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Comment by jcims | Hacker News Reader

One of my favorite statistics to highlight the engineering absurdity of the Apollo program is that the 'fuel pump' for each F1 operated at approximately 55,000 horsepower. And they still needed five of them to get off the pad.

The mind boggles.

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How does 55,000HP compare to modern launches (e.g. SpaceX)? Have they become more efficient in harnessing less power to produce more thrust? I’m a lay person when it comes to engineering, but my assumption would be that we do not need close to 300,000HP to lift a modern shuttle up. If we do, though, it again is a magnificent task to complete.

Note that the 300k hp is for the fuel pumps, the first stage max output is roughly 160 million hp.

for those wanting to learn more, here is a Q&A from NASA and they delve into some specs on the STS-111 main engines [1]

>Darrel from Ft. Payne >How much horsepower do the shuttle's main engines produce at the time of lift off?

>NASA: The three space shuttle main engines generate the maximum equivalent of about 37 million horsepower. The fuel pump alone delivers as much as 71,000 horsepower, the oxygen pump delivers about 23,000. Just as a basis of comparison, the fuel pump alone is probably the equivalent horsepower of 28 locomotives. And with the horsepower of the oxygen pump, that's probably the equivalent of 11 more locomotives.

[1]: https://www.nasa.gov/missions/highlights/webcasts/shuttle/st...

All five engines together exceeded the electric generation capacity of France at the time.

The 55khp is for each fuel pump; the first stage needed just short of 300khp just to bring fuel from storage to the five combustion chambers. (Probably not the correct term)

Edit: ninja'd by eventualhorizon, whose comment is way more informative than mine!

(please anybody that really knows what they are talking about correct the following)

Newer engines have much higher chamber pressure so your pump demands are going to go through the roof.

For example, Elon says 100,000hp per Raptor here: https://twitter.com/elonmusk/status/1076618886932353024

But Raptor is running 300 bar chamber pressure vs 70 bar of the Rocketdyne F1. You have to pump your propellant against that with enough margin to ensure proper atomization and mixture of the liquids. Hard to say what the outlet pressure of the Raptor pumps are but it's going to be intense.

i think a key thing to remember is the manufacturing/fabrication tech. available when the F1 engines where built. Like I said, the welds on it are from a guy with a welder, no CAD/CAM, no robots, no simulation, just some guys with some machine tools, paper, and a shop.

Another thing, if you ever get the chance to visit the Johnson Space Center you can look at some of the control panels and tech. they used. Man, I wouldn't trust a trip to Home Depot and back using that tech and they said, "screw it we're riding this to the moon".

edit: there's a youtube out there of a project to rebuild part of an F1 engine. I think they conclude that a complete F1 can't be built today because a lot of the hand fitting and "tricks of the trade" were never written and down and modern fabrication techniques can't replicate the shape of certain F1 parts. ...something like that

there is a youtube channel trying to rebuild the apollo launch computer.

Very nerdy. The memory is rings of magnets. It is pretty fun though:

https://www.youtube.com/watch?v=2KSahAoOLdU

Also, that Saturn V in Houston was flight ready. It's not a model, they separated the stages a little bit so you could see inside, but that is as real as it gets. I could have stayed in there all day.

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