In 1936 the Royal Navy developed the armored flight deck aircraft carrier which also enclosed the hangar sides and ends with armor. The addition of armor to the flight deck offered aircraft below some protection against aerial bombs while the armored hangar sides and ends helped to minimize damage and casualties from explosions or fires within or outside the hangar. The addition of armor to the hangar forced a reduction in top-weight, so the hangar height was reduced, and this restricted the types of aircraft that these ships could carry, although the Royal Navy's armored carriers did carry spare aircraft in the hangar overheads.