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Its certainly not too good... under 5% in any event for any reasonably sized rocket would guess, even with LOX/LH.
When you said "hopes on... X-prize class" my reflexes kicked in.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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That depends on what you consider to be a reasonably sized rocket. I think that a modern Saturn V- sized rocket should be able to get above 5% without much difficulty. If you consider the orbiter to be payload, shuttle actually gets over 6.5% (otherwise it is only 1.4%).
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Alot of the orbiters' mass is the engines and associated plumbing though, which I don't know if you can consider payload... Anyway, the size of rocket i'm thinking of would be intermediate, like Elon Musk's proposed Falcon-V rocket, which would be at or slightly smaller than the Russian Zenit-II I think.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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In theory a staged chemical rocket can put 10% GLOW mass into LEO. That 10% has to cover tanks, engines, hull guidance, life support. Payload can be more than half of that, the Saturn broke up easily and had intergrated tanks, used kerosene etc.
If you want the thing to be reusable then you use about 90% of your mass fraction in vehicle, leaving < 1% of GLOW for payload.
Easy rule of thumb though is to weigh your payload, then your rocket will way 100 times as much. Its the best number to work with for back-of-the-envelope Chemical rocket design.
Come on to the Future
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We wouldn't need to reach speeds of mach 25 if we had anti-gravity.
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yeah and if wishes were fishes we could build a really slimy space elevator.
Come on to the Future
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I dont see why we dont just build a really big railgun up the side of one of the Rockie Mountains and launch rockets that way.
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Even if you did have antigravity drive, you would still need to operate it continuously to hold altitude... turn it off, and down you go again since you don't have orbital velocity.
The reason why a cannon launch isn't such a great idea is that the payload size is fairly limited in volume and mass, and the extremely violent dynamics of it prevent launching of anything remotely delicate. Limited orbital inclinations and launch windows too.
I don't know if the mass fraction for an RLV is ~that~ bad, especially if you sneak around it a little... DC-X used aerobraking to slow down (in theory) and a TSTO could use airbreathing engines on the carrier plane.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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I was just kidding about anit-gravity, we won't see it in our lifetimes. A rail gun long enough, something on the sacle of the alaska pipline, wouldn' be too rough on delicate items.
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