Design Fuel Consumption?

[zgrssd]

I have not noticed until recently, but apparently the fuel consumption of a Vehicle engine depends on how heavily the engine is loaded.
When I noticed something like that for Airplanes I had asumed that was a Airplane specific rule, but it seems like it is actually a pattern that already exists for ground vehicles?

I think nobody has figured out any pattern for this yet. But I think if we gather some data across multiple games, we can figure something out.

Some information to start with:
Fuel Consumption on the Unit Card is per 1 Hex.
However the "Move Oil" cost stated under Management->Model->Op. Cost and in the Design Log seems to be per 10 hexes. So it is 10 times that.

Data Points:
3 instances of the "Cross Billy" buggy, where all 3 had the same Engine Design (wich simplifies this part), each of them with a different Fuel Consumption.

Starting Model:
Advanced MG, Medium Diesel Engine, 5mm Steel Plating
Stated Engine Consumption: 0.5
Fuel/Decihex: 9
Adjusted Engine Power: 270
Total Weight: 120
AEP/Weight: 2.25
Move Modifier: +15%

Model 2:
(I added 50mm Steel Plating)
Advanced MG, Medium Diesel, 50mm Steel Plating
Stated Engine Consumption: 0.5
Fuel/Decihex: 17
Adjsuted Engine Power: 270
Total Weight: 300
AEP/Weight: 0.90
Move Mod: -10%

Model 3:
(Upgraded engine to large Diesel over Model 2)
Advanced MG, Large Diesel, 50mm Steel Palting
Stated Engine Consumption: 1.0
Fuel/Decihex: 22
Adjsuted Engine Power: 360
Total Weight: 315
AEP/Weight: 1.14
Move Mod: +/- 0%

Noticeable things:
- Dropping the Relative Engine Power from 2.25 to 0.90 almost exactly doubeled Fuel Consumption
- Doubling the State Engine Fuel consumption did not double actuall consumption, as it changed the Relative Engine Power from 0.90 to 1.14
- between the 1st and 3rd Model, the Engines Stated Consumption Doubled. While the Fuel consumption more then Doubled, as the Relative Engine Power changed from 2.25 to 1.14
- the penalty for being underpowered is on another order of magnitude then the bonus for begin overpowered. This is a usual thing. It penalizes for being below the target and gives some bonus for being above - but without making being above a viable strategy
- the Engines Stated Fuel Consumption is off. Even if we asume a large modifier, I would say it needs to be multiplied by 20 or so.

Derived values:
I grew interested in:
- what would Stated Engine Consumption times 20 be and how far is the actuall consumption from it

Model 1:
20*Engine Fuel: 10
Actuall consumption: 9
Difference: -10%

Model 2:
20*Engine Fuel: 10
Actuall consumption: 17
Difference: +70%

Model 3:
20*Engine Fuel: 20
Actuall consumption: 22
Difference: +10%

While the Multiplier might be close to 20, it might not actually be 20. Let us try it again with 22:
Model 1:
22*Engine Fuel: 11
Actuall Consumption: 9
Difference: -18%

Model 2:
22*Engine Fuel: 11
Actuall Consumption: 17
Difference: +54.54%

Model 3:
22*Engine Fuel: 22
Actuall Consumption: 22
Difference: +/- 0%

Under thse calculations, it seems like the cost modifier is directly related to the Movement Cost Modifier.

Theory:
1. Take the engines stated Fuel Consumption, multiply it by 22
2. Take the Movement cost modifier
3. If Nr. 2 is a bonus, reduce Result from 1 by a equal amount*
4. If Nr. 2 is a penalty, increase the result from 1 by 6 times that amount*

*How to translate the known Modifiers into the Fuel one, is the tricky bit. I can say the penalty is very quickly increasing, while the bonus is very slowly increasing

[GuardsmanGary]

In my own attempts to decipher fuel usage I've found that move mod, aka effective engine power (or adjusted engine power for your calculations), does not have any influence on fuel usage. Rather the three factors of fuel usage are size, weight, and engine type. How they all interact with each other to determine final fuel usage remains a mystery to me but I have no found any other factor that impacts fuel consumption. Other than fuel efficiency tech, obviously, but its effect is very visible and easily controlled for.

As you can see in the image below I have two light tanks, both with 650 weight and both using heavy diesel engines. Despite the Abraham III having very poor engine performance giving it -50% move mod it still uses the same amount of fuel as the Crusader V, which has very good engine performance giving it no move mod. You'll also notice that the medium tank shown, despite using the same engine, having 5 less weight, and possessing a better move mod penalty than the Abraham III uses more fuel than either light tank. The movement modifier is entirely incidental and has no impact or bearing on fuel consumption.

[zgrssd]

ORIGINAL: GuardsmanGary

In my own attempts to decipher fuel usage I've found that move mod, aka effective engine power (or adjusted engine power for your calculations), does not have any influence on fuel usage. Rather the three factors of fuel usage are size, weight, and engine type. How they all interact with each other to determine final fuel usage remains a mystery to me but I have no found any other factor that impacts fuel consumption. Other than fuel efficiency tech, obviously, but its effect is very visible and easily controlled for.

As you can see in the image below I have two light tanks, both with 650 weight and both using heavy diesel engines. Despite the Abraham III having very poor engine performance giving it -50% move mod it still uses the same amount of fuel as the Crusader V, which has very good engine performance giving it no move mod. You'll also notice that the medium tank shown, despite using the same engine, having 5 less weight, and possessing a better move mod penalty than the Abraham III uses more fuel than either light tank. The movement modifier is entirely incidental and has no impact or bearing on fuel consumption.

Thanks for this information, it avoids me going down the wrong track.

However I would not exclude engine power totally. It might still use the Engine Power before the Design Roll. Time to do more math it seems

As for the Vehicle size having a Impact:
- Each Vehicle Type has it's own inherent Weight and HP. So even with the same gear, a medium tank will be slightly tougher and heavier then a light one
- some models also use entirely different engine sets. Meaning that even with the same name, Engine Power and rated Fuel Consumption are not the same

[BlueTemplar]

some models also use entirely different engine sets. Meaning that even with the same name, Engine Power and rated Fuel Consumption are not the same

Oh, come on, Vic !
Any examples ?

[zgrssd]

ORIGINAL: BlueTemplar

some models also use entirely different engine sets. Meaning that even with the same name, Engine Power and rated Fuel Consumption are not the same

Oh, come on, Vic !
Any examples ?

Buggies
Light Tanks
Mechanized Artillery

Similar to same engine names, totally differnet Fuel Consumption and Engine power.

[zgrssd]

Okay, given the information that the Movement Modifier has apparently no impact this time I looked at raw engine power compared to weight:

Starting Model:
Advanced MG, Medium Diesel Engine, 5mm Steel Plating
Stated Engine Consumption: 0.5
Stated Engine Power: 300
Fuel/Decihex: 9
Total Weight: 120
SEP/Weight: 2.5

Model 2:
(I added 50mm Steel Plating)
Advanced MG, Medium Diesel, 50mm Steel Plating
Stated Engine Consumption: 0.5
Stated Engine Power: 300
Fuel/Decihex: 17
Total Weight: 300
SEP/Weight: 1.0

Model 3:
(Upgraded engine to large Diesel over Model 2)
Advanced MG, Large Diesel, 50mm Steel Palting
Stated Engine Consumption: 1.0
Stated Engine Power: 400
Fuel/Decihex: 22
Total Weight: 315
SEP/Weight: 1.27

Size Calculation:
Light Tanks have a size of 1 default and 5 from Light Tank/Quad MG. But I do not know if those are additive or replace one another. So I have to look at it from both 5 and 6 as value.

Let us divide weight by size:
Starting Model:
5: 24
6: 20

Model 2:
5: 60
6: 50

Model 3:
5: 63
6: 52.5

I have to run and finish this math later, but I see indications of a pattern compared to fuel...

[BlueTemplar]

It's replaced (see popup).

What model are you looking at here, Mechanized Quad MG ?

[GuardsmanGary]

ORIGINAL: zgrssd
some models also use entirely different engine sets. Meaning that even with the same name, Engine Power and rated Fuel Consumption are not the same

Buggies
Light Tanks
Mechanized Artillery

Similar to same engine names, totally differnet Fuel Consumption and Engine power.

I'm looking at it now in the design process and everything is the same for those model types. I've checked multiple saves started in different versions, checked on the latest beta build and the current release version and it's consistent across all of them. Do you have a screenshot?

[zgrssd]

ORIGINAL: BlueTemplar

It's replaced (see popup).

What model are you looking at here, Mechanized Quad MG ?

And of course I had forgotten that my sampel Data was with buggies as well. Size 3, not 5
So the corrected division is:

Starting Model:
Weight/Size: 40
Fuel/Decihex: 9
Fuel/WS ratio: 4.44
Weight/Fuel: 13.33

Model 2:
Weight/Size: 100
Fuel/Decihex: 17
Fuel/WS Ratio: 5.88
Weight/Fuel: 17.65

Model 3:
Weight/Size: 105
Fuel/Decihex: 22
Fuel/WS Ratio: 4.77
Weight/Fuel: 14.32

Extending the sample a bit over more models:

Guards Abraham III
Weight: 650
Size: 5
Weight/Size: 130
Fuel/Decihex: 20
Fuel/WS Ratio: 0.15
Weight/Fuel: 32.5

Guards Crusader V:
Weight: 650
Size: 5
Weight/Size: 130
Fuel/Decihex: 20
Fuel/WS Ratio: 0.15
Weight/Fuel: 32.5

Guards Allrounder:
Weight: 645
Size: 7
Weight/Size: 92.14
Fuel/Decihex: 23
Fuel/WS Ratio: 0.25
Weight/Fuel: 28.04

Starting light Armor:
Weight: 320
Size: 5
Weight/Size: 64
Fuel/Decihex: 16
Fuel/WS Ratio: 0.25
Weight/Fuel: 20

Mechanized Artillery 1:
Weight: 1020
Size: 7
Weight/Size: 145.71
Fuel/Decihex: 80
Fuel/WS Ratio: 0.55
Weight/Fuel: 12.75


New Results:
- we can exclude the size having anything to do with consumption directly. But it seems to play some role in the Formula after all.
- you can see almost a pattern for Model 1 and 3. However Model 2 is still a outlier and this is only for buggies
- at this point I am asuming the bulk of fuel consumption comes from weight - the engine consumption is simply added to that, wich would make it a negligible amount overall
- It seems to be something as simple as Weight/~13 or so
- there might be two formulas at play: One having the clearly scaling result and the other providing a "lower bound" for fuel consumpion

[GuardsmanGary]

My tank designs were benefiting from 55% fuel savings, so that's going to throw off your attempts at finding a pattern using them in your data set. It's easily controlled for though, simply take the move cost: oil in the design log as that is what the fuel savings are applied to. Without any fuel efficiency tech the Abraham and Crusader has 45 fuel/decihex and the Allround 52 fuel/decihex.

[BlueTemplar]

Just to be sure : is that 55% fuel savings, or 55% Fuel Efficiency, which should give around 36.7% fuel savings ?

[GuardsmanGary]

ORIGINAL: BlueTemplar

Just to be sure : is that 55% fuel savings, or 55% Fuel Efficiency,

55% fuel savings.

[zgrssd]

Without any fuel efficiency tech the Abraham and Crusader has 45 fuel/decihex and the Allround 52 fuel/decihex.

ORIGINAL: GuardsmanGary

ORIGINAL: BlueTemplar

Just to be sure : is that 55% fuel savings, or 55% Fuel Efficiency,

55% fuel savings.

But my math says:
36*55% = 19.8
42*55% = 23.1
so it would have to be 36 and 42 after removing the bonus.

[GuardsmanGary]

ORIGINAL: zgrssd

But my math says:
36*55% = 19.8
42*55% = 23.1
so it would have to be 36 and 42 after removing the bonus.

A 55% savings means the fuel use is 45% of the original value, so it would be 45*0.45 = 20.25 for the lights and 52*0.45 = 23.4 for the medium. You can also divide the fuel decihex value by 0.45 to arrive at the original oil move cost, but you'll be working against rounding so it will be off somewhat.

[zgrssd]

Okay, I think I have enough data to try a simple formula:
(Weight / [WeightDivisor]) + ([Engine Rated Fuel Consumption] * 10)

Buggies:
Let us asume a WeightDivisor of 25 for this model

Starting Model:
Advanced MG, Medium Diesel Engine, 5mm Steel Plating
Stated Engine Consumption: 0.5
Fuel/Decihex: 9
Total Weight: 120
120/25 + 5 = 4.8+5 = 9.8

Model 2:
(I added 50mm Steel Plating)
Advanced MG, Medium Diesel, 50mm Steel Plating
Stated Engine Consumption: 0.5
Fuel/Decihex: 17
Total Weight: 300
300/25 + 5 = 12+5 = 17

Model 3:
(Upgraded engine to large Diesel over Model 2)
Advanced MG, Large Diesel, 50mm Steel Palting
Stated Engine Consumption: 1.0
Fuel/Decihex: 22
Total Weight: 315
315/25 + 10 = 12.6+10 = 22.6

Result:
- the rounding behavior is inconsistent (indicating a more complex formula on the weight side), but beyond that it seems to be in the right ballpark
- the hypothesis that the Engines Rate Fuel * 10 is just added, is supported by model 2+3. It is a simple formula and the difference happens to be +5.
- at least the part about the Engines Consumption impact should be easy to verify

[GuardsmanGary]

I think I figured out why engines display different fuel consumption values in the design process sometimes but not other times. I noticed that in one of my games I was seeing the same inconsistency in the fuel consumption display between the same engine types on different models that zgrssd reported, which was contrary to my early reply in which I found that it was entirely consistent across all model types. Would you believe it if I said the culprit is if you have airforces enabled or disabled? The game I noticed the difference on I accidentally started it without airforces enabled while the all the games I based my earlier post on had them enabled. Some testing starting new games with and without airforces revealed that the inconsistencies only appear in games without airforces. If Airforces are disabled you will see a proper calculations of fuel usage while in the model design window. I also discovered that the fuel use value shown is accurate to the fuel cost per hex before fuel efficiency savings are calculated.

This has actually provided some pretty good insight on how fuel use is calculated:
- We now know the base fuel consumption of engines. Light diesel is 0.1, medium diesel is 0.5, heavy diesel is 1, double diesel is 1.5, and triple diesel is 2. This base value is just a flat addition to the fuel use derived from the models size/weight.
- Double diesel engines double fuel use and triple diesel engines triple it; as the names suggest it is literally two and three engines. This multiplication happens before the base fuel consumption of the engines are applied.
- Weight does not increase fuel use if the total weight is below 150. This means any fuel use below that weight has to be from the size rating of the chassis. A 105 weight buggy and a 135 weight buggy both use 0.4 fuel with a light diesel engine before base engine consumption is added. Similarly a size 2, 65 weight truck uses 0.2 fuel before base engine consumption.
- There are weight bands for fuel consumption. Any weight value inside these bands use a set amount of fuel. From 0 to 149 weight is the first band, 150 to 249 is the second band, 350 to 449 the third, etc. A 207 weight light tank uses the same amount of fuel as a 222 weight or a 237 weight light tank.

Edit: The above two points need a slight correction. There exists a "0th" band starting at 0 weight and ending at 49. In this band the fuel use is equal to only the engine base consumption value; size and weight have no impact on fuel use in this band. Between 50 and 149 only the size contributes to fuel use. The only vehicle that can exist inside the 0 to 49 band is a truck with a light electric engine. The formula still accurately predicts its energy usage, however, so there are no changes there.

Having discovered all this I think I cracked the fuel use enigma. Base fuel use of a design is its size divided by 10. You then multiply this base value by the 'weight band number' to reach a weight adjusted fuel use value. This is added onto the base fuel use value. Multiply this by the number of engines, and then finally you add the base engine consumption. Weight band can be determined by dividing the weight by 100 and rounding to the nearest whole number. This formula will tell you the fuel use per hex before any fuel savings from the fuel efficiency tech is applied.

FUEL USE FORMULA:
(SIZE/10) * WEIGHT BAND * Number of engines + Engine Base Consumption

Now for some examples:
Light tank 1
Size 5, 40mm howitzer, 5mm steel armour, light diesel engine
Weight:
50 base
+100 40mm howitzer
+25 5mm steel armour
+45 light diesel engine
220 weight. This design falls into weight band 2

Expected fuel use:
(5/10)*2*1+0.1 = 1.1 fuel use
Comparing this to an identical design in the game I get 1.1

Light Tank 2
Size 5, 60mm howitzer, 100mm steel armour, heavy diesel engine
Weight:
50 base
+150 60mm howitzer
+375 100mm steel armour
+75 heavy diesel engine
650 weight. This design falls into weight band 7

Expected fuel use:
(5/10)*7*1+1 = 4.5 fuel use
Comparing this to an identical design in the game I get 4.5.

Monitor Tank
Size 11, beam Gun, 400mm polymer armour, triple diesel engine
Weight:
110 base
+400 beam gun
+962 400mm polymer
+125 triple diesel engine
1597 weight. This design falls into weight band 16

Expected fuel use:
(11/10)*16*3+2 = 54.8 fuel use
Comparing this to an identical design in the game I get 54.8

[BlueTemplar]

Wow, congratulations for figuring it out !

So, is this for games with or without Air Forces enabled ? What is the exact difference ? Do you think it's a bug ?

"Weight Bands" seem to be just rounding ? (Can you even go lower than 50 weight on a vehicle ?)

[GuardsmanGary]

ORIGINAL: BlueTemplar
So, is this for games with or without Air Forces enabled ? What is the exact difference ? Do you think it's a bug ?

I guess when vic added aircraft he did something to the code to disable the model screen from displaying the radjusted fuel usage. I also noticed models that lack either the option for a weapon or armour do not display the adjusted fuel use value with airforces enabled and disabled, it's just the base engine consumption values regardless.

"Weight Bands" seem to be just rounding ? (Can you even go lower than 50 weight on a vehicle ?)

Lightest vehicle is a truck with a light electric engine coming in at 40 weight. It has an energy consumption of 0.1, the same as the base value of the engine, meaning its weight band was rounded down to 0. How would you denote rounding in a formula, though?

[BlueTemplar]

Ah, electric engines, right...

https://en.wikipedia.org/wiki/Rounding
The general rounding sign is ≈ ... when it comes to a variable, I'm only aware of "round(x)" ?
For rounding up : ceiling : ceil(x) = ⌈x⌉
For rounding down : floor : floor(x) = ⌊x⌋

[zgrssd]

Would you believe it if I said the culprit is if you have airforces enabled or disabled?

Yes.
Without a second of doubt even.

- We now know the base fuel consumption of engines now. Light diesel is 0.1, medium diesel is 0.5, heavy diesel is 1, double diesel is 1.5, and triple diesel is 2. This base value is just a flat addition to the fuel use derived from the models size/weight.

I guess we could call it the "Idle Consumption"? In the sense that it is not affected by weight.
Not a perfect match, as it implies this consumption happens every turn regardless of movement.

Lightest vehicle is a truck with a light electric engine coming in at 40 weight. It has an energy consumption of 0.1, the same as the base value of the engine, meaning its weight band was rounded down to 0. How would you denote rounding in a formula, though?

I do not think Formula support the rounding operation.
A algorythm description does support. (1st, 2nd, 3rd, etc.)
And we can just copy how it is written in EXCEL Formulas "ROUND(something").

I think the Algorythm notation is easier to understand and read.