Yu'an Y.15

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Yu'an Y.15J
Y.15J.jpg
Role Fighter aircraft
National origin  Kodeshia
Manufacturer Yu'an Aircraft Industrial Corporation
First flight 19 April 1944
Introduction February 1945
Retired Retired from frontline military service 1960 (Kodeshi Air Force)
Primary users Kodeshi Air Force
See operators
Produced 1944-1954
Number built 1,632
Unit cost
$54,318 in 1945 ($739,703 in 2017)

The Yu'an Y.15J (Guoyu: 玉岸.十五 陸基戰鬥機; Yù àn. Shíwǔlù jī zhàndòujī) was an Kodeshi Great Kesh War single-seat fighter aircraft built by the Yu'an Aircraft Industrial Corporation. Along with the Dongfang Df.30J was built around the powerful Huangdi K-6B engine. It was built in the Chenghai factory in Yu'an and is widely regarded as one of the best Kodeshi piston engined aircraft of the Great Kesh War, it proved to be extremely effective, destroying a large number of Selengerian forces in the close air support role. During the early stages of the conflict before becoming a specialised fighter-bomber. Despite the advent of jet fighters, the Y.15J remained in effective as a close air support aircraft throughout the conflict and even acquitted itself fighting effectively even against the Ge 210 jet fighter. Although the it retired from frontline duties in favour of jet-propelled aircraft it continued in limited service post war as a counter insurgency design into the early 1960s.

Development and design

The program for the Y.15 began out of a development of the earlier Dongfang Df.26 fighter was seen to be outdated against the latest international competition. Yu'an Aircraft Industrial Corporation working with Huangdi’s K6 inverted V12 inline piston engine sought to maintain the sleek streamlined designs that had worked so well. Instead of shifting to the radial engine developments as the Dongfang Df.26 was redeveloped for naval operations and the Yu’an Y.16 carrier bomber. For the high-performance fighter and interceptor role the inline piston engine was the best option. The basic design was dominated by the massive Huangdi K6 engine with the pilot seated far behind it and the main guns mounted centrally and above the engine, with a low mounted wing. Building on the success of earlier streamlined designs, the Y.15Y-0 prototype was build and first flown on 19 of April 1944. It proved very successful with its mixed wood and steel construction and managed to reach speeds of over 500 km/h and was quickly approved for production. The first series production was begun in the outskirts of Yangyu in Yucheng Province. But production was slow due to initial teething problems and unfamiliarity with the new construction techniques.

Operational history

Profile of the Yu'an Y.15 depicting a Great Kesh War Kodeshi livery of the 43rd Reconnaissance Squadron stationed on the Alvak front.

The first serial production of the Yu’an Y.15 was the Y.15J-I "Jia" model entered service with the Imperial Kodeshi Air Force in February of 1945 but issues with early production models delayed major roll out and further refinements were made to improve production on these early models. Once the initial series production had entered service and several squadrons were up to speed improved production Y.15J-I "Yi" models would enter service featuring refinements in production quality. But due to the ongoing pace of aircraft development by mid-1946 further improvements were being made with the Y.15J-1 "Bing" and later models that increased the output with a newer engine and new cooling systems and radiators adding an additional 223 kW of power for only an extra 181 kg of weight to the design. At this stage a carrier-based Y.15J-1 was proposed and pitted against the Dongfang design that would become the Df.31 but the Y.15 was rejected. By 1948 the main production version had become the Y.15J-1G with improved K6-05 engine and numerous other improvements. A number of earlier Y.15J-1 "Bing"s were converted to the new Y.15J-II standard. This would be the main type to be in service during the brief conflict with the Haqiqatan Confederation of Central Kesh in 1949 where the type would saw its first combat debut. Although the outcome of this war was victory for Kodeshia it was generally seen as disappointing humiliation as they failed to retake the territory it sought it generally became a stalemate with little change in territory at great cost. But the Y.15 proved an effective platform against the almost non existence air force of the Haqiqatan Confederation of Central Kesh. During this war, the HCCK forces captured some Y.15s and some were known to be put back into flying condition and flight tested.

The end of the war led to a shift with the proposed development of a high-altitude interceptor cancelled as early jet designs were more promising as seen during the Aki-Chez conflict. It quickly became clear that current generation of Y.15 fighters would not maintain their effectiveness without improvements. The Y.15J-III "Jia" was developed with vastly improved aerodynamics and propeller and more fuel-efficient engines improving the range of the type. This variant would see plenty of action on the eastern and northern fronts once the Great Kesh War broke out in 1955. Additional changes made on the later variants saw the addition of new 20 mm canon. As the type was slowly withdraw from frontline fighter duties the Y.15J-III "Bing" models were developed for ground attack with wing mounted 20 mm cannons. Minors changes were implemented on the Y.15J-III "Ji" series being based on the earlier Y.15J-III "Wu" series, but changes improved the production and survivability of the aircraft. Largely the Y.15J-III "Ji" models very similar besides minor changes between them with production starting around mid-1952. During 1953 the new variants saw refinements to the engine cowling and streamlining to accommodate the changes to the engine cooling and weapons systems. Notably the Y.15J-III "Wu" which was based on the Y.15J-III "Ding" from 1954 this model featured new engine and larger supercharger for high-altitude performance needed on the northern front.

Despite appearance of jet designs in this era these models would see extensive action against Alvan fighters and bombers and later some Selengerian bombers. Several specialised high and medium altitude fighters were developed with the Y.15J-III "Geng" for the northern front and the Y.15J-III "Xin" for the eastern front. The late production Y.15J-III "Ji" which would become standard model on both fronts outside of specialised squadrons. A reconnaissance Y.15J-III "Gui" model was also developed and used extensively on both fronts for aero-reconnaissance but as the war continued this type saw heavy causalities as ground air defences improved and reconnaissance shifted to high altitude jets. But some Gui's would continue to serve as artillery spotters. A few specialised models were developed with the Y.15YZ-IV "Bing" night fighter version with searchlight and radio compass although this was quickly superseded by the larger Dongfang Df.29 night fighter. An interesting composite aircraft was developed with the Y.15J-IV "Qinzi" which saw a Y.15 mounted above a modified Df-29 which was converted into a large explosive carrying drone. This so-called parent and child combine was very effective but quite dangerous as take-off operations were extremely tricky and required a combat air patrol to allow the type to take off safely.

The definitive model was the Y.15J-IV "Gai" embodying the experience gained over the course of the war, with a new K6C-11 engine and 30mm cannon replacing the earlier 20mm canon. Tested in 1953 showed that it only comparable to Kodeshi fighter jet prototypes in terms of single engine performance with only the Dongfang Df.29 offering similar straight-line performance but the single engine Y.15 was far more agile that either the Df.29 or early jets. Issues with overheating required fixing with larger radiators and further aerodynamic improvements. Production began by the end of 1953 but full rate production would not come until 1954 and it was built in huge numbers but within a few years most would be relegated into ground attack and support roles as jet fighters would become dominate. But in less important theatres of war the type would continue to serve the fighter role and after the end of the Great Kesh War in 1959.

On 11 August 1955, Lieutenant Wei Jian of the 15th Squadron, flying an improved mark four Y.15J-IV "Gai" from Anyu Airfield, was credited with shooting down an Alvak Ge 210, this engagement marked Wei as one of the few pilots to achieve a confirmed jet kill while flying a piston-engine aircraft during the conflict.

The frozen nature of the end of the conflict and failure of the 1960 peace conference led the Guoist regime to delay full demobilisation and so vast numbers of Y.15s were kept in service until 1960s when the regime fell, and with the Xuanyi Restoration in 1964 Empress Xuanyi was restored to the throne. The type would see renewed use by rebels in the northern insurgency operations as an anti-insurgency aircraft in the remote jungles of the north west of Kodeshia. It would finally be retired in 1960 from service although a small number of models were protected in museums and some flying models still exist.

Variants

Y.15Y-0
Y = 原型; Yuánxíng ("Prototype"), 零; Líng ("Zero")
The first prototype of the Y.15J, built with mixed steel tube and wood construction. 3 built.
Y.15J-I "Jia" (Mark 1a)
J = 歼击机; Jiānjíjī ("Fighter"), Jia = 原型; jiǎ ("A")
first in serial production single seat fighters. Production of the initial 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.
Y.15J-I "Yi" (Mark 1b)
J = 歼击机; Jiānjíjī ("Fighter"), Yi = 乙; yǐ ("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.
Y.15J-1 "Bing" (Mark 1c)
J = 歼击机; Jiānjíjī ("Fighter"), Bing = 丙; bǐng ("C")
New radiators, cooling system and further performance improvements along with larger and longer Huangdi K-6C-01 engine was used, yielding an extra 223 kW (300 PS) at the cost of an additional 181 kg (400 lb).
Y.15J-1
J = 艦載型; Jiànzài xíng ("Shipborne type")
Proposed Carrier variant.
Y.15J-II (Mark II)
J = 歼击机; Jiānjíjī ("Fighter")
The Mark II became the main production version of this variant of aircraft. Along with the new Huangdi 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 Mark Ia and Mark Ic variants which were converted to Mark II standard by Yu'an Aircraft Industrial Corporation. Production started in early 1948.
Y.15LJ-II "Jia" (Mark 2a)
L = 攔截機; Lánjié jī ("Interceptor"),J = 歼击机; Jiānjíjī ("Fighter"), Jia = 原型; jiǎ ("A")
Proposed High altitude interceptor variant.
Y.15J-III "Jia" (Mark 3a)
J = 歼击机; Jiānjíjī ("Fighter"), Jia = 原型; jiǎ ("A")
Compared to the earlier Mark 1, the Mark 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 Mark 3-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 Mark 3-series offered a much increased maximum range.
Y.15J-III "Yi" (Mark 3b)
J = 歼击机; Jiānjíjī ("Fighter"), Jia = 乙; yǐ ("B")
From the Mark 3b onward, the new 20 mm Xiabei D-20 with 200 rounds was used. The first Mark 3bs reached units in July 1949. Production lasted exactly a year between June 1949 and May 1952, many of all Mark 3b-series variants produced.
Y.15DJ-III "Bing" (Mark 3c)
D = 對地攻; Duì dì gōng ("Ground attack"),J = 歼击机; Jiānjíjī ("Fighter"), Bing = 丙; bǐng ("C")
The Mark 3c model was capable of mounting two 20 mm Xiabei D-20 cannons under the wing in faired gondolas with 135 rpg. These were designated Mark 3c and 240 of them were produced in the first quarter of 1952. These were intended as ground support variants.
Y.15J-III "Ding" (Mark 3d)
J = 歼击机; Jiānjíjī ("Fighter"), Ding = 丁; dīng ("D")
The Mark 3d series was developed from the largely identical Mark 3c 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.
Y.15J-III "Wu" (Mark 3e)
J = 歼击机; Jiānjíjī ("Fighter"), Wu = 戊; wù ("E")
During the course of 1953, a number of improvements were gradually introduced. The Mark 3e 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.
Y.15J-III "Ji" (Mark 3f)
J = 歼击机; Jiānjíjī ("Fighter"), Ji= 己; jǐ ("F")
Subsequent Mark 3f variants were essentially modified versions of the basic Mark 3e airframe. Early in 1954, new engines with larger superchargers for improved high-altitude performance (Huangdi K-6C-13), or with water injection for improved low/medium-altitude performance (Huangdi K-6C-12), or these two features combined (Huangdi K-6C-09) were introduced into the Mark 3f. Maximum speed of the Mark 3f 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.
Y.15J-III "Geng" (Mark 3g)
J = 歼击机; Jiānjíjī ("Fighter"), Geng= 庚; gēng ("G")
High-altitude fighter with Huangdi K-6C-13 engine, MW 50 boost.
Y.15J-III "Xin" (Mark 3h)
J = 歼击机; Jiānjíjī ("Fighter"), Xin= 辛; xīn ("H")
Low/medium-altitude performance fighter with Huangdi K-6C-09 engine.
Y.15J-III "Ren" (Mark 3i)
J = 歼击机; Jiānjíjī ("Fighter"), Ren= 壬; rén ("I")
The standardized late-production Mark 3d series; Huangdi K-6C-10 engine, MW 50 boost.
Y.15ZZ-III "Gui" (Mark 3j)
ZZ = 照片侦察; Zhàopiàn zhēnchá ("Photo-reconnaissance"), Gui= 癸; guǐ ("J")
Photo-reconnaissance variant.
Y.15J-IV "Jia" (Mark 4a)
J = 歼击机; Jiānjíjī ("Fighter"), Jia = 原型; jiǎ ("A")
The Mark 4a-series was the last of the series to see operational duty and the last in the Y.15 evolutionary line.
Y.15JH-IV "Yi" (Mark 4b)
J = 歼击机; Jiānjíjī ("Fighter"), H = 轰炸机; Hōngzhàjī ("Bomber"), Jia = 乙; yǐ ("B")
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.
Y.15YZ-IV "Bing" (Mark 4c)
YZ = 夜間戰鬥機; Yèjiān zhàndòujī ("Night Fighter"), Bing = 丙; bǐng ("C")
Single-seat night fighter aircraft, equipped with a searchlight and an radio compass.
Y.15J-IV "Gai" (Mark 4 improved)
J = 歼击机; Jiānjíjī ("Fighter"),Gai = 改; Gǎi ("improved")
The definitive variant, the Gai, embodied the experience gained in the development the aircraft over its operational career. Equipped with the new Huangdi 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.
Y.15J-IV "Fuzi" (Mark 4 Parent and Child)
Qinzi = 親子; Qīnzǐ ("parent and child")
Used as composite aircraft, comprised a small piloted Y.15J control aircraft mounted above a large explosives-carrying drone. Known as the 親子 ("Parent and Child"). The drone was the Df.29WJK-5 which was an unmanned variant with the crew sections replaced by a large explosive nose. Operating like a very early cruise missile or glide bomb, the Df.29WJK-5 would be released near the target and guided in by the Y.15J-IV pilot.

Operators

 Kodeshia
 Alva

Specifications

Yu'an Y.15 3 View.png

Data from Kodeshi Aircraft 1940–1970 fact sheet[1]

General characteristics

  • Crew: one, pilot
  • Length: 9.13 m (29 ft 11 in)
  • Wingspan: 10 m (32 ft 10 in)
  • Height: 3.89 m (12 ft 9 in)
  • Wing area: 16.5 2 (178 sq ft2)
  • Empty weight: 2,619 kg (5,774 lb)
  • Max takeoff weight: 3,570 kg (7,871 lb)
  • Powerplant:Huangdi K-6C-11 V-12 inverted liquid-cooled piston engine, 1,253 kW (1,680 hp)

Performance

Armament

  • Guns: 1 × 30 mm Xiabei D-30 gun , 65 rounds; 2 × 12.7 mm synchronized Xiabei JQ-12.7T machine guns with 300 rounds
  • Bombs:4 × 50 kg bombs; 4 × 100 kg bombs; 8 × unguided rockets

References

  1. " Yu'an Y.15J Fighter Aircraft." Institute of Aviation History and Technology, June 2010. Retrieved: 2 June 2017.