A kerosene-fueled X-33 as a single stage to orbit vehicle.
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From: Pat Flannery on 2 Nov 2009 11:25 Sylvia Else wrote: > > I wonder how far aviation would have got if the first aircraft had been > required to be economically viable. When designing the Flyer, it was the intention of the Wright brothers to make a lot of money by selling them to the US and other governments for use as military reconnaissance devices. That's the reason they took out so many patents on it, as it was their intention to lock any competitors out of the profits that could be accrued that way. They were doing pretty good at that tactic until Glenn Curtiss developed aerilons to replace the Wright wing-warping system for roll control, and that was not judged as a infringement of the Wright patents. Pat
From: Pat Flannery on 2 Nov 2009 11:35 Robert Clark wrote: > The very key aspect of this proposal is that the tanks remain the > *same* size, but at a *lighter* weight. In fact the intent was to keep > the same shape of the X-33 and just switch out the propellant tanks > and engines. So in fact the vehicle becomes lighter for its volume > with hydrocarbon fuels. The mixture rate by volume is way different for LOX/LH2 and Kerosene/LOX, so the tanks well have to be changed in proportional size to each other. Also, due to the far higher density of the Kerosene versus LH2, during acceleration a tank strong enough to carry LH2 will rupture under the higher weight of Kerosene. The whole point of the composite tanks on VentureStar was to get their weight down to lower than ones made out of aluminum, so I'm keen to see what you are going to make them out of that is lighter than composite materials. > When you consider the other benefits of hydrocarbon fuels over > hydrogen, the higher Isp of hydrogen/LOX propellant becomes less of an > advantage. > In fact, kerosene is not necessarily the best hydrocarbon to use, > which I'll discuss in a following post. I'm breathless with anticipation. Pat
From: Jeff Findley on 2 Nov 2009 11:13 "Sam Wormley" <swormley1(a)mchsi.com> wrote in message news:B_fHm.110690$5n1.67859(a)attbi_s21... > Single Stage to Orbit really limits payload "weight". I think you meant to say that SSTO would limit the mass fraction of the vehicle which is payload. I'd like to note that is not necessarily a bad thing, despite the belief of traditional aerospace engineers to the contrary. What you *really* want to optimize is cost per kg to orbit, not the payload mass fraction of your vehicle. Since the current launch market is rather small, there hasn't been much effort made in this area by the traditional launch providers. But I'd also like to note that some start-ups have been making some progress in this area, even though they're not actively pursuing SSTO vehicles. The development costs for a reusable SSTO would be high and the reality is that the current launch market just isn't big enough to justify the investment. Jeff -- "Take heart amid the deepening gloom that your dog is finally getting enough cheese" - Deteriorata - National Lampoon
From: kT on 2 Nov 2009 11:20 Jeff Findley wrote: > "Sam Wormley" <swormley1(a)mchsi.com> wrote in message > news:B_fHm.110690$5n1.67859(a)attbi_s21... >> Single Stage to Orbit really limits payload "weight". What you *really* want to optimize is cost per kg to orbit, not > the payload mass fraction of your vehicle. Cost per kilogram doesn't give you much engineering directive. You may as well have an engineering competition.
From: Sylvia Else on 2 Nov 2009 20:22
Jonathan wrote: > The military > wants a missile defense base on the south pole of the Moon, which > is the only place the Earth can be continually observed. Seems a long way out for a defense base that can in any case only see just under 50% of the Earth at a time, and has most of Earth out of view for nearly 13 consecutive hours in each 25. Sylvia. |