FACTBOX-Royal Navy's new aircraft carriers

LONDON (Reuters) - Defence chiefs signed a three billion pound contract on Thursday to build two aircraft carriers that will be the biggest warships in the Royal Navy's history.

Here are some facts about HMS Queen Elizabeth and HMS Prince of Wales:

* Each carrier will be 280m (920 ft) long and will be taller than Nelson's Column.

* They each weigh the equivalent of 32,500 family cars.

* Their diesel and gas turbines will produce enough power to run a town the size of Swindon.

* Sixty-seven caterers in four kitchens will be able to feed 1,000 crew in an hour.

* Each ship can house about 40 Joint Strike Fighters or the GR9 Harrier, helicopters and unmanned drones.