Hmm. Considering that most early planes had only room for the pilot and anything he carried, I imagine that pistols or snub-nosed guns would be the primary armament, along with maybe a couple bundles of dynamite or some grenades.
I could see an airman trying to work his way up along a Lev's aft to chuck some explosive into the vane. I can also see them trying to drop dynamite into the steamstacks.
This gives me two ideas for roles for early craft: Suppression fire and a one-shot attack.
Anyone familiar with Risk: GodStorm? In the game there are these tiles that can be put over a region called 'Plagues'. They inhibit power pieces, or Gods, from using their powers in that region, or from entering them.
Since a squadron can be throwing around a lot of stray bullets, I imagine they'd be good at forcing crew in open areas to keep their heads down. What does this mean in game terms? Locations with crew cannot be used for things such as repair. Or, just can't be used to make repairs.
This would only apply to a ship location who has a hex occupied by an aeroplane squadron.
I imagine that eventually, modifications would be made to ships to allow for upward mounted Maxims, and then such affected crew could be used to make successful attacks against the squadron instead of being used for things they can't be used for.
And, then, with dynamite in hand, they can perform one normal style attack until they can land and rearm.