We all know that hydras are OP already and with hovering, they get more OP so I though of a solution to minimize that effect to the fair point.
A cool down time for hydra's rocket (like a kind of reload time) is the only way to minimize the spam of infinite rockets firing on the enemies. I am thinking of making 10 rockets available to shoot and after using them, Hydra will go in to cool down or reload time and pilot should wait for the reload in order to shoot again. The recommended time I am thinking is "10 seconds" as I have first tested this idea mentally so I think it will lead to fair gameplay