Tuesday 24 August 2021

Ki-46 Gone German by Dizzyfugu

What if the Mitsubishi Ki-46 had been license-built by Germany…?
Several German aircraft, including the Junkers Ju 87 or the Messerschmitt Bf 109E and Me 210, had been evaluated by Japan – and there had apparently interest in Japanese aircraft by the RLM, too. In literature the Mitsubishi Ki-46 frequently pops up as a hot candidate for potential license production in Germany, but the circumstances remain obscure, and in real life this never happened. However, this historic development offers a nice plain canvas for a “what-if” model of a Germanized Ki-46, and my interpretation became the fictional Gotha Go 146 reconnaissance aircraft, and a respective model of it: a 1:72 scale Gotha Go 146 B-1; aircraft ‘P3+KN’ of II(F)/FAG 104 (5. Staffel, 2. Gruppe, Fernaufklärergruppe 104), Deutsche Luftwaffe; Biblis (Hessia, near Mannheim), late 1944.

Some background
The Gotha 146 was a fast reconnaissance aircraft that was used throughout WWII by the German Luftwaffe, and one of the results of a mutual technology exchange program with Japan. The Go 146 was actually a license-built, but modified variant of the excellent Mitsubishi Ki-46. The latter type's career started in late 1937, when the Imperial Japanese Army Air Force issued a specification to Mitsubishi for a long-range strategic reconnaissance aircraft to replace the Mitsubishi Ki-15. The specification demanded an endurance of six hours and sufficient speed to evade interception by any fighter in existence or development at that time, but otherwise did not constrain the design by a team led by Tomio Kubo. 
The resulting design was a twin-engine, low-winged monoplane with a retractable tailwheel undercarriage. It had a small diameter oval fuselage with the pilot and observer situated in individual cockpits separated by a large fuel tank. The engines, two Mitsubishi Ha-26 radials, were housed in close-fitting cowlings to reduce drag and improve pilot view. 
The first prototype aircraft, flew in November 1939 from the Mitsubishi factory at Kakamigahara, Gifu. Tests showed that the Ki-46 was underpowered and slower than required, only reaching 540 km/h (336 mph) rather than the specified 600 km/h (373 mph), but, otherwise, the aircraft tests were successful. As the type was still faster than the Army's latest fighter, the Nakajima Ki-43, as well as the Navy's new A6M2, an initial production batch was ordered. To solve the performance problems, Mitsubishi switched to Ha-102 engines, which were Ha-26s fitted with a two-stage supercharger, while increasing fuel capacity and reducing empty weight. This became the Ki-46-II, and this type was also demonstrated to German officials who immediately noticed its potential.
Knowing that the German Luftwaffe lacked this specialized, fast type of aircraft (German reconnaissance aircraft of that time were either slow artillery observation types, or variants of bombers or heavy fighters), the RLM immediately asked for a batch of airframe kits to adapt it to the European theatre and test its capabilities. Seven engine-less airframe kits were delivered to Germany in early 1940. In the meantime, with the help of blueprints and other documentations, an alternative engine installation had been devised: the “Germanized” aircraft was to be powered by liquid-cooled DB 601 engines, which delivered more power than the Ha-102 and offered improved aerodynamics, despite the necessity to add radiators under the outer wings. Many stock parts from the contemporary Messerschmitt Bf 110 heavy fighter were incorporated, so that the development time was very short, and the commonality of mechanical parts eased logistics and maintenance. 
In May 1940 the first batch of the Gotha 146 A-0 pre-production aircraft (which had officially been described as a further development of a four seat, twin-engine transport aircraft from the 1930s to cloud its origins and mission) was ready. They were immediately transferred to the Western Front for field tests, and the specialized Go 146 became quickly popular among its crews. It was fast, agile and easy to fly – almost on par with state-of-the-art fighters like the Bf 109. During the test phase in summer 1940 the Go 146 proved to be slightly faster than its Japanese Ki-46 ancestor, and with a top speed of more than 375 mph (600 km/h) it was hard to intercept by any British or French fighter of the time. The results were so convincing that the type was ordered into serial production, and from October 1940 on the Go 146 A-1 was produced in limited numbers at the Gothaer Waggonfabrik in Thuringia. Even though production only ran at small scale, it was continuous, and the Go 146 was steadily developed further, including the change of the nose section that came with the Ki-46-III, stronger engines and an improved defensive armament. 
This evolution led to the Go 146 B, which had the traditional stepped windshield replaced with a smooth, curved, glazed panel extended over the pilot's seat. This not only provided a more aerodynamic nose profile, the modified nose section also offered room for an extra fuel tank. The space between the two crewmen, connected with a crawl tunnel, held another fuel tank, the radio equipment (a Sprechfunkgerät FuG 16 ZY and a FuG 25a „Erstling“ IFF beacon), as well as a ventral compartment for up to three cameras with several windows. Different combinations of Rb (“Reihenbildner” = serial picture device) 20/30, 50/30 and 75/30 camera devices could be mounted, for a wide range of mission profiles.
On the Go 146 B, power came from a pair of new Daimler-Benz DB 603A liquid-cooled piston engines, which offered 1,290 kW (1,750 hp) each for take-off. Since the engine mounts had to be re-designed for the different powerplants (the Go 146 A had used adapters to attach its shorter DB 601s to the original Ha-102 radials’ hardpoints), German engineers used the opportunity to redesign the complete engine nacelles. As a result, their diameter and “wet” surface was reduced, so much that the landing gear had to be modified, too. It now rotated 90° upon retraction, so that the main wheels were lying in shallow wells within the wing structure. Beyond better aerodynamics, structural measures all over the airframe saved almost 250 kg (550 lb). Instead of the Go 146 A’s single 7.92 mm (.312 in) MG 17 machine gun in the observer's cabin, facing rearwards, the defensive armament was improved and consisted of a pair of 13 mm (0.51 in) MG 131 machine guns, firing rearward from FDSL 131/1B remotely-operated barbettes, one per side. The guns were electrically fired, and an electrical contact breaker prevented the gunner from shooting off the aircraft’s tailplane. When not in use, the guns would return to a neutral position that would allow to fire directly backwards with both guns.
Furthermore, plumbed hardpoints were added to the inner wings, just inside of the engines. These could carry a 300 l drop tank each for an extended range and loiter time. Single bombs of up to 250 kg or racks with four 50 kg bombs each were theoretically possible too, but the aircraft lacked any bomb aiming support. Crew protection was slightly improved, too, but the airframe was overall kept as light as possible. Despite these efforts, however, MTOW rose to 6,500 kg (14,317 lb), but this was still relatively light in comparison with the similar contemporary Me 410 multi-purpose aircraft, which weighed more than 9 tons and was powered by similar engines. Consequently, and thanks to its clean lines, the G 146 B had a top speed of almost 700 km/h (434 mph) at ideal altitude and the aircraft retained its excellent handling, even though its structure was rather fragile and could not take much stress and punishment.

Two versions of the Go 146 B were produced, steadily but only at a low rate because the aircraft received, due to its highly specialized role and limited offensive capabilities, only a low priority. The B-1 was the main variant and kept the A version’s standard wing, a total of 54 were produced between 1943 and 1945. Additionally, the B-2 was produced between late 1943 and early 1944 as a dedicated high altitude photo reconnaissance aircraft. This sub-variant had an extended wingspan of 16.00 m (52 ft 5 in) instead of the standard 14.70 m (48 ft 2¾ in) and an improved oxygen system, even though the cabin was not pressurized. Its maximum service ceiling was almost 12.000 m (39.305 ft), with a maximum speed of 415 mph (668 km/h), a cruise speed of 250 mph (400 km/h) and a range of 3,200 km (1,987 nmi). Only twelve of these machines were produced and put into service, primarily for flights over Southern Great Britain. When the Arado Ar 234 became available from September 1944 on, though, this new, jet-powered type immediately replaced the Go 146 B-2 because it offered even better performance. Therefore, the B-3, a planned version with a fully pressurized cabin and an even bigger wingspan of 19.00 m, never left the drawing board.
Furthermore, the RLM had idea to convert the fast Go 146 into a fighter and even a night fighter in mid-1944 as the “C” series. But these plans were not executed because the light airframe could hardly be adapted to heavy weapons or equipment like a radar set, and it was unsuited for vigorous dogfighting. The type’s poor climbing rate made it ineffective as an interceptor, too. There were, nevertheless, tests with at least one Go 146 B-1 that carried four Werfer-Granate 21 rocket launchers under the outer wings, as a fast bomber interceptor esp. against the high-flying B-29, which was expected to appear over continental Europe soon. But this kind of weaponry never reached frontline units and the Go 146 was never operated as a fighter of any kind.
There were, however, other uses: in 1944 the Go 146 was enlisted as a fast liaison aircraft for the RLM (Ministry of Aviation) in Berlin. Stripped of any armament and cameras and outfitted with two passenger seats in the rear cabin, at least one Go 146 B (with the confirmed registration “ST+ZA”, others in similar configuration may have existed, too) was operated by the RLM’s Zentralabteilung (central command) from Tempelhof airfield for top brass officials between Luftwaffe locations on German terrain. ST+ZA’s fate after January 1945 is uncertain, though.

Gotha Go 146 B-1 specifications:
Crew: two (pilot and observer/tail gunner)
Length: 11.00 m (36 ft 1 in)
Wingspan: 14.70 m (48 ft 2¾ in)
Height: 3.88 m (12 ft 8¾ in)
Wing area: 32.0 m² (344 ft²)
Empty weight: 3,830 kg (8,436 lb)
Loaded weight: 5,661 kg (12,480 lb)
Max. takeoff weight: 6,500 kg (14,317 lb)

2× Daimler-Benz DB 603A V-12 inverted liquid-cooled piston engines, rated at:
- 1,290 kW (1,750 hp) each for take-off
- 1,360 kW (1,850 PS) at 2,100 m (6,890 ft)
- 1,195 kW (1,625 PS) at 5,700 m (18,700 ft)
- 1,162 kW (1580 PS) combat power at 2500 rpm at sea level

Maximum speed: 695 km/h (377 knots, 430 mph) at 5,800 m (19,000 ft)
Cruise speed: 450 km/h (245 knots, 280 mph)
Range: 2,800 km (1,522 nmi, 1,740 mi) with internal fuel
Service ceiling: 11,250 m (36,850 ft)
Wing loading: 157.8 kg/m² (32.3 lb/ft²)
Climb rate: 14.7 m/sec (2,900 feet per minute)
Climb to 8,000 m (26,250 ft): 15 min 20 sec

2× 13 mm (0.51 in) defensive MG 131 machine guns with 500 RPG, each firing rearward from FDSL 131/1B remote-operated turret, one per side
2× underwing hardpoints under the inner wings for 250 kg (550 lb) each, typically occupied by 300 l drop tanks

The kit, its assembly and paint scheme
This is a déjà vu build: I already did a “Germanized” Ki-46 in 2015, an Airfix Ki-46-II outfitted with DB 601s from a Bf 110 as a pre-series Gotha Go 146 A-0. However, as I built this modified Dinah back then I already felt that the concept had more potential, and the streamlined Ki-46-III just lent itself for an updated, later version.
This variant was based on the LS Models (ARII boxing) Ki-46-III kit from 1975. It was basically taken OOB, but, naturally, with some mods: inline engines and parts of their wing fairings were transplanted from a Bilek Me 210, together with the underwing radiators. This switch was insofar easy because the LS Models Ki-46 kit has separate parts for the engines and their fairings which also contain the main landing gear wells. The main wheels were replaced with slightly smaller and narrower ones from the scrap box.
Inside, I implanted a dashboard for the pilot and the rear cabin seat was reversed and moved further forward. A scratched targeting scope/weapon control column for the FDSL 131 installation was added. The wacky OOB figures were replaced with better Matchbox pilots. Due to the heavily framed canopies, little of the interior can be seen, though.
The gun barbettes were scratched from WWII bombs as fairings and leftover landing gear struts as gun barrels. The barbettes look somewhat superficial on the slender Dinah, but they are a nice, typically German detail, über-complicated for this type of fast aircraft that probably would have more benefited from leaving them away altogether. The 300 l drop tanks came from Hobby Boss Bf 109s, outfitted with four small, scratched pylons each.
The paint scheme evolved gradually and was inspired by real German late WWII aircraft. The basis became an overall coat of RLM 76 (Tamiya XF-23, Light Blue), with blotches of RLM 77 “Hellgrau” added to the flanks. I used XF-19 (Sky Grey) as a low contrast option (the real RLM 77 was almost white) and extended the mottles under the fuselage and the engine nacelles, for a semi-wraparound scheme.
The upper surfaces were painted with cloudy RLM 02 and 75 (Tamiya XF-22 and XF-XX as proxies) over the uniform RLM 76 base, and to further lighten everything up and break up the aircraft’s outlines, I added a meander pattern with RLM 77 (again XF-19).
Markings are intentionally minimal. Balkenkreuz markings only consisting of outlines were used for a low-visibility look. The model/aircraft belongs to a fictional unit, its code “P3” in front of the fuselage Balkenkreuze has no real-world reference and was done in small black 2mm letters, a typical late WWII measure. A fictional unit badge, depicting a running greyhound, was added under the cockpit, it belongs to a German tank unit (taken from a Hasegawa 1:72 Panzer V Panther sheet).
The “KN” part of the code, including the red “Ks” on the nose, came from an Airfix Ju 87 B sheet. As an aircraft belonging to the 5th squadron within the unit’s 2nd group, the 4th letter in the code became “N”, while the 3rd letter “K” denotes the individual aircraft. The color code associated with any 5th Luftwaffe squadron was red, incorporated on the aircraft as a thin red outline around the individual aircraft letter. Since this aircraft would operate over the Western front from German home ground, no further ID/theatre markings like fuselage or wing bands or wingtips in yellow or white etc. were added. After some exhaust and oil stains with graphite and Tamiya “Smoke”, a coat of acrylic matt varnish finally sealed the model and a wire antenna, made from heated sprue material, was added.