Yu'an Y.15

The Yu'an Y.15J was an Kodeshian Great Kesh War single-seat built by the Yu'an Aircraft Industrial Corporation. Along with the Dongfang Df.30J was built around the powerful Koudezhou K-6B engine. It was built in the Chenghai factory in Yu'an and is widely regarded as one of the best Kodeshian piston engined aircraft of the Great Kesh War, it proved to be extremely effective, destroying a large number of Crown bombers. During the early stages of the conflict before becoming a specialised fighter-bomber. Despite the advent of jet fighters, the Y.15J remained in service with the air force until the early 1960s.

Development and design
WIP

Operational history
WIP

Variants

 * Yu'an Y.15J-0A - The first prototype of the Y.15J, built with mixed steel tube and wood construction. 3 built.
 * Yu'an Y.15J-0B/C/D - first in serial production single seat fighters. Production of the intial variants progressed slowly and there were teething problems with the aircraft due to an untrained workforce with no aircraft manufacturing experience, unfamiliarity with the delta wood structure, incomplete technical drawings, a lack of jigs, and some factories hadn't fully converted from producing previous models.
 * Yu'an Y.15J-1A/B - After the delivery of the first series of production models, a further change was worked into the production lines to improve and streamline the process.
 * Yu'an Y.15J-1C/D/E - New radiators, cooling system and further performance improvements along with larger and longer Koudezhou K-6C-01 engine was used, yielding an extra 223 kW (300 PS) at the cost of an additional 181 kg (400 lb).
 * Yu'an Y.15A-1F - Proposed Carrier variant.
 * Yu'an Y.15J-1G - The 1G became the main production version of the 1 series of aircraft. Along with the new Koudezhou K-6C-05 was fitted as standard. As production progressed changes were incorporated, some of which became standard on all later Y.15s. Production started with several 1C/D/Es which were converted to 1G by Yu'an Aircraft Industrial Corporation. Production started in early 1948.
 * Yu'an Y.15J-2A - Proposed High altitude interceptor variant.
 * Yu'an Y.15J-3A - Compared to the earlier Y.15J-1, the Y.15J-3 was much improved aerodynamically.The engine cowling was redesigned to be smoother and more rounded. The enlarged propeller spinner, now blended smoothly into the new engine cowling. Underneath the cowling was a revised, more streamlined oil cooler radiator and fairing. A new ejector exhaust arrangement was incorporated, and on later aircraft a metal shield was fitted over the left hand banks to deflect exhaust fumes away from the supercharger air-intake. The supercharger air-intake was, from the 3B-series onwards, a rounded, "elbow"-shaped design that protruded further out into the airstream. A new three-blade, light-alloy propeller unit with a reduced diameter of 3 m (9 ft 8.5 in) was used. Propeller pitch was changed electrically, and was regulated by a constant-speed unit, though a manual override was still provided. Thanks to the improved aerodynamics, more fuel-efficient engines the new 3B-series offered a much increased maximum range.
 * Yu'an Y.15J-3B/C/D - From the 3B onward, the new 20 mm Xiabei D-20 with 200 rounds was used. The first 3Bs reached frontline units in July 1949. Production lasted exactly a year between June 1949 and May 1952, with 1,000s of all 3-series variants produced.
 * Yu'an Y.15J-3E/F - The 3E and 3F models were capable of mounting two 20 mm Xiabei D-20 cannons under the wing in faired gondolas with 135 rpg. These were designated 3E/F and 240 of them were produced in the first quarter of 1952. These were intended as ground support variants.
 * Yu'an Y.15J-5A/B/C - 5-series was developed from the largely identical 3-series airframe, although there were detail differences. Modifications included a reinforced wing structure, an internal bullet-proof windscreen, the use of heavier, welded framing for the cockpit transparencies, and additional light-alloy armour for the fuel tank. new windscreen, reshaped radiator, and reshaped oil cooler.
 * Yu'an Y.15J-5D/E/F - During the course of 1953, a number of improvements were gradually introduced. The 5Ds, 5Es and 5Fs saw a refinement of the engine cowlings. The formerly separate, added-on Beule blisters which had earlier covered the spent shell-casing chutes of the synchronized fuselage-mount Xiabei JQ-12.7T were completely integrated into the upper cowling panels, vastly improving their streamlining and allowing them to be lengthened and enlarged to cover both the weapons and the engine bearers.
 * Yu'an Y.15J-5G - Subsequent 5-series variants were essentially modified versions of the basic 5F airframe. Early in 1954, new engines with larger superchargers for improved high-altitude performance (Koudezhou K-6C-13), or with water injection for improved low/medium-altitude performance (Koudezhou K-6C-12), or these two features combined (Koudezhou K-6C-09) were introduced into the Y.15J-5G. Maximum speed of the 5G/5H was 530 km/h (320 mph) at sea level, 640 km/h (391 mph) at 6,600 m (21,650 ft)-rated altitude at 1.42 atm boost.
 * Yu'an Y.15J-5H - High-altitude fighter with Koudezhou K-6C-13 engine, MW 50 boost.
 * Yu'an Y.15J-5I - low/medium-altitude performance fighter with Koudezhou K-6C-09 engine.
 * Yu'an Y.15J-5J/K - The standardized late-production 5-series; Koudezhou K-6C-10 engine, MW 50 boost)
 * Yu'an Y.15J-5R - Reconnaissance fighter variant.
 * Yu'an Y.15J-6A - The 6-series was the last of the series to see operational duty and the last in the Y.15 evolutionary line.
 * Yu'an Y.15J-6B - Fighter-bomber variant with four vertical tube bomb bays aft of the cockpit with capacity for up to 4 × 100 kg (220 lb) bombs or 4 cassettes with 32 × 1.5 kg (3.3 lb) bomblets each, although normally only 200 kg (440 lb) of weapons were carried in the front bomb bays. Poor handling with a full bomb and fuel load and lack of special aiming equipment limited combat usefulness.
 * Yu'an Y.15J-6C - Single-seat night fighter aircraft, equipped with a searchlight and an radio compass.
 * Yu'an Y.15J-6D - The definitive variant, the Y.15J-6D, embodied the experience gained in the development the aircraft over the war. Equipped with the new Koudezhou K-6C-11 engine engine with 1,253 kW (1,680 hp), and the 30 mm Xiabei D-30 gun with 65 rounds replacing the D-20. Early test flights in 1953 indicated that the only comparable Kodeshi fighter were jet prototypes which was more difficult to fly and less agile due to higher weight. The prototype's top speed of over 700 km/h (435 mph) at 6,000 m (19,685 ft) was among the fastest for any piston engine production fighter aircraft in the world at the time. But early problems with overheating still needed to be fixed. These were addressed by enlarging the radiators and production aircraft had further improved aerodynamics. The engine radiators were built into the wing centre section with intakes in the wing roots while the oil cooler was located under the engine. This variant was built in huge numbers with many being relegated into ground attack and support roles later in the conflict has jet aircraft became dominate.
 * Yu'an Y.15J-6E - Used as composite aircraft, comprised a small piloted Y.15J-6E control aircraft mounted above a large explosives-carrying drone. Known as the 父子 ("Father and son").

Operators

 * Kodeshia
 * Kodeshi Air Force (1945-1960)
 * Alvakalia
 * Alvak Luftwaffe (captured) (1950-1957)