Kūtei-kan

A kūtei-kan (空挺艦) is a Japanese term that literally translates to "airborne ship" or "air-landing ship." In the context of naval history, it typically refers to a type of warship designed to support airborne operations or amphibious assaults involving aircraft. Specifically, the term is most commonly associated with Japan's planned but never completed modification of existing warships into vessels capable of launching and supporting autogyros or other aircraft for scouting, anti-submarine patrol, or airborne assault.

The most notable example of a kūtei-kan project was the modification planned for the Ise-class battleships during World War II. After suffering significant damage during the Battle of Midway, the Japanese Navy considered converting the Ise and Hyūga into hybrid battleship-carriers. The rear turrets were to be replaced with a flight deck capable of operating a limited number of aircraft, initially planned to be the Aichi M6A Seiran floatplane bomber, which would have been launched via catapult. However, due to practical limitations and resource constraints, the Seiran's availability dwindled, and the plan shifted to accommodating autogyros or other types of light aircraft for reconnaissance and scouting purposes, including the Kayaba Ka-1. The converted Ise and Hyūga retained their forward main battery turrets and thus functioned as hybrid battleship-carriers, although their aircraft capabilities were significantly more limited than dedicated aircraft carriers. Neither ship ever deployed aircraft operationally in their converted configuration.

The term kūtei-kan is therefore primarily linked to these conversion projects and the conceptualization of warships that could combine traditional naval firepower with limited airborne capabilities. It represents an attempt to adapt existing platforms to evolving wartime needs and to augment naval operations with air power in a unique, if ultimately unsuccessful, manner.