SpaceX Raptor Methane Fuel vs. NASA SLS Hydrogen Engine

Mar 17, 2020
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To Mr. Nelson and staff: Why was the SLS designed to use a hydrogen / oxygen mixture like the 1960's Apollo program? Let's stick to basics:

SpaceX uses methane (CH4) in their the new Raptor engines along with liquid oxygen as the oxidizer for their Super Heavy and Booster stages of the Starship. CH4 is cheap, a passive cooling gas where the system is enough to store in liquid form, significantly denser than Hydrogen, storable for a more extended period, does not leak, does not require insulation on the fuel tank, and the rocket design is less complex compared to Hydrogen-powered rocket.

There must be more than a few good engineers that work for SpaceX which is a pure commercial enterprise. They not are bound to elderly congressmen who insist NASA continue to use hydrogen because it worked 50+ years ago in Apollo rockets. That is why the public is continuing to hear the repeated delays in the Artemis I launch caused by the various hydrogen leaks. Unfortunately, it's probably too late for NASA to redesign the SLS without hydrogen fuel. Too bad, the public, democratic and republican, don't realize the tremendous waste of American citizen money from the SLS program's design. It's a real shame.
 
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Nov 16, 2019
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LH2 is best for nuclear engines. I hope SLS evolves into something like Energia. Side mount for outsized aerobrake disks…simplified Buran type orbiter.

Use spent cores as wet workshops. SLS is a lot like the Convair Atlas as a stage-and-a-half system, and the core emits no CO2. SuperHeavy to replace the SRBs…like the old ALS/NLS configuration.

Starship’s use of methane..it’s lack of an escape tower….and the fact that your spacecraft takes that huge unwieldy eggshell tankage is also worrisome.

If it works, fine—but I think both SLS and Starship will have roles to play. It doesn’t have to be either or.
 
Mar 17, 2020
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A replacement for methane is fine. The kerosene that SpaceX uses has a soot problem. But we can't keep using liquid hydrogen this way with all of the leak issues. Of course the best way is to get rid of the rocket technology altogether whenever that comes to be.
 
To Mr. Nelson and staff: Why was the SLS designed to use a hydrogen / oxygen mixture like the 1960's Apollo program? Let's stick to basics:

SpaceX uses methane (CH4) in their the new Raptor engines along with liquid oxygen as the oxidizer for their Super Heavy and Booster stages of the Starship. CH4 is cheap, a passive cooling gas where the system is enough to store in liquid form, significantly denser than Hydrogen, storable for a more extended period, does not leak, does not require insulation on the fuel tank, and the rocket design is less complex compared to Hydrogen-powered rocket.

There must be more than a few good engineers that work for SpaceX which is a pure commercial enterprise. They not are bound to elderly congressmen who insist NASA continue to use hydrogen because it worked 50+ years ago in Apollo rockets. That is why the public is continuing to hear the repeated delays in the Artemis I launch caused by the various hydrogen leaks. Unfortunately, it's probably too late for NASA to redesign the SLS without hydrogen fuel. Too bad, the public, democratic and republican, don't realize the tremendous waste of American citizen money from the SLS program's design. It's a real shame.
I disagree that SpaceX is purely commercial. It is being done for altruistic reason, to get to Mars and form a colony of back-up earth life. Most people cannot imagine altruism, well these is one very good example if you are watching and listening.

Remaining space shuttle engines are being used by SLS for Artemis. These cannot be modified to use methane. It would be the same as starting from scratch to build methane engines for Artemis. And, of course, the real pity is that these magnificent engines go into the ocean after one use. So how cheap is it to use existing materials (especially the engines) and it still cost $billions to get the thing going? Hopefully we will very soon see Space X show off their very large Starship rocket, which will be reusable.
 
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Nov 16, 2019
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The RS-25 just did a 600 second test. I doubt Raptor could match it. I think RS-25 could probably burn even longer. Perhaps converted to methalox with Raptors used for landing?
 

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