Spoiler


More possible planes:
Vickers E.F.B.7 armed with 37 mm cannon,

Breadmore W.B.V armed with different 37 mm, Le-Puteaux cannon.

While never reaching operational status and being unreliable some aircrafts did carry “special” 1.59-inch breech-loading Vickers Q.F. gun, Mk II.
Vickers F.B. 25

and Royal Aircraft Factory N.E.1

I am in favor of WW1-interwar vehicles.
I do have issues with current tech tree. The replacing reserve tier or ranks 0-0.7 would not be ideal in this case.
But I think tech tree issues are a separate thing, so your mini tree “rank 0” looks good at a first glance.
Would also flesh out the Hungarian tree within Italy (Austro-Hungarian obvs.)
I am in process of making TT of A-H + what Swiss had :). I would not make it part of Italy though since they were enemies during the war.
World War 1 vehicles are a must
+1
Bring Back WW1, return to roots!
+1
The US suggestion has finally been approved.
slow but interesting plane: Royal Aircraft Factory B.E.9.
Can not find photos of it being armed but sources state it was with 1 Lewis machine gun
Oh, absolutely. I love it! I can’t say yes enough. Triple the WW1 budget NOW!
The Sopwith Dolphin airplane is already in Tech Tree, but its listed armament can be updated. It could also mount two Lewis guns on lower wing, outside of the propeller arc.

Your missing two very common British types, the RE.8 and Vickers Vimy.
There are also bomber versions of the Strutter which could go to the UK or Russia if needed.


PS please make interwar trees too as there are some cool aircraft waiting there between the two world wars that are not in game.