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

["L. Parker" <lparker@cacaphony.net>]

Sorry, I sent this to Garth and forgot to cc the group...

-----Original Message-----
From: L. Parker [mailto:lparker@cacaphony.net]
Sent: Tuesday, September 22, 1998 4:44 PM
To: GVoigt8259@aol.com
Subject: RE: starship-design: Interstellar travel-using vacuum..ur
point?


Garth,

The original Bussard Ramjet concept, although meeting the basic interstellar
drive requirements of not carrying around huge amounts of fuel, quickly runs
into problems. Space is not homogeneous, that is, the concentration of
interstellar hydrogen and other matter is not consistent throughout space.
It is thought that a concentration of hydrogen of 1 atom per cubic
centimeter is necessary for a ramjet to work. Unfortunately, our solar
system is located in the middle of a giant cosmic "soap bubble" where the
interior concentrations of hydrogen are far lower than what is necessary for
a ramjet.

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?)
It may be that once the craft is up to a certain speed, the "apparent"
density might be great enough to sustain a decent acceleration. Perhaps a
hybrid between onboard tankage and scoop collection...

Lee