Aircraft designers stopped putting mashineguns on wings as soon as the problem of the propereller blades getting in the way has been solved, and mashineguns have RoF several orders of magnitude higher than SW weapons.
Actually that's just blatantly not true. Even after they solved that problem aircraft were still commonly designed with wing mounted weapons. The weapons were generally built to be pointed slightly inwards, giving the aircraft an optimum-range where all weapon's fire converged. This gave the pilot a kind of flexibility, as firing at another craft at that optimum-range dealt maximum damage, but firing slightly outside that optimum range gave a greater chance of scoring at least some hits as the fire was more diffuse.
Captain nitpick... AWAY!
Yup. One of my favourite facts about aircraft is that some of the very first mounted machineguns which were synced to the speed of the prop so that the bullets actually passed between the prop blades.
As early as 1913 in fact https://en.wikipedia.org/wiki/Synchronization_gear
I think the reason that it fell out of use for a while was the change to more complex engine types which couldn't be as easily geared in that manner, but I'm not sure.
This has been a derail about cool engineering. Back to your regularly scheduled bickering about heatsinks.
If I recall, before that they just put metal plates on the propellers, to deflect the bullets...and most of the time they wouldn't fly back and kill the pilot...mostly.
Edit: Oh, apparently the problem with deflector gear was more the loss of optimal propeller function, from having big deflector wedges on them.
They did that too, yeah.
In some cases they just sort of assumed that the gun would fire at about the right rate not to hit the prop most of the time and just shot it through the prop anyway. Which mostly worked.
Mostly.
Sometimes it chopped the end of the prop off though.
And sometimes they just dropped grenades on each other or beaned away with revolvers from the cockpit. Very early warplanes were... odd.
Edited by thespaceinvader