape system worked perfectly.

Just before liftoff a turbopump on one of the engines exploded, severing nearby fuel lines and starting a fire. The control system shut down two engines, but engineers could not determine why all the other engines were shut down, nor why one continued to operate after that point. Initial causes of the turbopump failure was speculated to be injestion of debris, and subsequently the rocket had fuel and oxidizer filters installed.

Flight 3 - An roll began shortly after liftoff, which quickly exceeded the rocket's ability to control. After the 2nd flight destroyed the launch pad, an interlock was installed to prevent the computer from shutting down the rocket until 50 seconds into flight, so the rocket continued to fly and the roll worsened until structural failure occurred, the first stage twisted apart at the interstage structure and separated from the rest of the rocket, both parts remained intact until impact with the ground. This rocket had a boilerplate spacecraft with no launch escape system.

The roll was later determined to be caused by aerodynamic forces from the rocket exhaust swirling around the base of the rocket.

Flight 4 - This rocket had a much more powerful stabilization system with dedicated roll control rockets and a beefed up flight control system with 13,000 sensors (the previous flight control computers only had 700 sensors). The flight went well until a programmed shut down of 6 engines to reduce aerodynamic loads on the rocket. This induced a shock wave that ruptured fuel and oxidizer lines, starting a fire. The first stage exploded 107 seconds into the flight, which caused the launch escape system to pull the prototype lunar spacecraft away from the rocket, which once again worked perfectly.

Could any of these doom another rocket? Yes, but we've learned a lot about how to fly rockets since then. All of these failure scenarios happened to the early Atlas, Titan, et al. rockets as well.

TL;DR?

Flight 1 - bad flight control computer wiring / programming and POGO - bad flight controls are most likely not a problem for SpaceX and POGO is very well understood now, and is relatively simple to design out of a system.
Flight 2 - turbopump explodes, possibly from injesting debris - Elon Musk has been famously paranoid about this, the Merlins were designed to handle small debris and they do have fuel filters.
Flight 3 - unexpected aerodynamic interactions - much less likely today, we've got fabulous computer simulations for aerodynamics that would help us avoid this.
Flight 4 - unexpected shock waves from engine shut downs - again, something SpaceX most likely has a handle on from previous flight experience.

As an addendum, none of the N-1 failures were because the rocket had too many engines, it had numerous other flaws that would have caused it to fail with fewer engines. Flight 4 came close to succeeding and the redesigned N1-L3 would likely have been successful. Sure, there are more fuel feed lines and turbopumps that could cause an issue, but good design work and computer simulations can help avoid those now.

I think the final take-away is this: no matter what, always have a launch escape system on your rocket.
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Offline Toast

Flight 1 - bad flight control computer wiring / programming and POGO - bad flight controls are most likely not a problem for SpaceX and POGO is very well understood now, and is relatively simple to design out of a system.
Flight 2 - turbopump explodes, possibly from injesting debris - Elon Musk has been famously paranoid about this, the Merlins were designed to handle small debris and they do have fuel filters.
Flight 3 - unexpected aerodynamic interactions - much less likely today, we've got fabulous computer simulations for aerodynamics that would help us avoid this.
Flight 4 - unexpected shock waves from engine shut downs - again, something SpaceX most likely has a handle on from previous flight experience.

Going back to what edkyle said:

And to
In my mind, the first key problem was that none of the first stages were ever test fired on a test stand!  The Soviets chose to skip that step and it cost them. 

The third failure was the only one that likely could not have been caught by more extensive testing of the rocket after assembly. The component testing was flawed, but there was pretty much no integration testing at all.

Offline whitelancer64


Going back to what edkyle said:

And to
In my mind, the first key problem was that none of the first stages were ever test fired on a test stand!  The Soviets chose to skip that step and it cost them. 

The third failure was the only one that likely could not have been caught by more extensive testing of the rocket after assembly. The component testing was flawed, but there was pretty much no integration testing at all.

Very true. One of the reasons we won the moon race was extensive pre-flight testing.

Though it is worth noting that Apollo 4 and 6 were all-up flight tests. Apollo 6 suffered from severe POGO oscillations and the 2nd stage controller was cross-wired such that it shut down a good engine when another one failed, nearly caused the failure of the entire flight.
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Offline savuporo

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Unproven either way with N1. Nor F9. However, N < 12 is adequately proved, so the need for a single engine per stage (as with Ariane 5/6, Atlas V, DIV, others) is no longer the "gold standard".
R-7 and Soyuz-U specifically is the single most launched carrier rocket ever, and kind of defines the gold standard with its reliability. Definitively not a single engine per stage.
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Offline Oli

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Unproven either way with N1. Nor F9. However, N < 12 is adequately proved, so the need for a single engine per stage (as with Ariane 5/6, Atlas V, DIV, others) is no longer the "gold standard".
R-7 and Soyuz-U specifically is the single most launched carrier rocket ever, and kind of defines the gold standard with its reliability. Definitively not a single engine per stage.

Definitively a single engine per stage. Unless you count the 4 boosters as one stage.
« Last Edit: 10/13/2016 06:40 AM by Oli »

Offline savuporo

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Unproven either way with N1. Nor F9. However, N < 12 is adequately proved, so the need for a single engine per stage (as with Ariane 5/6, Atlas V, DIV, others) is no longer the "gold standard".
R-7 and Soyuz-U specifically is the single most launched carrier rocket ever, and kind of defines the gold standard with its reliability. Definitively not a single engine per stage.

Definitively a single engine per stage. Unless you count the 4 boosters as one stage.
Uh, Soyuz has 32 liquid engine thrust chambers going off at launch, lit by a giant matches made out of birch wood. It's not single engine by any stretch of imagination.
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Offline rocx

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Unproven either way with N1. Nor F9. However, N < 12 is adequately proved, so the need for a single engine per stage (as with Ariane 5/6, Atlas V, DIV, others) is no longer the "gold standard".
R-7 and Soyuz-U specifically is the single most launched carrier rocket ever, and kind of defines the gold standard with its reliability. Definitively not a single engine per stage.

Definitively a single engine per stage. Unless you count the 4 boosters as one stage.
Uh, Soyuz has 32 liquid engine thrust chambers going off at launch, lit by a giant matches made out of birch wood. It's not single engine by any stretch of imagination.
Yet most rocket engineers qualify the RD-107 (or RD-108), which the core and each of the four boosters have one of, as one engine with four nozzles, because of its shared turbopump and other parts.
Any day with a rocket landing is a fantastic day.

Offline edkyle99

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Uh, Soyuz has 32 liquid engine thrust chambers going off at launch, lit by a giant matches made out of birch wood. It's not single engine by any stretch of imagination.
It is five engines at liftoff, one in the center "second" stage and one each on the four booster "first" stages.  Each engine has one turbopump feeding six to eight thrust chambers.  (The turbopump is really the "engine" part of the machine.)  The design was clever, because use of multiple chambers allowed each chamber to be shaped for higher ISP while still combining to produce the needed thrust.

 - Ed Kyle
« Last Edit: 10/13/2016 03:16 PM by edkyle99 »

Online ncb1397

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The general thought was that they'd accept the fact that the first ones WOULD BLOW UP, and they'd be smart enough to figure out why and fix before they exhausted the program. And that the "speed"/"cost" advantage they'd gain by NOT doing the testing/etc would mean they'd outmaneuver rivals, as sometimes (but not this time) they did.

Which is why it's a BAD IDEA(TM) to use N1 as a reference case for "too many engines" ...

SpaceX will be using the same N-1 philosophy of having to accept initial failures if Falcon is anything to go by. So far there has been 3 Falcon 1 launch failures, Falcon-9 Dev-1, a F9 pad failure, 5 Falcon 9 landing failures and CRS-7. Even assuming the booster or ship only costs ~$200 million each, we are talking a couple billion dollars for a similar number of failures.

Offline edkyle99

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SpaceX will be using the same N-1 philosophy of having to accept initial failures if Falcon is anything to go by.
I don't see that myself.  Unlike the N-1 planners, SpaceX has spent a lot of money and effort ground testing its stages, both during the development period and continuing now with acceptance testing.  It has suffered launch and pad failures, but I think that its failure rate is generally consistent with most "brand new" launch vehicle families.  You can compare with Ariane 5, and H-2, both of which suffered frustrating failures in their early years.   Ariane 5 had four failures in its first 14 flights.  H-2(A) had three failures in its first 13 flights.  Falcon 9 has had three failures in its first 29 launch campaigns if you count AMOS 6 and CRS-1 as failures.  Only one, the CRS-1 launch, suffered a problem with the 9-engine first stage (CRS-1 made orbit, but the secondary payload was lost).

 - Ed Kyle
« Last Edit: 10/14/2016 03:48 AM by edkyle99 »

Offline georgegassaway

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While lack of static test firing of the stages was a critical problem, there was also a lack of dynamic (vibration) testing.  Here’s a Wiki link about the stand at MSFC used for the Saturn-V, and later also used by the shuttle (First time a shuttle was stacked, was Enterprise inside of this building).

https://en.wikipedia.org/wiki/Saturn_V_Dynamic_Test_Stand



Since some of the N1 failures were related to vibration issues, lack of dynamic testing was a major issue.  Can’t find out everything by just a static test firing, that would not simulate the vibrations that shook some of the N1 components apart.

IIRC, maybe it was in “Stages to Saturn”, where it was stated that the Russians budgeted their Lunar program (or perhaps it was the N1 specifically), at about 20% of the cost of Apollo (or Saturn-V).  As such, they cut so many things to the bone, that they effectively cut off some appendages too by not doing static firings  and not doing vibration testing.

Now, in the case of SpaceX, modern computer programming and perhaps some small scale dynamic testing (models) may have allowed them  to get by without doing dynamic testing of a fully stacked Falcon, or perhaps they did do full size vibration testing (I am unfamiliar with the dynamic vibration testing done with any launch vehicles of today).  Certainly they static test fire the “heck” out of the stages.

Also as stated, the “KORD” control system was really screwy. 

So as regards FH with 27 engines vs N1 with 30, Apples and Bricks comparison.  Statistically, FH should have no more odds of one out of 27 engines having a problem, compared to any three Falcon-9 launches.  At least as regards the total of 27 engines and the three boosters that each 9 are mounted in, not counting any potential unique FH issues.

 If they lose one engine on say the left booster (without a “bang” to cause a RUD), they can throttle down the 9 on the right side to about 91% throttle, albeit with some performance hit to the orbit.   But so far they’ve only had one Falcon-9 engine fail during a launch and that was a long time ago.
« Last Edit: 10/14/2016 04:58 AM by georgegassaway »

Offline Arch Admiral

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The real problem with the NK-15 engines is that the actual flight engines could not be static tested. Many valves were opened and closed with pyros instead of hydraulic or pneumatic power. After a test run the valves were welded shut and could not be opened. I think this technique was developed for the GR-1 FOBS system, and retained for N-1 as a weight-saving device.

The test policy was to accept engines from the factory in lots of 6. 2 were sent to the Kuznetsov Bureau's test facility and tested, then scrapped. If these two completed one full burn, the other 4 were sent to Baikonur and installed in the stages without any testing. Thus it is not surprising that out of 120 flight engine runs, there were two turbopump explosions and one hot gas leak (the actual cause of the first flight failure). Every Saturn V engine had made three full-duration test burns, one of which was in the flight stages at Stennis.

The official causes of the 4 N-1 flight failures as given in Wikipedia are not accurate. The Soviets had the pernicious practice of having the Chief Designer of the suspected system lead the failure board. Of course Kuznetsov and his staff went to great lengths to exonerate his engines and blame everything on other designer's systems. These other designers pushed back and the final reports were political compromises. There was no evidence that debris in the propellant tanks caused any of the three engine failures. The most convincing account of the N-1 failures is in Vol. 4 of Boris Chertok's memoirs at the NASA History website.

The idea that N-1 could have been a success with the improved NK-33 engines is disproved by the terrible record of these engines in the Antares program. That failure board tore down many NK-33s in stock at Aerojet and found that about 1/3 had metal missing from the turbopump shaft. This was probably a machining error by the night shift at Kuznetsov's factory that was missed by quality control. (How was this missed by Aerojet when they rebuilt the engines????)

So N-1 failed because

A) there were too many engines
B) they were packed too close together
C) individually they had terrible quality control and nonexistent testing

plus many structural, aerodynamic, and electrical defects too numerous to mention.


Offline Toast

A) there were too many engines
B) they were packed too close together
C) individually they had terrible quality control and nonexistent testing

I disagree with you on both A and B. Having thirty engines was not what caused the failures, it was poor quality control practices. The rest of your post seems to support the same conclusion--the fact that the NK-15 engines could not be static tested is a massive problem. So the issue isn't that there's thirty engines instead of one really big one, it's that those engines weren't reliable. The close packing also isn't the root cause--had they been properly shielded from one another (e.g. Falcon 9 octoweb) then the proximity is irrelevant. It's your third point that's the real problem: Lax quality control and testing.

Offline baldusi

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Nothing was ground tested. Even the tanks were shipped in parts, welded on site and used. They didn't had a dynamic test stand, the NK-15 used munition acceptance testing (I think it was 3/8 rather than 2/6). And it didn't had economic nor performance reserved. They originally pretended to do with a 80 tonne to LEO rocket, and then they had to increase it to 95. Which was still insufficient.
In my mind, the N-1 was an example of how not to manage a project from a system engineering POV. They started with the rocket, rather than the payload. They didn't had the minimum budget nor schedule reserves. They didn't had any small demonstrator project. They did away with the ground validation and testing, both for the design and for each flight vehicle. Mishin went with the most complex system possible.
And they were used to that because Koroloev had been a genius and had had some luck. He died mid project and their lucky streak run out.
That's as short as I can state it.

Offline John-H

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Projects always seem to be more successful with a "hands on"  Chief Designer. I am having a hard time thinking of a large, successful project without a name attached to it.

John

Offline Patchouli

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Nothing was ground tested. Even the tanks were shipped in parts, welded on site and used. They didn't had a dynamic test stand, the NK-15 used munition acceptance testing (I think it was 3/8 rather than 2/6). And it didn't had economic nor performance reserved. They originally pretended to do with a 80 tonne to LEO rocket, and then they had to increase it to 95. Which was still insufficient.
In my mind, the N-1 was an example of how not to manage a project from a system engineering POV. They started with the rocket, rather than the payload. They didn't had the minimum budget nor schedule reserves. They didn't had any small demonstrator project. They did away with the ground validation and testing, both for the design and for each flight vehicle. Mishin went with the most complex system possible.
And they were used to that because Koroloev had been a genius and had had some luck. He died mid project and their lucky streak run out.
That's as short as I can state it.

Had Korolev not died the Soviets probably would been the second to land on the moon.

The N1 almost worked on flight four though a test stand probably would have exposed that failure mode.
« Last Edit: 10/21/2016 02:46 AM by Patchouli »

Offline savuporo

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Projects always seem to be more successful with a "hands on"  Chief Designer. I am having a hard time thinking of a large, successful project without a name attached to it.

John

Space shuttle. George Mueller's name is attached to it, but he wasn't a hands on chief designer. Hard to credit any single person
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Offline ThereIWas3

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The excellent BBC mini-series "Space Race" is currently on NetFlix.  It is one of the best dramatizations I have seen of what was going on in the US and Russian space programs at the time.  I think it is 4 episodes.   The lack of funding in the Russian program is covered as well as the personality conflicts.
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Offline Patchouli

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The excellent BBC mini-series "Space Race" is currently on NetFlix.  It is one of the best dramatizations I have seen of what was going on in the US and Russian space programs at the time.  I think it is 4 episodes.   The lack of funding in the Russian program is covered as well as the personality conflicts.

Conflict was one of the problems with in the Soviet space program.

Glushko and Korolev didn't exactly see eye to eye on issues such as use of cryogenic propellants and hypergolics.
One big issue the Soviets had was they never were able to solve the combustion stability issues for large chambers. Glusko's solution was in the end for the RD-170 was to just use four smaller chambers.


Offline baldusi

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Had Korolev not died the Soviets probably would been the second to land on the moon.

The N1 almost worked on flight four though a test stand probably would have exposed that failure mode.
From Chertok's memoir, I get the impression that even with Korolev's capability intact, it would have been a failure. They were on the verge of switching engines. They hadn't even proved the second stage, and they had five rocket stages, plus two spacecraft, each with its own propulsion module.
And those were basically dummies in the first three launches. Yes, Blok-D had worked on Proton-K, and LOK was closely related to the Zond 3 to 6, it was not complete.
But more importantly, they didn't had the mass reserves. When the Grumman engineers presented Von Braun with a 25% mass reserve, he increased that to 50%. That determined the size of Saturn V (a 4 F-1 rocket would have been needed otherwise). They had the equivalent of a 120 tonne to LEO launcher, and two hydrolox upper stages, which equated to 45tonnes to TMI.
Korolev started with 80 tonnes to LEO (not the correct TMI capability), and then had to add stages and engines until he was at a 95 tonne to LEO kludge. I simply don't see how it could have been a successful launcher without at least 20 missions. And they had no time, schedule nor political will for such a program.
And the fact that they basically had no acceptance testing for the big stages with tens of engines meant that they were never ever going to have a highly reliable rocket.
Just compare that to the Energyia/Buran program that was handled extremely professionally and which has left a legacy that has lasted for more than 30 years. It was very clear that they learned their lesson.

Offline Robotbeat

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I agree with everything Ed Kyle said.

N-1 could've worked if they either stuck with it for a few more failures or if they did significant ground testing.

Having 42 engines is a lot, but nothing that can't fundamentally be done.

And SpaceX has done a lot of ground testing. Perhaps even too much! Regardless, lots of testing will be critical to the success of ITS and is a big part of its multi billion dollar price tag.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Arch Admiral

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Another fundamental defect in the N-1/L-3 program was the timeline. Apollo was approved by Congress in May 1961, while N-1/L-3 got Politburo clearance in August 1964. You can't start 3.2 years late in a ~10-year race and win unless the other team screws up badly. This was Nikita Khrushchev's fault. He was scared by the projected cost and seems to have thought that Kennedy was bluffing.


Offline ThereIWas3

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That Glushko had been personally responsible for Korolev being sent to the Gulag could not have put either of them in a mood to cooperate.
"If you want to build a ship, don’t drum up people to collect wood and don’t assign them tasks and work, but rather teach them to long for the endless immensity of the sea" - Antoine de Saint-Exupéry

Offline Proponent

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Projects always seem to be more successful with a "hands on"  Chief Designer. I am having a hard time thinking of a large, successful project without a name attached to it.

John

Space shuttle. George Mueller's name is attached to it, but he wasn't a hands on chief designer. Hard to credit any single person

But the Shuttle failed to meet any of its major design goals -- cost, flight rate, safety, payload -- by margins ranging from substantial to enormous.
« Last Edit: 10/23/2016 08:30 AM by Proponent »

Offline Jim

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Projects always seem to be more successful with a "hands on"  Chief Designer. I am having a hard time thinking of a large, successful project without a name attached to it.

John

Quite the opposite.  Name the projects with them

Offline pippin

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Projects always seem to be more successful with a "hands on"  Chief Designer. I am having a hard time thinking of a large, successful project without a name attached to it.

John

Quite the opposite.  Name the projects with them
Well, R7 comes to mind...

Offline Arch Admiral

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Also R-9A, RT-1, RT-2, RT-15, RT-15M, RT-25 - All military missiles designed by Korolev, all pretty much failures. The Strategic Rocket Force high command was so angry at Korolev's poor performance on these projects that in 1964 they asked that he be sacked as Chief Designer of OKB-1. This might have happened had Khrushchev not been overthrown in October 1964. As it was, the unmanned lunar and planetary program was taken away from him in May 1965 due to a long series of dismal failures.

The whole popular picture of Korolev as an engineering and management genius just doesn't stand up anymore. His biggest failing was taking on too many projects for his limited staff to handle, and then resisting all attempts to switch them to other organizations. The worst example is the L-1 Zond manned lunar-loop mission. This project was switched to Chelomei's OKB-52 by Khrushchev, but then Korolev lobbied Brezhnev to get it back. Even Korolev's own staff thought this program was silly. The only reason for it was empire-building.

As an engineer, Korolev's big weakness was his opposition to complete ground testing. After Georgi Babakin took over the unmanned program, he found that none of OKB-1's Venus, Mars, or Moon probes had been tested in a vacuum chamber or a centrifuge. These facilities were reserved for the manned missions. When Babakin built a centrifuge and tested some of Korolev's Venus entry probes, they all collapsed well below the specified g levels. The N-1 and Soyuz-1 disasters were only the last of a long series of failures due to this "shoot and hope" philosophy.

Online Dmitry_V_home

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That Glushko had been personally responsible for Korolev being sent to the Gulag could not have put either of them in a mood to cooperate.

Actually, it no more than myth. Glushko is not guilty of S.P.Korolev's arrest. At least because Glushko himself was arrested three months earlier.
The reason of disagreements  Korolev and Glushko was another.
« Last Edit: 10/25/2016 06:51 PM by Dmitry_V_home »

Online Dmitry_V_home

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Also R-9A, RT-1, RT-2, RT-15, RT-15M, RT-25 - All military missiles designed by Korolev, all pretty much failures. The Strategic Rocket Force high command was so angry at Korolev's poor performance on these projects that in 1964 they asked that he be sacked as Chief Designer of OKB-1. This might have happened had Khrushchev not been overthrown in October 1964. As it was, the unmanned lunar and planetary program was taken away from him in May 1965 due to a long series of dismal failures.

The whole popular picture of Korolev as an engineering and management genius just doesn't stand up anymore. His biggest failing was taking on too many projects for his limited staff to handle, and then resisting all attempts to switch them to other organizations. The worst example is the L-1 Zond manned lunar-loop mission. This project was switched to Chelomei's OKB-52 by Khrushchev, but then Korolev lobbied Brezhnev to get it back. Even Korolev's own staff thought this program was silly. The only reason for it was empire-building.

As an engineer, Korolev's big weakness was his opposition to complete ground testing. After Georgi Babakin took over the unmanned program, he found that none of OKB-1's Venus, Mars, or Moon probes had been tested in a vacuum chamber or a centrifuge. These facilities were reserved for the manned missions. When Babakin built a centrifuge and tested some of Korolev's Venus entry probes, they all collapsed well below the specified g levels. The N-1 and Soyuz-1 disasters were only the last of a long series of failures due to this "shoot and hope" philosophy.

Several remarks.
The RT-15 rocket was designed in TsKB-7 (Leningrad/St. Petersburg) under the leadership of Tyurin. The sea version of the rocket - RT-15M - became in OKB-385 under the leadership of Makeev. The RT-25 rocket was created in SKB-172 (Perm) under the leadership of Tsirulnikov.

It is impossible to call the RT-1 rocket successful, but it was intended rather for experiments, than for fighting use.

The RT-2 rocket became the first Soviet intercontinental ballistic missile on solid fuel. It was considered as quite reliable and was on service more than 20 years.

R-9 probably became the first-ever rocket using the overcooled fluid oxygen. For half a century to Elon Musk  ;)

Offline RanulfC

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That Glushko had been personally responsible for Korolev being sent to the Gulag could not have put either of them in a mood to cooperate.

Actually, it no more than myth. Glushko is not guilty of S.P.Korolev's arrest. At least because Glushko himself was arrested three months earlier.
The reason of disagreements  Korolev and Glushko was another.

Apparently Korolev believed it, and added on to that was Glushko was rather obviously 'treated' better with an assignment to a penal engineering bureau where as Korolev went to a gulag. Overall it really didn't matter the actual 'truth' as it was something that drove the 'disagreements' into distrust and hatred. Both men were ambitious and over-reaching, Glushko managed to outlast all the rivals in the end.

What is really 'scary' is that the US missile and space program was in similar straights before everyone "united" against the Soviets after Sputnik and Vostok. Had we been more on par or perhaps less panicked at higher levels its possible the US would have been in similar disarray.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline john smith 19

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I'll just note AFAIK this is the only large rocket that has planned to be steered with differential throttling, not any kind of gimbaling, or object being moved into the engine thrust.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline IRobot

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I'll just note AFAIK this is the only large rocket that has planned to be steered with differential throttling, not any kind of gimbaling, or object being moved into the engine thrust.
VentureStar / X-33 also planned to use differential throttling.

Offline Arch Admiral

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Differential throttling in the X-33 might have worked in yaw, but I always had doubts that the lever arm in pitch was great enough. And pitch was the axis with the most problems with wind shear etc. due to the lifting-body shape. And how would this work in roll??

Offline e of pi

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Differential throttling in the X-33 might have worked in yaw, but I always had doubts that the lever arm in pitch was great enough. And pitch was the axis with the most problems with wind shear etc. due to the lifting-body shape. And how would this work in roll??
They had multiple engine "units" in the line. If port does a pitch positive diversion of its thrust and starboard does pitch-negative, the net effect is a roll.

Offline john smith 19

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I'll just note AFAIK this is the only large rocket that has planned to be steered with differential throttling, not any kind of gimbaling, or object being moved into the engine thrust.
VentureStar / X-33 also planned to use differential throttling.
Another design that wasted $Bn+ and delivered nothing, except a larger payday to LM stockholders.  :(
It's not looking good as design approach if you want reliability in a vehicle, is it.
« Last Edit: 10/24/2017 10:55 PM by john smith 19 »
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline acsawdey

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I'll just note AFAIK this is the only large rocket that has planned to be steered with differential throttling, not any kind of gimbaling, or object being moved into the engine thrust.
VentureStar / X-33 also planned to use differential throttling.
Another design that wasted $Bn+ and delivered nothing, except a larger payday to LM stockholders.  :(
It's not looking good as design approach if you want reliability in a vehicle, is it.

I really don't think X-33's failure had much to do with differential throttling, more the ability to make a LH2 tank shaped like a lifting body. And even there it's more failed technology management than a complete inability to actually build such a thing.

And the N-1, well maybe it wasn't such a good idea to have so many engines if all you have is analog computers (that are too slow to prevent RUD) to handle shutdown. Also one of the failed flights, the computer was miswired so when engines failed, it shutdown the wrong ones. Oh, and having engines that can't be test-fired so you have to do statistical testing of batches certainly didn't help either. The Merlin 1D is completely bulletproof by comparison. So differential thrust has to get in line behind a whole bunch of other factors for that one.

Really, anyone who wants the blow-by-blow narrative about why N-1 failed should go read Rockets and People Volume IV:

https://history.nasa.gov/SP-4110/vol4.pdf


Offline spaceman3

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Really, anyone who wants the blow-by-blow narrative about why N-1 failed should go read Rockets and People Volume IV:

https://history.nasa.gov/SP-4110/vol4.pdf


Or you could read my book at:

https://ntrs.nasa.gov/search.jsp?R=20000088626

(although it may have a bit too much detail)

Online Coastal Ron

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Really, anyone who wants the blow-by-blow narrative about why N-1 failed should go read Rockets and People Volume IV:

https://history.nasa.gov/SP-4110/vol4.pdf


Or you could read my book at:

https://ntrs.nasa.gov/search.jsp?R=20000088626

(although it may have a bit too much detail)

Any chance you could give us the Cliff Notes version?   :D
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline acsawdey

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Really, anyone who wants the blow-by-blow narrative about why N-1 failed should go read Rockets and People Volume IV:

https://history.nasa.gov/SP-4110/vol4.pdf


Or you could read my book at:

https://ntrs.nasa.gov/search.jsp?R=20000088626

(although it may have a bit too much detail)

Well ... by some definition the other is "your book" as well :-)

Offline Blackstar

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And the N-1, well maybe it wasn't such a good idea to have so many engines if all you have is analog computers (that are too slow to prevent RUD) to handle shutdown.

Perhaps "too many engines" is too simplistic an answer, and you really need to consider the overall complexity of the system. In other words, it was a failure of systems engineering, connecting all the stuff that has to be done right in order for it to work.

I wonder the extent to which the early choices really limited their later options. For instance, they did not do a static test of the complete first stage. Why? Was it too expensive, or did they think that it was unnecessary? (Or, as is often the case, it was too expensive, so they convinced themselves that it was unnecessary.)


Offline john smith 19

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I wonder the extent to which the early choices really limited their later options. For instance, they did not do a static test of the complete first stage. Why? Was it too expensive, or did they think that it was unnecessary? (Or, as is often the case, it was too expensive, so they convinced themselves that it was unnecessary.)
Yes.   :)

Earlier posters mentioned that only the manned programmes got more extensive testing, but that makes no sense, as the rocket carrying the crew to the Moon I'd have said the N-1 was part of the manned programme, except in the most pedantic sense of

Crew not carried in this part --> Not a manned programme.  :(

Skimming the accounts of the programme I'm hearing "Danger! Danger! Second systems effect." The tendency to throw away clean, known design in favor of radical, definitely higher risk but potentially higher performing systems.

How else to explain abandoning conventional gimbaling TVC (which I'm sure the Russians were aware was what the US was going to use) for differential throttling and batteries for on board generation when you've got a hard (immovable) deadline to meet with no extensions possible?

Couple that with low performance computer hardware and a failure to do a qualification test on every engine (a deeply undeserved reliance on what we would call Statistical Process Control) for foreign objects inside the engine and substantial underfunding given the scale of the task and you have a recipe for disaster.

I don't think the high number of engines was a show stopper, but multiplied  by the poor QC, and then multiplied further by unknown levels of interference from the new AC generating system on the power and data buses (How could you not see that coming??) and possible software development issues I think was a lethal combination.   :(

BTW People say the KORD computer system was low performing but is that by the US standard (the one on Saturn was only in the 10s of KIPS at most) of the time or by modern standards?
Pre-Shuttle any flight computer (literally) above the speed of a modern pocket calculator was "high performance"  by that yardstick.

Nemesis awaits all who would harbor false pride in their achievements and the N-1 programme got an extended visit from her.  :(

Had it all worked it would have been a technological triumph. Not just SoA but Start of the Art in several areas.

But it didn't.

Steering by diff throttling has become an emergency flight mode on some aircraft decades later. AFIK Shuttle is the only LV/spacecraft to not rely on batteries as a primary power source. Batteries are still the SoA for LV's. Even today no LV uses on board generation, despite electric TVC flying on Vega for a decade.
« Last Edit: 10/27/2017 08:37 AM by john smith 19 »
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline WallE

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The N-1 program was operating on something like 30% of Apollo's budget so no they didn't have the money for a test stand. A large number of factors were at work here including the less advanced Soviet technological capabilities and the fact that the Kremlin simply didn't place a high priority on science and exploration of space--national defense was paramount above all. They didn't mind scoring space firsts for propaganda value if it could be done cheaply, but landing on the Moon was not exactly cheap.

Technological handicaps aside, the Soviet aerospace industry did not have a sophisticated enough organizational and managerial structure for projects on this scale. The different heads of design bureaus did not trust each other and were constantly scheming against rivals, often because of feuds that went back to the Stalin-era purges.

As for the technical problems brought up in this thread, no, the Saturn instrument unit predated microprocessor electronics and was hardly an advanced computer. Unlike the KORD however, it had something resembling proper Q/C and testing, aside from not being asked to control 30 engines at once.

The N-1 first stage was a terrible design--30 engines made it far too heavy, way too much plumbing, and too hard to control in flight. The end result, absurd as it sounds, was a launch vehicle with more first stage thrust than the Saturn V but less lift capacity. This would have greatly limited the complexity and scope of a Soviet lunar landing--the crew couldn't do a lot more than plant a flag, take pictures, and grab a few soil samples. This was unfortunately another result of Soviet technological handicaps as they didn't have the ability to build large LOX/RP-1 engines and avoid combustion instability issues. The other option was Chelomei's UR-700 which required far fewer engines but flying a Saturn V-class launch vehicle with N2O/UDMH propellants would be a safety nightmare--they estimated that a launch failure within the first 20 seconds of flight would leave the impact site sterilized for at least 20 years.

As for other propellant options, the Soviets hadn't mastered large solid rocket motors either and Glushko considered LH2 unviable as a propellant--only in the 70s after the Saturn V proved otherwise did he cave and authorize the development of LH2 engines.

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In my opinion, failure of the N-1 project had three reasons:
1) Deficiency of resources
2) Lack of political support till 1964
3) Low level of management.

All other factors are a consequence of these reasons.

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