Know Your Plane #7 | Kyushu J7W1 Shinden: The Japanese B-29 Interceptor

Just another WordPress site

Know Your Plane #7 | Kyushu J7W1 Shinden: The Japanese B-29 Interceptor

In June of 1944 the Allied strategic bombing campaign against the Japanese home islands began The successive precision and area bombings would be essential to make the Japanese surrender, however Japan had one last trump card to destroy the large B-29 formations that rained death over the country: the Kyushu J7W1 Shinden fighter interceptor, aptly named ‘Magnificent Lightning’ as it would strike on the allied strategic bomber formations with its 4x Type 5 30mm cannons and shred the B-29s to pieces At least this was the whole premise of one of the most unique and advanced Japanese aircraft of WWII that did not arrive on time to either enter operation or much less ‘change the tide of war’ as some documentaries would say To those unfamiliar with the Know Your Plane series, I do like to feature unique aircraft to shed light on their history so in this episode let’s talk about the history and specifications of the Shinden, the only canard aircraft of WWII that was ordered into production The development of the Shiden dates back to Japan’s defensive strategy in 1943 At that time an invasion of Japan was unthinkable as the Japanese still controlled the Philippines, the East Indies and the islands in the Asian side of the pacific, however the military command was aware and expected Allied bombings against the four Japanese main islands: namely Hokkaido, Honshu, Shikoku and Kyushu By far Honshu was the most important of them all as it encompassed the largest Japanese cities like Tokyo, Osaka and Nagoya These cities were also home for the large aircraft companies of Japan like Mitsubishi and Nakajima and their respective manufacturing and assembly plants Meanwhile the island of Kyushu only had one minor aircraft manufacturer and that’s where the development of the Shinden took place The Japanese military leaders expected the allies to attack from two different ways: either by small bombers launched from American carriers close to the Japanese coast, like the Doolittle raid, or by large strategic bombers based in China In the first scenario the Japanese could use its network of patrol boats to identify the threat and have its ships or aircraft intercept the American task force with enough time, however things were more difficult in the Chinese front The allies could set up airfields very deep behind the front lines and use long range strategic bombers to attack the home islands, adding to that there were intelligence reports a new American bomber with a very long range and high operational altitude that was put into production: that was the B-29 and the Japanese estimated to faced by the fall of 1943 So the Japanese leadership knew that they would eventually have enemy bombers overhead so they began to prepare in advance The Japanese navy then stated out its requirements to replace the obsolete aircraft tasked with defending the home islands: “a superior high-speed land based fighter capable of mastering the shooting down of enemy bombers An altitude of more than 8,700 metres (28,500 feet) at 400 knots To be able to reach 8,000 metres (26,200 feet) in under 10 minutes, 30 seconds A maximum altitude of more than 12,000 metres Equipped with 4x Type 17 30mm machine guns.” By the way, it says machine guns because the Japanese navy considered anything below 40mm to be a machine gun at that time These requirements were handed off to Masaoki Tsuruno, a designer of the the Dai-Ichi Kaigun Kōkū Gijutsu-shō or the First Naval Air Technical Arsenal from Yokosuka Tsuruno had been researching the aerodynamics of a canard design, which was very unusual at the time, since 1940 and he thought it was the best way to minimize the the fuselage of the craft while increasing speed To prove the feasibility of such design the Naval Air Technical Arsenal designed the MXY6 glider in the shape of the Shinden Three prototypes made of wood were built by the Chigasaki Seizo company and tested in January of 1944 One of them was even equipped with a 22hp Semi 11 four cylinder air-cooled engine Given that the trials of a radical new design occurred without problems and the concept was deemed feasible, the Japanese navy gave the greenlight for the J7W1 project Since the Shinden was developed and ordered by the Japanese Navy and not Army, as Japan did not have an independent Air Force at the time, its name conforms to the Navy short designation system The J stands for land-based aircraft, the 7 because the Shinden was the seventh aircraft in the J category, the W stands for its manufacturer ‘Watanabe’ which was later renamed to Kyuushuu Aircraft Company but they kept the W, and the 1 refers to the first variant of the aircraft There were plans for the J7W2 which would be equipped with a jet engine, but we will talk about it later on in the video Meanwhile the nickname ‘Shinden’ also comes from a standard Japanese system where

fighters are named after meteorological phenomena and where all interceptors would have a name that ends with ‘Den’ which means lightning In the end they chose Shinden which means Magnificent Lightning Although the initial research with the glider prototypes was done by the navy’s Yokosuka technical arsenal, it’s important to point out that they are not a manufacturer so they had to approach a certain established manufacturer to further finish development and start serial production designed by them The manufacturer chosen by the Navy was the Kyuushuu Aircraft Company I’m sure you heard about Mitsubishi and Nakajima, but it wouldn’t surprise me if this is the first time you hear about Kyuushuu because it was one of the minor manufacturers throughout the war In the year of 1943 Kyuushuu produced only 12% of all the naval trainer and only 3% of all combat aircraft in Japan The reason for choosing Kyuushuu to finish the development was actually quite simple, all the other major manufacturers like Kawanishi, Mitsubishi and Nakajima were already busy with the production and development of other aircraft such as the Jinpu, Senden and Tenrai so they did not have the resources to accommodate another project, but Kyuushuu could As an added benefit, all of Kyuushuu’s plants were located around the city of Fukuoka in the island of Kyuushuu with the Zasshonokuma plant being the most important one and was where assembly of all its aircraft took place, these plants were so small, relatively speaking, that they were never targeted or damaged by an American bombing raid during the entire war Now surely Kyuushuu did not have the technical experience to handle a modern and complex project like the Shinden so the staff from the technical arsenal was dispatched to aid in the development and manufacturing of the plane Work on the Shinden began in June 1944, the same month as the first B-29 raid on home islands, but the Navy was in a hurry and wanted a prototype ready by January 1945 in order to commence flight testing In order to speed up development, the construction of the prototype began from the parts that had already been confirmed while the design was not yet completely finished In September of 1944, a mock up was completed for an exterior inspection by the staff of the Technical Arsenal That inspection was deemed successful and the Shinden was praised for its good visibility from the cockpit It was after this that things began to slow down The frequency and intensity of allied bombing raids increasing and by the end of 1944 Kyuushuu as a whole suffered several setbacks First, the Japanese army and navy’s conscription started to take away skilled labour from Kyuushuu because the military did not consider the current occupation of prospective soldiers As a result of that, half of the skilled labour of Kyuushuu, approximately 4,500 employees, were sent to the military and Kyuushuu had to make do with new, unskilled workers In December of 1944, the government also had two contradictory policies: they obviously wanted to increase the output of aircraft manufactured and at the same time they issued the mandatory dispersal program where aircraft manufacturers were ordered to move their facilities to bunkers, caves or anywhere necessary in order to avoid allied bombing as Japan’s aviation industry was their main target Needless to say, Kyuushuu’s monthly aircraft production plummeted from 133 units in November 1944 to only 33 aircraft in April of 1945 And besides moving all equipment and tooling to caves outside of the city, let’s remember the desperate situation on getting raw materials for the aviation industry as a whole Speaking of raw materials, the Shinden was an all-metal aircraft and since it was on the high priority list of projects, it did get better access to materials via the ministry of munitions With the exception of the engine and electronic components, all other parts like wings, gear and fuselage were made in the Kyuushuu island in close proximity to Kyuushuu’s main assembly plant so the project schedule was not so affected by allied bombings Meanwhile Mitsubishi, who was responsible for the production of the Shinden’s engine in Nagoya, was only able to deliver the MK9D engine to Kyuushuu in April of 1945 due to allied bombing Trials on the Mitsubishi engine began in May and the first prototype was officially finished by June 10 of 1945 At completion the first prototype was 100 kg heavier than expected and it was not equipped with weapons It was in this state that it was disassembled and sent for flight testing at the Mushiroda Airfield, the modern day Fukuoka Airport – also known as the FUK airport By June of 1945 the Japanese navy was so desperate that it had already ordered the Shinden into mass production even before the first flight of the aircraft The estimated monthly production was extremely optimistic considering the short availability of raw materials and skilled workers at 30 aircraft per month in the Zasshonokuma plant

and 120 aircraft in Nakajima’s Handa plant By the year of 1947 the navy expected to have over 1000 Shindens manufactured and operational The first attempt of a flight test happened in late July with Tsuruno, the main designer of the Shiden, at the controls During take off the propeller tips hit the ground as the aircraft pitched up and the take off was aborted To prevent this accident from happening again, Kyuushuu got the wheels of another aircraft they manufactured and placed them at the bottom of the wing tips The propeller of the first prototype was replaced with the propeller of the second prototype for the continuation of flight testing The first actual flight happened on August 3, 1945 with Kyuushuu test pilot Miyashi in the cockpit As the plane pitched up it yawed to the right thanks to the torque of the engine and this strong yaw continued on both cruise and landing The second flight test happened on August the 6, the same day as the atomic bombing of Hiroshima Even after hearing about the mysterious and tragic weapon unleashed against their own country, the team development team did not feel demotivated and continued to work on the Shinden intensely The third flight test and final flight of the Shinden took place on August 8, one day before the atomic bomb of Nagasaki, and a full speed flight test was scheduled for August 17 – a test that never took place In total, three Shinden prototypes were being built with the first one flying for approximately 45 minutes where the landing gear was always extended and it never carried weapons The only notable problem during flight testing was the strong pull to the right which was being corrected by adjusting the attachment angle of wings and flaps The war was officially over on August 15 but on the following day Tsuruno gave the order to burn all documentation of the aircraft so as not to contribute to allied technological advancement The second prototype was almost ready, just waiting for the engine delivery and its mounting The third prototype was a work in progress These aircraft were supposed to be dismantled, loaded onto a truck, placed into a pit and then doused with gasoline after being buried But in October of 1945, the Americans did find the first prototype, or the remains of it, and the craft was disassembled and shipped to the United States where it can still be found today at the National Air and Space Museum in Washington DC Design and Performance With the history of the craft out of the way, let’s talk about the Shiden’s design, performance and armaments starting from the rear to the front of the aircraft The Shinden’s engine was the Mitsubishi MK9D, part of the A-20 engine family that packed 18 cylinders, a supercharger and methanol injection The engine based on the Kinsei design that was originally meant for the Mitsubishi J4M1 Senden (an experimental twin boom interceptor that eventually got cancelled) was rated at 2,030 horsepower at takeoff capable of running at 2900 rpm and 1,160 horsepower at 28,545 feet at 2800 rpm In the Shinden the MK9D was mounted just behind the cockpit and it drove a Sumitomo VDM 6-blade constant speed propeller behind the craft which required a 750 mm extension to its shaft In total the Shinden had four problems related to the engine and its configuration First was shaft vibration when under load due to the long shaft extension Second, excessive torque especially during take off Third, insufficient engine cooling on the ground because there’s barely any cooling air coming into the air intakes and the cooling fan was installed just in front of the propeller which is far from the engine And the fourth problem was the low clearance between the 3.4 metre diameter propeller and the ground As you recall, the propeller did get damaged from hitting the ground on the Shinden’s first attempted test flight, to prevent the accident from happening again the designers added one wheel at the bottom of each wing to make them the lowest point of the aircraft during pitch up These two wheels were taken from another aircraft manufactured by Kyuushuu, the K11W1 Shiragiku bomber trainer The Shinden’s remarkable wings were angled at 20 degrees and had both slats and two tiered flaps on the the trailing edge The elevators had a deflection range of 25 degrees up or 30 degrees downward Each wing was fitted with an internal 200 litre fuel tank and a 75 litre methanol tank and the main fuel tank of 400 litres was located in the fuselage To further increase range, the Shinden could also carry a drop tank of 200 litres each under each wing The Shinden could also carry a total of 2x 60kg bombs or 4x 30kg bombs on the hardpoints located under the wings Both wings and fuselage were designed to withstand 7Gs The Shinden’s canards located on the nose of the craft were remarkably thin with a 5mm panel used for spars throughout the upper side and the canards also featured flaps that were moved by the same hydraulic actuator as the one from the main wings In regards to offensive armament, the Shinden was to be originally fitted with four 30mm

cannons or machine guns as they were called at the time by the navy The first choice was the Type 17 cannon but that later changed to the Type 5 Each gun weighted 70 kg and could fire 350 grams of ammo at 750 metres per second As you can expect from such a heavy armament aimed at destroying American strategic bombers, the recoil was strong so special reinforcing was necessary The pilot could also chose to either fire all guns at once or only the two lower ones To prevent damage to the propeller from ejecting shells from the cannon, all shells would be kept in internal storage compartments located in the nose of the Shinden and would be removed only on ground by the maintenance crew Speaking of maintenance, the Shinden was designed with removable panels to improve aircraft serviceability While in some aircraft a few items could only be adjusted from inside the cockpit, the maintenance crew of the Shinden could just remove the panel and fix the components from the outside Another remarkable feature of the Shinden of the tricycle gear configuration which was very unique for aircraft in the Japanese navy at the time The front gear was retracted by a single actuator and apparently from the records remaining, it did not have steering from the pilot so it would need a tow bar when the plane was on the ground If there was ever a problem with the hydraulic system the pilot could still lower and lock the gear by opening a compartment in the cockpit and letting the aircraft weight and wind do the work It is said that the front gear of the Shinden was the same as the one in the R2Y Kaiun reconnaissance aircraft which is said to be inspired, or copied, by the gear of a captured Douglas A-20A twin engine bomber Meanwhile the main gears came and the wheel covers came from the Nakajima C6N Saiun I cannot emphasize enough that the both the front and rear gears were massive, both exceeding 1 metre and 80 centimetres to provide enough clearance to the propeller . All in all the Shinden was a very tall aircraft at 3.92 metres It had a wingspan of 11.11 metres and length of 9.66 metres It’s weight ranged from 3,645 kg empty to 4,928 kg loaded to 5,228 kg as its maximum takeoff weight With the MK9D engine the Shinden was to reach a top speed of 405 knots at its operational altitude of 8,700 metres and a cruising speed of 228 knots at 4,000 metres As for climb, it was to go from sea level to 8,000 metres in 10 minutes and 40 seconds It’s service ceiling was 12,000 metres Without drop tanks the Shinden could carry up to 800 litres of regular fuel, 150 litres of methanol and 165 litres of oil Its range without drop tanks was of 460 nautical miles The Shinden had an endurance between 30 minutes in combat power up to 2 hours in a cruise setting it’s takeoff and landing distances were of 560 and 580 metres Based on the data given, the Shiden could absolutely create havoc among the B-29 bomber formations that bombed Japan with its powerful 4x 30 cannons in the early to mid phases of the allied bombing campaign as they were unescorted, but of course the aircraft’s development and production was just too late Interestingly, the designers of the Shinden did consider pilot survivability which let’s say was not a priority for the Japanese and their kamikaze stunts First, there was a 16mm bulletproof panel in front of the cannons to protect the pilot from frontal attacks There was also a 70mm bulletproof glass in front of the pilot The fuel tanks had 22mm thick layer of rubber, idea from a downed B-29 Aft of the cockpit there was also one brace to protect the pilot from overturning And last of all, the pilot could eject from the plane without getting shredded by the propeller An emergency separation lever located in the cockpit would open the movable windshield and blow the propeller and deceleration gearbox with a charge of gunpowder These are the features of the Shinden prototype but while I’m at it, let me go over some differences that would or could be implemented in the mass production of the Shinden First, mass production Shindens were supposed to have 4 propeller blades instead of 6 and four oxygen tanks instead of the two found in the prototype’s cockpit In the same location, the mass production plane was to have two protective braces, not just one Additionally, the nose of the aircraft which was empty in the prototype could be fitted with either a gun camera or two 7.9mm machine guns There were also plans another version of the Shinden called the J7W2 which would be fitted with one Ishikawajima Ne-130 axial-flow turbojet engine capable of providing 900 kg of thrust But unfortunately for the Japanese, their engine technology did not make progress fast enough even with the help of the Germans At the end of these videos I usually like to go over some trivia about the aircraft

featured on the episode What I found on the Shinden was that the pilot could enter from both sides of the cockpit and oddly enough, each side has two retractable steps which are very high on the fuselage There are no pictures of anyone using these steps and during all flight test people used ladders which were pretty much required for an airplane that was that high Also interesting that unlike western aircraft, in the Shinden the pilot would open fire by pulling the trigger that was located in the throttle lever, not in the stick Lastly, Watanabe Ironworks which was the parent company of Kyuushuu still exists today and in their website you can still see a section dedicated to the Shinden I thought it would be cool to point out that after over 70 years they still remember being the manufacturer of very unique design Unfortunately all text there is in Japanese and getting information on the Shinden in English make this video was a pain so I would be really appreciate if you subscribed, liked and shared this video with your friends to support the channel because episodes like this take a long time to make Anyway, hope you have enjoyed and let me know what you think of the Shinden in the comments, thank you for watching and see you next time