Zardnaar
Legend
You know the range for ballistae in a fictional world, huh? And how likely it would be for one to hit a moving target? And who says the ships are slow moving?
I get it if it didn’t work for you. I wasn’t crazy about how the scene where Rhaegon was killed either. But not because it was implausible....more that it was poorly presented.
AA fire in WW2 with exploding shells wasn't that effective and relied on lots of flak.
Shooting a Dragon down in the air at hundreds of metres range is fairly implausible, and shots at that range with military rifles is difficult for the average soldier through to WW2 (it's why the Germans invented the MP44).