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Re: New idea Laser launcher/scoop systems

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.

>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!)