RogerBW's Blog

Lots of wargames, particularly those simulating space combat, have some sort of acceleration value for their units: you were going at speed 5, you accelerate by 5, you're now going at speed 10, so you move 10 units this turn.

This is wrong.

Games have finite turn lengths, and acceleration is applied gradually over the entire duration of the turn rather than happening all at once at the beginning and not at all the rest of the time. (Unless you're using an Orion drive.) What would be more accurate would be to apply half the speed change on the turn it's happening, and all of it on subsequent turns.

This system is a way of doing that without long calculations. It's not as quick as the abstracted form, but it is accurate to physics.

You will need one marker per unit ("marker-1"), and one spare marker ("marker-2"). If the game requires it, plot your movement (amounts and directions of thrust) as usual. When it comes to moving the unit follow this procedure:

• Place marker-1 at the unit's current position.

• Work out where the unit will arrive without manoeuvreing, given its previous drift speed and direction; place the miniature at that position.

• Place marker-2 on top of the miniature, then take it through the current turn's movement orders (applying thrust, rotating, and so on).

• Find the half-way point between the miniature and marker-2. Move the miniature there (and turn it to match the final facing of marker-2).

• Measure the distance and direction from marker-1 (where the unit started) to marker-2; these are the drift speed and direction values for next turn's movement, which should be recorded (either with markers on the table or on pieces of paper).

• Remove the markers.

Note that since this halves the distance by which units can displace themselves from their predicted position you may well want to halve the radii of any area-affecting weapons.