Just wanted to post the URLs for the "original" Roton paper on the Web.
This paper asserts something like a 10:1 thrust contribution from the rotor "while in the sensible atmosphere". I haven't seen any detailed profiles, but I'd guess the rotor thrust contribution for this configuration does start to poop out at something like 10 miles' altitude. Still, the first miles _are_ where you have to burn most of your propellant--accelerating the rest--and the fact that the vehicle *is* being accelerated does make it potentially a bigger win than the old "rockoon" concept.
PS: it appears that Bevin McK., coiner of the "Roton" label, has agreed to dilute the term "Roton" to include systems that don't use rotors for boost phase. C'est la marketing. Long live the radical unRotonoids. :)
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