The material presented here is my original creation, intended for use with the OGRE system from Steve Jackson Games. This material is not official and is not endorsed by Steve Jackson Games.
Here's how to apply the point formula from the GEV calculator for Ogres.
Let's start with the Mark I.
The formula for the Main Battery is:
4 * (6 + (1 + X * 1.4)) + 2 * 4 * 1.8 * (6 + X * 1.4) = 114.4 + 25.8 * X
Where X is the movement rate of the Ogre in hexes.
The formula for an AP gun is:
1/3 * (2 + (1 + X*1.4)) + 2 * 1 * 1.8 * (2 + X*1.4)/3 = 3.4 + 2.15 * X
This assigns a weight to the AP gun that is a twelfth the weight of a Main Battery and GURPS Ogre says that the weight difference is 34, but it doesn't give the weight for the turrets.
But the Mark I has an additional weapon! It can ram for one die of damage, once per overrun. This I count as a one-shot weapon, due to the self damage and all, but the equivalent attack strength to average that amount of damage is 10.
So the value of the ram is: 10 * (X * 1.4) + 2 * 3 * 1.8 * (X * 1.4) or 29.12 * X.
So each movement point for the Mark I has a total value of 14.56 plus 17.22 or 31.78 or about 0.88 VP per tread. (Rather than carrying over the slightly changing value for each tread depending on the year of production and hence the load it can carry in that year I shall simply set the value of each tread as being 1 VP and let load factors limit the year of production.) I have also added a tweak of 2 VPs per die of ram damage over one, per hex of movement.
So the total cost of the Mark I is: Main Battery: 10 VPs Four APs: 1 VP 18 treads: 18 VPs
For a total value of 29 VPs or about five armor units.
To derive the speed factor of an Ogre we need the total weight divided by the total power.
Note that these are not the same as the victory points you get for "destroying" a system, as these include the internal structure of the Ogre required for mounting the weapon on. Also these costs are rounded and the actual calculator only rounds after totaling everything up.
A theoretical Atk 6/5, D4 weapon with unlimited ammo would be 17 VPs and load 23, so a missile rack with more than four missiles isn't much of a bargain.
The current calculator says the stats for each Ogre are:
LTPX: Load divided by threads per hex of move. This is a measure of mechanical efficiency which seems to match with year of introduction for everything except the Ninja.
|Load * Speed||Size Class|
The numbers in the size class table are completely arbitrary and simply what's needed to match the existing Ogres. Any pattern you might notice in these numbers is an accidental coincidence.
The Ninja's introduction year really sticks out, even if didn't have the stealth technology (multiply its cost by two thirds if it didn't) simply from the power factor for that year.
However if the Ninja was produced without the Missile Rack at first (until it was proven on the Mark-IV) and simply had the rest of its armament then it's load factor would be less than the Mark-V. And then you could assume that stealth was also in development until 2087 or so. The cost for this Ninja-Minus would only be 74 VPs (2 missiles in tubes, 1 MB, 2 SB, 8 AP, 10 treads per hex times 4 hexes of move) and it could have been seen as a scout replacement for the Mark-II until the stealth and rack technologies were available. Then when the Mark-IV was deployed, the Ninja was obsolete as a pure scout and so redeveloped with stealth and missile rack.
Note that this formula WILL NOT WORK for any Ogre with a starting speed less than two hexes or greater than four hexes.
Also note that the Combine at least was doing about the best that it could do and you shouldn't assume that any Ogre bigger than the designs they did produce was practical for any given year. Also note that the Ogre Missile first appeared in 2071 and the Missile Rack first appeared in 2084 and these probably could not be fielded before these years.
Other players have their own contraptions for calculating Ogre costs one example is the ACME OGRE Builder.