SpaceX (Vol. 2)
Discussion
Beati Dogu said:
This thing is super utilitarian and yet clearly state of the art. Even the engine numbers are just stencilled or hand painted on.
Elon said they aim to get the price of the engines down to about $1,000 per ton of thrust, or $250,000 a piece. That’s less than $10 million to equip each booster (even assuming 33 on the production models).
A single RS-25 engine on the SLS wouldn’t even get out of bed for that kind of money.
I suspect that is "Elon cost" at work there, I'm sure $250,000 per engine is possible but probably in a distant multi-planetary future. Aero gas turbines are made out of similar stuff with similar components, they compete in a competitive market and have much higher volumes (100s-1000s). They cost around $1-2 million per tonne, the Raptor is about 1 tonne in mass.Elon said they aim to get the price of the engines down to about $1,000 per ton of thrust, or $250,000 a piece. That’s less than $10 million to equip each booster (even assuming 33 on the production models).
A single RS-25 engine on the SLS wouldn’t even get out of bed for that kind of money.
SpaceX is cost efficient but they only look really good when competing against terrible opposition!
For reference a Falcon 9 costs on average about $2 million per tonne, about the same as a business jet. Going to stainless steel on the tank wall will have pretty negligible cost impacts for a finished vehicle.
I can’t get my head around the (lack of) spacing between the bells on the outer ring!
In my Luddite brain, those bells are going to be touching once the Raptors are lit and vibrating / oscillating. SpaceX have obviously done the maths and so my concern is baseless, perhaps the pics are deceiving and the gaps are larger than they appear!
In my Luddite brain, those bells are going to be touching once the Raptors are lit and vibrating / oscillating. SpaceX have obviously done the maths and so my concern is baseless, perhaps the pics are deceiving and the gaps are larger than they appear!
Talksteer said:
Scottish Wyldcat said:
That's why I don't like concrete!
However if it's not the dating item construction duration really doesn't matter.
Looking at the launch tower it's pretty clear to see that with modern CFD they can be a lot less conservative than the designers in the 1960's.
Scottish Wyldcat said:
CFD? I am always caught out by acronyms
Computational Fluid Dynamics. Modelling the gases coming off the rocket, the wind blowing over the structure etc. I suspect there's some other computer modelling (the accurate kind, not the Imperial College sort) going on for the structure too - finite element analysis is going to crop up next I bet!
Krikkit said:
Scottish Wyldcat said:
CFD? I am always caught out by acronyms
Computational Fluid Dynamics 
Although I suspect he really means FEA - finite element analysis. Used to evaluate material/structure strength.
Flooble said:
Scottish Wyldcat said:
CFD? I am always caught out by acronyms
Computational Fluid Dynamics. Modelling the gases coming off the rocket, the wind blowing over the structure etc. I suspect there's some other computer modelling (the accurate kind, not the Imperial College sort) going on for the structure too - finite element analysis is going to crop up next I bet!
king exciting 
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