Re: MIRRORS Argosy Class

[Brian Mansur <bmansur@oc.edu>]

 ----------
From: kgstar
To: Brian Mansur
Cc: bmansur; David; hous0042; jim; Kelly Starks x7066 MS 10-39; Steve 
VanDevender; Timothy van der Linden; zkulpa
Subject: Re: MIRRORS  Argosy Class
Date: Wednesday, March 06, 1996 8:26AM

>Brian 12:50 PM CT 3/6/96
>
>Okay.  My first draft for the Mars Hybrid (now renamed Argosy Class) has 
now
>officially been hulled.  The course correction problems needed avoid the 
Sol
>beam during decel phase has necessitated that I go back and rework my sail
>and retro mirror design.


===========

>Okay, for decel phase, we split the Asimov's sail into two parts (or into a
>washer-like sail with a hole)  to let the maser beam fire between/through.
>
>        Beam
>     From Sol
>              !
>              !
>              !
> --------------     ---------------
>\    \                /  /
>         \           \            /         /
>                    \  \        /  /
>             A
>
>     Asimov = A
>
>     !              !
>     !              !
>     !              !
>Beams From Retro Mirror
>
>The flat horizontal  lines represent the sail and the slants are the
>connecting cables.  A cable will probably stretch between the two sails and
>is not shown for covienince.  By the way, if this ASCII art is not comming
>through, I'm genuinely sorry.  Somehow fonts seem to be different from
>person to person.

>Kelly
>Try a non proportional font like courior.

Brian
I'll give it a shot next ASCII escapade.

Kelly
>The washer sail focusing back on a smallar drag sail is a design Forward
>used in his Dragon fly series.  Assuming you intended to drop the outer
>sail as a retro sail?

Brian
I'm not sure if we understand each on the last sentence.  This washer sail 
design is ALL part of the Asimov.  The retro mirror has long since been 
launched to position separated.  The whole point  of the design is to let 
the maser beam go between the Asimov sails to the retro mirror.

[text deleted]

>Brian
>Course corrections are a detail we are still working on.  I'm beginning to
>think that the tugs that I've envisioned elsewhere might be replaced by the
>ion engine of the Asimov.  It could be fired at angles although the exhaust
>would probably be into the sail.  More thought needed.

>Kelly
>Rather than tugs, you could pull in one side of the sail to generate an off
>angle thrust.  Otherwise if you tried to push with rockets the sai would
>get twisted out of shape, or draged behind slightly.

Brian
Yes, I'd like to do that if possible.  This is where my limited 
understanding of engineering starts to get on my nerves.  I can give 
theoretical concepts, but I don't know if they can be done from an 
engineering standpoint for lack of classes like statics, calculus based 
physics, and so on.  So I don't know if angling the sail is going to be 
easier than a tug.  Some voice in the back of my head tells me that it would 
be.

>Kelly
>Of course trying to keep the retro mirror focused, or even out of the
>shadow of the ships retro mirror is probably a lost cause.

Brian
See my idea in Mirrors round 3.

>Brian
>I noticed that for this sail to work, the diameter would be greater than
>Jupiter's to let the beam through.  ARRGGHH!  On the other hand it doesn't
>have to be as precisely shaped as the retro mirror.  Still not sure how to
>correct retro-mirror's course and keep its shape.  I'm trying to figure if
>there is a way to break it down into components that will reflect at the
>slight angle needed to hit the new rig.

>Kelly
>??????!!!!  Jupiter!

Brian
We could cut that down considerably with refocusing mirror aparatuses which 
I proposed when I first joined.  That was in fact what my ugly BMP file had 
on it: a very simple diagram to illustrate the point.  Fresnel lenses might 
work better.  Problem is that these things have to be unmanned and they will 
take time to get into place.

>Brian
>I also toyed with the idea of having a one-way mirror/sail for the Asimov.
> I don't know how light we'd have o get a plastic lens for this.  Obviously
>can't use glass.  By the way.  Can we actually make a one way mirror with
>plastics?  If so, how thin?  Also, just to be clear, do microwaves bounce 
of
>hand mirrors better or worse than wire meshes?

>Kelly
>One way mirrors don't really work that way.  They mainly are not very
>transparent, and you make sure only the room on one side has lights on.

Brian
Bumber!