Re: FW: starship-design: Interstellar travel-using vacuum..ur point?

["Kyle R. Mcallister" <stk@sunherald.infi.net>]

> I'm not so sure about Kyle's assertion that drag places an upper limit of
> .3c on a ramjet's velocity. I have also studied them for almost twenty years
> and don't recall having ever seen that statement. (Kyle, citation please?)

My mistake...it wasn't 30%c; it was 10%c as an upper limit. Nick
Herbert, PhD, has done his work on this, and here is your requested
citation:

"In 1960 Robert Bussard of TRW Corporation proposed using the
interstellar medium itself--which contains a few hydrogen atoms per
cubic centimeter--as a rocket fuel. The fact that the ships fuel is
obtained from the outside eliminates the exhaust-velocity limit; the
Bussard jet is capable of efficiently accelerating to speeds greater
than its own exhaust. The Bussard ramjet would employ an enormous scoop
constructed out of electromagnetic fields to collect and funnel hydrogen
into a nuclear-reaction motor. The Bussard jet actually becomes more
efficient at high speeds, because the faster it goes, the more hydrogen
it collects. Many science fiction writers have used Bussard ramjets in
their flights of fancy, however the Bussard principle suffers from the
fact that at high ship speeds the fuel is not standing still but impacts
the ship's scoop at enormous velocity. The incoming fuel constitutes a
huge headwind, which becomes increasingly difficult to overcome as the
ship goes faster. The speed of the Bussard jet soon reaches an upper
limit--about 10 percent of light speed--where thrust is equal to wind
resistance and the ship can accelerate no further."

That from Nick Herbert's book "Faster than light: superluminal loopholes
in physics." It might get you to 30%c in this thinned out region, if you
can get enough fuel. But then, there is our viscious fuel/velocity
circle again. It's just my opinion, and I don't want to start a thread
on this, but we need two things if we ever wish to seriously attempt
interstellar flight: 1. A way to interact with spacetime to provide
fuel-less propulsion, and 2. A method of travelling faster than light.
Both of which I believe are possible.

Kyle R. Mcallister