Navy Aviation Headquarters

Proposal for Prototype of High-Speed Long-Range Ship-Based Bomber with the Sole Purpose of Preemptive Strikes on Enemy Carriers

(1942.7.27 Navy Aviation Technical Arsenal Chief)

The Japanese and American Navies are now entering a shipbuilding race to acquire the largest number of aircraft carriers in their respective fleets. Ultimately, it will become clear that the United States, with its superior shipbuilding capabilities, can service a large number of aircraft carriers in a short time period compared to us. In order to crush them with a small number of aircraft carriers, it goes without saying that it would be necessary to preemptively suppress the actions of enemy carrier aircraft by planning to outrange them through increasing the attack radius of our on-board aircraft.

For this purpose, research is conducted on the plan for the High-Speed Long-Range Ship-Based Bomber with the sole purpose of conducting dive-bombing attacks on enemy carriers from as far of a range as possible, within the scope of currently feasible technologies, to obtain results like those of the supplementary document.

Characteristics of this plane:

  1. Aim for a maximum speed at least equivalent to enemy fighters, so that it can avoid interception as much as possible and push forward to the main objective of bombing enemy aircraft carriers.
  1. Increase the cruising speed and cruising capacity as much as possible.
  1. It should carry at least a Number 25 rocket-bomb.
  1. The form of the airplane should be as small as possible, so that a small aircraft carrier can carry as many as possible (the dimensions and weight of this plane are to be approximately the same as the 17-Shi Ship-based Fighter).
  1. The purpose of this plane is to dive-bomb enemy aircraft carriers, and because it will not participate in aerial combat with enemy fighters, it will not be equipped with forward-facing machine guns. It is designed to increase its cruising capacity as much as possible by being equipped with only a rearward flexible gun, self-sealing fuel tanks, and a bullet-proof steel plate for the pilot as protection.

Though a ship-based bomber according to ideas like those written above has not yet been considered in the ongoing airplane prototype plans according to the requirements of the General Staff, when considering the future naval combat of our aircraft carriers, it must be considered worthy of research nonetheless.

If the center recognizes the need for such a ship-based bomber, I have confidence that it will be realized with the completion of the first prototype within one year from the policy decision at the Kūgishō.

I hope for urgent consideration of this.


  1. The tactical philosophy of this plane is not the result of joint research with the Yoko-kū [Yokosuka Navy Air Corps]. It is my [Vice Admiral Misao Wada’s] independent opinion that has taken form through the calculations of the Airplane Department. In the case that this plane is to be realized, by initiation from the center, it will require joint research with the Yoko-kū.
  1. At present, it has been tentatively decided that the Kūgishō will prototype the 17-Shi Land-based Recon Plane, and it is under basic planning research, but it is expected that the basic research will require at least half a year. On the other hand, this plan, prototyped based on the experiences of the 13-Shi Ship-based Bomber and the Y20, can start being designed and drafted immediately, and this can potentially be completed before starting the manufacturing drawings of the Land-based Recon Plane. This would be the most effective utilization of the prototype capacity of the Kūgishō.
  1. Regarding the rocket-bomb, basic experiments have already been completed, prototyping will be completed by the end of this year, and testing of the actual bomb is scheduled to begin early next year.