The Yokosuka MXY-7, also known as the “Ohka”, was a manned missile designed by the Japanese. It housed a single pilot for a one-way mission. Translated into English, "Ohka" means "cherry blossom", but the Allies referred to it as the "baka bomb" or "idiot bomb". There were several versions of the “Ohka”, but this video focuses on the operational Model 11. The main fuselage was tubular in shape
and was 19 feet 11 inches long, with a diameter of just under 2 feet. At its core was an aluminium airframe. Longerons went the length
of the aircraft, which supported formers. Over the frame of the aircraft, aluminium sheets
were fastened to create the skin of the aircraft. This gave the aircraft a very light construction, apart from the warhead, which took up
most of the weight of the aircraft. A single piece of nose cowling covered the warhead. The wings were made of an aluminium structure
of spars and ribs. Attached to this was balsa wood
to form the skin of the aircraft. From what we've seen in photos, this looks like it was done with a self-tapping screw. The wings were 16 feet 10 inches wide. And had ailerons to control the roll. The “Ohka's” tail featured two horizontal stabilisers. This type of design is known as a "twin tail", which as well as giving more stability and control, acted as a counterweight to the heavy nose that carried the warhead. The long nose of the aircraft was mainly taken up by the warhead. The warhead was encased in steel so as to provide the maximum armour piercing capability upon allied shipping. The armour piercing warhead weighed in at 2,646 pounds, but 1,141 pounds was explosive material. The aircraft was 4,718 pounds in total. The nose warhead contained five fuses, one in the nose of
the bomb and four in the base. The nose fuse was armed by a spinner that could be freed to spin upon release of the “Ohka”. The other four fuses were armed by the pilot. Moving to the back, the “Ohka” was powered by three Type 4 Mark I Model 20 rocket engines. A solid rocket engine works by burning solid propellant to produce high pressure and high temperature gases, which are then expelled out of a nozzle at the back of the rocket to produce thrust. The basic components of a solid rocket engine are: The casing. This is the outer shell or body of the rocket engine that holds everything together. It has to be very strong, enough to withstand the high pressures generated from inside the engine. The nozzle. This is the opening at the back of the rocket where the gases are expelled out. The nozzle is designed to accelerate the gases and expel them
at high speed, generating thrust. And solid propellant. This is the fuel and oxidizer, mixed together in a solid form. The fuel is what burns, and the oxidizer is a chemical that provides the oxygen,
needed for the fuel to combust. The propellant is packed into the casing in a cylindrical shape with a hole running down the middle,
known as the core. According to US scientists that analyzed the “Ohka”, the chemical analysis of the propellant was 59.9% nitrosalulose, 26.9% nitroglycerin and 6.1% mononitronaphthalene, 2.9% ethyl centralite and 1.3% volatiles. The engine output was 588 pound feet of thrust. In each of the three “Ohka's” engines were six tubes of propellant. They were arranged in three groups of two, effectively making three long tubes of propellant. The motor was lit using a small igniter that was placed at the end of the engine, furthest from the nozzle. It was activated by the pilot by means of an electrical signal. When the igniter was lit, a very fast burning material that produced hot gases and particles was expelled into the core of each of the three tubes of propellant in the motor. These hot gases and particles ideally ignited the inside of the surfaces of the six sticks of solid propellant evenly along the length of the engine,
initiating the combustion process. Let's go through the inside of the cockpit. First, there was a red switch that would be set to arm four of the five fuses on the warhead. Then the rocket selector switch. This would allow the pilot to select which rocket motor would be activated when pressing a button on the joystick. The switch would usually have five settings: off, one, two
and three for the main rockets and another setting for some models of “Ohka” that had under wing rockets for extra range. The intercommunication switch was for sending and receiving Morse code to the carrying Betty. There was also a compass. An altimeter showed the height to sea level and worked
through an air pressure sensor. The air speed indicator used a pitot tube, located on the left wing to determine the air speed. There was also a turn and slip indicator that used a gimbal mounted gyro. The turn and slip indicator is a flight instrument that was used to understand the orientation and movement of the aircraft in the horizontal plane. It consisted of two components, a turn indicator and a slip indicator. The turn indicator shows the rate at which the aircraft is turning. It indicates whether the aircraft is in a coordinated turn without any side slipping or skidding. The slip indicator, when centered, shows the aircraft is in coordinated flight. If it moves to one side it indicates a slip or a skid. Together these two indicators help the pilot maintain coordinated flight during turns. Then there was an inclinometer that indicated the vertical angle of flight. The inclinometer, used in “Ohkas”, was a model 2, manufactured by Tokyo Koku Keiki Seisakusho. It differs from a standard inclinometer by having a modified scale, placing the zero mark near the top to better indicate steeper dive angles. The circuit test switch activated the aircraft electrical systems. The red light signaled the
activation of the electrical circuit. The pilot's controls consisted of a joystick and a rudder. The joystick, when moved left and right, moved the ailerons on the wings which controlled the roll of the aircraft. When pushed forward or pulled back, it moved the elevator in the tail and controlled the pitch of the aircraft. On the joystick was also a button to activate the rocket that was currently selected on the rocket selector dial. The rudder control wasn't pedals but was more rudimentary as a bar that pivoted upon its center. This activated the two rudder control surfaces on the tail and controlled the yaw of the aircraft. These simple solid rocket motors could not be shut off once they were lit. The rockets would propel the “Ohka” to a top speed of up to 400mph in level flight and 580mph in a dive. The rocket had a burning time of just 8-10 seconds which meant very short range. Contrary to most depictions of the “Ohka” in games and in art, the engines were not designed to be fired simultaneously. Instead to maximize range the pilot had a control dial which could be rotated and then a button pushed to fire one rocket at a time. We'll take you through that later on. In order to get the “Ohka” in position, it was carried underneath a Mitsubishi G4M2E Betty Bomber. The maximum range of the “Ohka” depended upon the height it was released. Typically the range was about 35 times the release height. However they could be released at 10,000ft and this would give a range of about 18 miles. Some 50 miles from the target, having set a formal farewell to the bomber's crew, the pilot crawled through the bomb bay and into the cockpit of the “Ohka”. The first thing the pilot would do is buckle up. Then, on the floor at the 8 o'clock and
4 o'clock positions were bungee cords secured to the foot bar
which were removed by the pilot. The bungee cords prevented the rudder from being activated while the Oka was being carried by the Betty Bomber. The pilot would also remove a pair of thin metal rods, attached to the joystick at the 10 o'clock and 2 o'clock positions. The cables and rods were always handed up to an assistant in the bomber as a safety measure because, if left inside the cockpit, they might jam the controls
or fly around and injure the pilot. There was a fifth restraining device that was a combination of a metal rod with an eye hook,
attached to a spring on the joystick. It stayed connected to prevent the pilot from pulling back on the joystick at the moment of release which could cause the “Ohka” to lurch up and strike the Betty. The pilot would then reach over his head to pull
a little wooden block until the canopy slid forward and snapped shut. He would then switch the engines to stand by and activate the fuse handle arming the warhead. He would take a padded earpiece. Once all was ready, he would announce into the mouthpiece "Seibi junbi Yoroshii", while pressing the button of the instrument panel to tap out the Morse code symbol for "Sei",
the Morse abbreviation of his message. A flashing light and a buzzer gave him visual and audio
confirmation of his Morse code message. The Betty pilot pulled the lever, the hook would release from the hoist point and the “Ohka” would drift away from
the Betty, the point of no return. The “Ohka's” flight began as a shallow, unpowered glide reaching a speed of 230-280mph. The spinner can now move freely. A cotter pin prevented the spinner from moving while it was attached to the aircraft. The warhead would now be fully armed. The pilot had a dial to select a rocket and then pushed the button on the joystick to light the rocket. When the rocket was lit, the pilot would experience instant accelaration When one rocket was burnt out
he would select the next one and so on. Standard operating procedure was to leave one rocket until the final part of the “Ohka's” approach to an enemy vessel. With the weight of the other two rockets already expended, the final rocket would be where the “Ohka” reached maximum speed. Having lined the target on the enemy vessel, the “Ohka” would impact above the waterline. Instantly the wooden and steel structure would disintegrate leaving the armour piercing warhead to push through the side of the vessel before detonating from within. We used many sources to get as much information as we can for this film. Please let us know in the comments where we got information incorrect. We're looking forward to as much dialogue as we can get with these films. Thank you.
