Dwayne_Knight

I was thinking a fanjet and long thin wings can get you altitude efficiently, and a jet engine can get you the first fraction of your delta V in atmosphere efficiently. I'm just guessing one platform can't get you both so easily. Have you guess seen any proposals for jet engine first stages? I've seen one before but it seemed questionable at best.

What if they were buried would the stone provide enough insulation?

I like the idea of burying it deep in a subduction zone so it eventually gets dumped into our core and in some tiny way helps with our magnetosphere. I'm glad someone mentioned it.

Chip it small and agitate it or melt it at slowly raising temperatures spinning it to separate it you should be able to get some useful materials at useful purities.

I don't know. I suspect you would have to get subsonic air to get a proper air fuel mixture. Also I hear they have reliability problems. I had a little looking around. A pump concept I initially dismissed because I was concerned about size valve switching speed and fuel pulsation may be perfectly viable. I'm not sure how they plan on keeping the gas from bubbling and such. The key thing is it's light simple and maintains the high pressure away from the storage tank. I'd guess you could even store your first shot of fuel in the pump. http://www.google.com/patents/US20090257888

Reminded me of this article I'd read once. I hope you find it interesting. http://www.nasa.gov/centers/marshall/pdf/173616main_pulse_detonate.pdf

I thought the weight penalty came from having to make the whole tank withstand the high pressure needed to force the fuel out. The turbo pump acts to regulate pressure between the high and low pressure sides so the fuel container just needs enough structure to hold the mass against acceleration and most of the is done by modest over pressure. I wonder if some other kind of pump could do the job cheaper. I could rattle off a few types of interesting pumps but they aren't cheap. It might seem silly but what about a helical roots type pump driven thermal electrically.

I wonder if nanofactor level nanotech will stumble across the source of all the cold fusion confusion and maybe come up with just such a device.

If I had the resources I'd do research on rechargeable molten carbonate fuel cells right now with some kind of co-generation. I think energy storage in carbon, methanol and dimethyl ether would either for use in the cell or as more traditional fuel use be beneficial. I also wonder if flywheels have long term prospects with future materials improvements in tensile strength and higher temperature superconductivity.

I'd try laser ablation to push the junk into collection paths with intercepts with a collection vehicle that don't lose momentum. I'd deorbit some of the junk to propel my system. The key thing I'm trying to imagine is what to do with the material other than propulsion. We have limited fabrication capability at this point. Perhaps building that asteroid tug that's been proposed. Junk mass is as good as any mass for that I suppose.

The thing about mufti-stage vehicles. I like the Idea of ditching (or unpowered return) of used fuel storage. I've never liked the feel of engine redundancy. It always seems it should be possible to use less mass to improve an engine you already have than include another. I wonder if skylon or one of our hypothetical vehicles wouldn't benefit from a glide return drop tank. I think the shuttles tank was mentioned in this thread. I'm sure if I go looking this has been mentioned somewhere before.

Thanks for the link to the raptor will take a look. I was thinking about the nozzle geometer and looking at some rocket based combined cycle papers on the web. Aerospike for the central rocket for space and entrainment would be fine and some more tradition geometry for the duct while in atmosphere. I like the look in the link bellow of profile C from figure 3.1 on page 36. Let me know what you think. http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CCkQFjAA&url=http%3A%2F%2Ftrace.tennessee.edu%2Fcgi%2Fviewcontent.cgi%3Farticle%3D1754%26context%3Dutk_gradthes&ei=DLNSU5GjIqP52wWF54CgDQ&usg=AFQjCNHUcJ77eZrq4WBgO6rYUCV4M_s1dA&sig2=m5oCjg2Zn56lpoC6P7VjFg&bvm=bv.65058239,d.b2I

I'm wondering what the disagreement is? I find at high speeds gasses in confined systems behave increasingly like fluids with flow characteristics and viscosity playing a role.

As others have mentioned I think the two lowest cost solutions are beamed power and air augmented rockets. Microwave beamed power using ground based nuclear seems cheaper since you can use existing reactors and of less cost politically. You won't get permission to create anything like a fission reactor rocket anywhere near earth any time soon. I'd suggest space based microwave emitters and a fan jet mother ship but a similar community of people object to "deathrays" from space as object to nuclear anything. Air augmented rockets should be simpler and with more versatile launch windows. I've seen a little comparison to the sabre engine suggesting temperature resistant materials are a problem offsetting some of sabres complexity. So right now I'm imagining a LNG/LOX air augmented rocket, with an adjustable scram jet intake, some type of aerospike nozzle, and fuel cooled engine and intake surfaces to reduce the material thermal load. So a sabre with the expensive radiator and turbo machinery gutted. Liquified natural gas should be a lot easier to store and handle than hydrogen and offers a somewhat middle ground between kerosene and hydrogen. Just spit balling needs a lot of math to back up the idea. Got me thinking so I did a little poking around and found an interesting concept for a space blimp. High altitude balloon ascent using a ion or similar efficient engine potentially solar powered. Pretty speculative. http://en.wikipedia.org/wiki/JP_Aerospace#Orbital_Ascender