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- From: Kevin C Houston <firstname.lastname@example.org>
- Date: Mon, 11 Mar 1996 16:59:32 -0600 (CST)
Here is a table of some maser sail numbers.
I think that 50 g/m^2 is kind of heavy, but as Tim said, this is going to
be subject to some severe torture. Perhaps the RR will sweep away the
ICM particles, but I don't know. No matter what the final density is,
i think these numbers will behave the same way, (ie limiting values on
heat load and stress)
Ship's Sail Sail Sail Total Accel Maser Refl Excess Stress
Mass Radius Dens Mass Mass Energy Eff. Energy
Kg Km g/m^2 Kg Kg M/s^2 Watts % KW/m^s Pascals
5E5 10 50 1.57E+07 1.6E+07 10 2.43E+16 0.99 773.8 0.515915
5E5 100 50 1.57E+09 1.6E+09 10 2.36E+18 0.99 750.2 0.500159
5E5 500 50 3.93E+10 3.9E+10 10 5.89E+19 0.99 750.0 0.500006
5E5 1000 50 1.57E+11 1.57E+11 10 2.36E+20 0.99 750.0 0.500002
5E5 5000 50 3.93E+12 3.93E+12 10 5.89E+21 0.99 750.0 0.5
5E5 10000 50 1.57E+13 1.57E+13 10 2.36E+22 0.99 750.0 0.5
5E5 100000 50 1.57E+15 1.57E+15 10 2.36E+24 0.99 750.0 0.5
Ship's mass is just the hab section (no core, no RM tanks)
sail density does not include guy wires to the ship.
Excess energy is the part of the maser beam that does not reflect
Several things have become clear to me since I ran these numbers (in Excell)
and I should think they will become clear to you as well.
1) the sail is the heaviest part of the ship. Even at 50 g/m^2, and 100
Km in radius, the sail alone approaches my original MARS design (now a
smoking ruin ;( )
2) both thermal energy and sail stress approach some limiting value as
the sail expands, so endlessly expanding the sail (even if we could do
it) would not solve any of the major problems (heat load and stress)
3) Stress is miniscule I don't where you guys have been getitng your
stress numbers, but they are out of whack.
for figure checking, reading line 3 with a sail of 100Km radius, and a
total mass of 1.57E9 Kg we find that the force of acceleration is
1.57 E10 newtons, and the total area is 3.14 E10 meters which of course
is .5 pascals (even a wet nose tissue could stand up to that)
4) smaller sails may be better. Why in the world you would need a sail
the size of Luna, much less Jupiter, is beyond me.
5) Thermal load is a big problem. 750 KW on .05 Kg is a big worry.
I have not calculated the limiting temperature yet, but I am hopeful that
titanium alloy will stand up to the load. To do this model, I will use
heat capacity and blackbody radiation equation. I do not have time right
now, but expect it soon.