[AR] Re: I took up a crazy challenge!

  • From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
  • To: Arocket List <arocket@xxxxxxxxxxxxx>
  • Date: Fri, 10 Feb 2023 00:33:23 -0500 (EST)

On Fri, 10 Feb 2023, Rocket Pavitra wrote:

...Expanders suffer from a limit to how much thrust they can produce because of the square cube law with the walls of the nozzle. ~300kN

It can go much higher, given clever design. Pratt & Whitney (builders of the original expander-cycle engine, the RL10) proposed a "split expander" cycle -- some of the fuel goes direct to the chamber, bypassing the cooling jacket, and hence can be pumped to a lower pressure -- for the RL200, their bid for the J-2 engine (200klbf, ~900kN). Much later, they proposed a variant of this cycle at 600klbf (~2.7MN).

Also, there was some successful experimental work on putting a heat exchanger in the chamber (!) to add more pump power.

Henry

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