mast at that time. Type 21 air-search radars were installed aboard the sisters in mid-1942. Aircraft Ise was briefly fitted with an aircraft flying-off platform for a Mitsubishi 1MF3 fighter on Turret No. 2 in 1927. It was replaced by a platform on Turret No. 5 for a Yokosuka E1Y reconnaissance floatplane in 1928–1929. A catapult and a collapsible crane were fitted on the stern during the mid-1930s modernization, and the ships were equipped to operate three floatplanes, although no hangar was provided. The initial Nakajima E4N2 biplanes were replaced by Nakajima E8N2 biplanes in 1938. Conversion to hybrid carriers The sinking of the British capital ships Prince of Wales and Repulse by Japanese land-based aircraft on 10 December 1941 led the IJN to realize that battleships could not operate in the face of enemy aircraft and required friendly air support to protect them. The loss of four Japanese aircraft carriers during the Battle of Midway in June 1942 severely limited the ability of the IJN to provide any air cover and alternatives were sought. Earlier proposals to convert one or more battleships into carriers had been made and rejected at the beginning of the war, but they were revived after Midway. Plans for more elaborate conversions were rejected on the grounds of expense and, most critically, time, and the IJN settled on removing the rear pair of turrets and replacing them with a flight deck equipped with two catapults to launch floatplanes. The Ise-class ships were selected for the conversion because Hyūga had suffered an explosion in Turret No. 5 in early May that virtually destroyed the turret and Turret No. 6 could not elevate to the full +43 degrees deemed necessary for the long-range engagement anticipated by the IJN. The Fusōs were scheduled to follow once the first two were completed. Armament changes The rear turrets, the barbettes and their supporting structures were removed beginning in early 1943 and the openings in the middle deck were covered by 152 mm plates salvaged from the turret armour. All of the 14 cm guns were removed and the casemate openings sealed off. Four additional twin 12.7 cm mounts were added, one pair abreast the funnel and the other abreast the conning tower. The original ten twin 25 mm gun mounts were replaced by triple mounts and nine new triple mounts were added, a total of 57 guns. Two each Type