Why do the Queen Elizabeth class carriers not have catapults? This is the Reason – YouTube

Incidentally, catapults are certainly not ‘new’ for the Royal Navy. They were the first to use them as standard, in the 1950, and the US Navy copied them. The plan agreed upon was that each carrier, should be able to operate up to 36 Joint-Strike-Fighters. This aircraft, which is now known as the F-35 Lightning, was originally conceived of as a replacement for both the F-16 and the Sea Harrier. It would have STOL capabilities, meaning that a catapult was unnecessary.

source: https://goo.gl/1Kwz8D