Just another note: The lighting/environment model could probably use a bit of tweaking as well. Y'know, like fixing the sun and moon rising at a fixed point in relation to your aircraft and instead give them their own orbits in relation to the world itself, throw in some colored lighting effects for sunrise/sunset, etc. For the environment, maybe add gusts to the wind effect so it's not a constant blow, turbulence, thermals, something to make the environment feel more ALIVE.
Flocks of birds (doesnt have to be collidable)
Personnel manning auto ack guns
Sun rays
Swaying trees/better looking trees
Better smoke/fire effects
Oil that streaks on your canopy instead of static black mesh
Similarily, water droplets flying through clouds
Contrails
Concussion effects from explosions
Better looking debris instead of plane parts that looks way out of place when they fall
Reflective canopy glass (it looks like glass in external view, but internal view, it's like the glass isn't even there)
Depth of field
Realistic/varied puffy ack explosions
Water (like you said)
Dust/water spray when flying close to the ground
Better damage effects on objects, planes and vehicles
New ship death animation
Fireballs that rolls on the ground relative to the impact direction instead of just a puff
Different effects for rockets, bombs, shells and cannons (they all look the same)
Tracers that corresponds with the plane historically
Oh my, I could ramble on for days.
