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Re: New idea Laser launcher/scoop systems

At 8:55 AM 3/11/96, Timothy van der Linden wrote:
>Lee wrote,
>>>Although, I don't know what this program or the equation looks like, I've
>>>serious doubts if they are right. This is because the numbers don't line up
>>>with my own and with Steve's calculations. (2 to 1)
>>I checked his equation source and it is the right equation for non
>>relativistic flight, I have the version for relativistic flight if you want
>>it. Actually his numbers don't look to far off. Because of the extremely
>>high specific impulses he listed, the mass ration is very low.
>I already see what makes the difference (besides the fact that formula
>doesn't take into account what the energy:mass ratio of the fuel is). For
>slightly different exhaust speeds (around 0.08c) the ratios are optimal. I
>must have overlooked that in Kellies table, where at the top this speed of
>25M is used. I don't understand however why all the other numbers are shown
>in the table.

I wanted to show all mass ratio's with various specific impulse numbers.

>>However, I would like to know where his choices of Specific Impulse I(sp)
>>came from they look a little outrageous.
>I can tell you (and show you, but would not recommend) that for a final
>velocity of 100,000,000 m/s an exhaust speed of 24,500,000 m/s is optimal
>(assuming a mass:energy ratio of 300) The initial:final weight ratio is 70:1
>in that case. (All these numbers are rather critical!)

Agreed, unfortunatly the papers weren't that interested in the systems with
spec impulse of over 1,400,000.  Which is anoying.



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