Weird question of the day

So, any mechanical or propulsion engineers out there?

What are the Shuttle\’s main engines made out of? The SSMEs?

My assumption given the temperatures they run at would be some form of high nickel alloy. But anyone actually know?

9 thoughts on “Weird question of the day”

  1. So Much For Subtlety

    Given that they run somewhat hotter than the boiling point of iron, wouldn’t it be irrelevant what they are made of? They only maintain structural integrity because they are constantly cooled. Now if they were cooled by the LOX there would be problems so I assume they are cooled by the liquid hydrogen. Hydrogen is not that reactive with most metals so why have a special alloy at all? Wikipedia seems to imply they are made of stainless steel. Why not? Why got for the exotic and expensive (apart from the fact that Uncle Sam is paying and so it is more or less mandatory)?

    Tim adds: Hydrogen does make a very large difference though. Not so much “reactive” as leads to cracking I think. High Ni alloys rather than stainless steel it seems. The copper is actually copper/silver and as far as I can work out the solder used is 20% Au. All of which makes them very interesting pieces of scrap metal….

  2. The hot side of the turbo pumps, which is exposed to the combustion products of the hydrogen/oxygen reaction, includes a multiplicity of small turbine blades which are typically investment cast from directionally solidified Mar-M 246 Hf alloy, an alloy which meets the previous definition of a high strength nickel base superalloy in that it contains more than fifty volume percent of the gamma prime phase and has a yield strength of more than 100 ksi (690 MPa) at 1000° F. (538° C.). The nominal composition of Mar-M 246 Hf, in weight percent, is 9 Cr, 10 Co, 2.5 Mo, 10 W, 1.5 Ta, 5.5 Al, 1.5 Ti, 1.5 Hf, balance nickel.

  3. Sorry, Julia, NASA isn’t on our list of approved purchasers. Besides, even if it was, they’d be out of luck. One Mr bin Laden seems to have bought the whole of next year’s production on behalf of the Iranian nuclear authority.

    As for the shuttle’s engines, I do know the O-rings used to be made out of rubber, but I think they changed the design a couple of years ago. Not sure why.

  4. The SSME nozzle is A248 stainless steel tubes ( through which hydrogen fuel is passed for cooling), in an Inconel 718 jacket.

    The combustion chamber is a CuAgZr liner in an Inconel 718 jacket

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