Red Star: A Soviet Lunar Landing

[fasquardon]

So yes, alot of people around Baikanour will be living healthier happier lives.

Huzzah!

And I'd forgotten the UR-500 lost out. It's going to reduce the anti-Soviet feeling in Central Asia for sure.

Not so sure Chelomei's career will be completely destroyed - the man was a good designer and a canny political opperator. I could see him focusing more on satellite design, for example.

fasquardon

 

[SpaceGeek]

Huzzah!

And I'd forgotten the UR-500 lost out. It's going to reduce the anti-Soviet feeling in Central Asia for sure.

Not so sure Chelomei's career will be completely destroyed - the man was a good designer and a canny political opperator. I could see him focusing more on satellite design, for example.

fasquardon

For the focus of this TL (Manned Spaceflight) he's basically dropped out. No TKS no VA no LK-1 no LK-700. But I'm sure he's engaged in some kind of activity whether it's engines or satellites or even unmanned planetary probes.

 

[fasquardon]

For the focus of this TL (Manned Spaceflight) he's basically dropped out. No TKS no VA no LK-1 no LK-700. But I'm sure he's engaged in some kind of activity whether it's engines or satellites or even unmanned planetary probes.

Maybe Chelomei emerges as the leader of the Soviet robot probe faction.

fasquardon

 

[SpaceGeek]

Maybe Chelomei emerges as the leader of the Soviet robot probe faction.

fasquardon

I don't know, maybe, maybe not. It's not really that relevant anyway.

 

[brovane]

Why did the Air Force keep Titans in service until 1980 and beyond, when we had the solid-fueled Minutemen already? I'm not sure but it probably has to do with the economics of having procured them already, and the synergistic fact that Titan derivatives were therefore more attractive to the Air Force as launch vehicles, which in turn fed back to favorable economics of keeping the Titans set up as strategic ICBMs in place.

Looking at the Titan II versus the Minuteman. I suspect the reason the Titan II was kept around for so long was the payload capacity. The Titan II used the W53 warhead which weighed 2,800kg. The Minuteman missile carried warhead(s) that where smaller. The original single warhead version of the Minuteman carried a 1.2 Megaton warhead the W56 which weighed less than 400kg. The W53 warhead had a yield of 9 Megaton's. I would expect that the Titan II missiles where aimed at hardened Soviet facilities that where deep underground where their 9 Megaton warhead could more easily insure destruction than the smaller yielding Minuteman warheads. The Titan II W53 was the highest yield warhead ever deployed on a US Missile.

 

[Bahamut-255]

A short update I know, but time is tight for me right now so I just gotta do what I can. And now onto the next part!


As 1973 neared its end, the NASA Skylab Programme began to pick up the pace with Al Bean (Cmdr), Jack Lousma (CMP), and Owen Garriot (Science Pilot) launched on the Skylab 3 mission in the late November of 1973. While the flight performed well during the Ascent-to-Orbit, as they approached the Skylab Station, one of the thruster quads in the Apollo SM developed a leak, and while the Apollo Spacecraft was able to safely dock with the station, the troubleshooting into the problem was continued. Then a few days later, a second thruster quad began to leak which raised concern in Mission Control leading to (for the first time) an Apollo CSM being rolled onto the Launch Pad for a rescue mission. It was later determined that even with the failed quads, the safe manoeuvring of the Skylab 3 CSM was still possible, leading to the rescue mission not being launched.

Skylab 3 approaching the station

Over the course of their 59-day mission, they collected a wide range of experiments data, with particular emphasis on medical research. The previous mission had photographs of the crew that showed the “puffy face syndrome” which saw an increase in the tests to determine the nature of the headward shift in body fluids, resulting in measurements of torso and limb girths to supplement the calf girth and leg volume measurements that Skylab 2 had conducted. Further supplemented by arterial blood flow, haemoglobin and urine mass measurements alongside photographs taken before flight, and over the course of the mission to gain new insight into the fluid balance and distribution in microgravity environments.

The main station repair activity involved the setting up of the twin-pole sunshade (that had actually been delivered in the previous flight) during their first EVA. Installed over the parasol, it provided further protection from the Sun to keep the conditions within Skylab comfortable. Thy also tested a Manned Manoeuvring Unit (MMU) Prototype that was hoped to see later use in future missions, while constant measurements of crew health and station habitability were made to understand the aspects of living and working in space, a must-know for their future plans.

Al Bean testing an MMU Prototype

Other experiments conducted included a pair of animal biological experiments involving Vinegar Gnats and Pocket Mice, though a power failure 30 hours into the mission killed them. The single-cell and cell culture medium experiments, however, yielded better results.

By the end of their mission, they had set a new NASA record for in-flight duration, just a week shy of the Soviet record, and their decision to use the docked CSM, even with its failed quad thrusters paid off as they safely returned just a very few hundred miles off the Western Coast of California.

 

[SpaceGeek]

In a hope to upstage the Americans (who sent spacecraft to all the planets out to Jupiter) the Soviets now launched their most ambitious planetary mission of all, to land a roving vehicle on the surface of Mars! Laden with instrumentation it would explore tens of kilometres beyond it's own landing site. To launch this complex vehicle was the N11 rocket, daughter to the larger N1.

It was not only hoped to gain experience about Mars itself but also to learn about how to land large, heavy payloads softly on the surface, in preparation for a Sample Return mission later in the decade. This was an ambitious project to take on especially considering the long running tradition of mission failures for the Mars Program. The USSR had successfully orbited mars only twice out of countless failed attempts and their two prior landing attempts ended in either a bone shattering impact, or a mysterious cut of communications 20 seconds after touchdown.

The planned Mars 5NM Sample-Return Probe

Nicknamed "Marsokhod" largely because of it's similarity to the Lunakhod rover. To their advantage the Soviets had countless hours of experience operating unmanned rovers. But that was the Moon, a mere quarter of a million miles, how will they face the hundred million mile journey to Mars!

The July 29th launch followed just days after the launch of two Mars Orbiters, Mars 4 and Mars 5. The launch was flawless as every command was carried out without a single error or malfunction. The TMI burn came with great celebration from mission control. Unfortunately it was all short-lived as just three months into it's eight month outbound voyage the radio suddenly went silent. The engineers and scientists attempted to regain the signal (and did briefly with a faint signal) but to no avail. The now inert Marsokhod would suffer the fate of countless Mars probes before it, losing contact with earth and flying by the beautiful Mars without revealing any of her secrets to Earth.

Colour Image of Mars from another, rather more successful mission

 

[SpaceGeek]

While Aleksei Gubarev and Anatoli Voronov tended to their own business onboard Zarya-2 the crew of yet another Soviet space mission prepared to visit a very different destination. The North pole of the Moon itself.

Unlike in the American Space effort the Soviets chose their landing sites largely as a way to garner attention and set milestones for themselves to break in triumph. They noticed that the public had largely lost interest in many "boring" Apollo flights while their own (much less capable) missions to exciting locations around the Moon would garner attention and make headlines. Inline with this continuing strategy was the idea to land on the lunar north pole, somehow appropriate for the Northern, icy Russians.

With eyes watching them from Earth and Space their N-1 suddenly came to life just as the countdown reached it's climax. Even after all the successful launches they had enjoyed previously, the Soviet engineers would still sigh in relief whenever the N1's Block A stage jettisoned safely, given its troubled past.

Their outbound journey was largely another chance to showcase the "advanced multi-modular spaceship" nature of the Soyuz/LK combo. An EVA had been planned exactly halfway between the Earth and Moon as yet another publicity stunt aimed at gaining headlines but was cancelled because of concerns about needlessly adding risk to a already risky mission.

The descent was notable for when the Block D crasher stage impacted it triggered a notable spike in seismographic experiments left behind on previous occasions. The landing was also notable for producing a larger than expected dust cloud although it settled quickly and did not pose any danger to the crew. Speaking of the crew, the flight crew of Soyuz 10 had showed such promise that they were actually rescheduled to fly again on L3-7. Commander Vasili Lazarev hence became the first person to visit both a Space Station, and the Moon. Meanwhile his comrade, Flight Engineer Valeri Kubasov, watched the spectacle alone onboard his own personal lunar space station, the Moon's own Moon.

Without the aid of a lunar rover Lazarev was forced to walk to all his destinations. As health experts and geologists raged over what was an acceptable distance for long race moonwalks Lazarev continued unimpeded. With minutes of life support to spare he had walked the longest distance on any celestial body other than the Earth. This was an intellectual point. What was really exciting was the headlines which boldly proclaimed "Soviets land Man on Moon's North Pole: Can America Keep Up?". The superiority of the Soviet space program was now reasserting itself after years of overshadowing by the Apollo missions. It was a short lived lead, but one the Soviets enjoyed.

The mission would ultimately be cut short to just 22 hours because of a concern related to Lazarev's growing exhaustion. Having returned countless colour photographs of the Earth against the pale lunar surface, the crew returned to Earth without a single scratch or bruise. As they refined their techniques and strategy, lunar missions were becoming more and more a known art. Which meant more safety for the crew and more glory for the great Union of Soviet Socialist Republics.

 

[Constantinople]

This is wonderful. The competition and oneupmanship is driving lunar and space exploration forwards quickly. I look forward to the moon bases and eventual Mars mission.

 

[Bahamut-255]

This is wonderful. The competition and oneupmanship is driving lunar and space exploration forwards quickly. I look forward to the moon bases and eventual Mars mission.

Well IMHO, one of the problems that faced NASA in the 1970's IOTL was the perceived lack of competition when they hammered the USSR in the Lunar Race. ITTL, with the USSR still making some headway - publicity-minded - NASA needs to keep pushing on to try and take the lead in the minds of the US public.

 

[Shevek23]

Bahamut, can you comment on the performance of the N-1? e of pi has extensive training and lots of experience running spacecraft performance numbers. I have a lot less knowledge, but running the basics as I understand them and using figures from Mark Wade's Encyclopedia Astronautica for the N-1 stages, I get mass figures that are compatible with the claims this timeline makes.

That is, I find the target of 75 tonnes to orbit (presumably at 185 km altitude or so, more or less circular, presumably inclined 51 degrees to the equator as per normal Soviet/Russian practice OTL) pretty reasonable. To get that I find the Ghe stage must burn a bit, mainly because if it doesn't and the Veh stage is sufficient to get into orbit by itself, the resulting payload is greater than 75 tons! (And the accumulated delta-V, naively ignoring both gravity loss and air loss, is a bit less than the 10 km/sec that is my rule of thumb for typical naive delta-V for a successful launch; the amount of burning the Ghe stage must do to bring the total orbited mass to exactly 75 tons just about brings it to that magic number, so...)

Then in turn the Ghe stage alone does not have enough propellant to launch the De and Soyuz on to TLI, not quite, but if the De burns a bit, the resulting mass sent on that kind of orbit is greater than the 16 ton figure e of pi produces.

Some variables I can't narrow down without sheer guesswork are:

How much does the average ISP and thrust of the A stage engines get reduced by atmospheric pressure toward the sea level thrust and ISP?

How much does the Soyuz mass? Is it indeed intended to have enough propellant so that in case of a De stage failure, it can escape a low Lunar orbit with enough energy left over to achieve a return orbit to Earth and still retain some maneuvering margin, all on its own? For that matter, is the De stage meant to achieve both Lunar orbit insertion and TEI?

My figuring suggests it can indeed be done that way, or anyway almost! If it can than the cosmonauts can survive the failure of any of the upper stage engines including the Soyuz. If the Ghe stage fails it will presumably do so right off, as they are trying achieve parking orbit--then they abort to suborbital landing far downrange. If it fails during TLI the De and Soyuz together can possibly get them on a return to Earth orbit; if the De fails during TLI I presume the targeted orbit is quite near a free return, well within Soyuz margins. If it fails approaching Luna, perhaps even if they approach for a polar orbit the Soyuz can maneuver into a return orbit. If it fails to fire for TEI, the Soyuz alone can perhaps manage a slow but feasible Earth return--and if all the other engines work but the Soyuz doesn't, the first time they learn that will be during midcourse corrections headed home, and perhaps the auxiliary thrusters can manage well enough to guide them to a safe return. Especially if these thrusters are fed from the same fuel supply that feeds the main engine.

Here is the data and figuring I've done based on Mark Wade's figures for the 5 stages and a guess as to Soyuz mass, based on the idea that the Soyuz has emergency return from Lunar orbit capability:


Block A
(30 engines as given here; 24 ITTL)
Gross mass: 1,880,000 kg (4,140,000 lb).
Unfuelled mass: 130,000 kg (280,000 lb). (delete 6*1250 kg engines. 7500 kg)

Gross mass: 1,872,500 kg
Unfuelled mass: 122,500 kg
Height: 30.10 m (98.70 ft).
Diameter: 10.30 m (33.70 ft).
Span: 16.90 m (55.40 ft).
(OTL, 30 engine)Thrust: 50,300.00 kN (11,307,800 lbf). vacuum thrust.
ITTL, replace with 39,214 kN
Specific impulse: 330 s.
Specific impulse sea level: 284 s.
This implies
37,091 sea level thrust--note that is a whole lot more than the weight of the stack!
Burn time: 125 s. (156.25)

Block B

No Engines: 8.
Gross mass: 560,700 kg (1,236,100 lb).
Unfuelled mass: 55,700 kg (122,700 lb).
Height: 20.50 m (67.20 ft).
Diameter: 6.80 m (22.30 ft).
Span: 9.80 m (32.10 ft).
Thrust: 14,039.98 kN (3,156,313 lbf).
Specific impulse: 346 s.
Burn time: 120 s.

Block V

Gross mass: 188,700 kg (416,000 lb).
Unfuelled mass: 13,700 kg (30,200 lb).
Height: 14.10 m (46.20 ft).
Diameter: 4.80 m (15.70 ft).
Span: 6.40 m (20.90 ft).
Thrust: 1,608.00 kN (361,492 lbf).
Specific impulse: 353 s.
Burn time: 370 s.

Block G

Gross mass: 61,800 kg (136,200 lb).
Unfuelled mass: 6,000 kg (13,200 lb).
Height: 9.10 m (29.80 ft).
Diameter: 4.40 m (14.40 ft).
Span: 4.40 m (14.40 ft).
Thrust: 446.00 kN (100,264 lbf).
Specific impulse: 353 s.
Burn time: 443 s.

Block D

Gross mass: 18,200 kg (40,100 lb).
Unfuelled mass: 3,500 kg (7,700 lb).
Height: 5.70 m (18.70 ft).
Diameter: 2.90 m (9.50 ft).
Span: 2.90 m (9.50 ft).
Thrust: 83.30 kN (18,727 lbf).
Specific impulse: 349 s.
Burn time: 600 s.

1,872,500+560,700+188,700+61,800+18,200

assume 7 tonne Soyuz (dry) that has delta-V budget of 1000 m/sec with isp of 319, this masses 2640 more in fuel or 9640. Allow 4500 for SAS/fairing. (based on this site)

To be sure a suitable escape system from the N-1 stack might need to mass a lot more, to get the capsule much farther away from a much bigger fireball than the Soyuz rocket could produce. On the other hand, I've often wondered if the Soviets could have been more economical with their fairing masses--you two showed an illustration of a Vostok that was enclosed in a fairing and there were vast amounts of empty space above the orbital craft in the fairing!

And anyway, even quite large masses don't deduct a whole lot from the performance of the massive first stage; I assumed the launch escape system and fairing were ejected after first stage burnout. Perhaps I should have kept it through the Be stage burn as well?

Anyway all up this gives us

2716 tons.

So thrust is some thousand tons greater; the whole thing should take off the pad at a brisk third of a G acceleration! I noticed much the same is true of the R-7 derived rockets; Soviet engineers seem to believe in quite high pad accelerations and pulling pretty high G's during launch.

First stage should achieve at least 1295.5 m/sec real velocity straight up, over 156 seconds. Perhaps less considering air drag, but this is based on sea level thrust and ISP applying all the way, so is probably too pessimistic.
Averaging with vacuum isp brings it to 1529.

Anyway the rocket will not go straight up, it will start to turn, so being more precise than this requires I have some clue what its turning schedule is!

From this point on I just note total ideal delta-V, figuring gravity loss and air drag are deducted from the traditional goal of 10,000 m/sec.

Vacuum-no grav impulse is 3346.5

2nd stage 3126, total 6472.6

3rd 3431.14, total 9903.74

burning 14640 kg of Ghe stage fuel brings orbited mass to precisely 75 tons, gains 617.5 more m/sec--well over 10,000!

The remaining delta-V from the Ghe stage takes us to 2755.95 toward TLI.

Assume a 180 km parking orbit, speed is 7800.7 m/sec

To reach a transfer orbit that reaches out to 500,000 km, we need 403.5402 more m/sec.

That requires 3095.412 kg from De block, leaving a gross mass of

15105+9640=24,745
So there is 11,605 kg of fuel in the De block still.

Allowing 1100 for Lunar orbit capture and escape, we'd need just a bit more. Going back over the sequence with a higher Soyuz mass is beyond me for the moment.!

Plugging these figures for stage, fuel, thrust and ISP into the Silverbird Calculator and assuming launch from Baikonaur, to a 185 altitude orbit and 51 degree inclination, tend to endorse your claims of performance--only by putting in the sea level values for the first stage and selecting the Earth escape velocity option did the lower range of the bracket of masses given go as low as e of pi's 16 tons to TLI.

But I believe the Silverbird calculator wants vacuum figures and automatically figures the sea level loss of thrust for you.

Can you confirm or deny that the stage figures Wade gives, suitably modified as I did to deduct 6 engines from the A stage, match the ones you are using?

 

[Bahamut-255]

Shevek

The Block G and D ITTL are not the same as OTL's Block G and D, being slightly smaller to get it into the 75,000 Kg to LEO limit, and able to send either a Soyuz-LOK or LK Lander to TLI. And the Block D that's attached to the LOK is needed for both LOI and TEI, the LOK only having enough for mid-course corrections during the Trans-Earth Coast Phase. And while talking to E of Pi about it when he punched in his own numbers, it was only late into the TL that I realised that there had been a serious error when calculating the TLI Payload Limit, chiefly that a significant portion of the payload fairing remains attached to the L3 stack during the LEO burn and TLI burn and needs to be factored in.

But the key difference in how he does it and how I did it was that he puts a LOT more time and effort into it, the numbers I got are a lot more approximate.

But one thing about the USSR at the time was their far greater willingness to take major risks with their Manned Space Effort, it should be noted that Gagarin was sent into LEO in Vostok 1 with the knowledge that his chances of survival were little better than 50%. And it's still largely more of the same with regards to their Manned Lunar Programme.

The high initial acceleration was preferred because, AFAIK, that means being able to punch through the thicker lower atmosphere quickly, reducing the atmospheric drag losses suffered, meaning a greater payload to LEO. The obvious penalty is that the T/M Ratio easily becomes very high towards the end unless you have some way of controlling the engine thrust, either by multiple MECO or engine throttling.

 

[fasquardon]

Been thinking about ways that the Soviets could evolve the N1 rocket. I wonder, how likely is it that the Soviets would look into larger engines for the A block? What effect would, for example, giving the N1 something like an RD-170 have?

I gather it would have much less of an effect than an upgrade of the upper stages to hydrogen/LOX technology.

fasquardon

 

[fasquardon]

chiefly that a significant portion of the payload fairing remains attached to the L3 stack during the LEO burn and TLI burn and needs to be factored in.

Now that's interesting. Why did the payload fairing remain attached? I assume they wouldn't pay that mass penalty without it being useful in some way.

EDIT:

The high initial acceleration was preferred because, AFAIK, that means being able to punch through the thicker lower atmosphere quickly, reducing the atmospheric drag losses suffered, meaning a greater payload to LEO. The obvious penalty is that the T/M Ratio easily becomes very high towards the end unless you have some way of controlling the engine thrust, either by multiple MECO or engine throttling.

I thought the high initial thrust was because the number of engines is high due to the expectation that some of them will fail (and take out other good engines due to the need to balance the thrust). So the theoretical thrust is higher than the thrust available in practice, because in practice some of the engines will have failed.

fasquardon

 

[Bahamut-255]

Been thinking about ways that the Soviets could evolve the N1 rocket. I wonder, how likely is it that the Soviets would look into larger engines for the A block? What effect would, for example, giving the N1 something like an RD-170 have?

I gather it would have much less of an effect than an upgrade of the upper stages to hydrogen/LOX technology.

You'd be correct here, with LOX/LH2 upper stage application being the best way to boost the BEO payload.

As for the first three stages, the most effective way, IMHO, would be to end the use of spherical tanks inside the stages and have the stage walls being a part of the tank structure to allow for a much greater propellant load. To the best of my (admittedly limited) knowledge, they didn't do this at first since they didn't have the means of building the stages in such a way when the 85 degree cone design was selected. But this would constitute a major N1 redesign that would require a fair bit of time and money.

Now that's interesting. Why did the payload fairing remain attached? I assume they wouldn't pay that mass penalty without it being useful in some way.

I think the conical design of the N1 was why, they didn't have a good way of blowing the fairing well clear of it while it was accelerating, so they needed to keep it attached throughout. But for the OTL N1-L3 design, I'm certain that that had to do with how they designed the LOK and LK, which required keeping parts of the fairing attached to hold the pieces together.

I thought the high initial thrust was because the number of engines is high due to the expectation that some of them will fail (and take out other good engines due to the need to balance the thrust). So the theoretical thrust is higher than the thrust available in practice, because in practice some of the engines will have failed.

That was one reason why for the N1, given its high engine count, but the one I gave I believe to be another valid reason.

 

[fasquardon]

Interesting... Makes me wonder if the Soviets will incrementally improve the N1, or opt for developing an Energia-equivalent as per OTL. It sounds like the N1 has alot less room for growth than the Saturn V.

fasquardon

 

[Shevek23]

Shevek

The Block G and D ITTL are not the same as OTL's Block G and D, being slightly smaller to get it into the 75,000 Kg to LEO limit, and able to send either a Soyuz-LOK or LK Lander to TLI.

Aha. From everything I've seen of the OTL N-1 mission proposals it seemed the stages' functions overlapped a bit; I guess because the first draft designs intended them to serve distinct purposes but then on fine calculation it turned out they would overlap unless radically redesigned; at some point they froze the design and accepted the overlap.

With a more deliberate pace it is plausible that the five stages each serve their separate functions. A,B, and V serve as a three stage booster that can put 75 tons (beyond the spent mass of the V stage, presumably) into LEO; I go with about 185 km altitude until you say otherwise. Just a bit higher, at 186 plus, makes orbital velocity exactly 7800 m/sec so I have worked with that altitude as the nominal orbital height.

That leaves G for the entire TLI boost and D for LOI for both components and crasher-braking for the LK, TEI for the Soyuz.

Starting with 75 tonnes total in parking orbit, and supposing a translunar trajectory that requires boosting to 10,997 m/sec (EDIT--last night I posted a howling typo, with a 9 for a 0--I've been sick, sorry./EDIT) working backwards from assuming a 950 m/sec delta V for LOI or TEI, and taking the ISP and ratios of full to empty weight of the OTL stages Mark Wade gives, I came up with this mass schedule:

G or the TLI stage--50,068 kg
D or Lunar Orbital stage--13,146 kg
This leaves 11,785 kg for the Soyuz itself.

That's really plenty of mass for it to contain plenty of propellant to get out Lunar orbit should the D stage fail there with maneuvering margin left over. I'd quite understand if the engineers preferred to use the mass for some other purpose, but since none has been suggested, I reiterate that it makes sense to give the Soyuz the backup capability to get back to Earth.

(Earlier when I was too optimistic, I claimed just 700 m/sec or so suffice--they do to escape the Moon but not for TEI. which involves not only getting away from Luna but also achieving an orbit around Earth with a perigee low enough for atmospheric braking--that's harder. But I estimate 950 is a good compromise between the absolute minimum impulse, which puts the Soyuz into a Hohmann orbit, and the practical red-line maximum of !050 that I estimate an Apollo could achieve both ways--with no safety factor at all. I then worked out the necessary orbital energy (with respect to Earth) that 950 escape or capture impulses imply.)

And the Block D that's attached to the LOK is needed for both LOI and TEI, the LOK only having enough for mid-course corrections during the Trans-Earth Coast Phase.

Having run the numbers just for TLI and LOI based on the assumptions I noted, I don't see what prevents the LOK from carrying a lot more fuel than that...unless...

And while talking to E of Pi about it when he punched in his own numbers, it was only late into the TL that I realised that there had been a serious error when calculating the TLI Payload Limit, chiefly that a significant portion of the payload fairing remains attached to the L3 stack during the LEO burn and TLI burn and needs to be factored in.

Oh dear heavens, that would throw a monkey wrench in things, wouldn't it! But I'm not the only one of your readers who is puzzled why they didn't fix that; more below.

But the key difference in how he does it and how I did it was that he puts a LOT more time and effort into it, the numbers I got are a lot more approximate.

We all admire e of pi's work along with Workable Goblin's, but I think such a bizarrely low figure as 16 tons to TLI has to be overpessimistic, given 75 to start with. Perhaps there are yet more fudge factors diminishing performance we don't know about?

I can certainly see some that might degrade the N-1's ability to get 75 tonnes into orbit in the first place--such as for instance the Soviet practice of starting the next stage up before the one below is quite burned out, to take advantage of the latter's thrust to provide a reliable up-down situation in the next stage for starting. The open truss between stages that this practice requires would tend to increase air drag--I could go on.

But on the other hand, before you tackled the task of sorting out the alt-development of this rocket, Korlev and company also did so, and presented their design to the Kremlin. I think there's good reason to think it can orbit at least 75 tons.

But one thing about the USSR at the time was their far greater willingness to take major risks with their Manned Space Effort, it should be noted that Gagarin was sent into LEO in Vostok 1 with the knowledge that his chances of survival were little better than 50%. And it's still largely more of the same with regards to their Manned Lunar Programme.

The high initial acceleration was preferred because, AFAIK, that means being able to punch through the thicker lower atmosphere quickly, reducing the atmospheric drag losses suffered, meaning a greater payload to LEO. The obvious penalty is that the T/M Ratio easily becomes very high towards the end unless you have some way of controlling the engine thrust, either by multiple MECO or engine throttling.

The launch philosophy makes sense to me, as long as space travel is going to be a matter for highly selected cosmonauts only, and as long as the engineers prefer to rely on robust safety factors matched by sheer brute force, rather than paring off every gram they possibly might.

I thought the high initial thrust was because the number of engines is high due to the expectation that some of them will fail (and take out other good engines due to the need to balance the thrust). So the theoretical thrust is higher than the thrust available in practice, because in practice some of the engines will have failed.

fasquardon

As I said taking what are apparently excessively high stage masses and boosting them with just 24 engines rather than 30, I was impressed. I think there is considerable margin for engine failure, and if two or four shut down, even during early launch phases, the fuel consumption will also slow down and the burn will last longer.

This is indeed a worse situation than if all were burning together for the shorter time.

But while Bahumut does seem to want to defer to e of pi on the mass that his version can deliver from TLi to the Moon, he is not budging on the 75 tonne to orbit target, so presumably engine failures have been factored in.

Now that's interesting. Why did the payload fairing remain attached? I assume they wouldn't pay that mass penalty without it being useful in some way.

...
I think the conical design of the N1 was why, they didn't have a good way of blowing the fairing well clear of it while it was accelerating, so they needed to keep it attached throughout. But for the OTL N1-L3 design, I'm certain that that had to do with how they designed the LOK and LK, which required keeping parts of the fairing attached to hold the pieces together.

That's confusing! The Soyuz version of the launcher at least would have an escape tower, sized to pull both manned modules of the Soyuz briskly off the failing stack below; it clearly has to pull off the shroud as well. Wouldn't all that go once tower jettison is enacted?

Unless of course it were necessary to leave behind some fairing elements for structure, but then either we'd look for ways to improve the structure so this isn't necessary--or else, factor it into the gross empty weight of the stage it stays attached to.

Interesting... Makes me wonder if the Soviets will incrementally improve the N1, or opt for developing an Energia-equivalent as per OTL. It sounds like the N1 has alot less room for growth than the Saturn V.

fasquardon

After developing hydrogen stages--starting with the Ghe block, which would be quite challenging indeed, the next most obvious increment is to add the 6 engines to the center of the A stage. As the years pass the engine design is improved and with that, its reliability. Whereas the structure of the A stage can clearly take it!

That's 25 percent increase in launching pad mass right there.

The biggest problem with developing hydrogen upper stages is that they will be very bulky. If the rocket is not tapered but maintains the diameter it has on the bottom of the A stage, that might allow for the very low density of liquid hydrogen. But sooner or later the rocket must start stretching up.

I'd think though that by the time this impasse is reached the upgrades will have already made the N-1+ the equal of the Saturn V.

 

[Shevek23]

Actually I'm not sure that upgrading the N-1 merely by replacing upper stages with hydrogen-burners will yield the dramatic results we might hope for. The problem is that while the mass consumed for a given impulse is less, the structure necessary to contain the hydrogen is heavier; also, the engine will be harder to make achieve a given thrust/weight ratio so it too is likely to be heavier. And aside from massing more, the hydrogen tanks will be very very large!

I figured the Ghe stage is the one to modify first; it has the mission most appropriate to a high-ISP engine. I made no attempt to nail down just what form the fuel tanks would take. Out of the 75 tons the lower three stages deliver to orbit, the kerosene burning Ghe stage would require 45 tons of fuel and have a mass of five tons itself, leaving just under 25 tons for the De stage and final Lunar payload. Using hydrogen at an ISP of 430 on the other hand, we save just 5 tons of fuel consumption--the residual is 35 rather than 30 tons, but this 5 ton surplus is eaten into by the stage mass itself. I don't know just what is a reasonable guess as to that mass but if it could have the same ratio as the kerosene burner to its fuel mass it would be 4.3 tons; it has to be more than that. If the mass penalty is greater than .7 tons, it cuts into the 5 ton gain of TLI mass; at a guess it might cut into it a whole lot, perhaps even negate it!

The Veh stage, the one that achieves orbit, might be a more useful candidate for a hydrogen burner; my estimate is that this substitution can raise the mass to orbit to 83 tons, or an addition of 8 tons. Again I don't know just how much of that 8 ton bonus gets swallowed by the stage itself needing to mass more to contain hydrogen.

Going down to the Beh stage, we are looking at igniting a hydrogen rocket while it is still well within the atmosphere, which hurts its performance more than kerosene--it is well on the way out and going up fast to be sure so perhaps this should not deter us!

But note that in modifying this stage, the bulk problem comes at us with a vengeance, because of the very large amounts of fuel involved.

Cumulatively, I do think we can approach Saturn V's 100 tons to orbit by replacing all the upper stages with hydrogen burners, and then perhaps pull ahead by adding on more engines to the first stage.

But I have to admit it isn't easy.

 

[nixonshead]

Cumulatively, I do think we can approach Saturn V's 100 tons to orbit by replacing all the upper stages with hydrogen burners, and then perhaps pull ahead by adding on more engines to the first stage.

But I have to admit it isn't easy.

Perhaps getting to the point where it would be easier to develop an all-new heavy lifter (Energia or RLA-135) rather than trying to shoehorn mods into N-1?

 

[Michel Van]

Perhaps getting to the point where it would be easier to develop an all-new heavy lifter (Energia or RLA-135) rather than trying to shoehorn mods into N-1?

There were two proposals 1965:

the N1F 1965 version
modified first stage with 11D51F Kuznetsov engines (is that the NK-33?)
in later version NIFV-II-III, All upper stage are replaced by Hydrogen/ Oxygen stage.


and
the N1M
here first stage is complete new design.
with two Hydrogen/ Oxygen stage, it would launch 250 tons LEO
and would be biggest rocket ever build: 200 meter high and 17 meter ø at base.