# RE:

```
> >Kevin
> 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
> >
>
> Brian:
> How are these %reflections figured.  Is it .99% efficiency, 99%, .0099%?

..99 is 99% I just pulled that number from air.

> Also, are these stresses acounting for the stress at cable connection points
> or what?

This stress is on a per meter basis.  so if you attached a cable to each
square meter, that would be the stress on each cable.  but since that
would be rather wasteful, I would suggest one cable for every 10 by 10
meter area.  this would increase the stress to 50 pascals per cable.

>
> >Kevin
> >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.
>
> >Kevin
> >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.
>
> Brian
> Jupiter size was to make sure we could keep our now defunct retro mirror
> inside of a distance diverged beam.  A Luna sized sail was, I think,
> proposed to be certain that the E18W that we were putting into it wouldn't

but with my idea for launching the decell beam ahead of the ship, we
don't need a jup sized RR.  and my table above, shows that increasing the
size, increases the mass, which increases the energy needed which
increases the thermal load...... etc etc etc.  thus, the smaller the sail
the better

> melt the thing.  Also, the models that I was working with hoped for a sail
> that weighed closer to 50g/km^2, not 50g/m^2.  But if you can keep the
> thermal load managable on say a 10km^2 sail, and keep enough power focused
> on that sail for 1E4 to 2E4 AU, then I think we have a way to at least
> launch ships via masers.
>
>
>
> Kevin
Kevin

```

• References:
• RE:
• From: Brian Mansur <bmansur@oc.edu>