Air | National focus Hearts of Iron IV Guide
Last update: 01 February 2017
In this case the technology tree resembles the ideology one. There are two possibilities that exclude each other and you must decide whether to use the bonuses provided to the fighters, or to the bombers. Note that the air tree gives significant benefits and if you see your chances of success by using air units, you shouldn't delay the development of those national focuses. An interesting thing about this tree is the situational reduction in the research times, which can be used to gain a bonus. It all depends whether the technology you're interested in is located or not within the actual timeline.
Below you can find national focuses associated with air units. The tree doesn't have a lot of different routes, but the final part of it is quite interesting.
Air Innovations
If you decide to develop air units, you are sure to complete this section of national focuses. Note that before completing the second focus in the above table you will have to decide whether you will focus on developing fighters or bombers. It all depends on your playing style, as the bonuses provided by both routes are equally interesting.
Icon | Name | Benefits |
Air Innovations | Air Experience +25 Air base +2 Air Doctrine 1x 50% | |
 | Air Innovations II | Air Experience +25 Air base +2 Air Doctrine 1x 50% |
Commentary: by completing the focuses from the above table you will be able to get 4 air bases and experience points needed to create an advanced air squadron. Note the additional bonuses to the Air Doctrine researches - similarly to the other doctrines they have routes that exclude each other, which is why you can develop only a single one of them. Finally, you will be able to get free air bases without the need to use your own supplies and factories to do so.
Fighters
Think carefully when you want to start developing those focuses and manage technologies in such a way that before you start the "CAS Effort" you will have all of the technologies associated with the current timeline completed. If you don't do that, you will be given an immediate bonus to the research time reduction, but you will waste half of the benefits of this focus, the one that allows you to research units outside of the timeline without suffering additional penalty. Before starting this focus pay attention to how much time is remaining before the technology is normally available.
Icon | Name | Benefits |
 | Fighter Focus | Interwar Fighter 2x 50% Fighter I / II / III 2x 50% Heavy Fighter I / II / III 2x 50% |
 | CAS Effort | Reduce ahead of time penalty by 100% or gives a 50%, research bonus if not ahead of time. |
Commentary: If you decide to develop fighters, you will be given bonuses from the above table. Thanks to them you will be able to decrease the research times for those units, which will in turn affect your army strength in the air.
Bombers
Similarly to the previous tree, you must figure out if the benefits coming from this tree and those focus will bring anything to your game. If you won't be using bombers, you should focus on developing the fighter tree, especially because you will need both focuses of that tree while developing rocketry. If you decide to develop units from the bomber tree you should try to get a general development of naval aviation.
Icon | Name | Benefits |
 | Bomber Focus | Strategic Bomber I / II / III 2x 50% Tactical Bomber 2x 50% |
 | NAV Effort | Reduce ahead of time penalty by 100% or gives a 50%, research bonus if not ahead of time. 1x Naval Bomber models |
Commentary: in the case of this tree the benefits are equally as attractive as with the fighters and it's up to the player whether he want to dominate in the air, or finish off the enemy with a massive bombing attack. Note that the second focus in the table is related to the possession of aircraft carries, which is why you must consider whether developing it will be useful to you.
Rocket Effort
You shouldn't wait for too long. If you are interested in activities related to rocket technology, you should aim to complete this focus regardless of the costs. The use of jet engines won't suddenly grantee you victory in the war, but if you manage to use them before your enemies do, you will have greater chance of success. Additionally, you should devote a single research slot to develop technology associated with the bonuses, so that you can benefit from it earlier.
Icon | Name | Benefits |
 | Rocket Effort | Reduce penalty for premature work Rocketry 2x50% Rocketry 2x50% |
Commentary: one of the most important national focuses. With it you will be given a significant reduction to the penalty for premature work and will be able to gain large advantage in the air. Note that the bonus applies to up to four technologies and those technologies can have a significant impact on the course of action on the battlefield.