• Edward

    Last weekend, one of my brothers and I went with a couple of cousins to see the Endeavor in Los Angeles. My brother was impressed with the engine (the same type that SLS uses), because the display plaque told us that three of these Shuttle main engines produce as much power as 13 Hoover Dams, meaning that each engine produces about 9,000 MW — roughly the equivalent of nine large power plants.

    He was also impressed that the temperatures within the engine reached 6,000 degrees (F), or as the display plaque noted: hot enough to boil iron.

    He than felt the need to look up the pressure on his phone, and found that the engine operates at a pressure of 3,001 psi (it wasn’t rounded down to 3,000).

    I pointed out to him that it produced all that power at that temperature and pressure in the small combustion chamber, much smaller than the boilers (reactors) of the nine power plants, and much much smaller than the turbines of the 4-1/3 Hoover Dams.

    Yet the engine does not melt (cooling is a big part of the design), or explode from the pressure (well, technically, the drop in pressure and expansion of the exhaust *is* an explosion, where explosion is defined as a rapid drop in pressure or rapid expansion of gas, often with a loud noise).

    He concluded that it really *is* rocket science.

    Fortunately for the test Robert writes about, the engine performed better than the test stand. Then again, they may put more attention and maintenance into the engine than they do the test stand. And for good reason!

  • pzatchok

    SLS is sad.

    Are they just using old left over engines from the shuttle or have they actually built a few new ones with all those billions spent?

    All they are really doing is redesigning a tube.
    The tube that makes the rocket body.
    Strap the old shuttle main engines to the bottom, put the old shuttle liquid fuel tanks inside, strap on the old shuttle solid boosters to the sides.
    After that just how much of a second stage would they need? They have at least three other second stage rocket systems and engines in production now. Just use those.

    By an idiots estimations that could or should get them 2000 tons for the second stage. the weight of the shuttle, empty.

  • Alex

    Pzatchok: Yes, you are right, SLS is very sad. No system innovation (beside some tank manufacturing), 45 years propulsion technology (SSME / SLS main engine was designed around 1972). What for a dinosaur and expensive system! The technological solutions chosen for Shuttle propulsion, made between 1969 and 1972 (solid rocket booster, complex and sensitive, extrem high pressure SSME) was already wrong at this time and today even more. It would have been much better to use Saturn-IB launcher further for decades following Apollo’s end , increasing performance of the system incrementally, lowering cost and try to make first reusable as already discussed at those days.

  • pzatchok

    Sorry I got the weight of the total launcher and the orbiter wrong.

    The total weight was 2000 ton with the orbiter being just 70 tons.

    It doesn’t change the idea that the value per return just doesn’t add up.

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