Hello guys and gals! Most of the HOI4 team is currently on a much neededvacation, but we figured we couldn't just leave you hanging without a diary this month, so let's get to it *puts down beer* *cracks knuckles*.The Air Technology tree is similar to the Armor tech tree we showed back in diary 2 in that we are focusing around chassis and unlocking specific historical equipment/models that those versed in WWII will be familiar with.Hearts of Iron III had a lot of different airplane classes but that still ended up not being able to match what nations historically did with their planes, which was use them for many different roles. In HOI4 we have gone the other way and dropped a few classes while instead letting you specialize them in the direction you want to go yourself using field experience (see Diary 8 for more details). This means that Interceptors, CAG (Carrier Air Group) and Multi-Role from HOI3 are gone and its up to you to decide what models to tailor for each role. Do you specialize to create the perfect plane for a role, or try to develop a fighter that can fulfil all your different fighter/interceptor/escort needs for ease of production?Air technology is split up around 3 airframe sizes: Light, Medium and Heavy. Light is single engine while mediums are generally twin engine and Heavy have 4 engines or more. After the invention of Jet engines it's also possible to research powerful jet models. Each of the light airframe techs also has a sub-tech that unlocks a carrier capable model. We felt that extra research investment was necessary for this because of the trouble many nations had with perfecting their carrier-based planes. This also highlights another important change from HOI3 - instead of the CAGs you are free to put any planes that are capable on your carriers and thereby configure their capabilities for different types of missions. There are also experimental rocket interceptors available, but they live among the Secret technology tree so we will talk about those later.That's all for now folks, time to get back to the beer! Next diary is probably going to be about the naval aspects of the game.oops, I almost forgot we promised to include a picture of one of Darkrenown's dogs. Here is Domino testing out the new naval invasion code for HOI4: