[AR] Re: Injector Material

  • From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
  • To: Arocket List <arocket@xxxxxxxxxxxxx>
  • Date: Mon, 11 Oct 2021 16:56:31 -0400 (EDT)

On Tue, 12 Oct 2021, Jonathan Adams wrote:

The engine I'm working on now runs Jet-A and LOX at 350 psi and r = 2.3 (when operating at its limit). For reasons relating to cost I've so far been looking at 6061-T6 aluminum, but I'm now wondering whether that's the right choice... Can aluminum get the job done?

Yes, but. It's certainly been done; it's seen significant use -- mostly with slightly cooler-burning propellant combinations, but if I recall correctly, the LR-101 (Atlas vernier) injector is aluminum. The downside: it's unforgiving -- the cooling must be just right -- because it loses strength so rapidly with even mild heating. With an aggressive oxidizer like LOX, it can even ignite. Most likely not a good choice for early experimental work.

Is there a grade of copper that is preferable for something like this?

C145, aka half-hard tellurium copper, seems to be what people like -- properties much the same as pure copper but a lot easier to machine.

Henry

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