[Spaceships] Query: Activating Mag-Sails

[DaltonS]

Originally Posted by thrash

Sean Barrett's 1992 (!) Roleplayer article, "Stellar Windjammers: The Magnetic Space Sail Drive," has the following:

Radius (mile) = sqrt(thrust in tons)
Energy (MW-hrs) = 25.7 * sqrt((thrust in tons)^3)

Note that since Mars lacks a magnetosphere, any magsail (or plasma sail, for that matter) maneuvering would be in relation to the solar wind, not the planet as such.

Wow! Talk about a blast from the past! I found this article online if anyone wants to read the whole thing. (The radius should be 200*sqrt(thrust in tons) miles according to the article.) Now to translate this into Spaceships terms. To keep things simple, let's assume the charging time is the deployment/retraction rate of one minute per mile of radius. Thus the energy required would be 1 PPh per mile of radius / 60. Thrust in tons would be 0.001 * LWT of ship making the radius=sqrt(40*LWT) miles. (The units might not exactly match but I don't want to get into the MW per PP debate.)

Dalton “Looks like I may have to retract my previous post” Spence

[DaltonS]

Just in case anyone is interested, here's a quick table of magsail radiuses and energy requirements.

| Size Radius  Energy|Size Radius  Energy|Size Radius  Energy|Size Radius  Energy|
| (SM) (miles) (PPh) |(SM) (miles) (PPh) |(SM) (miles) (PPh) |(SM) (miles) (PPh) |
+--------------------+-------------------+-------------------+-------------------+
|  +3   10.95   0.18 | +5.5 48.99   0.82 |  +8   200.0  3.33 | +10.5 894.4 14.91 |
| +3.5  15.49   0.26 |  +6  63.25   1.05 | +8.5  282.8  4.71 |  +11  1095  18.26 |
|  +4   20.00   0.33 | +6.5 89.44   1.49 |  +9   346.4  5.77 | +11.5 1549  25.82 |
| +4.5  28.28   0.47 |  +7  109.5   1.83 | +9.5  489.9  8.16 |  +12  2000  33.33 |
|  +5   34.64   0.58 | +7.5 154.9   2.58 |  +10  632.5 10.54 |                   |

* A spacecraft cannot be given a space sail if its SM exceeds its TL.

Dalton “I hope this is helpful.” Spence