Infinite Wishes 🏳️‍⚧️🚀

Is a weblog by Emma Humphries

01 Jun 2023 » Starship vs. N1

A screenshot of a chart describing a trade off between the number of engines in a rocket and its reliability. The chart starts with a small number of engines on the x-axis, and reliability increases with the number of engines, before falling off as the number of engines increases, describing a bell curve.
Credit: Tim Dodd

Tim Dodd, the Everyday Astronaut, will go to the Moon on SpaceX’s Starship/Heavy rocket which, especially after its spectacular initial outing, is often compared to the Soviet N1 Moon rocket.

Dodd recently released a video talking about the comparison, where he thinks it’s apt, and where it’s not. I have been a Starship skeptic, treating it as a side project to SpaceX’s main business, but Dodd’s video has changed that somewhat.

It hasn’t, however, changed my opinion of Musk. I still think he’s an authoritarian techbro dabbling in eugenics, and SpaceX can do better.

The obvious similarities are that both rockets are huge and use many engines (the Heavy first stage of Starship/Heavy has 33, and the N1 used 30 in it’s first stage.)

The differences between the two are driven by the half-century between the projects: advances in machining mean that you can make lots of relatively-small engines (Raptor is a beast of a rocket engine) and more importantly make them testable. SpaceX can put every Raptor engine on a test stand and validate it before putting it on a booster. The N1’s engines used pyrotechnic activated valves, which made testing every motor much more complex and costly (you had to rebuild and refurbish the engine before you could use it again.)

More engines do not mean more risk. The Falcon 9 and Rocket Lab Electron, two of the most reliable contemporary launch vehicles, have nine first stage engines. All of which have been validated on the test stand.

In a graphic, which I think is the best illustration of Dodd’s thesis, he explains why more engines doesn’t mean more failure. It’s a trade off: fewer engines mean that losing one can cause you to lose the vehicle or mission, more engines gives you redundancy, but more complexity. And even that, as Dodd explains, has some nuances.

SpaceX has a lot of smart people, not just Elon Musk and his baggage, and I agree with Dodd that, as long as SpaceX has time and resources to put into development of Starship, it’ll fly reliably and hopefully change the economics of getting to space as Falcon 9, Electron, and other new-generation launch vehicles have.

The things I think that hamper SpaceX, besides Musk’s many faults, include Boca Chica not being a good launch site. SpaceX is building out a launch site for Starship at Cape Canaveral. (This is ignoring that neither Florida are Texas are safe places to be unless you’re a wealthy, white cisgender man.) And there’s the cavalier attitude shown towards SpaceX’s neighbors, both people and habitats, in South Texas which needs to change.

Ideally, SpaceX’s workers can organize for better working conditions and pay, give Musk the boot, and build great rockets in the service of everyone, not just a handful of rich people with dreams of colonizing space.

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