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Developer Diary | Plane Designer

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Hello, and welcome back to another Dev Diary for the upcoming By Blood Alone DLC and accompanying Patch 1.12! The team has returned from the summer vacation, and we are now back fixing bugs and tweaking the balancing of the new features and focus trees.

Today, we are taking a look at the Plane Designer. As always, any number value that you are going to see in this DD is subject to change.

The Plane Designer became a subject of discussion, both inside the team and in the community, almost as soon as we announced that No Step Back would feature a Tank Designer. We felt that it would mesh well with the rework of the Italian focus tree, not least because the Italian aviation industry was very well developed and produced some of the best combat airplanes of the war - hampered mostly, as Italy so often was, by lacking production capacity.

We also felt that a Plane Designer would help plug some gaps in the lineup of available aircraft. Over the years, many players have commented on the fact that many nations modified their fighters to also be able to carry bombs, or their tactical bombers to also carry torpedoes. One of the big goals of the Plane Designer was to allow for these types of multi-role aircraft.

At the same time, we didn’t want to make these multi-role planes too powerful. Instead, a plane design optimized for a single mission should still be more effective than a multi-role plane. Where multi-role planes offer flexibility, optimized designs offer top performance, if you can afford them.

The basics of the Plane Designer are probably not a surprise for anyone who is familiar with the Ship or Tank Designers. The base is called an airframe, which roughly corresponds to the hulls and the chassis of the ship and tank designers. The Airframes have a number of module slots, where you can put the modules that give the final design its actual stats. There are three different size classes of airframes: Small, Medium, and Large. Small planes also come in a carrier-capable variant of the airframe.

The types of module slots in the Plane Designer are slightly different from the Tank Designer. There are effectively only three types of slots: Engines, Weapons, and Special modules.

Engine modules are perhaps the most straightforward of them. Unlike tanks, where this slot dictates what type of engine the tank uses and a separate stat determines what its speed is, engine modules in the plane designer determine the number and power of the engines mounted on the aircraft. These engine modules produce a new stat called Thrust, while all other modules have another new stat called Weight. These two stats are effectively the limiting factor of what and how many modules you can put on the plane. A design is only legal if Weight does not exceed Thrust (some people might point out that the only planes with a Thrust/Weight ratio of 1 or better in reality are modern, high-performance fighter jets, but these people will be summarily ignored).

Any excess Thrust is converted into extra speed, which is intended to provide a reason not to fill every module slot.

One thing to note here is that jet engines (and rocket engines, for that matter) are part of these engine slots, which means that they are available for all types of planes. This, by necessity, means that Jet Fighters and other jet-powered airplanes are no longer their own unit type - they are now simply fighters with jet engines. Jet fighters will therefore reinforce regular fighter wings, and also that you can now effectively make jet carrier planes, jet CAS, jet heavy fighters etc.with the plane designer.
Or Rocket Naval Bombers, one supposes, if you really hate your pilots on a personal level.
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Weapon modules are also fairly self-explanatory. But beyond providing offensive stats like Air Attack, weapon modules fulfill two other major functions. The first is that the weapons define what type of plane a design ends up being. For this the designer has a Primary Weapon Slot. The module in this slot defines the role of the final design, i.e. Fighter, CAS, Naval Bomber etc.

This is relevant because the weapon modules also unlock what missions a design has available. That means that the strict separation of mission by type of aircraft will be gone. You can now create fighters that can provide ground support, or Strategic Bombers that can do naval strikes, depending on the modules you put on the plane. There are, of course, some restrictions - strat bombers can never mount the modules necessary to unlock air superiority missions, for example.

We still wanted to give you an easy way to classify your designs on a high level and it also makes it a lot easier to tell the AI what a design actually is and how it should be used. Without accounting for doctrines, there are no stat differences between, say, a fighter that has a set of 4 Heavy MGs in the Primary Weapon Slot and bombs in a secondary weapon slot, and a CAS that has the bombs in the primary weapon slot and the MGs in the secondary slot - but one goes into Fighter Airwings and the other goes into CAS Airwings.
CAS planes have a large variety of weapons available to them to attack ground targets.
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There is a full list of weapons, the missions they unlock, and what they classify a plane as if mounted in the primary weapon slot, below (stats omitted because balancing is still ongoing):

ModuleMissions UnlockedType
2x Light MGAir Superiority, InterceptFighter, Heavy Fighter
4x Light MGAir Superiority, InterceptFighter, Heavy Fighter
2x Heavy MGAir Superiority, InterceptFighter, Heavy Fighter
4x Heavy MGAir Superiority, InterceptFighter, Heavy Fighter
Cannon IAir Superiority, InterceptFighter, Heavy Fighter
2x Cannon IAir Superiority, InterceptFighter, Heavy Fighter
Cannon IIAir Superiority, InterceptFighter, Heavy Fighter
2x Cannon IIAir Superiority, InterceptFighter, Heavy Fighter
Rocket RailsClose Air Support, Logistics StrikeCAS
Bomb LocksClose Air Support, Naval Strike, Port StrikeCAS
Small Bomb BayClose Air Support, Logistics Strike, Port StrikeCAS
Tank Buster IClose Air Support, Logistics StrikeCAS
Tank Buster IIClose Air Support, Logistics StrikeCAS
Torpedo MountingNaval Strike, Port StrikeNaval Bomber/Maritime Patrol Plane
Guided Anti-Ship MissileNaval Strike, Port StrikeNaval Bomber/Maritime Patrol Plane
Fixed Explosive ChargeKamikaze StrikesSuicide Craft
Medium Bomb BayClose Air Support, Logistics Strike, Strategic BombingTactical Bomber
Large Bomb BayStrategic Bombing, Port StrikeStrategic Bomber

While some of these weapons are unlocked in the (reworked) Air Tech Tree, some of them are also found outside of it, in a similar manner as the tank weapons are found in various trees. I will note that the total number of techs in the Air tech tree has actually decreased.
A view of the Air Tech tree. It has a total of 28 techs, compared to the old tree’s 38 techs.
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One notable aspect is that a lot of these modules provide different stats only for specific missions. For true multi-role planes to make sense, we wanted to make sure that building a design with a mixed set of missions didn’t make the plane useless in some of them. Hanging bombs off a plane should make it less agile and slower, but a fighter that was able to do CAS missions shouldn’t be useless in air superiority missions. Thus, the weight and agility penalties only apply to the fighter if it is actually on a CAS mission, not if it is on an air superiority mission.

Modifiers only apply to certain missions. Here, the bombs the Stuka carries make it less agile, but the dive brakes give it better air defense
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Finally, we have the so-called “Special” module slots. These are effectively a catch-all term of various different items, a list of which you can find below:​

Armor Plate: Increased Air Defense, reduced range
Self-Sealing Fuel Tanks: increased Air Defense, costs Rubber
Drop Tanks: increased range (small airframes only)
Extra Fuel Tanks: increased range, reduced air defense
Dive Brakes: increased air defense, increased naval strike hit chance
Radio Navigation I: reduced night penalty, increased strat attack
Radio Navigation II: reduced night penalty, increased strat attack
Air/Ground Radar: reduced night penalty, increased strat attack, increased naval detection
Air/Ground Radar II: reduced night penalty, increased strat attack, increased naval detection
Air/Air Radar: reduced night penalty when on intercept mission
Air/Air Radar II: reduced night penalty when on intercept mission
Floatplane: increased naval spotting (small airframes only)
Flying Boat: increased naval spotting (medium+large airframes)
LMG Defensive Turret: increased Air attack, reduced agility
2x LMG Defensive Turret: increased Air attack, reduced agility
HMG Defense Turret: increased Air attack, reduced agility
2x HMG Defense Turret: increased Air attack, reduced agility
Cannon Defense Turret: increased Air attack, reduced agility
2x Cannon Defense Turret: increased Air attack, reduced agility
Recon Camera: unlocks recon mission (LaR only)
Demining Coil: unlocks demining mission (MtG only)
Bomb sights I: increased strat attack
Bomb Sights II: increased strat attack
Non-Strategic Materials: reduced Aluminum cost, reduced air defense

Special Modules are primarily intended to help optimize planes for various missions or give them different niches.

The eagle-eyed amongst you have already spotted that planes now have a surface and sub detection stat. Up until now, planes that were active in a sea zone always provided a flat bonus to the spotting speed of any navies active in the seazone. This will now change, with planes having dedicated spotting stats that determine how well they do with helping the navies spot. There are modules, like the Air-Ground Radar and the Flying Boat hull, which give bonuses to naval spotting.

Vanilla planes have those stats already baked in, with some being better than others - carrier planes are better than their land-based counterparts, naval bombers are better than fighters etc.

To further support this, we are adding two more things: Maritime Patrol Planes as a dedicated unit type and a special Naval Patrol mission for planes with the right modules.

Maritime Patrol Planes are built on the Large Airframe, giving them exceptional range. They are able to mount the whole array of naval bomber weapons, but naval strike is really not intended to be their primary role. Maritime Patrol Planes are meant to help with spotting raiders in the deep ocean, where smaller planes with shorter ranges struggle to provide much mission efficiency.
You can run naval patrol missions with many different types of planes.
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Finally, let’s talk a bit about art! While we already have a large amount of historical art for various plane types, we also wanted to give you more options to visually distinguish your designs, even if it is just to find the plane design more easily in the production menu. For the tank designer, we split up the existing art and recombined it into various combinations to quickly generate a large number of assets. We realized early on that this wouldn’t work for the plane designer. So instead, we decided to fill in some gaps in the existing art as well as add some art for a number of prototypes that flew but were historically passed over for mass-production.
Here is a partial list of new plane icons coming in BBA. Which one’s your favorite?
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We also decided that we wanted to add more 3d art. Much like the tank designer, you can select these assets when you design the plane. We are adding about 80 new 3d models for planes to the DLC, but more on that in the future!
Here is just a teaser of some of the new assets coming in the DLC:
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That is about it for this week. We hope that you will enjoy playing with the Plane Designer as much as we enjoyed making it. To end this DevDiary on a personal note: The Plane Designer will be my final contribution to Hearts of Iron 4. After close to 6 years on the project, all the way from the early days on Together for Victory, the time has come for me to leave the company and move on to greener pastures. It has certainly been an eventful and productive couple of years, and there are many things that I am very proud of (and a few that I regret - like adding Austria-Hungary as a joke and then finding out that people love monarchism). Working on the Hearts of Iron series has always been a dream for me, since the day I launched Hearts of Iron 1, almost 20 years ago now. Few people can say that they had an impact on a piece of entertainment that has had a similar impact on themselves. But the thing I am most proud of is the team we have built. Hearts of Iron is in very good hands, and there are years of content still to be released. I’m looking forward to it - but, once again, as a player.​

Weird designs that QA came up with:
This single plane outguns an entire tank platoon, unfortunately it can’t ever turn:
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And then we restricted the number of bomb bays you can have on a plane:
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6 engines, 8 cannons, 4 cannons in turrets, and a production cost 50% higher than a strategic bomber. Needless to say, this combo is no longer possible:
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When you look at the Spitfire Mark I’s armament and wonder: but what if…more guns?
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thank you so very much for all of your hard work @Archangel85 :)
and also for giving us austria-hungary XP
best of luck with everything :)
 
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The original point I was responding to was that producing 1k bombers was “insane number”, I merely brought up the thousand bomber raids to show that it really wasnt a massive number in terms of total bombers produced during the war, especially since that was just one theater of the war

The UK built around 15,000 of the different 4-engine heavy bombers during the war. but the RAF was only ever able to field like 1100 heavies in total at any given time, some of which were in Coastal Command, rather than Bomber Command.
The USAAF also didn't field that many heavy bombers at the same time, despite having built many airframes.

I don't think that many of them were purpose designed with fighter-bombers in mind

Sir Henry Tizard led a project, that led to rocket & bomb equipped fighter/strike aircraft to be vastly preferred to light/dive bombers, and most fighters introduced after like 1941 or so, were built with that use in mind, with only some of the Spitfire models continuing to be designed purely as fighter/interceptors.
 
Let's say I want to design a plane that is very agile but with paper armor/inadequate speed like A6M with basic airframe. How could we achieve it using current modules?

I'm wondering about the "Non-Strategic Materials" special module there. That would give the cheap/light armour aspect of the Zero, but I'm not sure about how the agility/speed/range could be modelled.

Maybe a "Lightweight Airframe" special module, with some different stat effects ?

@Archangel85 what do you think ?
 
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Looks very interesting! Some questions:

1. I find it unfortunate that you excluded transport planes from the designer, mainly because transport planes have quite bad range and it would be nice to upgrade it. Maybe you could atleast add upgrade options for the transport planes, in the same way as we can upgrade mechanized infantry with army experience?

2. Is there any penalty to the mission efficiency for multi-role planes assigned to multiple missions at the same time? For example, would a fighter-bomber assigned to air superiority and close air support run both missions at the same time on full efficiency?

3. I find it very weird and unlogical that naval patrols can't spot independently as that is pretty much the whole purpose of doing that mission. Is there any chance that this could be changed? For example, the naval patrol would do the spotting without ships, and then the strike force would attack the target?

4. Could you please allow nations to use the plane and tank pictures of other nations? For example, when playing as Sweden, I research my own planes and tanks but I'm forced to use that boring generic picture, while it would be awesome if I could for example use the picture of German planes and tanks?
 
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The UK built around 15,000 of the different 4-engine heavy bombers during the war. but the RAF was only ever able to field like 1100 heavies in total at any given time, some of which were in Coastal Command, rather than Bomber Command.
The USAAF also didn't field that many heavy bombers at the same time, despite having built many airframes.



Sir Henry Tizard led a project, that led to rocket & bomb equipped fighter/strike aircraft to be vastly preferred to light/dive bombers, and most fighters introduced after like 1941 or so, were built with that use in mind, with only some of the Spitfire models continuing to be designed purely as fighter/interceptors.
I mean, outside of the Typhoon and Tempest are there any other examples of this? Typhoon being designed prior to this and Tempest basically being an improved continuation of the same basic design. Not doubting you, but those two are the only examples I can think of right now outside of lend-lease aircraft employed as FB's. I suppose maybe the Fairey Firefly counts too for the FAA.
 
any chance of adding WEP as a special module?
Adding WEP, or war emergency power, as a dedicated module doesn't really make sense. Many aircraft had different systems which would be considered WEP, which varied from just overpressuring the engine intake manifold or sophisticated systems found on late war German altitude interceptors which had mixes of methanol-water which could be injected into the engine for increased performance. The later would be a nice module to have - especially if it gave a boost in efficiency to interception missions (the methanol-water injection system had little impact at lower altitudes so wouldn't be of much use in CAS missions).
 
I do like the ship designer, but the addition of the tank designer scared me off of using tanks, sicne i don't trust the autoassemble to give me the best results and don't want to pause the game forever to design a proper tank. And i fear that i'll have the same with the aircraft designer. But i do want to use all the other DLC-Features! Will there ever be an option to toggle the designer off, without not using the DLC in question?
 
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Will there be the option to choose between radial air-cooled and inline liquid-cooled engines? And will there be the possibility to add the methanol-injection kit that German engines had?
Supercharges and methanol-injections kit mattered most at high altitudes - where atmospheric engines started to suffocate.
Since there is no altitude (service ceiling or combat ceiling) stat on planes in HOI4, there is little point in them.

IRL it was another sword-vs-shield competition - Allied bombers and escort fighters travelled at higher and higher altitudes - making it impossible for AA fire to aim or reach and German engine and aircraft designers developed interceptors that could actually do something at attitudes over 5 - 6 km.

Unfortunately this part of air arms race and development is completely omitted from HOI4.

Look up history of Ta-152 if you want to know more.
 
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That is about it for this week. We hope that you will enjoy playing with the Plane Designer as much as we enjoyed making it. To end this DevDiary on a personal note: The Plane Designer will be my final contribution to Hearts of Iron 4. After close to 6 years on the project, all the way from the early days on Together for Victory, the time has come for me to leave the company and move on to greener pastures. It has certainly been an eventful and productive couple of years, and there are many things that I am very proud of (and a few that I regret - like adding Austria-Hungary as a joke and then finding out that people love monarchism). Working on the Hearts of Iron series has always been a dream for me, since the day I launched Hearts of Iron 1, almost 20 years ago now. Few people can say that they had an impact on a piece of entertainment that has had a similar impact on themselves. But the thing I am most proud of is the team we have built. Hearts of Iron is in very good hands, and there are years of content still to be released. I’m looking forward to it - but, once again, as a player.​
I am not really happy about this, because this way Hungary will certainly not be reworked normally in a later version. :confused:
Somehow I guessed that there was no need to overdo the information gathering for my suggestion regarding Hungary. By the way, the creation of the Monarchy is not a joke, since at that time Hungary had the greatest support for a Habsburg restoration. And there was a significant difference between the engine types, because inline engines performed better in high-altitude flights compared to radial engines. But it doesn't really play a role in the game.
I wish you the best of luck for greener fields!
 
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Without accounting for doctrines, there are no stat differences between, say, a fighter that has a set of 4 Heavy MGs in the Primary Weapon Slot and bombs in a secondary weapon slot, and a CAS that has the bombs in the primary weapon slot and the MGs in the secondary slot - but one goes into Fighter Airwings and the other goes into CAS Airwings.​
This is debatable: a plane designed as a fighter will never be as good as a CAS for the latter mission, still carrying the same armament. And vice-versa. Possibly, the second slot stats should be nerfed?
 
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I mean, outside of the Typhoon and Tempest are there any other examples of this? Typhoon being designed prior to this and Tempest basically being an improved continuation of the same basic design. Not doubting you, but those two are the only examples I can think of right now outside of lend-lease aircraft employed as FB's. I suppose maybe the Fairey Firefly counts too for the FAA.

Not too many examples, since the Typhoon/Tempest were basically the only other aircraft introduced in any numbers during the war.

The Air Ministry in the UK though, which controlled the design and production of aircraft, issued specifications which included armaments, and not many were issued for fighters armed solely with guns, other than some for Spitfire models. Most specifications were for fighter/strike aircraft.

The Blackburn Firebrand was originally designed to a specification for a carrier fighter, but there were problems with development, and the specification was changed to a fighter/strike aircraft.
 
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Because of the effect strategic bombing already has in the game. Strategic bombers are overpowered.

I would actually like to claim the opposite: they are underpowered if you play somewhat realistically. Sure, if you mass multiple thousands of bombers in a single state, they will wreck havoc, but that is also an extremely "gamey" situation. As Germany, try to put 200-400 strategic bombers over southern Britian and bomb their AA, airfields and radars. Even if you have full air superiority you will notice that they hardly cause any damage at all and the little damage they do cause is repaired within 1-2 days.

The main issue in my opinion is that it's far too easy to mass produce large quantities of strategic bombers while the damage they inflict is far too small and the repairing is done far too quickly. Even factories repair within a few weeks while in real life it could take months to repair. I think it would be more realistic to switch it around - losing strategic bombers should be much more costly and defending against bombing should be easier but bombing something successfully should be much more rewarding.
 
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Will there be a way to make pure interceptors? Like how the rocket interceptors work currently? A primary module that only unlocks interception?

Mostly to be able to earmark a design for interception wings, they have a different stat profile than a fighter or fighter/bomber and I quite like the way RI wings work, IE I would rather not have my fast short range interceptors reinforce my frontline long range fighter wings.
 
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@Archangel85 - best of luck and good health!
I have been playing HOI since HOI2 and it has been a hell of a ride!

Questions on planes/plane related stuff:
1. Will only Small Frame planes be able to land on CVs?

2. Why no Air-to-Air rockets in armaments?

3. Will Air/Air radar give bonus to other planes in the region during the day interception/Air Superiority missions?

4. Will Air/Air radar give bonuses to static AA / units AA in the region? It would be logical that radar equipped plane that spotted incoming bomber flight could warn ground-bases AA units giving them more time to prepare.

5. Please, please do some re-working on AirBases:

Pleas for AirBases related improvements:
5.1. Please limit the size of plane that can be based at low-level airbases - grass strips can hardly support strategic bombers or jet fighters

5.2. Please make larger planes take up more space at air bases

5.3. Maybe something special for Flying Boats - for example setting up a forward base for Flying Boats at a pacific island is far easier, than creating even the most rudimentary airstrip at the same island.

5.4. Please add improvements for AirBases, like integrated radar, local fuel supply storage (giving some grace time to operate if logistics is disrupted), sheltered aircraft bays etc.

5.5. Please add air missions for targeting air assets on the ground, targeting AirBases themselves and for airbase suppression (not sure if I am calling it correctly, but in 1944-45 Allies had such air superiority that they could put semi-permanent patrols around German airbases to catch planes when they were landing/taking off and thus most vulnerable. This tactics proved especially good against Me-262, whom most Allied planes had trouble catching once it was at full speed.
 
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The eagle-eyed amongst you have already spotted that planes now have a surface and sub detection stat.

Will there be special modules which affect submarine subsurface detection by aircraft?

  1. aircraft can only improve the ship spotting of deployed ships, the planes do not spot in the absence of a fleet attempting to spot.
  2. No changes from current

While the proposed system is major improvement, the necessity to pair Maritime patrol aircraft squadron with naval spotting task force adds more ingame complexity, more effort to arrange air/fleet assets with matching range.
It can be better to allow MPA to do independent spotting as they did IRL in WW2, as long as it may be accomplished by the game system.
 
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Having been mildly irritated by yet more country content, this looks wonderful, really immersive. Will be be able to modify retrofit existing air frames? So, if I had a CAS, could it be modified to fly from a CVS if I designed a carrier CAS?

This looks very, very good Paradox.
 
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Could you add a condition to see if airframes (and tank chassis) are valid? - meaning they are at least somewhat functional? at the moment, it is all too common to see empty tank chassis with empty values rolling around in tank divisions because a country's focus granted them free tanks without first making sure there was an existing design.

the most common example of this is Turkey's focus to buy Italian tanks. If they purchase inter-war tanks, only empty chassis are sent because Italy is missing the Fiat 3000 design. Or when the Baltics take their focus to buy German tanks, the may receive hundreds of empty chassis if Germany is in a civil war.
 
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