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HoI4 Dev Diary - Fuel Review and Motorized Artillery

Hello and welcome back for the first dev diary of 2019! Today we will update you on the state of fuel as well as show you a little something many people have wanted for a long time.

Changes and Updates to the Fuel Implementation

When the game launched, oil was used as other resources for the purpose of production. This was an abstraction done for fuel consuming equipment. We have removed this abstraction but are still using a simplified version of what happens in the real world. Oil refining was and is not as simple as simply processing it into a multipurpose “fuel,” but we felt that this simplification was necessary for gameplay and consistency of depth of detail.

We have added fuel as a resource to the top bar. With this UI element we convey a few bits of information. The numbers show the amount of time you have before being full or dry. Here the number is green and indicates that the stockpile will be full in 361 days. The numbers will become red if fuel is being lost. The green bar indicates the state of the stockpile, showing how full it is. The arrows indicate that fuel is currently being gained.

top bar fuel.png


Oil is still traded as it was previously but is no longer used in any production. Instead, excess oil is converted to fuel at an hourly rate. The trade UI has had some slight updates to take this into account. What was formerly the “production” category is now “need.” Oil now has special subcategories of this section. Active need and potential need are now represented with “A” and “P,” explained more thoroughly in tooltips. This helps give the player an understanding of how much oil needs to be traded if they wish to try and cover their current fuel needs with a constant supply from oil refining.

fuel trade ui DD.png


Refineries have also been changed from giving Oil resources to giving hourly fuel. This both makes more sense from a historical perspective and makes it easier to control how much resource is produced by refineries. Previously, tech increases could only allow for a minimum increase of a single unit of oil. This gives developers and modders much better granular control over the output of a synthetic refinery.

For countries that will not have enough fuel production during wartime to meet their needs, developing a healthy stockpile is an option. Most nations will not start with a large stockpile capacity. Stockpile potential will be reduced by economy laws for many nations. Also, increasing stockpile capacity requires some investment, and will take space away from industry through the production of silo facilities. Japan is a good example of a nation that may run into a situation during the war when their usage far outstrips their potential fuel gain, so they will need to have a decent reserve of fuel if they want to fight the US in the Pacific.

fuel_1.jpg


To help understand what is going on with your fuel stockpile and to manage distribution when fuel has become tight, we have added fuel as a special section to the logistics tab. This includes a breakdown of usage by military branch of the military and the ability to control who gets priority for fuel distribution. A special variant of the stockpile menu used for other equipment shows a breakdown of fuel consumption by day, month, and year as well as a breakdown of the state of the stockpile over time.

fuel stockpile menu.png


The logistics support company has also been changed and will help with keeping your armor fuel usage more manageable.

image (1).png



Motorized Artillery Units

When Hearts of iron 4 was released, it featured a very large number of possible battalion types that you could use to design your divisions. However, there were a few unit types that were pointedly absent. For example, if you wanted to make a motorized infantry division that was a faster version of your regular infantry division with line artillery - you couldn’t, unless you were okay with slower speed.

Part of the reason for this was the feeling that a motorized artillery unit didn’t have enough of a drawback to be a meaningful choice - it would just be better than regular artillery, and the added cost of a handful of trucks was not a major issue if you were building trucks anyway.

mot_arty_1.jpg


With the addition of fuel, that has changed. Now it is a long-term decision to motorize more of your force, and it requires more planning as your army suffers increasing penalties if you can’t meet fuel demands. So we decided to add motorized artillery units in regular artillery, rocket artillery, anti-air and anti-tank flavors. They are, by and large, identical in firepower to their horse-drawn versions but require 50 trucks each, have a roughly 50% bigger supply footprint and, of course, require fuel to run properly.

mot_arty_2.jpg


No special tech is required to unlock motorized artillery; having motorized equipment and the respective artillery type researched also unlocks the motorized unit.

That’s all for today, tune in next week when we talk about changes to research and show off the new naval tech tree!
 
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I would be okay with the AI having heavily reduced fuel consumption if there was a similar modifier applied to fuel siezed when they capitulated.

So if AI france only used 50% of normal fuel and had 100 fuel when they capitulated, germany would only get 50.
 
Fantastic, both fuel and the long awaited motorised Art variants.

Starting to think that there may be nice impact across the board, like spamming Aircraft may need more thought about it.

Just hope the AI moderates its operations according to its fuel outlook.
 
I think it will add nice flavour but i presume most Germany players will produce enough synthetic fuel and have enough silos so that it doesn't affect them. Might make life more troublesome for countries like Italy, Hungary, Sweden, etc. Which usually use tanks planes and ships at times with no substantial oil of their own and not enough industrial base to build up syn. Factories like Germany.
 
Very nice. Now we need somewhat similar food mechanics (or army maintenance cost)
 
I know this is a bit of a nit pick but can you guys reduce the number of guns in a battalion as the average was about 18, six per battery 3 batteries per battalion
 
I think it will add nice flavour but i presume most Germany players will produce enough synthetic fuel and have enough silos so that it doesn't affect them

There will, at least, be a heavy industrial cost associated with doing so to the extent that all three branches can operate completely unconstrained by it.
 
Very nice. Now we need somewhat similar food mechanics (or army maintenance cost)

Yes, hopefully, if a South American DLC ever comes rearing, they will add foodstuff then.
That was basically the reason that Brazil joined the war, after having some of their merchant navy ships sunk by U-boats because although they were neutral, they kept selling all kinds of goods (mostly foodstuff, though) to both sides.
 
QUOTE="


"....oil was used as other resources for the purpose of production"

"Oil is still traded as it was previously but is no longer used in any production." END QUOTE


However the Fuel Prioritization screen below:

index.php


This shows Fuel for Military Factories and Naval Dockyards.......Is fuel need for equipment and ship production after all?
 
Presumably that's fuel used by transport trucks and civilian vehicles.
 
So will our troops get extra lengths of hose to "acquire" fuel from inactive allies with large reserves? And more seriously, will this stop AI divisions running around like headless chickens?
 
I have to say, i like the towards more feasible mobile units. Maybe that will prevent the WW1 wars, which result in heavy foot infantry usage. But i would also like to have the penalties of motorized compared to normal infantry getting lowered (stats-wise). I mean terrain modifiers already penalize motorized infantry and with the fuel system, this could be the exchange for the sats-penalty.
 
QUOTE="


"....oil was used as other resources for the purpose of production"

"Oil is still traded as it was previously but is no longer used in any production." END QUOTE


However the Fuel Prioritization screen below:

index.php


This shows Fuel for Military Factories and Naval Dockyards.......Is fuel need for equipment and ship production after all?
No its just a poorly laid out ui.
 
They are, by and large, identical in firepower to their horse-drawn versions but require 50 trucks each, have a roughly 50% bigger supply footprint and, of course, require fuel to run properly.

Firstly, finally HOI brings in motorised Art/AT/AA - thankyou.

Secondly, please have a look at the 50% bigger supply footprint. It is not realistic. Motorisation is a manpower saver*, as truck drawn heavy equipment requires fewer men to look after a small number of trucks compared to hundreds of horses, and the fodder for those horses is much more bulky than the non-fuel parts needed to keep the trucks running. Historically, some armies motorised some parts of leg infantry divisions. There is no rationale to do that in game as it would stand under this proposal, however if the supply footprint was reduced at the cost of needing trucks and fuel it's an interesting trade off decision for players to make.

* Examples:
1. In a Japanese Infantry division's transport regiment, a wagon company with 350 men could transport 62.5 tons while a motorised company with 150 men & 50 1.5t trucks could transport 75 tons. Then there's also the matter of both wagons & trucks requiring roads and the trucks can travel much further per day acting as an additional multiplier in the amount of supplies they can bring forward.
2. A German 1939 motorised infantry division had 16,445 men vs a 1st wave infantry division of 17,734. With identical structures, except for very minor differences, the motorised division which has to provide drivers for the trucks to transport all the infantrymen still has 1,300 fewer men. Also, the 1st wave division isn't fully horse drawn requiring 615 trucks (1,687 in the motorised division) and 4,842 horses. So, in rough terms, the extra 1,000 trucks in the motorised division transported all the infantrymen (say 400-500 trucks) and did the job of 4,800 horses (500-600 trucks).
 
In the diary it was mentioned that excess oil is turned to fuel - where is oil expended now besides fuel production? Is it just trade? Or will there be new ways to spend oil?
Keep in mind that you are now able to train your air and naval units and will want to do so. This means a substantial need for fuel even during the prewar buildup.