Quote:
Originally Posted by davester65
Yeah, I suppose I need to remember to take stuff in Wikipedia with a healthy dose of salt.
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Well, Wikipedia is accurately reporting on what the Skylon people want to achieve. It's just that they probably won't -- the history of spaceflight is littered with the debris of clever plans.
Jets have an extremely high nominal Isp when used in atmosphere at moderate velocities, for the simple reason that they're getting the vast majority of their reaction mass from the atmosphere instead of from the fuel (LOx/hydrocarbon is 75-80% oxygen by weight, LOx/LHd is 89%). This advantage drops off as air speed increases, but it's still very substantial.
However, they haven't even taken the first step of building some experimental planes and having them blow up when they try to fly them (c.f. the
HTV-2 Falcon and the
X-43). It's realistic for them to achieve that step by 2019, but it's a long way from there to production (I can't think of a space launch system that didn't blow up a few times in development and testing).