Was the Soviet R-7 rocket a good design?

[Nell_Lucifer]

While I am aware that the Soviet military considered the R-7 unfit as an ICBM, it nonetheless shined as a space launcher, however, was it a good, upgradeable design compared to what other alternatives were available during the 50s?

I do get the impression that Korolev from the start designed the 8000 km ICBM as a ~260 tons, 20 engines colossus (at the time) with the options for a third and fourth stage, compared to Yangel's R-12, 14 that remained limited to a ton or so of LEO payload, while the R-7 could put as much as 6+.

However, the question I have is if he could have gotten a better design for both military and space launching purposes? And earlier? Because, from my (admittedly barebones) calculations, a rocket with 6/7 RD-102/103 engines (2.8 x 20 m - R-3 dimensions) with 4 boosters (based on the R-5 and feeding the main core as was proposed with the R-3 in 1949 during the design phases - while it could also utilize 4 first stage boosters) and a Alcohol/Kerosene/Hypergolic upper stage (RD-110/RD-109/RD-215/RD-103/RD-58) would be able to place more than 6 tons into LEO. Something that would bore a resemblance to the R-16 tbf.

Was there any particular reason why they avoided the alcohol engine and insisted on kerosene? (I am aware that kerosene is better, but there were no suitable Kerolox engines during 1949-1951 when the R-3 project was underway) when they were still making upgrades to them?

 

[Mad Bad Rabbit]

Was there any particular reason why they avoided the alcohol engine and insisted on kerosene?

Grain shortages?

 

[jsb]

I do get the impression that Korolev from the start designed the 8000 km ICBM as a ~260 tons, 20 engines colossus (at the time) with the options for a third and fourth stage,

Is one of the main points of the design (like the first US design Atlas) that all the engines can be lighted on the ground, it did not require any staging ignition to work? The 3rd/4th stage etc added as it evolved as a space rocket are later additions that much increase the payload but were not needed for the design to work?

 

[Nell_Lucifer]

Grain shortages?

Don't think that was a problem, they still developed and employed Ethanol-Lox ballistic missiles up to the mid 1960s.

Is one of the main points of the design (like the first US design Atlas) that all the engines can be lighted on the ground, it did not require any staging ignition to work? The 3rd/4th stage etc added as it evolved as a space rocket are later additions that much increase the payload but were not needed for the design to work?

It is more that the design had a higher weight margin to allow the later stages addition compared to say the R-12. (I don't think the engines could be ignited my flight except for the hypergolic RD 215 - though they perhaps could have made one alcohol/kerosene that could given they made on in 1960 for the Mars/Venus mission)

 

[anotherlurker]

20 engines colossus

It's 20 nozzles for 5 engines, it's a way to get around unstable burning that occurs in bigger rocket engines that cause dangerous vibrations. And the question... it was so good it basically froze the Russian space launcher development in place.

 

[jsb]

it was so good it basically froze the Russian space launcher development in place.

I mean with full hindsight of the OTL shuttle would using Saturn IB not be cheaper and safer than OTL timeline?

 

[Polish Eagle]

It's 20 nozzles for 5 engines, it's a way to get around unstable burning that occurs in bigger rocket engines that cause dangerous vibrations. And the question... it was so good it basically froze the Russian space launcher development in place.

Well, not exactly. Zenit was supposed to replace it (around the same time the US began trying to replace Titan and balloon-tank Atlas), but they built the factory for that in the Ukrainian SSR, and so the program kind of became untenable in the 1990s.

 

[RanulfC]

While I am aware that the Soviet military considered the R-7 unfit as an ICBM, it nonetheless shined as a space launcher, however, was it a good, upgradeable design compared to what other alternatives were available during the 50s?

Well it has been upgraded significantly over time and it was "unfit" pretty much on par with how the US Atlas was 'unfit" for ICBM work as it was a rather quick design to get some kind of ICBM capability as soon as possible. (My personal favorite possible time line is one where the US ends up freezing the Atlas design on the five engine behemoth because they don't want to risk waiting on the light weight H-Bombs so we end up having the US with an equivalent launch vehicle early on

I'd say it was a good launcher and a good design for what they wanted early on.

I do get the impression that Korolev from the start designed the 8000 km ICBM as a ~260 tons, 20 engines colossus (at the time) with the options for a third and fourth stage, compared to Yangel's R-12, 14 that remained limited to a ton or so of LEO payload, while the R-7 could put as much as 6+

Keep in mind it really only had four (4) engines, just 20 exhaust nozzles The thing was the R-7 was actually predicated on the need to put a certain payload on a target in the US from the USSR and having the ability to put something in orbit (at all) was seen as a bonus not a design quality. The later was something Korolev wanted but the military was adamant they wanted a missile first and foremost.
(Similarly US missiles were designed to deliver payload not put things in orbit and it showed, due to our lighter warhead sizes we had even less orbital payload capability)

However, the question I have is if he could have gotten a better design for both military and space launching purposes? And earlier? Because, from my (admittedly barebones) calculations, a rocket with 6/7 RD-102/103 engines (2.8 x 20 m - R-3 dimensions) with 4 boosters (based on the R-5 and feeding the main core as was proposed with the R-3 in 1949 during the design phases - while it could also utilize 4 first stage boosters) and a Alcohol/Kerosene/Hypergolic upper stage (RD-110/RD-109/RD-215/RD-103/RD-58) would be able to place more than 6 tons into LEO. Something that would bore a resemblance to the R-16 tbf.

Cross feed is a lot harder to actually do than it looks which is why it's still pretty rare. This gets worse if you're feeding from an stage with active engines to a stage with active engines I might add. In context they wanted initially to have the ability to light all the engines on the ground to ensure the vehicle would lift off and to reduce the number of possible ignition events and/or failures. (Atlas did the same thing for the same reason) They were leery of separate upper-stages and multiple ignition events even using hypergolic propellant.

Was there any particular reason why they avoided the alcohol engine and insisted on kerosene? (I am aware that kerosene is better, but there were no suitable Kerolox engines during 1949-1951 when the R-3 project was underway) when they were still making upgrades to them?

Mostly that kerosene was better and engines were in development, (to reach orbit they had to replace the Redstone's alcohol fuel with a hydrazine based one for performance purposes) so it was something that was going to be needed to come for better performance.

Randy

 

[Sasza]

Well, not exactly. Zenit was supposed to replace it (around the same time the US began trying to replace Titan and balloon-tank Atlas), but they built the factory for that in the Ukrainian SSR, and so the program kind of became untenable in the 1990s.

I wonder if if LH2 was used in the second stage, it would be possible to obtain 20 tons of LEO

 

[RanulfC]

I wonder if if LH2 was used in the second stage, it would be possible to obtain 20 tons of LEO

For the R-7 or the Zenit? In context they had no actual LH2 engines when the R-7 was designed (and for most of its use ) though other propellant combinations might have been used.

Randy

 

[Nell_Lucifer]

For the R-7 or the Zenit? In context they had no actual LH2 engines when the R-7 was designed (and for most of its use ) though other propellant combinations might have been used.

Randy

I believe he means a LH2 stage for Zenit, though, did they not have a LH2 engine (or engine prototypes) by 1970? Also might those other combinations for the early R-7 be propane and pentaborane?

 

[Polish Eagle]

I wonder if if LH2 was used in the second stage, it would be possible to obtain 20 tons of LEO

Possibly? I'd have to do a spreadsheet to check. The USSR had kind of a shortage of LH2 engines, so unless they go over-powered and put an RD-701 on this notional second stage, they'd have to cluster lots of KVD-1 engines.

 

[njslim]

While I am aware that the Soviet military considered the R-7 unfit as an ICBM, it nonetheless shined as a space launcher, however, was it a good, upgradeable design compared to what other alternatives were available during the 50s?

I do get the impression that Korolev from the start designed the 8000 km ICBM as a ~260 tons, 20 engines colossus (at the time) with the options for a third and fourth stage, compared to Yangel's R-12, 14 that remained limited to a ton or so of LEO payload, while the R-7 could put as much as 6+.

However, the question I have is if he could have gotten a better design for both military and space launching purposes? And earlier? Because, from my (admittedly barebones) calculations, a rocket with 6/7 RD-102/103 engines (2.8 x 20 m - R-3 dimensions) with 4 boosters (based on the R-5 and feeding the main core as was proposed with the R-3 in 1949 during the design phases - while it could also utilize 4 first stage boosters) and a Alcohol/Kerosene/Hypergolic upper stage (RD-110/RD-109/RD-215/RD-103/RD-58) would be able to place more than 6 tons into LEO. Something that would bore a resemblance to the R-16 tbf.

Was there any particular reason why they avoided the alcohol engine and insisted on kerosene? (I am aware that kerosene is better, but there were no suitable Kerolox engines during 1949-1951 when the R-3 project was underway) when they were still making upgrades to them?

Was there any particular reason why they avoided the alcohol engine and insisted on kerosene? (I am aware that kerosene is better, but there were no suitable Kerolox engines during 1949-1951 when the R-3 project was underway) when they were still making upgrades to them?

Took a while to develop a kerosene grade fuel utilized in a regenerative cooled engine - if too volatile would boil causing bubbles and cavitation in the cooling channels Unsaturated hydrocarbons polymerize and form gums which clog plumbing Also issue of thermal breakdown or coking where material decomposes forming carbon deposits Final spec was naphthenic based fuel free of unsaturated hydrocarbons with Sulphur impurtiies removed

 

[njslim]

Don't think that was a problem, they still developed and employed Ethanol-Lox ballistic missiles up to the mid 1960s.

It is more that the design had a higher weight margin to allow the later stages addition compared to say the R-12. (I don't think the engines could be ignited my flight except for the hypergolic RD 215 - though they perhaps could have made one alcohol/kerosene that could given they made on in 1960 for the Mars/Venus mission)

Soviet R 5 - Nato designation SS 3 SHYSTER MRBM with range up to 750 miles (1200 km) Used 92.5 % alcohol (185 proof) vs 75 % (150 proof) of V2 and REDSTONE to give improved performance

 

[njslim]

Well it has been upgraded significantly over time and it was "unfit" pretty much on par with how the US Atlas was 'unfit" for ICBM work as it was a rather quick design to get some kind of ICBM capability as soon as possible. (My personal favorite possible time line is one where the US ends up freezing the Atlas design on the five engine behemoth because they don't want to risk waiting on the light weight H-Bombs so we end up having the US with an equivalent launch vehicle early on

I'd say it was a good launcher and a good design for what they wanted early on.



Keep in mind it really only had four (4) engines, just 20 exhaust nozzles The thing was the R-7 was actually predicated on the need to put a certain payload on a target in the US from the USSR and having the ability to put something in orbit (at all) was seen as a bonus not a design quality. The later was something Korolev wanted but the military was adamant they wanted a missile first and foremost.
(Similarly US missiles were designed to deliver payload not put things in orbit and it showed, due to our lighter warhead sizes we had even less orbital payload capability)



Cross feed is a lot harder to actually do than it looks which is why it's still pretty rare. This gets worse if you're feeding from an stage with active engines to a stage with active engines I might add. In context they wanted initially to have the ability to light all the engines on the ground to ensure the vehicle would lift off and to reduce the number of possible ignition events and/or failures. (Atlas did the same thing for the same reason) They were leery of separate upper-stages and multiple ignition events even using hypergolic propellant.



Mostly that kerosene was better and engines were in development, (to reach orbit they had to replace the Redstone's alcohol fuel with a hydrazine based one for performance purposes) so it was something that was going to be needed to come for better performance.

Randy

?

Well it has been upgraded significantly over time and it was "unfit" pretty much on par with how the US Atlas was 'unfit" for ICBM work as it was a rather quick design to get some kind of ICBM capability as soon as possible. (My personal favorite possible time line is one where the US ends up freezing the Atlas design on the five engine behemoth because they don't want to risk waiting on the light weight H-Bombs so we end up having the US with an equivalent launch vehicle early on

I'd say it was a good launcher and a good design for what they wanted early on.



Keep in mind it really only had four (4) engines, just 20 exhaust nozzles The thing was the R-7 was actually predicated on the need to put a certain payload on a target in the US from the USSR and having the ability to put something in orbit (at all) was seen as a bonus not a design quality. The later was something Korolev wanted but the military was adamant they wanted a missile first and foremost.
(Similarly US missiles were designed to deliver payload not put things in orbit and it showed, due to our lighter warhead sizes we had even less orbital payload capability)



Cross feed is a lot harder to actually do than it looks which is why it's still pretty rare. This gets worse if you're feeding from an stage with active engines to a stage with active engines I might add. In context they wanted initially to have the ability to light all the engines on the ground to ensure the vehicle would lift off and to reduce the number of possible ignition events and/or failures. (Atlas did the same thing for the same reason) They were leery of separate upper-stages and multiple ignition events even using hypergolic propellant.



Mostly that kerosene was better and engines were in development, (to reach orbit they had to replace the Redstone's alcohol fuel with a hydrazine based one for performance purposes) so it was something that was going to be needed to come for better performance.

Randy

Well it has been upgraded significantly over time and it was "unfit" pretty much on par with how the US Atlas was 'unfit" for ICBM work as it was a rather quick design to get some kind of ICBM capability as soon as possible. (My personal favorite possible time line is one where the US ends up freezing the Atlas design on the five engine behemoth because they don't want to risk waiting on the light weight H-Bombs so we end up having the US with an equivalent launch vehicle early on

Always wondered why the TITAN 1 (LOX/Kerosene) rocket was never developed into a space launcher TITAN was fallback in case the ATLAS design did not work out

 

[RanulfC]

Always wondered why the TITAN 1 (LOX/Kerosene) rocket was never developed into a space launcher TITAN was fallback in case the ATLAS design did not work out

The Titan I was only deployed as a missile and then withdrawn to reconfigure them as Titan II (hypergolics) which did their "lifetime" no good and they ended up being retired early. Then the Titan II turned out to be better performing so they stuck with that instead and used it to build up the Titan line.

Randy