One way to create a heavy launch vehicle is by clustering large numbers of small engines together in a stage. An example of this approach is the SpaceX Falcon 9:
Falcon 9 first stage engines
Now I've heard people arguing against this approach, saying that the engines may interfere with each other and that you're better off using fewer, large engines. This argument often refers to the N-1 which used 30 engines on the first stage:
N-1 first stage

Now I realize that when you get more engines, you get more parts and as a result, more possible problems. But does the engine arrangement itself pose a problem when you have more than a few in close proximity?


The N-1 suffered from a lack of testing, at a test stand level, and instead had to do all up tests that exposed the failures, which their leadership could not tolerate.

There are probably lots of different issues that can happen in multiple engine configurations.

One upstream one that can happen is that the fuel/oxidizer flow, through the piping, which clearly gets more complex as the number increases, can generate resonance vibrations that cause fuel flow issues.

Here is the SpaceX LOXtpus manifold, for just 9 engines!

enter image description here

Imagine the plumbing for 32 engines. These are not small volume pipes where variations in flow do not matter.

Then you get exhaust impinging on each others exhaust. I recall reading somewhere that the RS-68's under an SLS model would get too hot, from the exhaust of the SRB's or would trap some of the heat, making it an issue. That was just a 2 SRB + 3 or 5 RS-68 model. Again, extrapolate to 32.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.