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Re: starship-design: New Idea from non member

In a message dated 7/23/97 1:31:36 PM, zkulpa@zmit1.ippt.gov.pl (Zenon Kulpa)

>> From: KellySt@aol.com
>> In a message dated 7/22/97 3:46:35 PM, jimaclem@juno.com wrote:
>> >---------start new idea -------------------
>> >
>> >Each transmitter could be a stationary fusion rocket with the beam
>> >pointed in one direction, and the fusion exhaust (at very low speed)
>> >pointed in the other.  Since the whole thing is stationary, it could be
>> >refueled periodicly by robot tenders.  The fusion motor could tap most
>> >of the kinetic/thermal energy of the fusion products to provide
>> >electricity to power the transmitter, with a little left over kinetic
>> >energy and a fair amount of mass to provide a counter balancing force.
>> >
>> >---------end new idea -------comments?-----
>> Cool, that would also get around the problem of the transmiters 
>> moving during the transmition period.
>Eh, what do you mean by "stationary"?
>Nothing in space is stationary, it will always orbit
>around (or falling at) some other body.
>You may make it "stationary" with respect to the Sun
>making it hover at a distance due to constant thrust
>toward the Sun --

Yes, fixed (give or take) relative to the Sun and the target star.

>--(I wonder how large thrust it should be 
>in the gravitational field of the Sun near the Earth orbit -
>can physicists here calculate this?). However, the thrust
>should also compensate for the recoil from the emitted
>beam (quite large, I am afraid).
>Moreover, refueling them would be a problem - a robot tender
>going from Earth (or the asteroid belt) with the fuel
>will have to decelerate away all its orbital speed
>(30 km/s in the vicinity of Earth's orbit),
>stay "stationary" on its rocket exhaust when at the transmitter
>(or be firmly hooked to it, using transmitter increased thrust 
>for hovering) and then accelerate again to this speed when going back.
>And such a manoeuver will certainly shatter a little 
>the transmitter itself, making the beam jiggling.

If we can consider launching a starship, the fueling tug would be a trivial

>There will be similar problem with positioning the starship itself
>on the straight-line (along the beam) course to the target system - 
>first you must somehow annihilate its orbiting speed around the Sun
>(which will be essentially perpendicular to the direction 
>of the beam...).
>-- Zenon

Again.  Compared to the 100,000 kps the ships tring to push itself up to.  30
kps is noise.  The equvelant to a ships manuvers in port to dock.