Chikai Type 40 fighter
| Type 40 fighter | |
|---|---|
| File:Chikai Type 40 fighter short list.png Three common Type 40 variants spanning the course of the war | |
| General information | |
| Type | Fighter |
| Designer | Chikai Aviation Company |
| Status | withdrawn from service |
| History | |
| Manufactured | 1939-1945 |
| Introduction date | 1940 |
The Chikai Type 40 fighter (Menghean: 치카이 40식 전투기 / 치카이四〇式戰鬪機, Chikai sallyŏng-sik jŏntugi) was a Menghean fighter aircraft designed during the late 1930s and introduced in 1940. It was powered by the Donghae Gi-27 12-cylinder inverted-V engine, a license-produced variant of the Ostlandian DB 601, giving it a sleek appearance and very good performance for its time. With over 5,500 units produced between 1940 and 1945, the Type 40 was the most widely produced Menghean fighter of the war, and it became a lasting icon of Menghe's military effort.
When it arrived on the front lines in early 1940, the Chikai Type 40 represented a radical improvement over all Menghean fighter aircraft already in service, including the biplane Chikai Type 34 fighter and the monoplane Nakajima Ki-27 purchased from Dayashina. Allied pilots considered it a formidable opponent with versatile flight characteristics, balancing speed, maneuverability, armament, and protection. In the right hands, it could outperform contemporary Allied fighters like the P-40 Warhawk and Hawker Hurricane, and most of Menghe's highest-scoring aces scored their kills in the Type 40. As the war progressed, the Type 40 received new upgrades to its engine and armament, keeping it moderately competitive with later Allied fighters, though bombing attacks on its production facilities slowed the delivery of new airframes.
Background
From the outset of the Pan-Septentrion War, Menghe's main Army fighter was the Chikai Type 34, a sesquiplane powered by the Ostlandian KMW VI engine. At the time it entered service, the Type 34 was in keeping with contemporary global trends in military aviation, representing the final generation of biplane fighters. In early engagements over Innominada and Themiclesia, it earned a proven combat record and a generally favorable kill-to-loss ratio, even against newer opponents like the P-26 Peashooter.
By late 1937, however, the Type 34's limitations were becoming increasingly clear. The Gloster Gladiator, New Tyran's main colonial fighter, out-performed it in all areas, including pilot visibility. The Royal Air Force's Hurricanes, though a minority of its fighters in Khalistan, were even deadlier; Type 34 pilots could only win by forcing the enemy into a turn fight, where the biplane's lower wing loading and lighter weight worked to its advantage. By diving from above and then climbing away, Hurricanes and Gladiators could decimate Type 34 formations, forcing the Menghean Army to rely on its numerical advantage over Tyrannian colonial detachments. A similar situation was unfolding in Maverica and Themiclesia, where new P-36 Hawks flown by foreign volunteers appeared in 1938.
The Donghae Heavy Industries Group attempted to correct this problem by designing a domestic monoplane fighter, the WH 18, but it relied on the same KMW VI engine as the Type 34, leaving it underpowered even with weight-saving measures like partial wooden construction and fixed landing gear. Only five prototypes were built, and after their disappointing performance in testing, none of them saw combat. As an interim solution, the Imperial Menghean Army Flying Corps purchased Nakajima Ki-27 monoplane fighters from Dayashina, but these were also inferior to newer Allied aircraft in speed, armament, and pilot visibility.
A period of local Menghean naval supremacy following the naval battle at Portcullia in July 1938 allowed Menghean diplomats to contact Ostland and negotiate the shipment of three Messerschmitt Bf 109 E3s, a single Heinkel He 100 D-1, and the blueprints and documentation necessary to produce more. These were run across the ocean on a high-speed cargo ship, which managed to arrive in Sunju without incident. As Allied fleets still had a large presence near Ostland and Rajland and the Luftwaffe needed all the fighters it could get, Messerschmitt and Heinkel agreed to grant Menghe a production license in place of regular shipment, with payment postponed until after the war's end.
Development
Flight tests with the Bf 109 and He 100 revealed impressive performance and combat characteristics, but the Imperial Menghean Army was not fully satisfied with either aircraft. The Bf 109's angular fuselage imposed too much drag, they believed, and the He 100's retractable radiator was an unnecessary source of complexity. Army procurement staff were particularly dissatisfied with the Bf 109's narrow landing gear configuration, which were already causing problems for Type 34s operating from the rough and improvised airfields which had become common in the Themiclesian and Khalistani campaigns. One of the test Bf 109s crashed during a rough landing and had to be written off, and another tipped over during a sharp turn while taxiing, though it was later repaired and continued its tests. Other complaints included the sideways-opening canopy and the sub-optimal arrangement of the wing gun mounts.
While tests with the imported airframes were still underway, the Army procurement board commissioned the Donghae and Chikai aircraft companies to design their own monoplane fighters, this time using the more powerful DB 601 engine imported with the Bf 109 and He 100. Both companies took this blank slate as an opportunity to correct inherent flaws in the foreign samples while copying all successful features, though their plans ultimately evolved in different directions, with Donghae's later developing into the Donghae Type 41 fighter.
The Chikai Aviation Company accepted the commission in December 1938, combining it with their past work on a prospective DB 601-driven fighter. They copied a number of features from the Bf 109, including the layout of the removable engine panels and the pilot's oxygen system. Yet the overall design of the plane was entirely new. Chikai's engineers used their blank slate to correct a number of inherent flaws in the Bf 109, including the narrow forward landing gear, the blocky canopy, and the lack of compact ammunition boxes in the wings. The first prototype, bearing the prototype designation WH 25, made its maiden flight on August 4th, 1939.
In November, the Imperial Menghean Army held competitive performance trials of Chiaki's WH 25, Donghae's WH 24, a Bf 109, an He 100, and a captured Hawker Hurricane. Although it was unable to match the He 100's speed, the WH 25 had better maneuverability than any of the other tested fighters, and remained the second-fastest in level flight. Particularly impressed with its superiority to the Hurricane, the Army ordered it into production as the Chikai Type 40 fighter - the Menghean year 40 had started in October.
Design
<imgur thumb="yes" w="300" comment="Cockpit of the Type 40. Note the charging handle for the nose-mounted 12.5mm MG extending past the dashboard at right.">9pCH607.png</imgur> Chikai's Type 40 fighter resembled the Bf 109 in layout but was structurally unique. The wings, fuselage, canopy, and tail were smoother and more aerodynamic, and the wing area was somewhat larger. The forward landing gear used a more conventional inward-folding layout, with the legs joined to the wings rather than the wing roots. Rearward visibility was somewhat improved, though it still left much to be desired, and the canopy slid backward rather than outward, allowing the pilot to open it in flight. All aircraft carried a short-range (~50-kilometer) radio set, for the first time allowing planes within a squadron to talk to one another without the use of the hand and wing signals which had proven impossible to read during aerial combat.
Armament on the Type 40-I consisted of two 7.5mm machine guns, one in each wing, and two 12.5mm machine guns in the nose. These were slightly staggered so that their ammunition feeds could sit one in front of the other. In contrast to the Bf 109, where wing armament was added as an afterthought, on the Type 40 the wings were designed from the start to accommodate ammunition boxes and gun mountings. The original prototype actually left additional space around the wing gun mounts, anticipating a future need to modify the design to accommodate 12.5mm or 20mm weapons.
The canopy differed significantly from that on the Bf 109, with smoother glass plates around the top and sides to improve aerodynamics. The center front plate was made of bulletproof glass to protect pilots from rear gunners on enemy aircraft, and behind the pilot's seat was a 10mm steel plate offering some protection against pursuing fighters' machine guns. Unlike the Type 34 and Ki-27 before it, the Type 40 used a holographic reflector gunsight, offering improved visibility and ease of targeting. On the Type 40-III onward, this sight incorporated a gyroscopic delay mechanism which caused the targeting reticle to properly lag during high-speed turns.
Operational history
Early service
The Type 40-I made its first combat debut in Khalistan in June 1940. Tyrannian pilots initially mistook it for a license-built Bf 109, given their similar profiles when seen at a distance, and gave it the reporting code Hans. It came as a harsh surprise for Allied pilots accustomed to dealing with biplanes and Ki-27s, possessing much better speed than any previous Menghean aircraft. With a larger wing area than the Bf 109 but a nevertheless respectable power-to-mass ratio, it could out-climb, out-dive, and out-turn the Hawker Hurricane, though not by a very large margin.
Combat experience on the Hemithean mainland unfolded similarly. The new fighter could out-turn the P-40 Warhawk, which by then was becoming increasingly common in Allied air forces, and had a superior rate of climb, though the heavier P-40 could fly faster in a dive. As in Khalistan, its main advantage was initial complacency among Allied pilots who had trained and fought against biplanes and did not anticipate an opponent requiring a new set of tactics. A version of this tactical lag existed on the Menghean side as well; Type 40-Is suffered relatively high loss rates against the Maverican Fokker D.XXI, which, though much slower, had a lighter wing loading and still held the upper hand in turn fights.
Mid-war development
Once allied tactics adjusted for the new fighter's capabilities, the Type 40 lost its advantage, though it remained a parity opponent for Spitfires and P-40s throughout the war. A steady progression of new variants brought improved gun armament, with the wing-mounted machine guns progressing from single to double 7.5mm machine guns, and eventually to 20mm and 30mm cannons. When armed with bombs and rockets, the Type 40 performed well in the ground-attack role, and from its introduction onward it was used in strafing attacks on enemy airfields. Nevertheless, its cooling pipes and large radiator proved vulnerable to small-arms fire, and later variants focused more on aerial combat.
The Type 40-III, introduced in 1943, had an improved engine with a new supercharger and air intake, both of which increased performance at higher altitudes. The under-fuselage radiator was also redesigned to take advantage of the Meredith effect, with a revised intake profile and narrower exhaust duct which produced a useful if marginal amount of thrust. Further improvements to the engine and supercharger took place on the Type 40-IV. These changes, along with the addition of autocannon armament, allowed later Type 40 variants to keep pace with improving Allied fighters throughout the middle of the war.
Anti-bomber operations
<imgur thumb="yes" w="400" comment="Diagram showing performance (in kW) of Menghean V-12 engines at altitude (in meters). Gi-27 was used on the baseline Type 40-I and II, and Gi-29 was used on the Type 40-III and later variants.">VciEatp.png</imgur> Following Ostland's surrender and the steady retreat of the Menghean front lines, the Allies were able to redirect their strategic bombing efforts from Casaterra to Hemithea. Bombers operating from Maverican airbases, and later from Portcullia, began conducting long-distance raids on Menghean cities in 1944. With its more advanced single-engine interceptors still in development, the Imperial Menghean Army Flying Corps began using the Type 40 in the anti-bomber campaign.
With their improved engines and radiators, the later Type 40 variants performed adequately at high altitudes, but they were never stellar. The Type 40-III had the speed and service ceiling to engage mid-war Allied bombers such as the B-17, B-24, and Avro Lancaster, but it struggled against the new B-29, which was faster, higher-flying, and better-defended. As the front lines drew closer, the Allies were able to send escort fighters deeper over Menghean territory, presenting an additional threat.
By early 1945, the IMAFC had adopted a combined-arms strategy in which Type 40 fighters would accompany a group of dedicated interceptors toward enemy bomber formations. If hostile escorts were present, the Type 40s would break off and engage, attempting to draw them away from the bombers so that the better-armed but less maneuverable interceptors could attack in relative safety. This tactic had some successes early in the bombing campaign, especially where Allied pilots were drawn into turn fights, but it took a long time to assemble the combined fighter-interceptor mass formation, and as Allied airfield strike and air supremacy operations intensified, the massed anti-bomber attack became less viable.
Against the West Hemithean P-51D Mustang, which formed the backbone of Allied air forces over Menghe by 1945, Type 40-III, -IV, and -V lost their remaining edge in speed and climb rate. Menghean pilots reported that they could consistently overtake the Mustang in a prolonged turn fight, owing to their fighters' lower wing loading, but the Mustang's roll rate was on par with their own in short maneuvers. Mustang pilots were better able to choose the time and place of the engagement, especially as Allied numerical superiority in aircraft increased.
Post-war service
As part of Menghe's surrender, Imperial Menghean Army high command ordered the grounding of all military aircraft to await the signing of a formal armistice. Not all units obeyed this order. Several squadrons under the command of General Yang Tae-sŏng's Eighth Resistance Army remained formally operational, as the Pan-Septentrion War bled into the Menghean War of Liberation. Some of these fighters saw combat at the Battle of Hwalsu Pass in October 1946, mainly in the ground-attack role, where they surprised Tyrannian forces who had not expected enemy air support. Severe shortages of ammunition, fuel, and spare parts, as well as a renewed Tyrannian campaign of bombing Eighth Army airfields, promptly drove this small guerilla air contingent into submission, but only after it had earned fame among the Menghean independence movement.
A number of other squadrons reacted to the grounding order by flying across the East Menghe Sea to Dayashina, where they would continue fighting for a few more months before Dayashina's own surrender. In peace negotiations, the Imperial Menghean Army upper leadership claimed that these squadrons had deserted the country in defiance of orders to remain grounded, and denied any role in their relocation. Historians later uncovered a mix of circumstances around the move; the 5th Fighter Wing moved as a single unit under the orders of Captain Hwa Sang-jun, while other groups of pilots made their own pacts to depart in imitation, an act which some commanding officers deliberately ignored or tacitly encouraged. Motivations also varied, ranging from a determination to continue the anti-bomber campaign to a fear of mistreatment in captivity.
Despite growing Menghean-Dayashinese political tensions in the preceding years of the war, the Menghean squadrons in Dayashina earned the respect of their hosts for their determination to continue fighting, and were loosely integrated into Dayashina's air defense command structure. Some were transferred north to the Menghean-speaking enclave of Hanhae. As on the mainland, the later Type 40 variants were increasingly obsolete, especially as faster, higher-flying B-36 Peacemakers adopted a larger role in the strategic bombing effort. The Dayashinese military's decision to favor its own units in the allocation of scarce aviation fuel also kept many Menghean Type 40s grounded, and revived political resentment between Menghean and Dayashinese pilots.
Variants
<imgur thumb="yes" w="300" comment="Diagram showing major variants and camouflage schemes of the Chikai Type 40 fighter.">9icv0Xc.png</imgur>
Pre-production
The prototype flown in the 1939 fighter competition was designated Chikai WH 25, with WH indicating wŏnhyŏng (prototype). Six were built. Its armament consisted of four 7.5mm machine guns: two above the nose, and one in each wing. Each gun was fed from a 500-round belt.
Type 40-I
This was the designation given to the original production aircraft. It was similar to the WH 25, but had a larger under-nose intake for oil cooling. It also replaced the nose-mounted 7.5mm guns with 12.5mm Type 31 heavy machine guns (250 rounds per gun), to improve performance against aircraft incorporating armor plates. This variant accounted for all production in 1940, and was the variant Allied fighter pilots first encountered.
Type 40-II
The Type 40-II was introduced in early 1941, based on experience gained in operational service. The most visible change was the installation of one additional 7.5mm machine gun in each wing, bringing the total to four. The guns were placed side-by-side but staggered slightly to separate the ammunition feeds. A sub-variant, the Type 40-II yŏldae, added a prominent external filter over the left-side intake to prevent dust and sand from entering the engine in arid climates.
Some Type 40-II fighters were fitted with two hardpoints, one under each wing, each capable of carrying a 50kg or 100 kg bomb. These were designated Type 40-II JG or jisang gonggyŏk.
Type 40-III
The first major modification, the Type 40-III appeared in the spring of 1943. It was equipped with the Gi-29 engine, itself an improvement on the DB 601 design. This new powerplant had an output of 1,320 hp (984 kW) at sea level, and used a new supercharger for improved performance at medium altitudes. These changes necessitated a "stretching" of the nose section, and a reconfiguration of the under-nose oil cooling intake to reduce drag. The left-side air intake for the supercharger was also enlarged, and was fitted with a new dust filter design. This filter was removable, allowing ground crews to install it while operating in arid theatres and remove it to reduce drag and enhance performance elsewhere. The area behind the engine was also reconfigured to allow the installation of 20mm cannon and ammunition boxes in the future, a change which was not implemented on this variant.
As the engine was longer and heavier, it shifted the fighter's center of gravity further forward. To compensate for this, the designers extended the rear-fuselage fuel tank further aft and added a 4mm armor plate behind it. This change also compensated for the higher fuel consumption of the second-stage supercharger. All fuel tanks on the Type 40-III and its successors were self-sealing, a change which improved protection against machine-gun fire.
Other changes concerned the main armament. The wing guns were replaced with Type 40 autocannons, which were themselves copied from the MG FF cannons on the imported BF 109 Es but had been modified to accept 120-round belts. This change was intended to improve lethality against bombers and better-protected fighters. The autocannons were capable of firing mine-shell-style projectiles with a thin steel shell and a higher explosive filling, resulting in greater brisance and increased lethality on impact.
Some Type 40-IIIs were outfitted with the longer-barreled Type 42 20mm cannon, a transitional step toward the Type 40-IV. These received the designation Type 40-III GP. Initially they were used as testbeds to ensure that the Type 40's wing struts could withstand the more powerful impulse of the Type 42 autocannon's 20x100mm cartridge, but production was expanded during the transitional period and many of these fighters saw combat service.
Type 40-IV
This variant, introduced in 1944, replaced the wing-mounted Type 40 cannons with Type 42 cannons. Although both autocannons shared a 20mm caliber, the Type 42 had a longer barrel and fired a more powerful 20x100mm cartridge with greater accuracy and range. The Type 40-IV also had a smoother semi-bubble canopy, offering somewhat greater visibility. The central sliding section of the canopy bulged out slightly, a feature apparently borrowed from the Spitfire, which helped the pilot look rearward. The flat bulletproof glass panel at the front of the cockpit was retained.
In a further effort to achieve greater speeds, one Type 40-IV was built with a wing-surface cooling system, similar to that used on the imported Heinkel He 100. This prototype was designated Type 40-IV JN, with "JN" indicating jŭngbal naenggak or "evaporative cooling." By removing the radiator, the designers significantly reduced air resistance and achieved a greater top speed, but they also added additional complexity to the design and guaranteed coolant leakage if the wings were hit by machine-gun fire. It was not approved for wide-scale production.
Type 40-V
First seen in early 1945, the Type 40-V was the pinnacle of the Type 40's design process. It had a revised rear fuselage profile, with a teardrop-shaped tapering canopy rather than a straight transition from the canopy to the raised upper fuselage. This moderately reduced empty weight and dramatically improved rearward visibility. To replace the lost pilot protection, the designers also mounted a trapezoidal plate of bulletproof glass across the canopy behind the pilot's headrest. The engine was also modified with further refinements to the supercharger to improve performance at high altitudes. Even with a two-stage supercharger, these changes produced problems with overheating at lower altitudes, so a new water injection system was installed to cool the air-fuel mixture and the compression chambers in low-level flight.
Another distinct feature of the Type 40-V was its nose profile, which had a more pronounced step down near the propeller hub rather than a gradual taper on previous models. This change allowed the type to mount the longer-barreled Type 42 20mm autocannon in the nose, with the barrels extending over the engine. To increase offensive capability even further, some Type 40-Vs were built with the experimental Type 44 30mm autocannon in the wing mounts. Airframes completed in this configuration were designated Type 40-V DP (dae pokgyŏkgi, "anti-bomber"). Imperial Air Corps calculations and operational service demonstrated that this weapon could shoot down a B-17 or B-29 with only 2-3 hits to the fuel tanks or engines, as opposed to 10-15 hits for a 20mm autocannon firing thin-shelled rounds. Its main drawbacks were reduced accuracy and muzzle velocity, which forced the pilot to fly his pass close to the target aircraft before breaking off and somewhat negated the advantage of a shorter lethal burst.
These later aircraft also saw an increasing use of plywood construction. Contrary to some Allied accounts that late-war Menghean planes used plywood wings and fuselage skin, these changes were only applied to the pilot seat and instrument panel on initial Type 40-Vs, and later to the tail fin and control surfaces. The changes were intended to reduce weight and conserve aluminum, which was growing scarce at this point in the war. Aircraft built with plywood control surfaces were designated Type 40-V G, with G euphemistically indicating "lightened." There were also plans to develop a further-lightened Type 40-V G2, with thinner metal frame components, but after a prototype's tail broke off in a test flight the design team decided to retain the existing metal skeleton.
Specifications (Type 40-I)
<imgur thumb="yes" w="500">34yFV4y.png</imgur> General Characteristics
- Crew: 1 (pilot)
- Length: 8.50 meters
- Wingspan: 10.77 meters
- Height: 3.82 meters (landing gear to propeller tip)
- Wing Area: 18.52 square meters
- Empty Weight: 1,310 kilograms
- Loaded Weight: 2,784 kilograms
- Powerplant: 1x DB 601Aa V-12 engine, 864 kW (1159 hp) at takeoff
Performance
- Maximum Speed: 595 km/h
- Range: 740 kilometers
- Service Ceiling: 11,200 meters
- Rate of Climb: 15.7 meters per second
- Wing Loading: 150.49 kg/m2 (30.82 lb/ft2)
- Power-to-Mass ratio: .310 kW/kg (0.189 hp/lb)
Armament
- Guns:
- 2x forward-firing 12.5mm machine gun in nose, 250 rounds per gun
- 2x forward-firing 7.5mm machine gun in wings, 500 rounds per gun
- Bombs: hardpoints for 2x 100kg bomb (some field modifications)