[Spaceships] Homebrew - Alternate Contragrav

[DaltonS]

Another new design switch suggestion for GURPS Spaceships:
Force Screen Variant

Gravity Screen: Provides no DR (although it does affect Tractor Beams[1] and Graviton Guns[2]) but instead lessens the gravitational effect of outside masses on the ship. Read "dDR" as the divisor applied to a planet's gravity to determine its effect on the ship*. You can have both a gravity screen and another force screen.

* The ship's mass remains the same however, so the rate of ascent in a vertical take-off would be A-G/dDR where A is the spacecraft’s drive acceleration in G, G is the world’s gravity and dDR is the gravity divisor. To find the effective escape velocity of planet while using the screen, divide its natural escape velocity by the square root of the dDR. (FWIW: The solar escape velocity from a planet's orbit is that planet's mean orbital velocity times sqrt(2).)

Example: An SM+10 (10,000 ton) ship with a gravity screen installed has an effective weight of 66 2/3 tons on a 1G planet. If that planet is Earth, its effective Ve would be 6.96/sqrt(150)=0.568 mps.

While not a defensive system, the gravity screen does have an effect on gravity-based weapons:

1. Tractor Beams: The force applied to a target with a gravity screen is divided by the screen's dDR.
2. Graviton Guns: Gravity screens protect with 1/10 dDR.

Dalton "treating this with the appropriate gravity" Spence