I was expecting one of our members who studies the R.A., would jump on this question.
From Dunning pp. 13-14.
It depends on the type of unit.
Fighters: 4 a/c in a sezione. three sezioni in a squadriglia, two squadriglie in a gruppo. Three gruppi in a Stormo (72 a/c + 4 support/trans.)
Bombers/recce: 3 a/c in a sezione. three sezioni in a squadriglia, two squadriglie in a gruppo. Two gruppi in a Stormo (36 a/c + 4 support/trans.)
Pista! Jeff