of the flight deck were rounded off to make them more streamlined. This reduced the length of the flight deck by . Aircraft were transported between the hangars and the flight deck by two elevators; the forward platform measured and the rear . The small rear elevator became a problem as the IJN progressively fielded larger and more modern carrier aircraft. Of all the aircraft in front-line service in 1941, only the Nakajima B5N "Kate" torpedo bomber would fit, when positioned at an angle with its wings folded. This effectively made Ryūjō a single-elevator carrier and considerably hindered transfer of aircraft in and out of the hangars for rearming and refueling during combat operations. Armament As completed, Ryūjōs primary anti-aircraft (AA) armament comprised six twin-gun mounts equipped with 40-caliber 12.7-centimeter Type 89 dual-purpose guns mounted on projecting sponsons, three on either side of the carrier's hull. When firing at surface targets, the guns had a range of ; they had a maximum ceiling of at their maximum elevation of +90 degrees. Their maximum rate of fire was 14 rounds a minute, but their sustained rate of fire was around eight rounds per minute. Twenty-four anti-aircraft (AA) Type 93 13.2 mm Hotchkiss machine guns were also fitted, in twin and quadruple mounts. Their effective range against aircraft was . The cyclic rate was adjustable between 425 and 475 rounds per minute, but the need to change 30-round magazines reduced the effective rate to 250 rounds per minute. During the carrier's 1934–1936 refit, two of the mountings were exchanged for two twin-gun mounts for license-built Hotchkiss 25 mm Type 96 light AA guns, resulting in a reduction of approximately of top-weight that improved the ship's overall stability. This was the standard Japanese light AA gun during World War II, but it suffered from severe design shortcomings that rendered it a largely ineffective weapon. According to historian Mark Stille, the weapon had many faults including an inability to "handle high-speed targets because it could not be trained or elevated fast enough by either hand or power, its sights were inadequate for high-speed targets, [and] it possessed excessive vibration and muzzle blast." These guns had an effective range of , and an effective ceiling of at an elevation of +85 degrees. The maximum effective rate of fire was only between 110 and 120 rounds per minute because of the need to frequently change the