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To: LibWhacker
...For example, PLT-powered spacecraft could transit the 100 million km to Mars in less than a week.” ...

How many G's would you be pulling?

7 posted on 09/10/2007 11:36:36 AM PDT by FReepaholic (Vini ,Vidi, VD: I Came, I Saw, I Cankered)
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To: FReepaholic

And, is that a ‘transit’ using steady acceleration for 7 days — in which case you blast by Mars doing a gazillion mph — or is it 3.5 days to mid-point, at which time you do a 180 and start decelerating (presumably maintaining a constant G load throughout?)

Anybody know how long a human can function under sustained multiple g-loads?


15 posted on 09/10/2007 11:44:18 AM PDT by Clioman
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To: FReepaholic

They now need to invent photonic brakes..........


19 posted on 09/10/2007 11:51:51 AM PDT by Red Badger (ALL that CARBON in ALL that oil & coal was once in the atmospere. We're just putting it back!)
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To: FReepaholic; RightWhale

He’s going to have to scale up the power considerably. I think RightWhale has it right... If my back of the napkin calculations are right, and If he can scale it up by a billion-fold (i.e., to 35,000 Newtons), a million kilogram ship (i.e., one of respectable size), starting at an initial velocity of zero, would travel about one kilometer towards Mars in a week’s time. LOL, not too good. So he’s going to have to scale up by a factor on the order of quadrillions or so.


20 posted on 09/10/2007 11:53:22 AM PDT by LibWhacker
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To: FReepaholic
If you wanted to start and stop at rest you would need to have your thrusters on for half the trip in one direction and then reverse direction for the second half.

In the simple case of a constant force (assuming a constant mass):

x(t) = x_0 + v_0t + 0.5 * a t² (x_0 and v_0 are assumed to be zero)
a = 2*x(halfway)/t² = 2*50e9 m/(3.5 days)² = 1.09 m/s²

This is about 1/9th of a g. If they had the capability to have 1 g of acceleration then the transit time would only be 56 hours (1/3 of a week).

46 posted on 09/10/2007 6:53:15 PM PDT by burzum (None shall see me, though my battlecry may give me away -Minsc)
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To: FReepaholic

F=ma

F = 35 µN
m = Mass of your spacecraft

Solve for a!

(Hint, not a lot of G’s, but you don’t need a lot as long as the acceleration is constant for a long period of time...)


60 posted on 09/10/2007 9:11:42 PM PDT by Frank_Discussion (May the wings of Liberty never lose a feather!)
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