Unofficial rules for variable thrust engines in GURPS Spaceships

I had made up some unofficial rules for variable thrust engines in GURPS
Spaceships; you can review them to see if it is good or if you believe
there is something wrong with it and should be changed. (If you want to
include this in Path of Cunning, that is OK with me.)

These rules are valid for the following classifications of engines:
Electric, Nuclear Pulse, Fusion, and Antimatter.

The design parameters are a number from 0 to 1 called x, and the specific
type of engine (e.g. "Fusion Torch"). Do not select the "high thrust"
option; these rules supersede that option. (I don't know if any of the
other options are compatible; my guess is that they are not compatible,
but please tell me if you believe otherwise.)

Write the engine name as "Variable Thrust ([x]) [engine name]". (You should
also write down the acceleration and delta-V before you play a game
session, so that you do not need to calculate it during the game play.)

To determine the delta-V, acceleration, and power requirement, of each
mode (low and high), multiply the numbers for the standard engines by the
numbers in the appropriate table below.

For Electric, Nuclear Pulse, and Fusion:
                  Low        High
Acceleration     (1-x)       (1+x)
Delta-V            1        (x+1)/(3x+1)
Power            (1-x)         1

For Antimatter:
                  Low        High
Acceleration     (1-x)       (1+4x)
Delta-V            1        (4x+1)/(24x+1)
Power            (1-x)         1

Cost and other characteristics are unaffected.

Example: You will have a Variable Thrust (0.5) Orion Drive, with one system
of engines and one system of fuel. When it is operating in low thrust mode,
it has 8 mps delta-V and 1G acceleration. When it is operating in high
thrust mode, it has 4.8 mps delta-V and 3G acceleration. Since Orion Drive
is not a high-power system, neither is this one.


--
Don't laugh at the moon when it is day time in France.