Requiring a fast medium bomber for dive-bombing, low-altitude bombing or torpedo attack, the Imperial Japanese Navy instructed the Yokosuka First Naval Air Technical Arsenal in 1940 to begin design of such an aircraft. The resulting Yokosuka P1Y prototype flown in August 1943 was a mid-wing, all-metal monoplane, powered by two Nakajima NK9B Homare 11 radial engines. Its performance was satisfactory, but the P1Y suffered from maintenance problems that plagued its service life.
The entry into service of the P1Y1 Navy Bomber Ginga Model 11 was in 1943.
As the war neared its end, Japan required defensive fighters and steps were taken to produce a night fighter version of the Ginga.
The contract for this was awarded to Kawanishi, who’s P1Y2-S Kyokko (Aurora) utilised the less troublesome 1850 hp Kasei 25 engines, was fitted with an AI radar ad three 30mm cannon. Only 97 P1Y2-S were completed before VJ day, although a few P1Y1-S conversions from Nakajima-built bombers saw limited operational service.
P1Y1-S
Production totalled 1098, built by Kawanishi (96) and Nakajima (1002), and if there had been adequate manpower to service these aircraft before each operational sortie they would have proved formidable adversaries. This was not possible and as a result the Ginga (Milky Way), allocated the Allied codename ‘Francis’, was tried unsuccessfully in a variety of alternative roles; its brief operational life of only six months was terminated by the end of the Pacific war.
P1Y1 Engines: 2 x Nakajima Homare-21, 1370kW Max take-off weight: 10500 kg / 23149 lb Empty weight: 7265 kg / 16017 lb Wingspan: 20.0 m / 66 ft 7 in Length: 15.0 m / 49 ft 3 in Height: 4.3 m / 14 ft 1 in Wing area: 55.0 sq.m / 592.01 sq ft Max. speed: 550 km/h / 342 mph Cruise speed: 380 km/h / 236 mph Ceiling: 9400 m / 30850 ft Range w/max.fuel: 4650 km / 2889 miles Range w/max.payload: 1900 km / 1181 miles Crew: 3 Armament: 2 x 20mm cannons Bombload: 1000kg
P1Y1 Engines: 2 x Nakajima Homare-11, 1820 hp Wingspan: 65 ft 7 in Length: 49 ft 3 in Height: 14 ft 1 in Empty weight: 14748 lb Loaded weight: 10500 kg / 23149 lb Max speed: 345 mph at 19,260 ft Service ceiling: 33,530 ft Max range: 1600 mi Armament: 1 x 20mm cannons / 1 x 13.2mm mg Bombload: 1760 lb or 1 x 1875 lb torpedo (externally Crew: 3
Japan’s naval officers, in the summer of 1944, were faced with the almost sure knowledge that their country’s defeat was simply a matter of time. Even before Vice Admiral Ohnishi ordered the creation of the Kamikaze Special Attack Force in October 1944, some naval officers were seeing suicide attacks as the only way to defeat the Allied fleets. One of these men was a transport pilot of the 405th Kokutai, Ensign Mitsuo Ohta. He conceived the idea of a rocket-propelled suicide attack plane, and with the aid of personnel from the University of Tokyo’s Aeronautical Research Institute, he drafted preliminary plans for his brainchild. In August 1944 he submitted his drawings to the Naval Air Technical Arsenal at Yokosuka. The Navy decided that Ensign Ohta’s idea had merit, and so the Arsenal was instructed to prepare a set of detailed blueprints – the engineers involved were Masao Yamana, Tadanao Mitsugi, and Rokuro Hattori. The Ohka (Cherry Blossom) was, in effect, a manned anti-shipping cruise missile of the Pacific War.
The MXY7, as the design was named, was intended as a coastal-defense or anti-invasion weapon, launched by a “parent” aircraft. Once released by its “mother” ship – usually a G4M twin-engined bomber – the MXY7 would glide downwards, and once the pilot had selected a target, the weapon would accelerate to attack speed using the power of three solid-fuel rockets mounted in the tail. These rockets could be fired one at a time or all three simultaneously. Theoretically, when it was at its terminal velocity, the MXY7 would be virtually impossible to stop, and only pilot error could cause it to miss. This small but lethal aircraft was to be built of wood and non-critical metal alloys, utilizing unskilled labor, and as it would be flown by pilots with only limited aerial experience, flight instruments were to be kept to a bare minimum and good maneuverability was required to achieve accuracy in flying and aiming the “manned missile”.
The actual aircraft itself looked like a torpedo to which wings and twin tail surfaces had been added. Barely 20 feet long, and with wings spanning just over 16½ feet, its sliding canopy was hump-backed. In front of the canopy was a ring sight, with a bead sight in front of that, for precise aiming when in the terminal dive on a target. The Ohka was built by unskilled workers using as much non-strategic material as possible. The fuselage was a standard aluminium structure, but the wings were made of moulded plywood covered in fabric. Cockpit instrumentation consisted of only four instruments: a compass, an airspeed indicator, an altimeter and an inclinometer for turn indication.
Ten MXY7s were completed by the end of September 1944. Unpowered flight trials began at Sagami the following month, and in November the first powered flight was made at Kashima. The MXY7 was accepted for Navy service under the name Navy Special Attacker Ohka Model 11. It was powered by a battery of three Type 4 Mark 1 Model 20 rockets, which produced 1,764 pounds of thrust, combined, for 8 to 10 seconds of powered flight. Performance measured during an unmanned flight at Kashima in January 1945 indicated that the Ohka could reach a top unpowered speed of 288 mph and a top powered speed of 403 mph, both speeds being attained at a height of 11,485 feet.
The Imperial Navy didn’t bother to wait for all test results to come in; production began with the first ten Ohka Model 11s in September 1944, and 755 were built by the end of March 1945, when production of this variant ceased. One hundred and fifty-five were built by the Naval Air Technical Arsenal at Yokosuka, and 600 more by the First Naval Air Arsenal at Kasumigaura; Nippon Aircraft Ltd. and Fuji Aircraft Ltd were subcontractors for the wings and tail units. But barely a hundred of them were actually used in operations.
Ohka Model 11
The Ohka’s debut was highly inauspicious. Sixteen G4M2e mother planes of the 721st Kokutai, each carrying a single MXY7, took off from Kanoya on March 21, 1945 to attack an American carrier task force 320 miles off the coast of Kyushu, the southernmost of the four main Japanese home islands. Two additional Bettys went along as navigation and radio planes. Their commander was Lt. Cdr. Goro Nonaka, a veteran torpedo bomber pilot. Nonaka’s last words, just before he entered his bomber for the mission, were “This is Minatogawa.” He was referring to the battle in the 14th Century Japanese civil war between the Northern and Southern imperial courts, where one of Japan’s greatest military heroes, the Southern commander, Masashige Kusunoki, killed himself after losing, saying, “Shikisei hokoku!” (I wish I had seven lives to give for my country!) The attack was a complete, humiliating fiasco. Fifty-five Zero fighters from the 201st Kokutai were assigned to fly escort, but mechanical failure caused by poor maintenance forced some fighters to abort without leaving the ground, and others had to abort when airborne. Only 30 Zeros actually accompanied the 18 Bettys to the combat area, where fifty F6F Hellcats attacked them well before they reached optimal launching range. Ignoring the escort fighters, the American carrier fighters concentrated on the bombers and their strange under-belly cargo. All of the Ohkas were jettisoned (the pilots remained with the mother ships), but 15 of the Bettys were destroyed.
Three more, including Cdr. Nonaka’s, tried to take cover in a nearby bank of clouds, but they were soon found and shot down as well. Fifteen of the 30 escorting Zeros were also lost, with the remnant returning home in varying states of damage.
This episode pointed up the worst failings of the Ohka, or Baka (“stupid” in Japanese. Widely known as Gizmo before Baka was selected on the suggestion of a US Navy Petty Officer) as the Allies called it: the mother aircraft, when carrying it, was a fat, wallowing aerial whale, lacking speed and maneuverability, easy meat for defending interceptors. And the Ohka lacked range, even when gliding; it had to be launched from no more than 20 nautical miles (23 statute miles) away from its prospective target. Very few Ohkas actually struck their targets, as it was so difficult to launch and to maneuver under its pilot’s hands. But once released, and once the rockets were ignited, the Ohka was impossible to stop. Its first successes were scored the first day (April 1, 1945) of the American invasion of Okinawa, when the battleship West Virginia and three transports were hit, and on April 12, an Ohka scored its first sinking by sending the destroyer Mannert L. Abele to the bottom of the sea. The destroyer-minesweeper Shea was hit by an Ohka on May 4, and barely escaped total loss, as a fire started by the Ohka almost reached the ship’s magazines before the damage-control men brought it under control. Its last success came on June 16, when an Ohka and a bomb-carrying Zero almost simultaneously struck the destroyer Twiggs, which sank within a few minutes.
In all, the Okinawa campaign cost the US Navy 40 ships sunk or damaged beyond repair and 368 damaged to varying extents, often seriously. The US Navy lost more sailors dead and wounded than the Army and Marines lost in the ground combat, making Okinawa, next to the Guadalcanal campaign, the bloodiest and most difficult of the war for the Navy. The Japanese lost about 7,600 planes, more than half of which were suicide planes; the Americans lost 763 planes of their own. It is not known for sure exactly how many Ohkas scored hits and sinkings.
It might be well to mention here that a number of Ohkas were captured on Okinawa itself. Apparently, the Japanese shipped several Ohkas to that island before the campaign opened, probably meaning to use the airfield at Yontan as a refuelling and arming point. But American aerial supremacy never allowed the Japanese to base any aircraft there after about March 25, and the Americans took Yontan very quickly after the landings. And so, the MXY7s were never used, and quite a few “Baka bombs” were captured intact. Most of the surviving examples in museums came from this source.
Further development of the basic Ohka theme continued, but no other variants other than the Model 11 were used in combat.
K-1 Forty-five examples of the Ohka K-1, an unpowered trainer with water ballast replacing the powerplant and warhead, were produced by Yokosuka to provide pilots with limited experience in handling a simulation of the real thing in flight. Both water ballast tanks would be emptied during the practice terminal dive, slowing the landing speed to 138mph, and the glider would then land on retractable skids.
Ohka K-1 trainer
Ohka Type 22
Ohka 22
The Ohka Model 22 was intended as an improved version to be launched from the faster and more maneuverable P1Y3 variant of the Navy’s Ginga bomber. Because the Ginga could not carry the same payload as the G4M2e, and because of the limited space under the P1Y3 compared to the Betty mother plane, the Ohka 22 was to have shorter wings and a lighter explosive payload (1,323 lbs.). The Ohka 22 received a Tsu-11 turbojet – a Campini-type jet engine – with a 100-hp Hitachi HA11 four-cylinder inline engine driving a single-stage compressor as a gas generator. The engine was fuel injected but engineering analysis after the war suggests that this had limited effect and that in reality the unit was little more than an afterburning ducted fan engine as the majority of the thrust came from the compressor. The Ohka was adapted to accommodate the engine by lengthening the fuselage with intakes on the side. It was hoped that the Ohka would have greater range with this jet engine, and so the mother ships could more easily survive attack by releasing the Ohka 22 farther away from target.
Fifty Ohka 22s were built by Yokosuka, and an ambitious production scheme was planned, with Aichi doing most of the final assembly and with the smaller concerns of Murakami, Miguro, and Fuji serving as subcontractors. But due to the increasingly bad war situation, Aichi was unable to begin production, so the Imperial Navy planned to concentrate Ohka 22 production in underground factories managed by the Air Arsenal at Kasumigaura. The war ended before any of the underground factories could be completed. One Ohka 22 was test-flown in July 1945, launched by a Betty because the proposed P1Y3 Ginga was not yet built, but auxiliary rockets installed under the Ohka’s wings ignited prematurely just after release, and the Ohka 22 went into an unrecoverable stall, killing its pilot.
A single example of a Tsu-11 engine is preserved at the National Air and Space Museum in Washington DC. In 1997 it was installed in the museum’s Ohka 22 during its restoration.
Ohka Model 43 K-1 Kai Wakazakura (Young Cherry) The Ohka Model 33 was an enlarged Model 22 powered by a Ne-20 turbojet and fitted with a 1,764-lb. warhead. Its intended mother ship was the G8N1 Renzan four-engined bomber, but the low priority given the G8N program led to the Ohka 33’s cancellation before any examples could be completed. Also unbuilt was the Ohka 43A, a still larger variant with folding wings intended for launching from surfaced submarines. The Model 43B, a development of the 43A, was to have been a shore-launched manned missile, stored in and catapulted from caves. Once in the air, the Ohka 43B’s wingtips would’ve been jettisoned to increase the type’s speed, but no prototypes were built by the time of Japan’s capitulation. But three examples of a two-seat training version of the 43B, designated Ohka Model 43 K-1 Kai Wakazakura (Young Cherry), were produced before the surrender. These had retractable skids and flaps for landing, and the warhead was replaced by a second cockpit for the student. One Type 4 Model 1 Mark 20 rocket was mounted in the tail for limited powered-flight experience.
Ohka 43-K1-Kai
Other Ohka developments included a single example of the Model 11 experimentally fitted with wings fabricated by Nakajima out of thin steel; the Ohka Model 21, a hybrid consisting of the rocket powerplant of the Model 11 married to the airframe of the Model 22; and the Ohka Model 53, to be powered by a Ne-20 turbojet, and towed aloft like a glider and released over the target by its towplane. Total production of all Ohka variants was 852 examples.
Yokosuka MXY7 Ohka (Baka) Model 11 Type: Single-seat suicide attack plane Powerplant: 3 x Type 4 Model 1 Mark 20 solid-fuel rockets with a total thrust of 1,764 lb Wing span 5.12 m (16 ft 9.5 in) Length 6.07 m (19 ft 10.75 in) Height 1.16 m (3 ft 9.5 in) Wing area 6.02 sq.m (64.6 sq.ft) Empty weight 440 kg (970 lb) Max¬imum take off weight 2140 kg (4,718 lb). Max level speed: 650 km/h (403 mph) at 11,485 ft Terminal diving speed 927 km/h (576 mph) Range 37 km (23 miles) Warhead: 2,646 lb / 1200kg
Yokosuka MXY7 Ohka (Baka) Model 21 Type: Single-seat suicide attack plane Powerplant: 3 x Type 4 Model 1 Mark 20 solid-fuel rockets with a total thrust of 1,764 lb
Yokosuka MXY7 Ohka (Baka) Model 22 Type: Single-seat suicide attack plane Powerplant: 1 x 551-lb.-thrust Tsu-11 turbojet, with a Hitachi 100-hp four-cylinder inline gas generator Wingspan: 13 ft. 6 7/32 in Length: 22 ft. 6 7/8 in Height: 3 ft. 9 9/32 in Wing area: 43.055 sq. ft Empty weight: 1,202 lb Loaded weight: 3,197 lb Wing loading: 74.3 lb./sq. ft Maximum powered speed: 276 mph at 13,125 ft Range: 81 statute miles Warhead: 1,323 lb
Yokosuka MXY7 Ohka (Baka) Model 43B Type: Single-seat suicide attack plane Powerplant: 1 x 1,047-lb.-thrust Ne-20 axial-flow turbojet Wingspan: 29 ft. 6 11/32 in Length: 26 ft. 9 ¼ in Height: 3 ft. 9 9/32 in Wing area: 139.930 sq. ft Empty weight: 2,535 lb Loaded weight: 5,004 lb Wing loading: 35.8 lb./sq. ft Maximum powered speed: 345 mph at 13,125 ft Range: 173 statute miles Warhead: 1,764 lb
Yokosuka MXY7 Ohka (Baka) Model 53 Type: Single-seat suicide attack plane Powerplant: 1 x 1,047-lb.-thrust Ne-20 axial-flow turbojet
The Yokosuka E14Y1 was built to a total of 126 as the Navy Type 0 Small Reconnaissance Seaplane. Used aboard ocean-going submarines of the Japanese fleet, these aircraft made some notable flights: one from the submarine 1-7 made a post-attack assessment of damage at Pearl Harbor.
On 9 September 1942, launched from the Japanese submarine I-25 under Frigate Captain Meija Tagami, Naval pilot N.Fujita used a Yokosuka E14Y1 seaplane to bomb forests in Oregan, USA. The first raid on the United States of America. On 29 September a second raid was made at the same spot, 50 miles west of Cape Blanco. This was the last raid made on the USA.
E14Y1 Engine: 1 x Hitachi Tempu-12, 255kW Max take-off weight: 1450 kg / 3197 lb Empty weight: 1119 kg / 2467 lb Wingspan: 11.0 m / 36 ft 1 in Length: 8.54 m / 28 ft 0 in Height: 3.8 m / 12 ft 6 in Wing area: 19.0 sq.m / 204.51 sq ft Max. speed: 245 km/h / 152 mph Cruise speed: 165 km/h / 103 mph Ceiling: 5420 m / 17800 ft Range: 880 km / 547 miles Crew: 2 Armament: 7.7mm machine-guns, 60kg of bombs
Influenced by flight tests with a Heinkel He 118 in 1938, the Japanese navy decided that future carrier based aircraft should be much cleaner aerodynamically. A 13 Shi (1938) specification was issued to the Yokosuka naval air arsenal for a carrier-based dive bomber of exceptionally high performance. It had to operate from small carriers and carry a 250 kg (551 lb) bombload for 800 nautical miles (1481 km) and reach 280 knots (519 km/h).
Designed as a fast carrier-based attack bomber and powered by an imported Daimler-Benz DB 600G engine, the D4Y1 was first flown in December 1941.
Achieving excellent performance despite having only a 960 hp DB 600G, the D4Y1-C reconnaissance aircraft were ordered into production at Aichi’s Nagoya plant, the first of 660 aircraft being completed in the late spring of 1942.
It was not until March 1942 that the first production D4Y1 Model 11 emerged from the Aichi factory at Nagoya (the Allies later thought this an Aichi design). Powered by the 1200 hp, Aichi AE1A Atsuta 12 inverted V 12 (licence built modified DB 601A) the aircraft had such speed and range it was ordered as the D4Y1 C reconnaissance aircraft, with rear fuselage camera(s) and underwing drop tanks, and the C model remained in use until Japan’s final surrender. Work continued to perfect the basic D4Y1 and eventually it entered service in March 1943. The first service aircraft were lost when the Soryu was sunk at Midway. The Model 21 was generally similiar. Many D4Y1s were completed as dive-bombers, and 174 Suiseis of the 1st, 2nd and 3rd Koku Sentais were embarked in nine carriers before the Battle of the Philippine Sea. However, they were intercepted by American carriers, and suffered heavy casualties without achieving any success.
Production amounted to 660 by Aichi, with the Japanese name Suisei (Comet) and the Allied code name ‘Judy’, but in the first big action at the Marianas ‘turkey shoot’ they suffered severe casualties at the hands of US Navy fighters and failed to sink any major warships. Their chief faults were complete absence of armour or self sealing tanks and the armament of two fixed 7.7 mm (0.303 in) Type 97 machine guns in the nose and a 7.92 nun (0.312 in) Type 1 aimed by the radio operator/navigator/gunner in the rear seat. Normal bombload was 310 kg (683 lb), but for short ranges 560 kg (1234 lb) could be accommodated.
Like many of the best Japanese aircraft of the Second World War, the D4Y had the misfortune to enter service just as the era of Japanese superiority was coming abruptly to an end. The fleet carriers were fairly soon all sent to the bottom of the Pacific, and most of the total of 2038 of all versions of D4Y operated from escort carriers and shore bases, often in roles quite different from those for which the type was designed. The first new sub type, other than the C, was the D4Y2 (Model 22), which had the 1400 hp Atsuta 32 engine, and the fin and rudder were modified and increased in area, and, in the main D4Y2a variant, a 13mm (0.51 in) Type 2 gun in the rear cockpit. Entering service just in time for the Leyte Gulf and Philippines battles in October 1944, the new model was coolly received, because it still had neither armour nor tank protection. Aichi built 326, plus about 100 by Dai Juichi Kaigun Kokusho (Hiro Naval Air Arsenal), but they were shot out of the sky and soon appeared as kamikaze suicide attackers, usually with an 800 kg (1764 lb) bombload, carried externally.
D4Y3
From the start the liquid cooled engine had been unpopular, owing to its difficult main¬tenance and poor reliability. The general feeling about the trim Suisei had been that there was not much wrong with it that proper protection and a radial engine would not cure, and in the winter of 1943/4 the Aichi team schemed an installation for the 14 ¬cylinder two row Mitsubishi Mk8P Kinsei 62.
The D4Y3 prototype, flown in May 1944, showed acceptable handling qualities and almost identical performance to the earlier models, with marginally lower speed but longer range and improved takeoff and climb capability. Production was authorized at once, and both Aichi and Hiro arsenal deli¬vered a total of about 350 in all. These still did not have any protection for crew or fuel, and only the later D4Y3a had a 13 mm (0.51in) rear gun. Most had provision for catapulting but as there were virtually no carriers, the majority were also equipped to have three RATO rockets clipped below the rear fuselage to assist takeoff from island airstrips.
The last sub type was the D4Y4, a pur¬pose designed kamikaze aircraft. A single-¬seater, it carried an 800 kg (1764 lb) bomb or explosive charge (made from a mine or tor¬pedo) semi externally. 296 were deli¬vered by Aichi in 1945.
The proposed D4Y5, with 1825¬hp NK9C Homare engine and proper armour and protected tanks, did not fly. The D4Y2 was later converted to a night fighter.
A total of 2,319 D4Ys was completed. Aichi handled most of the payroll and 500 were completed by Hiro Arsenal.
In the first year of the war some types were given more than one code name due to inaccurate descriptions. ‘Dot’ was assigned to a carrier dive bomber, later also assigned the name ‘Judy’. ‘Dot’ was dropped in favour of the more accepted ‘Judy’.
D4Y2 Engine: 1 x Aichi AE1P Atsuta, 1050kW Max take-off weight: 3840 kg / 8466 lb Empty weight: 2640 kg / 5820 lb Wingspan: 11.5 m / 38 ft 9 in Length: 10.2 m / 33 ft 6 in Height: 3.75 m / 12 ft 4 in Wing area: 22.8 sq.m / 245.42 sq ft Max. speed: 575 km/h / 357 mph Cruise speed: 425 km/h / 264 mph Ceiling: 10700 m / 35100 ft Range: 3600 km / 2237 miles Crew: 2 Armament: 7.92 or 13mm machine-guns Bombload: 1 x 500-kg, 2 x 30-kg
D4Y3 Engine: Mitsubishi Kinsi 62, 1560 hp Span: 11.5 m (37ft 8.75in) Length: 10.22 m (33 ft 6.5 in) Height: 10 ft 9.5 in Empty weight: 5514 lb Gross weight. 4657 kg (10267 lb) Maximum speed: 575 km/h (357 mph) at 19,360 ft Service ceilig: 34,450 ft Max range: 944 miles Armament: 1 x 7.9mm mg, 2 x 7.7mm mg Bombload: 1650 lb Crew: 2
Yokosuka’s B3Y1 Navy Type 32 carrier biplane first flew in 1932. Some 200 B4Y1 attack aircraft followed, those remaining in service Second World War known as “Jean” to the Allies. The D4Y Suisei (“Judy” two-seat carrier dive-bomber was in service by the Battle of Midway in 1942 and appeared also in D4Y2-S nightfighter and D4Y4 suicide attack variants. The P1Y1 Ginga (“Frances”) twin-engined naval attack bomber/nightfighter entered production in 1943 at Nakajima factories. Yokosuka developed also the MXY-7 Ohka (Cherry Blossom) kamikaze piloted missile-bomb, derisively dubbed Baka (“fool” in Japanese) by the U.S. Navy, and of which production by various manufacturers totalled about 800.
Roberto Bartini had designed and built the Stal-7 airliner whilst he was the chief designer at the ZOK NII GVF (Russian: Zavod Opytno Konstrooktorskoye Naoochno-Issledovatel’skiy Institoot Grazdahnskovo Vozdooshnovo Flota — “Factory for Special Construction at the Scientific Test Institute for the Civil Air Fleet”). The performance of the Stal-7 was extremely good, particularly in respect to its payload; at gross overload weight over 56% of the total weight was payload. During flight trials with maximum all-up weight the prototype crashed on take-off in early 1938, resulting in the arrest of Bartini and his imprisonment in a Siberian Gulag in February 1938. The Stal-7 lay unrepaired until Vladimir Yermolaev was appointed as chief designer at OKB-240 after Bartini’s arrest, with the task of transforming the Stal-7 design into a long-range bomber, a task made easier since Bartini had reserved space for a bomb bay in the fuselage. After repair the Stal-7 carried on with the flight-test programme, including a record-breaking non-stop flight on 28 August 1939 when it flew Moscow—Sverdlovsk—Sevastopol—Moscow; a distance of 5,086 km (3,160 mi) at an average speed of 405 km/h (252 mph).
Preliminary design of the DB-240 (Russian: dahl’niy bombardirovschik—”long-range bomber”), as the bomber version was designated, was complete by the beginning of 1939 and the construction of two prototypes began the following July. The DB-240 retained little apart from the general layout of the Stal-7 as the structure was almost completely redesigned. An all-metal mid-wing monoplane of inverted gull-wing configuration and with a twin fin-and-rudder tail unit, the Yer-2 had tail-wheel landing gear, the main units retracting into the nacelles of its two M-105 engines; accommodation was provided for a crew of four. The pilot’s cockpit was offset to port to improve his downward view and the navigator/bomb aimer sat in the extensively glazed nose with a 7.62-millimeter (0.300 in) ShKAS machine gun, the radio operator sat below and to starboard of the pilot and the dorsal gunner in a partially retractable turret with one 12.7-millimeter (0.50 in) Berezin UBT machine gun. Another ShKAS was fitted in a ventral hatch. Up to 2,000 kg (4,409 lb) of bombs could be carried in the bomb bay and two 500-kilogram (1,102 lb) bombs could be carried externally. Up to 4,600 kg (10,141 lb) of fuel could be carried. The DB-240 had been designed to use the experimental Klimov M-106 V12 engines, but the less-powerful Klimov M-105 engine had to be substituted because the M-106 was not available.
The DB-240 prototype flew for the first time on 14 May 1940 and began its State acceptance tests on 27 September 1940. The weaker engines prevented the DB-240 from reaching its designed performance. It could only attain 445 km/h (277 mph) at 4,250 m (13,944 ft) instead of the expected 500 km/h (311 mph) at 6,000 meters (19,685 ft). Its defensive armament was deemed inadequate and other problems included an excessively long take-off run and engine defects. However, these did not offset its virtues of a heavy bomb load and long-range (4,100 kilometers (2,548 mi) carrying 1,000 kg (2,205 lb) of bombs). It was ordered into production at Factory No. 18, in Voronezh, as the Yermolayev Yer-2.
A second prototype followed in September, by which time preparations for mass production at Voronezh were in hand. Manufacture began in March 1941, with approximately 50 aircraft delivered by 22 June 1941. These aircraft were about 5–8 km/h (3.1–5.0 mph) slower than the prototype and their normal weight increased 1,220 kg (2,690 lb) to 12,520 kg (27,602 lb). Production was terminated in August to allow the factory to concentrate on the higher-priority Ilyushin Il-2 ground-attack aircraft. By July 1941, 128 examples of the DB-240 had been delivered under the designation Yermolayev Yer-2
A Yer-2 was modified with experimental Mikulin AM-37 engines, a reinforced undercarriage, armored seats for the navigator and gunner, and 12.7 mm UBT machine guns in place of its original ShKAS weapons. It first flew in July 1941 and was able to reach 505 km/h (314 mph) at 6,000 m (19,685 ft), but the range was reduced to (3,500 km (2,175 mi) carrying 1,000 kg (2,205 lb) of bombs. One significant problem with this version was the excessive take-off roll which hindered operations from grass airstrips. The engine was unreliable, however, and had cooling problems that the Mikulin OKB did not have the resources to resolve so it was cancelled in October when the factory was forced to evacuate from Moscow by the German advance.
The Charomskiy M-40F Diesel engine was also evaluated in a Yer-2 in 1941. This engine, like all Diesels, offered a greatly reduced fuel consumption compared to a standard gasoline-powered engine, but at a great penalty in weight. These engines increased the gross take-off weight to 13,500 kg (29,762 lb) which required the undercarriage to be reinforced and the wing area increased to keep the same wing loading. The M-40F-powered aircraft reached a maximum speed of 430 km/h (267 mph) at 6,050 m (19,849 ft). However, the M-40 was not yet ready for service use and the project was cancelled.
The cockpit was modified to accommodate two pilots side-by-side and the wing and tailplane areas were increased. The 12.7 mm UBT machine gun in the dorsal turret was replaced by a 20-millimeter (0.79 in) ShVAK cannon and the nose and ventral ShKAS machine guns were exchanged for 12.7 mm UBT machine guns. Up to 5,460 kg (12,037 lb) of fuel could be carried. The Yer-2/ACh-30B was placed into production at Factory No. 39 in Irkutsk at the end of 1943 and the first production aircraft was submitted to its State acceptance trials the following month. Some excess aircraft were converted as Yer-2ON VIP transports.
The Yer-2 was not in squadron service when Germany invaded on 22 June 1941, but the 420th and 421st Long-Range Bomber Regiments (Russian: Dahl’niy Bombardirovchnyy Aviapolk—DBAP) were formed shortly afterwards. However neither regiment flew any operational missions until later in the summer. On the evening of 10 August Yer-2s of the 420th DBAP, accompanied by Petlyakov Pe-8s of the 432nd DBAP, attempted to bomb Berlin from Pushkino Airfield near Leningrad. The airfield was too short to accommodate a fully loaded Yer-2, but three bombers did manage to take-off regardless. Two managed to bomb Berlin, or its outskirts, but only one successfully returned; the other was shot down by ‘friendly’ Polikarpov I-16s when it reentered Soviet airspace and the third aircraft went missing. Three crews from the 420th DBAP bombed Königsberg during the nights of 28–29 August and 30 August–1 September from Ramenskoye Airport, southeast of Moscow.
Yer-2 2M-105
On 1 October 1941 sixty-three Yer-2s were in service, but only thirty-four were operational. The 420th DBAP had flown 154 sorties by the beginning of November (6 in August, 81 in September, 67 in October) and had lost thirty of its forty aircraft. Over half of these (nineteen) were due to non-combat losses. Losses were extremely high over the autumn and winter as they were inappropriately committed against German tactical front-line targets during the Battle of Moscow at low altitudes and only twelve were in service on 18 March 1942. On 4 August 1942 the 747th DBAP had only ten Yer-2s on hand and it was briefly committed during the Battle of Stalingrad. The survivors were flown, in ever dwindling numbers, until August 1943 when the last few aircraft were transferred to schools by the 2nd Guards DBAP and the 747th DBAP.
The Yer-2 was placed back into production at the end of 1943, but none of the new bombers had been issued to combat units by 1 June 1944. However forty-two were in service on 1 January 1945 and one hundred and one on 10 May 1945 after the war ended. The first combat mission undertaken by Yer-2s after they returned to production was a raid on Königsberg on 7 April 1945 by the 327th and 329th Bomber Aviation Regiments (Russian: Bombardirovchnyy Aviatsionyy Polk). It remained in service with Long-Range Aviation units until replaced by four-engined bombers like the Tupolev Tu-4 in the late 1940s.
A Yer-20N special-purpose long-range transport version, which carried 18 passengers, was developed from the bomber.
DB-240 Two prototypes of the Yer-2 series with two 1,050 hp M-105 engines.
Yer-2 Production version with two M-105 engines, 128 built.
Yer-2/AM-37 One aircraft re-engined with two prototype 1,380 hp Mikulin AM-37 engines, the fastest of all Yer-2s.
Yer-2/M-40F The first diesel-powered Yer-2, with modified wings. One converted with two 1,500 hp Charomskiy M-40F diesel engines.
Yer-2/ACh-30B Production model of the diesel-engined version. Performance was excellent despite the poor reliability and rough running of the Charomskiy ACh-30B diesel engines. Range increased 1,500 km (930 mi) from the version with M-105 engines.
Yer-2ON (Russian: Osobogo Naznachyeniya–Special Assignment) Two aircraft from the Yer-2/ACh-30B production line were modified with a 12-seat VIP cabin, military equipment removed and long-range fuel tanks in the bomb-bay. A third aircraft was converted from a Yer-2 (1941 production) and used for shuttle flights between Irkutsk and Moscow.
Yer-2N (Russian: Nositel—Carrier) One aircraft was modified as an engine test-bed for captured Argus As 014 pulse jet engines.
Yer-2/MB-100 One production aircraft used as a test-bed for the 2,200 horsepower (1,600 kW) Dobrotvorskii MB-100 engine in 1945.
Yer-4 The final iteration of the Yer-2 series was a 1941 production aircraft re-engined with ACh-30BF engines and redesignated as the Yer-4. It had a slightly larger wingspan, increased take-off weight and improved armament. The prototype was tested in December 1943, but did not enter production.
Operators:
Soviet Union
VVS (Russian: Voyenno-Vozdooshnyye Seely—Soviet Air Forces)
ADD (Russian: Aviahtsiya Dahl’nevo Deystviya—Long Range Aviation) 420th Long-Range Bomber Aviation Regiment, later the 748th Long-Range Bomber Aviation
Regiment 421st Long-Range Bomber Aviation Regiment, later the 747th Long-Range Bomber Aviation
Yer-2 Engine: 2 x M-105, 770kW Max take-off weight: 11300-13700 kg / 24912 – 30203 lb Max. speed: 445 km/h / 277 mph Cruise speed: 380 km/h / 236 mph Ceiling: 7500 m / 24600 ft Range w/max.fuel: 3000-4500 km / 1864 – 2796 miles Armament: 1 x 20mm machine-guns, 2 x 12.7mm machine-guns Bombload: 1000-5000kg Crew: 4
Yer-2/ACh-30B Engines: 2 × Charomskiy ACh-30B V12 diesel engines, 1,118 kW (1,500 hp) each Wingspan: 23 m (75 ft 5.5 in) Wing area: 79 sq.m (850 sq.ft) Length: 16.42 m (53 ft 10½ in) Height: 4.82 m (15 ft 10 in) Empty weight: 10,455 kg (23,049 lb) Gross weight: 18,580 kg (40,961 lb) Maximum speed: 420 km/h (261 mph) Range: 5,500 km (3,418 miles) Service ceiling: 7,200 m (23,620 ft) Crew: 4 Armament: 1 x 12.7 mm UBT machine-gun in nose flexible mount. 1 x 12.7 mm UBT machine-gun in ventral flexible mount. 1 x 20 mm ShVAK cannon in a TUM-5 dorsal turret. Up to 5,000 kg (11,023 lb) of bombs in the internal bomb-bay.
USSR On Stalin’s orders Vladimir Gregorovich Yermolaev began design work on a long-range bomber, the DB-240 prototype of which first flew in 1940. This twin diesel-engined low-wing monoplane was based on the design of R. L. Bartini’s Stal’ 7 and had the same distinctive inverted-gull wings. Designated Yer-2, more than 400 were built 1940-1944 and used principally as long-range night bombers. A Yer-20N special-purpose long-range transport version, which carried 18 passengers, was developed from the bomber.
The George Yates of Beaverton, Oregon, Oregon O was developed into the 1935 twin-engined Greenwood-Yates Bi-Craft (NC15546) with 50 hp engines.
Yates and partner Allan D. Greenwood (a pilot and Oregon state aircraft inspector) formed the North Pacific Aircraft Corp. to market the Bi-Craft geodetic-construction light twin design.
In 1945, an updated Oregon O parasol was built. An open cockpit, midwing monoplane Oregon O was powered by a 125 hp Martin 4-333 inverted 4-cylinder, it had wooden geodetic basket-weave construction.
All Aero 