Yakovlev Yak-9

Wingspan	9.77 meters	32.05 feet
Wing area	17.15 sq_meters	184.6 sq_feet
Length	8.55 meters	28 feet
Height	2.96 meters	9.71 feet
Empty weight	2,716 kilograms	5,988 pounds
Max loaded weight	3,395 kilograms	7,485 pounds
Maximum speed	675 KPH 420 MPH	365 KT
Service ceiling	11,900 meters	39,000 feet
Maximum range	1,200 kilometers 745 miles	650 NMI
Engine	1,650-hp Klimov VK-107A	V-12 piston engine

The history:

* The lessons learned in the Yak-1, Yak-3, and Yak-7 were finally put to use in the most potent, and most heavily produced, of the Yak prop fighter family, the "Yak-9". The Yak-9 was conceived as a natural progression from late model Yak-7 fighters. In the late spring of 1942, the increased availability of aviation metals led to the development of a reconnaissance variant of the Yak-7 with a new wing, featuring metal H-section spars with Bakelite-impregnated wood skinning. The new wing had shorter span but the same wing area. The metal spars permitted an increase in fuel capacity, with eight tanks in the wings along with the single fuselage tank, and this variant was designated the "Yak-7D", with "D" standing for "Dal'ny (Long Range)".

Since the Yak-7D seemed promising, Yakovlev then ordered the development of a comparable fighter variant, the "Yak-7DI" (where "DI" stood for "Dal'ny Istrebitel"). This was based on the Yak-7B with the new Yak-7D wing, though with only four fuel tanks; the right UB 12.7 millimeter machine gun removed to reduce weight; an M-105PF engine; and a new all-round vision canopy.

Trials of the Yak-7DI were completed in the late summer of 1942, and the type was put into production as the "Yak-9", with the number of wing tanks reduced to two to cut weight. The new Yak-9 variant reached full production in late 1942 and early 1943. By December 1942, early production Yak-9s were in combat, participating in the great winter counteroffensive at Stalingrad.

* The first refinement of the Yak-9 was the "Yak-9T", where "T" stood for "Tyazhelowooruzheny (Heavily Armed)", fitted with an NS-37 37 millimeter cannon firing through the propeller spinner instead of the ShVAK 20 millimeter cannon. The variant went through evaluation in early 1943 and was in field service by the spring of that year. It proved very popular, with 2,748 built.

To accommodate the cannon, the cockpit was moved 40 centimeters (1.3 feet) towards the rear. While some sources claim that the Yak-9T was designed as a close-support aircraft, it seems more plausible that the fit of the NS-37 cannon was mainly to correct the inadequate firepower that had dogged the Yak-series fighters, and the Yak-9T was primarily used for air combat. The USSR had a better machine for close support, the heavily armored Ilyushin Il-2 Shturmovik.

A long-range "Yak-9D" variant was introduced at roughly the same time, and featured four wing tanks, giving the machine a range of 900 kilometers (560 miles). The VVS had acquired a need for a longer-range fighters as the Red Army was now on the advance, and it was not always possible to have forward airfields behind the lines. Over 3,000 were built. The additional wing tanks led to a reduction in performance, and so in early 1944 a number of aerodynamic improvements suggested by TsAGI were incorporated into Yak-9D production to compensate.

The "Yak-9M" was as a modest change to the Yak-9D, with the cockpit moved back to improve production compatibility with the Yak-9T. This was actually an improvement from the pilot's point of view as well, since moving the cockpit back did not reduce the pilot's view, while it helped reduce the degree of noseheaviness that the Yak-9 had inherited from the Yak-7. The Yak-9M was also fitted with a jettisonable cockpit canopy, an engine dust filter, and other minor refinements. The variant went into production in the spring of 1944, and over 4,200 would be built.

* Considerable effort was made to reduce production defects in the Yak-9M. The managers responsible had been personally and angrily reprimanded to their faces by Stalin himself when they informed him of problems with the delamination of the wing skinning of the Yak-9: "Oh, but do you know that only the most perfidious enemy could do such a thing?! Producing aircraft at the plant that proved unfit for service at the Front! The enemy could not damage us so cruelly! He could invent nothing worse! This is work for Hitler!"

Stalin did not make empty threats, and he rarely made a threat twice. Defects were fixed with a literally round-the-clock effort, and then Yakovlev and production engineers went on to add improvements. The result was the "Yak-9U", where "U" stood for "Uluchshenny / Improved". The Yak-9U was difficult to tell from the Yak-9M from the outside, but it incorporated a wide range of small changes to improve performance and survivability.

The Yak-9U was initially fitted with the Klimov M-107 engine, but problems with the engine led to the loss of the prototype in late February 1943. As a result, the Yak-9U retained the M-105PF engine. It also featured two UB 12.7 millimeter guns, as well as the ShVAK 20 millimeter cannon. The Yak-9U was regarded as equivalent in performance and handling to its American counterpart, the P-51D Mustang.

Over 3,900 Yak-9Us were built, the majority of them before the end of the war. Over 280 similar "Yak-9UTs" were built as well, the only real difference being that the design permitted the installation of a heavier cannon on the production line, a concept derived from the experimental "Yak-9TK" discussed below.

The last version of the Yak piston fighters was the "Yak-9P", which was introduced into service in 1946. The Yak-9P featured all metal construction, except for the earliest production, which retained wooden elements in the fuselage. It had four wing fuel tanks and various niceties such as a radio compass; an "identification friend or foe (IFF)" unit; a gun camera; and "glow in the dark" cockpit indicators.

About 800 Yak-9Ps were built. The Yak-9P was supplied to many Soviet satellite air forces in the early postwar period, including North Korea. During the early parts of the Korean War, North Korean Yak-9Ps came head-to-head with American F-51D Mustangs and F-82G Twin Mustangs. The Yak-9P seems to have come off the worse in these encounters, though it seems more because of limited North Korean pilot training rather than any inferiority of the aircraft. The US captured and evaluated a Yak-9P, and pilot reports indicated that it was an extremely capable aircraft, though its manufacturing and finish quality were rough by Western standards.
Apparently a different Yak-9P variant had been built earlier in World War II, featuring armament of twin 20 millimeter cannon, but it never got beyond the prototype stage, and the designation was recycled later for a more successful version.

An experimental "Yak-9TK" variant, where "TK" stood for "Tyazhelowooruzheny Krupnokaliberny (Heavily Armed Large Caliber)", was tested in the fall of 1943. This aircraft was designed to permit the mount of a ShVAK 20 millimeter cannon; a VYa 23 millimeter cannon; an NS-37 37 millimeter cannon; or an NS-45 45 millimeter cannon firing through the prop spinner. Use of the heavy NS-37 or NS-45 cannon proved a bit troublesome, and the designers went back to the drawing board.

One of the consequences of this reconsideration was development of the "Yak-9K", which had a dedicated fit of the NS-45 cannon with a long and distinctive muzzle brake. A batch of about 50 of these fighters was built in the first half of 1944, and were put through tests and operational evaluation. The cannon was devastating in both air combat and close support, but it proved unreliable, and its recoil shock was too much for the airframe, cracking fuel and coolant lines. The Yak-9K was not put into production.

The "Yak-9B", where "B" stood for "Bombardirovschik (Fighter-Bomber)", was an interesting attack aircraft that first flew in early 1944. This machine stored four 100 kilogram (220 pound) FAB 100 bombs or four clusters of two kilogram (4.4 pound) PTAB hollow-charge anti-armor bomblets, stored near-vertically in the fuselage behind the pilot's seat in a 2x2 arrangement.
The Yak-9B was put into limited production and combat evaluation. It was used as a precision-strike weapon to attack heavily-defended targets, but did not prove successful enough to be put into wide-scale production. Loading the bombs was a nuisance for armorers; the machine was so heavily laden as to be a danger to get off the ground; and the pilot had no bombsight. The VVS report back to the factory concluded: "Pilots did not want to fly the aircraft. The Chief Designer must redesign the aeroplane." That was effectively the end of the matter.
The "Yak-9DD" was a very long range variant, with all eight wing tanks, a radio compass, and a long-range US-built SCR-174N radio. Armament was reduced to the ShVAK 20 millimeter cannon. It was built in limited numbers. Pilots were not fond of it since it was overweight, calling it the "flying cistern". A group of these were flown from the Ukraine to Italy to provide support for Tito's forces in Yugoslavia, operating against the Germans.

The "Yak-9R" was a reconnaissance variant, where "R" naturally stood for "Razvedchik (Reconnaissance)", and featured cameras fitted in the fuselage behind the cockpit. Some were built as field conversions of the Yak-9 or Yak-9D, but a small batch were also produced at the factory for evaluation. The evaluation showed that the Petlyakov Pe-2 was the better reconnaissance platform.

A small number of "Yak-9PD" high-altitude interceptors were built in 1943 with the M-105PD engine, and used to defend Moscow against Luftwaffe Junkers Ju-86 high-altitude reconnaissance aircraft. The M-105PD engine proved troublesome, and a second small batch of aircraft were built in 1944 with the M-106PV engine. However, by this time the Germans had given up high-altitude reconnaissance and the high-altitude Yaks were no longer needed.

Work was done during the war to develop a tandem-seat advanced trainer based on the Yak-9, resulting in production of the "Yak-9V" after the war. The Yak-9V was also produced in a modified form as a two-seat fast liason aircraft, the "Yak-9 Kur'yer (Courier)".
* After World War II, the Yugoslav designers Sivar, Znic, and Popovic designed a fighter based on the Yak-9 named the "S-49" that would serve into the 1950s. It was the last of a significant line of aircraft.

A total of 16,769 Yak-9 fighters were built in all by the time production ceased in 1947, making it not only more common than all other Yak fighter variants put together, but one of the most heavily produced aircraft of all time. The total number of all Yak fighter variants was 36,737. Many Yak pilots would become aces, and a few would score 50 kills or more in the Yak and other fighters. Among them were Dmitri Glinka, with 50 kills; Grigori Rechakov, with 56 kills; and the famous Alexandr Pokryshin, with 59 kills.