The first US catapult shot was on Nov 18,1922 , by Lt. Cdr K. Whiting. It was a seaplane, so was probably fired off from the side. Early catapults were hydraulic, but the RN were using steam cats. to fire off Seafires in 1941.
I found the info on a " google" search, and it of course is US biased. I always believed that the RN were the first to use "cats", and steam driven ones too, but I can`t find a site.
Just like most good inventions , like angled decks, mirror landing -sights, ski -jump ramps, we pass them over the pond so history gets changed!!
