Donghae Type 45 heavy fighter

Type 45 heavy fighter
File:Donghae Type 45 main.png
Comparison of the Type 40 and Type 45 fighters
Role	Interceptor
National origin	Greater Menghean Empire
Designer	Donghae Heavy Industries Group
First flight	October 11th, 1944
Introduction	1945
Status	withdrawn from service
Primary user	Imperial Menghean Army Flying Corps
Produced	1945
Number built	435

The Donghae Type 45 heavy fighter (Menghean: 동해 45식 중 전투기 / 東海四五式重戰鬪機, Donghae Sal-o sik jung jŏntugi) is a type of interceptor aircraft designed in the Greater Menghean Empire during the later years of the Pan-Septentrion War. It was powered by the heavy Donghae Gi-28, a water-cooled X-block 24-cylinder engine capable of generating 1600 kW of power at an altitude of 6000 meters. It was also fitted with a supercharger, turbocharger, and nitrous oxide injection system, giving it very good performance at high altitudes where other fighters and interceptors struggled.

Many historians regard the Type 45 as the best medium-range interceptor produced by Menghe during the war. It was a potent threat to Columbian B-29s and Tyrannian Victory Bombers, able to maintain high speed and energy at their cruising altitudes. The plane's complex powerplant, however, made it expensive to build and difficult to fly, and the power settings required sensitive input from the pilot to avoid stalls and fires at low altitude. Late-war Allied bombing campaigns hindered efforts to expand production, and overall only a few hundred Type 45s were built, but collectively they scored more four-engine bomber kills than any other Menghean aircraft type.

Development

The Type 45 originated with a mid-1943 design competition, and was the first of many aircraft drawn up to counter the threat of Allied strategic bombing. Although Menghe itself had not yet become a bombing target at this time, news was steadily tricking in about the presence of massive Columbian and Tyrannian bomber formations over Ostland, and their ability to reduce entire cities to ash. With Ostland crumbling and Menghean forces in retreat across the Hemithean theatre, the political leadership directly intervened in the Imperial Army Air Corps to demand a new interceptor design.

By this time, Menghe already had twin-engine heavy fighters for reconnaissance, interception, and ground attack, but their larger head-on cross sections increased drag and made them a bigger target for enemy defensive gunners. Most had been designed to counter small flights of tactical bombers, rather than large combat box formations containing hundreds of well-armed B-17s. While the IMAAC continued work on twin-engine interceptors, it ultimately saw them as too vulnerable to defensive gunners and escort fighters, and focused its core effort on a fast single-engine interceptor which could make high-speed passes through bomber formations and outrun escort fighters.

WH-112

The first such prototype, WH-112, was designed by the Chikai Aviation Company, better known for its Type 40 and Type 34 light fighter designs. As the Donghae Gi-28 engine was still under development and considered immature, Chikai stacked two Gi-29 inline engines in a tandem arrangement, one in front of the pilot and one behind him. The crankshaft from the rear engine ran under the pilot's feet and through the center of the forward crankshaft, driving the forward unit in a contra-rotating propeller arrangement. The forward engine drove the rear unit.

During development, the Army leadership had high hopes for the aircraft, and advised Donghae Heavy Industries - the main competitor - to slow down its own design work and concentrate on a twin-engine fighter to complement the new design. Unfortunately, when the WH-112 prototype began flight testing in 1944, its performance turned out to be worse than the Army had anticipated. While the ambitious design requirement had called for a top speed of over 700 kilometers per hour, the WH-112 only achieved 660. Its rate of climb was also underwhelming, as was its performance at high altitude. The power advantages of the tandem-engine design were largely negated by the added mass, which also created an unfamiliar weight distribution that led to the fatal crash of one test aircraft in a spin.

Perhaps more importantly, the WH-112 was also very expensive to manufacture. Chikai had initially opted to use the Gi-29 engine in order to maintain parts commonality with the Type 40-III fighter, but this also meant that the two planes would have to compete for engine production; the Gi-29 was the main bottleneck in Type 40 production. And by design, the WH-112 required twice as many Gi-27 engines than the Type 40-III, meaning that unless Gi-29 production were expanded, each one built would take two Type 40s off the assembly line. The contra-rotating propeller assembly also required more gearing equipment and ball-bearing surfaces than a conventional propeller, adding complexity to the manufacturing process.

WH-144 and 145

After the loss of the first WH 112 prototype, Donghae Heavy Industries decided to enter the design competition as well, building a single-engine interceptor around its Gi-28. This effort was intended to address two problems at once, securing a lucrative production contract and saving the still-troubled Gi-28 from cancellation. Their base prototype, WH 144, was a thoroughly conventional design resembling a scaled-up Chikai Type 40 fighter. Its most distinctive feature was the presence of two rows of exhaust pipes from the engine, reflecting the Gi-28's X-block layout. In addition to serving as an interceptor proposal, the WH 144 also became a valuable flying testbed for the Gi-28, allowing the designers to identify and address some of its remaining flaws.

While the WH 144 was still in development, Menghe encountered a stroke of luck. Soviet forces advancing in Casaterra had captured the blueprints to the Ostlandian FW 190 C V-18 high-altitude fighter, including detailed diagrams of its turbocharger assembly. Through a combination of espionage and diplomatic maneuvering, Menghean intelligence agents arranged for a copy of the plans to be shipped to the FSR's ally Polvokia, where they were then smuggled across the border into Menghe. The fighter's blueprints proved to be incomplete, but the documentation on the turbocharger was complete enough for Menghe to rush it directly into production.

The fourth WH 144 prototype was built with an early-production turbocharger slung underneath the fuselage in what resembled a large radiator assembly. As the rest of the fuselage remained in place from before the conversion, the exhaust piping ran on the outside of the aircraft, and the air piping back to the engine required that the central fuel tank be split in two. The converted prototype was designated WH 145. While heavier and a bit more ungainly, it offered better performance at high altitudes, where the B-29 superfortress was rumored to operate. As a result of Allied misinformation efforts, Menghean military planners had overestimated the B-29's planned cruising altitude, and demanded that the new interceptor be able to comfortably engage bombers at 12,000 meters.

WH-147 and 148

Even before the WH-145 made its first flight, the Army's procurement team was already concerned about its layout. The large belly-mounted intercooler-turbocharger created excess drag, and it all but ensured that the expensive turbocharger would be destroyed if the landing gear failed and the pilot had to attempt a belly landing. It also left the turbocharger somewhat more exposed to enemy fire from the rear. In response to these concerns, Donghae Heavy Industries developed the WH-147, which shifted the turbocharger further up into the rear fuselage itself and relocated the turbocharger intakes to either side. The air piping remained exposed, as its revision would require a thorough redesign of the frame and skin of the forward fuselage, and the manufacturer was on an urgent schedule.

This redesign produced two prototypes: WH-148, in which the single engine was geared to a contra-rotating propeller, and WH-147, which used a conventional single propeller. In theory, the WH-148 had greater speed, as it could press each propeller to a higher rotational velocity. Yet its gearing system also added weight and complexity to the design, and with Allied bombing already underway, the Imperial Menghean Army Air Corps was desperate to streamline production. As such, the WH-147 was selected as the production version of the new aircraft, which would bear the designation Donghae Type 45 Heavy Fighter.

Design

Powerplant

<imgur thumb="yes" w="400" comment="Diagram showing performance (in kW) of Menghean inline engines at altitude (in meters). Gi-28, used in the Type 45, held onto its high performance at high altitude but was artificially limited below 6000 meters.">VciEatp.png</imgur> The Type 45 heavy fighter's main strength was its powerplant. The engine consisted of a Donghae Gi-28 24-cylinder X-block engine, the result of five years of development. At an altitude of 6,000 meters, this could produce an output of 1,590 kilowatts (2,132 horsepower). Behind the engine was a supercharger with three compression settings, for use in low, medium, and high altitudes. Further back, behind the cockpit, was a turbocharger assembly to further boost engine output at high altitudes. As the turbocharger was added to the WH-144 prototype without a full redesign of the fuselage, the air channel from the engine exhaust to the intercooler ran along the outside of the airframe, giving the Type 45 a distinctive set of metal "pipes" along either side. The airflow from the turbocharger back to the engine was piped through the lower fuselage, between the lower fuel tanks.

Between the cockpit and the turbocharger was a tank of nitrous oxide, which the pilot could inject into the engine cylinders at high altitude to increase oxygen richness. This feature was copied from Ostlandian blueprints smuggled to Menghe in 1944. Due to the maturity of its prewar industry and the effects of Allied bombing, N₂O production never reached the IMAAC's needs, and pilots were instructed to engage N₂O injection only when absolutely necessary to evade pursuing fighters or catch up with high-altitude bombers. The Type 45 also had a separate injection system to cool the cylinders and fuel mixture at low altitudes; originally this was intended to use an MW 50 methyl-water mixture, but due to similar industrial constraints, many aircaft were flown with pure water injection. The tank's proximity to the engine was intended to provide adequate heat to prevent the water from icing up.

A consequence of this powerplant configuration was added weight and, in the case of the exhaust piping, added drag. This resulted in poor handling characteristics, especially at low altitudes. To reduce the risk of failure in automation, the propeller blade angle, fuel-air mixture, chemical injection systems, supercharger stage, exhaust feed, and surplus exhaust vent angle were all controlled by switches in the cockpit, meaning that the pilot had to manually fine-tune all of them during ascent and descent. Using the wrong settings in oxygen-rich altitudes could result in rapid overheating and engine fires, and even during takeoff the engine could not be run at full power.

In response to this complexity, the Imperial Menghean Army Air Corps required longer training periods for Type 45 pilots, and where possible brought in pilots with extensive prior flight experience. Even here, in-plane familiarization took a long time, and the IMAAC was constantly at pains to balance shortages of skilled personnel with the need to minimize non-combat airframe losses. A positive side effect of this higher training requirement is that Type 45 pilots were generally more skilled than other late-war Menghean pilots, making them more adept at downing bombers and evading pursuing aircraft.

Armament

The main armament of the basic Type 45-I fighter consisted of four Type 42 autocannons firing the Menghean 20x100mm cartridge. These were typically equipped with "mine shell" ammunition designed to inflict maximum damage on lightly armored bombers through percussive power. Wartime calculations by the IMAAC determined that 10-20 hits with this ammunition were necessary to shoot down or disable a four-engine bomber, depending on where they hit. Each gun had a rate of fire of roughly 700 rounds per minute, for a combined fire rate of 2800 rounds per minute. The relatively high muzzle velocity of the long-barreled Type 42 cannon made for a relatively accurate barrage, and the stability of the heavy, fast-moving airframe somewhat compensated for the high recoil.

During the spring and summer of 1945, there were a number of experiments with improved armament on the Type 45. Type 45-II airframes were equipped with four Type 44 30mm autocannons, which Army planners calculated could bring down a bomber in 3 to 4 hits when using mine shell ammunition. In operational testing, fighters in this configuration withstood the high recoil surprisingly well, but the Type 44 cannon's lower muzzle velocity and the increased vibrations on the airframe made for greatly reduced accuracy, forcing pilots to wait until they were 200 meters or less from the bomber before opening fire. As a compromise arrangement, a few airframes were equipped with two 20mm and two 30mm cannons: pilots were instructed to use the former in the initial approach to the target, and switch to the latter at the end of the pass if they had failed to score a critical hit.

As in Ostland, Type 45 fighters were also equipped with a variety of supplementary armament options as an experimental measure to improve single-pass lethality against bombers. One popular option was the installation of six 50mm rockets under each wing; using a switch on the control stick, the pilot could fire all rockets in a single slightly staggered burst, a shotgun-style approach designed to down a bomber if even one rocket hit. Aircraft refitted in this way were given the designation suffix HJ for hwajŏn, "rocket."

Cockpit

One of the drawbacks of the Type 45 was its canopy, which made extensive use of flat panels and bracing at a time when bubble canopies were becoming common on fighter aircraft. There was also a recessed glass panel extending back behind each side of the pilot's head, but in general rearward visibility was quite poor. In part, this reflected the age of the original design and the designers' focus on interception rather than air supremacy. To prevent the glass from fogging up at high altitudes, all panels were made from twin-layered glass with a 5mm space in between; some sources report that the flat-panel layout was retained in order to streamline manufacturing of the double-skinned canopy, as the individual panes could be made in separate facilities without the complexity of a precisely molded twin-layer bubble canopy.

The cockpit itself was relatively spacious by Menghean standards. In part, this reflected the larger size of the fighter, but it also reflected the wider array of switches, dials, and other controls needed to manage the complex powerplant. Pilots with prior experience in the Type 40 reported that the Type 45 was more comfortable to fly, especially on long-term patrol missions.

Protection

Despite the requirement to minimize weight, the designers added relatively generous armor protection to the Type 45 in order to reduce losses. An 8mm armor plate behind the cockpit protected the pilot from pursuing fighters' machine-guns, and the placement of the radiator and intercooler offered an additional buffer against fire from the rear. An additional 10mm plate behind the pilot's head and upper back covered areas above the rear machinery when viewed rear-on. The fuel tanks, which were located in the wings and under the fuselage, were all self-sealing.

Additional armor plates covered the front of the engine and the space between the top of the engine block and the cockpit. These plates were 15 millimeters thick, and were intended to protect the engine and pilot from bombers' defensive machine guns. The center-front panel of the canopy was also made from bulletproof glass. At moderate ranges, and with assistance from other panels and structural supports in front, these plates could stop the .50 caliber ball ammunition used by Columbian defensive gunners.

The radiator and turbocharger, however, remained vulnerable. Located just below the engine, the radiator could easily suffer damage from bombers' defensive gunners, and once it started leaking the pilot would have to land quickly in order to prevent the sensitive engine from overheating during the descent. The turbocharger was also easily damaged by machine-gun or cannon fire from the rear.

Operational service

Production

The first Type 45 heavy fighters were delivered to the Army in March 1945, after a rushed development process in which three separate prototypes were developed more or less in tandem. By this time, Allied forces had crossed over onto Menghean territory at several locations, but they still had a long distance to advance before reaching the coastal cities. This left relatively generous time for Menghean planners to organize the production and deployment of the new interceptor.

To make maximum use of strategic depth, the Type 45's main assembly line was established at Jang'an, in the central-eastern province of Goyang. When factory construction was underway in the summer of 1944, this city was still outside the reach of Allied bombers, and it was far enough inland that naval strike aircraft would have to fly over 250 kilometers of well-defended Menghean territory in order to reach it, and only after their carrier had passed into the East Menghe Sea.

Jang'an's location in a mountain valley also allowed industrial planners to move many industrial facilities into manually excavated bunkers or natural caves, where they were protected from high-altitude level bombing and low-altitude firebombing. The production lines for the engine, armament, turbocharger, and other internal systems were all expanded to underground facilities, though final assembly of fighters was conducted in a large warehouse nearby.

Jang'an was hit by Allied bombers several times in the summer of 1945, but the Type 45's production facilities remained mostly intact. An air raid on the night of July 24-25 hit the assembly hall and destroyed several in-progress airframes, but operations were quickly resumed in a new facility further outside the city, with more operations moved underground. After a few more failed attempts, a formation of Tyrannian Victory Bombers led a targeted attack against the engine production facilities, using 10,000-kilogram Grand Slam bombs to collapse the main underground caves and bunkers housing factory equipment. Production slowed dramatically after this point, though this had more to do with a shortage of raw materials, an urgent priority placed on small-arms production, and the Army's new focus on dispersed manufacturing facilities, which stalled efforts to salvage the remaining engine assembly equipment.

Anti-bomber operations

Despite its optimistic designation of "heavy fighter," the Type 45 was better thought of as a dedicated interceptor with minimal effectiveness in the dogfighting role. Its high wing loading and large size gave it poor maneuverability, and even P-38 pilots reported that they could out-turn it under favorable conditions. Like twin-engine interceptors, the Type 45 had to rely on late-war Type 40 fighter models to draw away enemy escorts, an approach which grew ineffective once Allied pilots changed their tactics to prioritize the interceptors.

At altitues above 6000 meters, however, the Type 45 was an outstanding anti-bomber platform. With its supercharger, turbocharger, and nitrous oxide injection system all active, it thrived in the oxygen-poor conditions at high altitude, where drag on the ungainly airframe was also reduced. Unlike the Type 40 and Menghe's twin-engine interceptors, which had to operate at reduced speeds and climb rates on high-altitude interception missions, the Type 45 could comfortably climb above bomber formations and dive through them at high speeds before climbing again for a second pass. Its higher approach speed and generous use of forward armor made it a challenging target for defensive gunners and fighter pilots alike. In this regard, its poor maneuverability was an easily managed issue; standard operating procedure if tailed was to nose into a gentle dive, optimize the fuel mixture, and open the throttle in the hopes of outrunning the pursuer.

The airframe's own capabilities are somewhat hard to sift out, as the IMAAC exclusively assigned experienced pilots to Type 45 interceptor formations - though not fighter aces, who were retained in more maneuverable aircraft. As a result, by the late war there was a significant skill gap between Type 45 pilots and pilots of other Menghean aircraft. This practice of reserving experienced pilots for the ungainly Type 45 was partly intended to maximize the number of hits scored per defensive sortie, but it was also a response to the engine's sensitivity and complex controls, which could result in non-combat airframe loss if mismanaged by a rookie pilot.

Even when flown correctly, however, the Type 45 had very poor maneuverability at low altitudes. It required a very delicate climb procedure in the initial period after takeoff, and a long, steady approach prior to landing. As Allied fighters armed with drop tanks reached further and further into Menghean territory, this provided them with an opportunity to attack the heavy interceptors when they were most vulnerable, as any evasive maneuvers or sudden speed changes by the target could result in a stall or crash. In response, the IMAAC assigned special squadrons of conventional Type 40 or Ki-84 fighters to defend airbases where interceptors were stationed. These squadrons would sortie to patrol airspace around the airfield and its approaches while Type 45s or other heavy aircraft were taking off or landing, and if necessary would accompany the heavier aircraft during their ascent or descent.

Postwar evaluation

After Menghe's surrender, the Allies took control of all surviving Donghae Type 45 heavy fighters. Most were sold for scrap, but at least a dozen were retained for testing and evaluation by Allied pilots. Initial flights confirmed the Type 45's good performance at high altitude, and its generally sub-par handling characteristics when climbing. One test pilot, Oliver Campbell, compared it favorably to the Focke-Wulf Ta 152 prototype which he had flown after Ostland's surrender, noting that while it was less elegant in the air its turbocharger and large engine made it an ideal interceptor.

For a time, there was some interest in Maverica and Polvokia in developing a similar aircraft for use as an interceptor, with an eye to the high-altitude B-36 Peacemaker unveiled by the OSAAF in the closing months of the war against Dayashina. In the end, however, pure jet propulsion emerged as a favorable alternative to piston engines on fighter aircraft, and the Donghae Type 45 remained the last of its kind.

On December 14th, 1945, a test pilot by the name of Willy Hayes took to the air in a Type 45 with the goal of testing its maximum performance at various altitudes. During an initial low-level flight at 1,000 meters, the fighter's engine abruptly caught fire, sending it spiraling to the ground; Hayes did not manage to bail out and was killed on impact. Analysis of the wreckage revealed that the turbocharger and nitrous oxide injection system were active, despite stern warnings from collaborating Menghean ground crew to never activate them below 6,000 meters; the engine appeared to have experienced strong internal detonation due to excessive manifold pressure.

While the ultimate cause of the accident was pilot error, evaluation teams attributed it to poor-quality engine construction. Allied military leaders suspended all future test flights of the Type 45, including subsequent flights by museums or civilian collectors, to avoid further accidents. The Type 45 thus gained a somewhat unfair reputation for poor safety, though in the 1990s with the opening of new archives a new debate broke out around its safety when flown in accordance with Menghean technical instructions.

Variants

Type 45-I

Standard production variant armed with four 20mm Type 42 autocannons, one in each wing.

Type 45-I HJ

Field modification of the Type 45 with ten air-to-air rockets mounted under each wing. These were intended to be fired in a single burst while approaching a bomber.

Type 45-I R

Rare field modification with R-10 air search radar, based on captured schematics for the Ostlandian Neptun system. Rows of vertical antennae protruded from the wings, upper nose, and rear fuselage. The Type 45-I R was apparently intended to work as the leader of an interceptor formation during nighttime operations, directing non-radar-equipped aircraft toward a bomber formation.

Type 45-II

Improved variant with two 20mm and two 30mm autocannons, used mainly for evaluation. Fewer than 20 built.

Type 45-III

Design for a mixed-propulsion Type 45 fighter with a rocket engine mounted in the rear fuselage and protruding through a modified tail assembly, to increase climbing speed when intercepting bombers nearby. It is unknown if any airframes were converted to this configuration for testing before production ended.

Survivors

Despite the widely-enforced post-war prohibition on flying the plane, the Type 45 became an attractive item for Allied museums, air forces, and private collectors due to its unusual role and its impressive size. Nine complete examples remain in existence in aviation museums around Septentrion.

Menghe

• 115-Ho: On static display at the National Aviation Museum in Donggyŏng. The Menghean Army Aviation Branch painstakingly restored it to flyable condition, but ultimately opted for a one-off reproduction for use in airshows. Purchased from a Columbian collector in 1993.
• 241-Ho: Currently on static display at the Museum for the Anti-Bomber Campaign in Jang'an. It is painted in the colors of Menghean ace Baek Sŭng-su, who scored fourteen bomber kills in his Type 45 while operating out of Jang'an, but the airframe itself belonged to a different squadron. Purchased from New Tyran in 1997.

New Tyran

• 336-Ho: A rare Type 45-I R on static display at the Royal Air Force Museum in Lyncaster.

Organized States

• 151-Ho: On static display at the National Air and Space Museum outside Fairford.
• 397-Ho: On static outdoor display at the National Air Force Museum in Lexington.
• 205-Ho: A privately-owned and carefully maintained Type 45-I in Sacramento, 205-Ho was one of the few surviving Type 45s to be kept in flyable condition.

Ostland

• 397-Ho: On static display at the Foreign War Museum in Krossa.

Rajland

• 304-Ho: On static display at the Pan-Septentrion War Museum in Metsälinna.
• 97-Ho: On static outdoor display at the Northern War College in Alalinna.

In popular culture

Within Menghe, the Donghae Type 45 heavy fighter became an iconic symbol of the anti-bomber campaign in the late-war period. It featured prominently in wartime posters and newsreels, accompanied by exaggerated claims about its performance and kill numbers. Amidst the ever-increasing threat from Allied bombers, the Type 45 was especially valued in the public's eyes as one of the few aircraft able to effectively intercept B-29s and Victory Bombers on their high-altitude daylight raids.

Even after the war's end, this impression remained strong in Menghean art and culture, with propaganda created during the Menghean War of Liberation and under the Democratic People's Republic of Menghe periodically featuring the Type 45 as a symbol of resistance to Allied dominance. After the Decembrist Revolution, the private entertainment industry picked up on this theme, and the heavy fighter plays a central role in a number of Menghean war films, video games, and animated series produced from the 1990s onward, including Ha Jŏng-hyŏn's award-winning animated movie Blue Sky. Its newfound reputation has given rise to a number of popular rumors and misconceptions about its performance, as well as claims among Menghean nationalists that it was the best fighter of the Pan-Septentrion War.

There is a monument to the Donghae Type 45 in the city of Jang'an, the city where the heavy fighter's factory was located. The monument itself consists of an enormous 2:1 scale bronze sculpture of a Type 45 fighter elevated on a pedestal inscribed with relief images of pilots and ground crew, as well as a depiction of the bombing of Jang'an.

Specifications (Type 45-I)

<imgur thumb="yes" w="650">deCtB0t.png</imgur> General Characteristics

• Crew: 1 (pilot)
• Length: 11.82 meters
• Wingspan: 15.36 meters
• Height: 3.43 meters (landing gear to propeller tip)
• Wing Area: 28.10 square meters
• Empty Weight: 1,310 kilograms
• Loaded Weight: 5,224 kilograms
• Powerplant: 1x Donghae Gi-28 X-24 engine, 1590 kW (2132 hp) at 6,000 m

Performance

• Maximum Speed: 734 km/h
• Range: 1,800 kilometers
• Service Ceiling: 16,500 meters
• Rate of Climb: 16.4 meters per second
• Wing Loading: 185.9 kg/m2 (38.08 lb/ft2)
• Power-to-Mass ratio: .304 kW/kg (0.185 hp/lb)

Armament

• Guns: 4x forward-firing 20mm Type 42 cannon, 2 per wing
• Rockets: 20x air-to-air rocket (refitted variants)

See also

• Chikai Type 40 fighter