Yakovlev's Yak-9 was a development of the line of Russian fighters that started with the inferior Yak-1 and evolved into the far better Yak-3 and Yak-9, the latter being the subject of this article. The Yak-9 was the mainstay of the Soviet Air Force in the middle and late years of World War II and was produced in greater numbers than any other Soviet fighter. By the middle of 1944 there were more Yak-9s in service than all other Soviet fighters combined. Like other Russian fighters, it was designed for mass production and durability. It offered little in new technology and, due to chronic Soviet shortages, incorporated a minimum of scarce strategic materials, especially in the earlier models. Soviet fighters of the era, including the Yak-9, were designed to achieve numerical rather than technical superiority.

Nevertheless, it could be a formidable fighter, particularly at low altitude and when Soviet pilots had numerical superiority over the Luftwaffe fighters opposing them. This was a common scenario on the Eastern Front. The Yak-9 was not the best of the breed one-on-one in the air superiority role, that honor being reserved for the contemporary Yak-3. The Yak-9 was more the all-around Soviet fighter and could be identified by the large scoop under the engine, which was absent in the Yak-3.

The Yak-9 had an excellent (small) sustained turning diameter at low speeds, which allowed it to turn inside of the German fighters it faced. It could also turn inside of most of the famous American fighters of the war, including the P-38, P-47, and P-51. The Bf 109 had a slightly superior turn rate, but a larger turning diameter. This means that a Yak-9 could usually get inside of an opponent in a sustained turn. By all reports it was also a durable fighter, capable of absorbing a lot of battle damage and still making it home. It was also a successful ground attack fighter, and some variants were specialized for that role.

On the debit side, compared to most other contemporary fighters, the Yak-9 is relatively slow, climbs poorly and performs poorly at high altitude. It was a short-range fighter (combat radius of most models was similar to that of the Bf 109) and not particularly well armed.

The Yak-9 entered service in October 1942 and subsequent versions remained in service with the Soviet Air Force and later its client states (including Poland, Hungary, China, Yugoslavia and Bulgaria) into the early 1950's. The Yak-9 first made its presence felt during the Battle of Stalingrad in early 1942.

The first production Yak-9s had wooden wings with metal spars and a mixed construction fuselage with a molded plywood skin. Power came from a liquid cooled "Vee" engine, the M-105PF, rated at approximately 1,100 hp. Armament consisted of one 20mm cannon firing through the center of the propeller boss and one 12.7mm (.50 caliber) machine gun firing through the engine cowling. The Yak-9 could also carry six rockets or two 220-pound bombs.

By February of 1943, the Yak-9M was in production. This standard version was armed with one 20mm cannon and two .50 cal. machine guns, all concentrated in the nose of the airplane. The wingspan was reduced and the ribs were made of lightweight duralumin. The engine was upgraded to the 1,240 hp. M-105PF-3. The Yak-9MPVO was a night fighter variant equipped with a searchlight and a radio compass.

The Yak-9T was an anti-armor, ground attack version that entered service early in 1943. It was usually armed with a 32mm or 37mm cannon and had wing racks for 5.5 pound anti-personnel bomblets in special containers. Later in 1943 came the limited production Yak-9K, which featured a 45mm cannon. The Yak-9B was another limited production version, this time a light bomber variant with internal stowage for up to four 220-pound bombs in a bay behind the pilot.

The Yak-9D, introduced in the summer of 1943, was a longer-range escort fighter version carrying additional fuel in two outer wing panel tanks and an optional tank under the cockpit. (Soviet pilots must have been viewed the latter as a mixed blessing.) It was powered by a 1,360 hp. M-105PF-3 engine. Specifications for the Yak-9D are as follows (from The Complete Book of Fighters by Roy Cross): Max speed 374 mph at 10,170 ft., 332 mph at sea level; Climb to 16,405 ft. in 6 minutes; Max range 870 miles; Empty weight 6,107 lbs.; Max loaded weight 6,790 lbs.; Span 31 ft. 11.5 in.; Length 28 ft. .75 in.; Height 9 ft. 10 in.; Wing area 184.6 sq. ft.

The Yak-9DD was an even longer-range version (up to 1,367 miles). It was used to escort U.S. heavy bombers on shuttle missions against the Romanian oil fields, and also over Italy and Yugoslavia.

The second generation of Yak-9 fighters began with the Yak-9U prototype, which first flew in December 1943. The "U" stood for Uluchshennyi ("improved" in Russian). The Yak-9U in fact represented a major redesign. It incorporated an improved airframe with a new wing of all metal construction, which had a greater span and area. It was intended to power the improved fighter with the Klimov VK-107A engine of 1,650 hp. Due to production difficulties, the M-105PF-2 engine was substituted until the Fall of 1944, when the VK-107A finally became available in quantity. The Yak-9U became the definitive interceptor/fighter version of the Yak-9 series. The Yak-9UV was a two-seat conversion for training purposes.

The subsequent Yak-9UT had a skin entirely of light alloy. It entered service early in 1945.

The Yak-9PD was an interesting experimental high altitude variant. It had an M-105PD engine with a two-stage supercharger. The armament was reduced to just a single 20mm cannon, firing through the propeller boss, to reduce weight. I suspect, but could not confirm, that other weight saving measures were also taken. It may have been deployed in very limited numbers against high-flying German reconnaissance airplanes late in the war.

The Yak-9P version appeared after the end of hostilities in 1946 and featured an increased armament with one or two fuselage mounted 20mm cannon synchronized to fire through the propeller arc, in addition to the usual cannon mounted in the propeller boss. It saw action in North Korean hands in 1950.

The basic specifications for the Yak-9U (taken from The Complete Encyclopedia of World Aircraft, David Donald general editor) are as follows: Powerplant one 1,650 hp. Klimov VK-107A liquid cooled Vee engine; Max speed 434 mph at 16,405 ft., 367 mph at sea level; Service ceiling 39,040 ft.; Range 541 miles; Armament 1-20mm MP-20 cannon, 2-.50 in. UBS machine guns, plus up to 2-220 lb. bombs on underwing racks; Empty weight 5,988 lbs.; Max T.O. weight 6,830 lbs.; Span 32 ft .75 in.; Length 28 ft. .5 in.; Height 9 ft. 8.5 in.

Production of the Yak-9 continued into 1947 and a staggering total of 16,769 were built. China received Yak-9P fighters from the USSR after the Communist take-over and supplied some to North Korea, where they were used against NATO forces at the beginning of the Korean War. A few were shot down by American P-51's. In the five years since the end of WW II, uneasy allies had become active enemies.