So, we can either spend a revision to make an air to ground weapon and basically make a light bomber, or a revision telling the AI pilots "Oi, you have antigrav and plasmacannons, over there are Xcom squads. FIGURE IT OUT!!!"...
Welp, I had an idea for a heavy fighter that might do well for ground support then.
Heavy Fighter: The Heavy Fighter is a Medium fighter with more armour, and two turrets. One on the top of the craft for dealing with anything above it and one at the bottom for attacking ground targets. Naturally, should it need to for any reason, like say a turret breaking, it can do a half roll to switch the turrets around. Naturally, such changes will come at a cost of maneuverability but that shouldn't be a issue for the heavy fighter due to its armour and its turrets. It can be used for air support and help the enemy find a nice non solid state to sit in.
Alternatively.
Light Bomber: The light bomber is a Medium fighter with its front armament ripped right out and instead equipped with two heavy turrets at the bottom of the craft to blast away at anything below it and the AI told to use said turrets for destroying things on the ground. There is also a normal turret on top of the craft made to just simply to help protect the craft against any enemy aircraft that decides to try and take it down. It is slightly more armoured then the Medium fighter, but not by much as to not reduce the aerodynamics by much more then we already have.
And considering this vein of thinking...
Tactical Bombing: By bombing key military assets, we can reduce the will and ability of a nation to protect themselves against our power and strike out against Xcom and their antics. The goal of these missions is the destruction of ground, air, and naval forces in the targeted nation by sending out craft to blast any military instillation they come across, such as military air bases, naval ports, and barracks. Along with this, we are to strike out against any mass of soldiers or military vessels out in the open sea. Of course, primitive aircraft are to be watched but not engaged unless they approach and are attempting to attack. After all, things on the ground and in the sea are the targets of this mission, not things in the air.
Edit: So, our fighters took at least a couple of minutes to destroy the enemies fighters? because it seemed like it was only at most one...considering they saw the ground battle as pointless and thought that the skyrangers that shot down our UFO and in that same vein of thought probably where providing ground support weren't worth shooting down...