Yeah Karnak that thought crossed my mind too
Large fields with extra long runways being the only place the heavies could launch.
Med fields, medium buffs and jets
small fields light buffs , and fighters
Oh yeah, and "overloads" for fighters such as F4U-4 only available from land bases.
Seen reports of the F4U-4 able to actually carry more than the P47, but only when launched from land bases.
SKurj