But then the AV designation is for fixed-wing aircraft, right?
this is all squadron and not aircraft designation, but might help your project still:
VA- is a squadron designation. V= fixed wing. A= attack Example VA-85. Throw in a M for Marine squadrons. Example VMA-311
When Medium Heli squadrons converted to Osprey they went from HMM (Heli, Marine, Medium) to VMM (Fixed Marine Medium) but since its still in the Helicopter format ( _, Marine, Size) everyone knows its an osprey since helicopters are Light (HML), Medium (HMM), or Heavy (HMH). But Fixed wing (like actual fighters)is not designated in such a way (VMA, VMFA, VMAQ, VMO)
Current Huey and Cobra Squadrons are designated HMLA (Heli, Marine, Light, Attack) So an "Attack" Osprey squadron would become VMMA (fixed, Marine, Medium, Attack) VMMA would work since fixed wing squadrons (like actual fighters) are either VMA, or VMFA, (VMAQ will be a thing of the past here possibly. VMO already is)
I hope this makes some sense!