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Re: Laser Aperture Size
- To: "L. Parker" <lparker@destin.gulfnet.com>
- Subject: Re: Laser Aperture Size
- From: kgstar@most.fw.hac.com (Kelly Starks x7066 MS 10-39)
- Date: Mon, 18 Mar 1996 08:27:13 -0500
- Cc: kgstar@most.fw.hac.com (Kelly Starks x7066 MS 10-39), David <David@InterWorld.com>, hous0042 <hous0042@maroon.tc.umn.edu>, KellySt <KellySt@aol.com>, rddesign <rddesign@wolfenet.com>, Steve VanDevender <stevev@efn.org>, "T.L.G.vanderLinden" <T.L.G.vanderLinden@student.utwente.nl>, bmansur@oc.edu, zkulpa@zmit1.ippt.gov.pl, jim@bogie2.bio.purdue.edu, DotarSojat@aol.com
At 9:28 PM 3/16/96, L. Parker wrote:
>At 01:31 PM 3/15/96 -0500, you wrote:
>>
>>!!! If your getting about a G of decel out of a charged sail, You could
>>adgust the sail so it only reflected absorbed enough to keep the sail
>>charged. (It would act like a sheet as long as the voltage could stop the
>>mass farther out then the gaps in the mesh.) Given that that power should
>>be much less than the amount to push the ship at 1G. You'ld cut your
>>forward thrust, and THE SAIL WOULD ACT LIKE A BRAKE! That might be the way
>>to get your ship stoped at the target system.
>>
>>
>>Why didn't you follow up on, or talk more about this? Whats the dragdrop off?
>>
>It is called magnetic scoop deceleration or an electrostatic drag screen. It
>can also be done similarly to the Lorentz Force turning by simply trailing
>charged wires.
>
>For an elastic sail the equation is:
>
>V(s)=2*A*p*m(p)*[(V(s)^2)/M(s)]
>
>for an inelastic sail the equation is:
>
>V(s)=A*p*m(p)*[(V(s)^2)/M(s)]
>
>Where A=scoop field area, p=interstellar ion density, M(p)=proton mass,
>V(s)=ship velocity, and M(s)=ship mass. Because of the V(s)^2 factor in
>these equations, deceleration eficiency decreases rapidly as the ship
>decelerates.
>
>Other than as something to be concerned about as far as drag goes, this
>method will not generate sufficient deceleration to be useful in
>decelerating from near light speed. As a braking method for a ship that was
>accelerated purely via sail to a maximum velocity of about .2c to .3c, it
>might be feasible, but you will be looking at a 20 to 25 year deceleration
>even then.
Ouch, if we could get down to .2-.3 I'ld figure we could do the rest by
rocket. But if we're talking about that kind of time to get down to .3c it
won't help much.
Kelly
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Kelly Starks Internet: kgstar@most.fw.hac.com
Sr. Systems Engineer
Magnavox Electronic Systems Company
(Magnavox URL: http://www.fw.hac.com/external.html)
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