RE: Old RAIR drive system

[Brian Mansur <bmansur@oc.edu>]

 ----------
From: kgstar
To: KellySt; hous0042; T.L.G.vanderLinden; stevev; jim; zkulpa; rddesign; 
David; bmansur; lparker; kgstar
Subject: Old RAIR drive system
Date: Tuesday, February 27, 1996 1:38PM

>From Brian 5:00 PM CT 3/5/96

>Kelly
>Heres some more text to look over.  Attack at will.  This was what I
>consider the baseline drive system for my Explorer class design.  Untill I
>figured out it probably wouldn't work.

Brian
Ready.  Aim, Fire!

A note to the Discussion Group.  I'm leaving the some of the text in the 
form of Excerpts and other with > signs for my convience.  If anyone wants 
to make a comment on my comments, you should probably delete the excerpts as 
we've had requests to cut down on repetitous volumes of info.  I'm only 
leaving the material in so that everyone can refresh their memory at least 
once on what I'm talking about.

Not that I have a tendency to interchange fuel and RM.  I'll try to be 
consistent but I'm pressed for time again.

[Begin Excerpt]
 -----------------------------------------------------------------------
multi-cycle Ram Augmented Interstellar Ramjet (RAIR)

Spring 1995

A drive idea I came up with, and used as the assumed system for this ship,
is A multi-cycle Ram Augmented Interstellar Ramjet (RAIR). It would scoop
up reaction mass from interstellar space like a pure ram scoop, but it
would only use it as reaction mass, not fuel. But the scoop system could
simultaneously scoop up fuel thrown ahead of the ship by a fixed launcher
back in our solar system.

The system is basically an electromagnetic accelerator running through the
core of the ship, powered by onboard fusion reactors. The accelerator could
accelerate scooped-up interstellar matter (or ram flow), or reaction mass
carried in the ship. Again, this kind of system is different from a true
Bussard ramscoop drive in that the ram flow is not fused for power. Indeed,
it normally isn't even slowed down. The engine functions in various ways at
various speeds.
 ------------------------------------------------------------------------
[End Excerpt]

Brian
Okay, this basically says that you overcome drag by not slowing the RM when 
you run into.  We still need numbers on the power required to ionize the RM. 
 I have the feeling that it will be way over what we can produce with our 
fusion powerplants.  This says nothing about how much fusion fuel we'd have 
to carry.

[Begin Excerpt]
 -----------------------------------------------------------------------
Acceleration To InterStellar Cruise

[Text deleted]

The idea I came up with to get around this fuel problem is to launch the
fuel ahead of the ship with orbital accelerators (thus the externally
fueled part of the name). The accelerators back home throw out HUGE
quantities of frozen pellets of whatever fusion fuel is selected, in the
path of the ship (called the acceleration track). The fuel is launched at
measured and timed speeds, so that the ship will encounter a fairly steady
stream of fuel during its run down the fuel loaded acceleration track.
 ----------------------------------------------------------------------
[End Excerpt]

Problem here.  You want to accelerate HUGE quantities of fuel and RM up to 
at least 1/3c.  Where do you get the power for this?  To do it you'd need 
 almost if not more power than a maser array would (groan).

>As the ship accelerates, it catches up with fuel going at increasing 
speeds,
>but always at speeds slightly slower than the ship itself.

Let me see if I understand something here.  You are laying a track of fuel 
that runs slow at first.  Then you plan on having the ship catch up to 
faster RM as you accelerate.  Have you laid the whole track out before you 
launched.  If so, you'd have to fire slower RM pellets first, then the 
faster moving pellets.  If this is done all along a straight track, you may 
have some fuel bumping into slower fuel.

Also, the rate of fuel launching increases as  you have to launch  higher 
velocity fuel.  Otherwise your faster fuel speeds ahead of the slower 
pellets and the Asimov can't accelerate fast enough to catch up.  Also, if 
it tries to accelerate too fast in a fuel stream with predetermined 
velocities along any given part of the stream, you start to get drag.

I have to stop now but I'll try to get you guys a solution that I worked on 
a while back.