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Re: MIRRORS Argosy Class

At 12:57 PM 3/6/96, Brian Mansur wrote:
> ----------
>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
>>officially been hulled.  The course correction problems needed avoid the
>>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.
>>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?
>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.

???  Over interstellar distences your expecting to  shoot between the sail?
Besides the beam diameter would be the size of jupiter or something, and
fading out to almost forever.  You couldn't make a sail that has a hole
bigger than the beam.

>[text deleted]
>>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.
>>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.
>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

That would just involve SLOWLYYYY!, pulling in or letting out some line on
the right support cables.

>>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.
>See my idea in Mirrors round 3.
>>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.

While surfing a microwave fire house at near light speed?

>>??????!!!!  Jupiter!
>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.

But then you'ld need to aim the refocused beam to interstellar optical
precision.  Also you'ld need to be able to build a freznel lense the size
of a planet and carry it to interstellar space, and have it automatically
center itself on the beam and aim at the target star.




Kelly Starks                       Internet: kgstar@most.fw.hac.com
Sr. Systems Engineer
Magnavox Electronic Systems Company
(Magnavox URL: http://www.fw.hac.com/external.html)