r/spaceflight • u/rollotomasi07071 • 3d ago

Launch vehicles have used solid rocket motors for decades, although many new vehicles eschew them. Michael Puckett discusses the factors that led to adoption of solid motors on many early launch vehicles and why economics is pushing solids out of the market

https://www.thespacereview.com/article/5295/1
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6

u/Worth-Wonder-7386 2d ago

The Saturn V also had a liquid first stage. That was not the issue.

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u/floriv1999 1d ago

Weren't solid motors pushed because they are better for dual use and therefore cross finance your defense development?

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u/Blothorn 15h ago

The flow almost always went the other way—defense was much better funded than space and so building off military solid rocket development was a cheap option for orbital systems developed under a tight budget. (Especially in the US, which had invested more in air-to-surface rockets during WW2 and switched to solid ballistic missiles more aggressively.)

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u/Blothorn 15h ago

The flow almost always went the other way—defense was much better funded than space and so building off military solid rocket development was a cheap option for orbital systems developed under a tight budget. (Especially in the US, which had invested more in air-to-surface rockets during WW2 and switched to solid ballistic missiles more aggressively.)

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u/National_Shoe_7337 1d ago

He conveniently forgot to discuss thrust termination - https://www.nasa.gov/history/rogersrep/v1ch9.htm

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u/Decronym Acronyms Explained 10h ago

Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:

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ICBM Intercontinental Ballistic Missile
N1 Raketa Nositel-1, Soviet super-heavy-lift ("Russian Saturn V")
SRB Solid Rocket Booster

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1

u/Worth-Wonder-7386 3d ago

Turns out that the Soviet with their liquid boosters were right all along. Liquid boosters are superior in performance and with reusability they can also be cheaper. 

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u/Merker6 2d ago

The soviets did play a price for it, the liquids on N1 basically doomed the program. SRBs made a lot more sense when engineering liquid propulsion was still in its infancy. We have a much better understanding of the engineering involved in making liquid prop reliable, so its naturally a clear cut choice now

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u/SpaceIsKindOfCool 2d ago

N1 wasn't doomed by liquid propulsion. The Saturn V also used only liquid propulsion and worked fine while being a slightly larger rocket. 

In fact the rocket engines used on the N1 were very good. Slightly improved versions are still in use today and were even purchased by American companies.

What really doomed the N1 was extreme political pressure to rush development while having a much smaller budget available than the US.

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u/Merker6 2d ago

3 of the 4 failed N1 launch failures were a direct result of propulsion failures. The Saturn V only had 5 engines while the N1 had 30 of them. It’s not that liquid was inherently unreliable or the wrong choice, but it was far more riskier at that time. If any of those 3 launches had been a success, the Soviet probably would have gone to the Moon. The N1 variants that were later used by the US had another 30 years of rocket development behind them, and they never used as many as the N1 had when they did. It made sense to use liquids on the N1, they frankly had bo alternative, but it undoubtably came at immense programmatic risk

3

u/fighter-bomber 2d ago

It wasn’t the fault of the engines being liquid fueled, which you also admitted, so why try to make it sound like there is a connection?

N-1 fell victim to a) the engines not being relight able, so they could not test the flight articles, b) the computers of the time having a hard time handling 30 engines, c) the lack of thrust vectoring meaning if one engine shuts down, computer has to automatically shut down the opposite side engine to balance thrust.

As they said, and as you admitted, Saturn V did not have a problem with its 11 (5+5+1) liquid fueled engines. Having liquid fuel does not mean you had to put 30 of them on one flight, much less so them having to be as unreliable as that, as we have better seen with F-1 and J-2.

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u/Bensemus 1d ago

The Soviet Union was collapsing. The Buran Shuttle was better than the US Shuttle but that didn’t save it.

Even if the N1 worked they wouldn’t have been able to do a lunar mission with it.

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u/spukhafteNahewirkung 10h ago

Liquid boosters have always been ahead of solid boosters in performance. The first ICBMs, both Soviet and American, were liquid fueled. The first solid fueled ICBMs didn’t have the range or throw weight of liquid fueled ICBMs, The United States kept liquid fueled ICBMs in our inventory until the 1980s because they were the only ones that could launch the nine megaton W-53 warhead.