Combat Lynx by Durell Software, released in 1984, allowed you to fly the Westland Lynx in a ground Attack role.
This must qualify for the most esoteric combat sim of all time! It was released for the Sinclair Spectrum with 48K of RAM and the Commodore 64.
"Combat Lynx (at least the spectrum version, I've never seen others) had a couple of interesting features. It was a third-person game, with the helicopter in the centre of the screen, and a fairly complex control set. Among the neat features were a 'projected targeting sight' for air-to-surface missiles that rolled nicely over a set of 'real' 3d hills (I think they were done as contour lines). Pretty advanced stuff in 1984!
Gunship didn't even do that!"