I've made this dual rotor helicopter/bomber which carries 9 bombs and is quite maneuverable.

Dual Rotor Bomber.bsg (20.99 KB)

The design for the propellers was inspired by a thread I found that had a build that I really liked
besiege.freeforums.net/thread/883/bicopter-bomber

It does have a bug that makes it so it will not work some of the times the simulation is started (the bottom two rotors will not work or wing panels will fly off)
this can be fixed by restarting the simulation until everything is stable (all four rotors are spinning for at least a second)
it can take up to 20 tries to get it, but once it has been done once, it usually doesn't take more than 3 to 4 tries
controls

y/h ---- (pitch) forwards/backwards
g/j ---- (roll) left/right
t/u ---- (yaw) left/right

up ---- drop three bombs
down ---- drop four bombs

left ---- power up
right ----- power down

keys can be rebound if ya hate my controls