<blockquote><font class="small">In reply to:</font><hr /><p>"The cost of fuel is a negligible percent of the total cost of launching today. The best way to reduce launch costs are to eliminate the standing army." <br /><br />Very true. But when you reduce the standing army, fuel costs aren't no longer negligible. Also propellant change from ordinary LOX/RP-1 etc to the exotic stuffs will skyrocket propellant costs. <br /><br />"Boron slurried Kerosene, for example." <br /><br />Pure elemental boron costs several dollars per gram. <br /><br /><p><hr /></p></p></blockquote><br /><br />Why does NASA need to be its own fuel company? Subcontract it out to a chemical firm.<br /><br />Methyacetylene, which provides 25% more payload in orbit than RP-1, and 2.5 times more than LH2 (for an equal volume of fuel) is merely a slightly distilled form of common welders MAPP gas, which runs about $6/kg in bulk.<br /><br />Cyclopropane, also another 'exotic' of comparable performance to MA, is similarly cheap when bought on the open market.<br /><br />Liquid oxygen is considered a waste product by the chemical industry, and generally charges the costs of transportation, storage, etc plus distributors markup (and they have a hefty markup if you are a mom and pop user).<br /><br />I know these are facts, I'm in the welding and plasma cutting business.<br /><br />And, no, boron doesn't cost that much per gram, its about $10/kg. It doesn't need to be perfectly pure, this isn't subatomic physics we are dealing in here, this is hot rodding. 5% boron slurry in kerosene gives a 107 sec boost over plain RP-1.<br /><br />What that means, even if your 'pure atomic boron' were necessary, that for every 19 kg of RP-1 (at typically $5-10/kg, at worst), you put in one kg of boron, your fuel cost per kg has gone up two to three times at worst, more like 10-20% in reality, while your launcher retains the volumetric energy density of kerosene while gaining the high Isp of LH2 without the vehicle size problems. The size of the payload