The Yakovlev Yak-10 was a four-seat multipurpose light aircraft designed in 1944 as a replacement for the Polikarpov U-2 (Po-2), a biplane which served as a liaison and passenger transport aircraft. Although the Yak-10 successfully passed state acceptance trials in January of 1945, it proved rather unsatisfactory with Soviet Air Force pilots, and thus, only 41 examples, including the prototype, were produced in 1946 before being replaced by the redesigned and superior Yak-12 light aircraft in 1947. Though unsuccessful in service, the Yak-10 provided valuable experience in light aircraft design and served as a stepping stone for the more successful Yak-12.
In early 1944, the Soviet High Command was beginning to realize the obsolete nature of the Polikarpov U-2 (Po-2) in its liaison role. In the wake of the quickly advancing aircraft industry, Yakovlev OKB (Experimental Design Bureau) was called upon to design a multipurpose light aircraft capable of performing liaison missions, ferrying passengers, cargo, and aerial ambulance duties for the Air Force to replace the Po-2. In response, Yakovlev OKB initiated a project with G.I. Gudimenko assigned as chief engineer and work commenced on a four-seat, high-wing monoplane using the firm’s pre-war AIR-6 design as a basis, which had similar traits. The new aircraft design was assigned the designation of Yak-14.
Due to the rather obscure nature of the project’s development, it is unknown when the first prototype was produced, but it is most likely sometime before or in early January of 1945. First flown by test pilot F.L. Abramov, the Yak-14, powered by a 5-cylinder, air cooled Shvetsov M-11FM radial engine producing 145 hp, proved to have unacceptable handling characteristics. This prompted minor redesigning and modifications to the prototype which would address the issues that emerged from the test flight. Amongst the various modifications, the aircraft was also redesignated as the Yak-10 (the Yak-14 designation would later be reused for a 1947 assault glider project). With the completion of modifications, the Yak-10 was resubmitted for state testing. The aforementioned handling characteristic issues appeared to have been addressed, and the Yak-10 passed state trials in June of 1945.
Now authorized for service, production of the Yak-10 was assigned to the No. 464 aircraft plant in Dolgoprudny (Долгопру́дный), approximately 12 mi / 20 km north of Moscow. A total of 40 models were produced in 1946, which were then delivered to air force units. An important difference between the prototype and production models was the conversion from the 145 hp M-11FM engine to the 160 hp M-11FR engine. During the Yak-10’s service life, several variants were designed. These included a dual-control trainer variant known as the Yak-10V, an aerial ambulance variant capable of carrying two stretchers and a doctor known as the Yak-10S, an experimental floatplane variant known as the Yak-10G, and an experimental ski landing gear conversion without a proper designation. Due to the scarcity of documents regarding the Yak-10, it is unknown how many Yak-10V and Yak-10S models were produced, but the Yak-10G and Yak-10 with ski gear were converted from standard Yak-10 models. Curiously, the Yak-10 also had a competitive experimental low-wing development in 1944 known as the Yak-13 (originally designated the Yak-12, which is unrelated to the 1947 development) which featured a split landing flap and various smaller modifications. Though the Yak-13 was superior to the Yak-10 in speed, the Yak-10 possessed operational advantages and thus won the favor of the Soviet high command. Though the Yak-13 was considered to be produced alongside the Yak-10, the act was deemed economically unviable and thus the Yak-13 remained a one-off prototype.
In Soviet service the Yak-10 proved to be lacking in terms of performance, which also impacted the aircraft’s ability to be adapted to more roles. Within a year of the Yak-10’s fielding, the Yakovlev OKB was once again called upon to produce a better aircraft. In early 1947, the bureau initiated another project to fulfill the demands of the Air Force. G.I. Gudimenko was once again assigned as chief engineer, but now M.A. Shchyerbina, M.N. Beloskurskii and L.L. Selyakov joined the team as designers. The new project was designated as the Yak-12 (recycled from the Yak-13’s initial designation) and was essentially a redesigned Yak-10 that featured a redesigned rear fuselage contour and a shallower upper decking. Along with some other modifications to the wings, structure and fuselage, the Yak-12 would undergo flight testing within the same year. Though slower than the Yak-10 in speed, the Yak-12 proved to be more versatile for other roles and had greater operational characteristics. Such improvement was deemed satisfactory by the Air Force and mass production thus commenced. The success of the Yak-12 overshadowed the Yak-10 and all examples were withdrawn soon afterwards. The Yak-12 would be produced in the thousands with dozens of variants and conversions designed. It would see service with several Eastern Bloc countries, as well as the People’s Republic of China, Mongolia and possibly Cuba (it is unknown if they operated this type). The Yak-12 was saw military service well into the 1970s but were all retired prior to the 21st century. Several Yak-12 models are still flown to today for recreation, airshows and other roles.
The Yak-10, despite passing state acceptance trials, was still an operational failure and saw only limited production. However, the Yak-10 was an important stepping stone in the development of the Yak-12, which was much more successful and had a fruitful service life within the Soviet Union and several other countries.
The Yakovlev Yak-10 was a four-seat, high-wing, single-engine multipurpose light aircraft designed in 1944. The standard production Yak-10 was powered by a 5-cylinder air-cooled Shvetsov M-11FR radial engine providing 160 hp, accompanied by a two blade aluminum VISh-327 propeller. The Yak-10’s fuselage and tail was of metal construction while the wings were wooden. The wooden wings possessed a thickness to chord ratio of 11% and utilized the Clark YH airfoil. The fuselage consisted of a welded tubular steel truss while the tail possessed duralumin frames. Fabric was utilized throughout the entire aircraft for skinning. Twin bracing struts constructed of airfoil section steel tubes joined the wings and fuselage. The Yak-10 also had a non-retractable undercarriage in a taildragger configuration. It consisted of pyramid type, rubber-sprung main units and had a castoring tailwheel.
The Yak-10V dual control trainer variant would have featured a new set of controls next to the regular pilot seat. This would allow a co-pilot to fly while both pilots sat side by side. The Yak-10S ambulance variant would have a hatch on the port side of the fuselage for loading stretchers. A total of two stretchers could be accommodated in the Yak-10S along with a seat for a doctor. The Yak-10G featured the replacement of the conventional landing gear with floats previously used in the Yakovlev OKB’s previous AIR-6 multipurpose light aircraft design. Little is known about this variant, but it is known that it did not go into production due to the loss of performance caused by the floats’ drag. The experimental Yak-10 ski conversion had the landing gear replaced by Canadian manufactured wood skis of 6 ft 3 63/64 in x 1 ft 25/64 in / (1,930 x 340 mm). These skis weighed 44.7 lb (20.25 kg). The tail wheel was also replaced by a ski which measured at 1 ft 6 7/64 in x 4 47/64 in (460 x 120 mm) and weighed 4.25 lb (1.93 kg). This modification caused the aircraft’s performance to deteriorate and proved to be only capable of operating in rolled-down airfields. Consequently, the type was not adopted for use.
Yak-10 – Standard production variant powered by a 5-cylinder air-cooled Shvetsov M-11FR radial engine providing 160 hp.
Yak-10V – Dual control trainer variant of the Yak-10. An unknown amount were produced.
Yak-10S – Medical variant of the Yak-10 which featured a hatch on the port side of the fuselage for loading stretchers. The passenger compartment could accommodate two stretchers and one doctor. It is unknown how many Yak-10S models were manufactured.
Yak-10G – Experimental floatplane variant of the Yak-10. A single Yak-10 was modified to carry AIR-6 type floats in 1946. The Yak-10G underwent manufacturer’s tests but this type was not accepted for mass production, likely due to the degradation of performance generated by the floats’ drag.
Yak-10 (Skis) – Experimental conversion of a Yak-10 to replace the conventional landing gears with Canadian manufactured wooden skis. A single example was converted from a standard model in February of 1947 but was rejected for service as the skis caused the Yak-10’s performance to deteriorate. The ski variant was also deemed only capable of being operated from rolled-down airfields, thus limiting the operable areas.
Yak-13 – Development of the Yak-10 in 1944 which saw a redesigned low-wing configuration, a split landing flap and various smaller modifications. The engine was also switched to a M-11FM radial engine producing 145 hp. The Yak-13 was superior to the Yak-10 in terms of performance, but this aircraft was not accepted for mass production as the Yak-12 was deemed better in some regards and as a result, the Yak-13 remained a one-off prototype. This variant was originally designated as the Yak-12 but the name was changed to Yak-13 during trials and the designation was reused for the 1947 development project of the Yak-10.
Yak-12 – Redesigned variant which first appeared in 1947. The Yak-12 featured a redesigned rear fuselage contour and a more shallow upper decking. Though the base model was slightly inferior to the Yak-10 in speed, the redesigned variant proved more capable in other aspects and was thus mass produced and replaced the Yak-10 in service.
Soviet Union – The Yakovlev Yak-10 and it’s variants were briefly operated by the Soviet Air Force from 1946 to 1947 before being replaced by the superior Yak-12.
The Yer-2ON was a VIP passenger transport aircraft designed in 1944 by Vladimir Grigoryevich Yermolayev and his Yermolayev OKB (design bureau). Based off of the firm’s preexisting Yer-2 bomber, the Yer-2ON was meant to fulfill the role of a government VIP transport aircraft which would carry government members to and from meetings in or out of the Soviet Union. Shortly after Vladimir Yermolayev died on December 31st of 1944 from a typhoid infection, the Yermolayev OKB firm was integrated into Pavel Sukhoi’s Sukhoi OKB firm where the project continued. Despite showing relatively promising performance, the Yer-2ON would eventually be cancelled due to the conclusion of the Second World War and the Sukhoi OKB’s need to concentrate resources on other projects. Thus, the three produced Yer-2ON would never be used for their intended purpose and were presumably scrapped some time post-war.
Diplomacy between the Allied countries during the Second World War was an essential step in defeating the Axis powers. With the increasing successes of the Allies during the war, meetings between representatives from the United States, Soviet Union and United Kingdom were held to discuss the future of Europe along with battle plans. In order to attend these meetings, the Soviet government became aware of the need for a long-range VIP passenger transport aircraft capable of carrying 10 to 12 people while maintaining comfort, reliability, cruising abilities at 13,000 ft to 16,400 ft (4,000 m to 5,000 m) and range of 2,500 mi to 3,100 mi (4,000 km to 5,000 km). After Joseph Stalin himself made a request for an aircraft meeting these requirements in January of 1944, a meeting was held between government and Soviet Air Force officials discussing the feasibility of converting existing bomber aircraft to meet this need. Not only would this save time, but also had the benefit of sharing the same airframe as aircraft already in production. In the end, the Yermolayev OKB’s liquid-cooled Charomskiy ACh-30B V-12 diesel engine powered Yer-2 bomber was chosen for conversion. Curiously enough, Yer-2 being used as a transport aircraft is quite ironic, as it reflects on Roberto L. Bartini’s 1937 Stal-7 transport aircraft, from which the Yer-2 bomber was originally developed from.
Shortly after the NKAP (People’s Commissariat for Aviation Industry) approved Order 351 on May 23, 1944, the head designer of the Yermolayev OKB firm, Vladimir Grigoryevich Yermolayev, began work on converting the Yer-2 into a VIP passenger transport aircraft. In his address to the NKAP on that day, he promised that a completed example would be converted by Factory No.39 and be ready for tests by November 15th. This new variant would be designated Yer-2ON (Osoboye Naznachenie – Special Purpose). With most of the groundwork already completed, Yermolayev was able to complete the conversion blueprints by August. An inspection was conducted on the Yer-2ON’s plans on August 28th and was approved for production. The difference between the Yer-2ON and the standard bomber variant was the removal of all armament and replacement of the bomb bay with a passenger compartment. The passenger compartment would have been able to hold 9 passengers, as well as a flight attendant. All relevant technical drawings were sent to Factory No.39 in the Irkutsk Oblast. A total of four Yer-2 bombers were ordered for conversion, but standard Yer-2 production would run into difficulties as the diesel powered Charomskiy ACh-30B engines manufactured at Factory No.500 were found to have defects and needed to be addressed. As such, the project was put on hold for a considerable amount of time.
On December 31st, Vladimir Grigoryevich Yermolayev passed away due to a typhoid infection. As a result, the Yermolayev OKB and its assets were integrated into Pavlov Sukhoi’s Sukhoi OKB firm. It would appear that N.V. Sinelnikov took over as head designer once the project was integrated into Sukhoi OKB. Once the issue with the engines was resolved, three Yer-2 bombers were set aside and were prepared to be converted into the Yer-2ON. Due to the relatively poor documentation of the Yer-2ON’s development, it is unknown when precisely the first Yer-2ON was completed, but most sources allege it was completed at the end of December. The manufacturer’s flight tests and maiden flight appeared to have taken place sometime in February of 1945. Through these tests it was revealed that the Yer-2ON was capable of covering a distance of 3,230 mi / 5,200 km while maintaining a flight ceiling of 19,700 ft / 6,000 m and a top speed of 270 mph / 435 kmh.
On April 16th, the first Yer-2ON made a record non-stop flight from the Irkutsk Aviation Plant’s airfield in Eastern Siberia to Moscow. This flight was accomplished by Heroes of the Soviet Union M. Alekseev and Korostylev over a flight time of 15 hours and 30 minutes and covered a distance of approximately 2,611 mi / 4,202 km. It would appear that a second flight would be conducted sometime near the end of April with the second converted aircraft once it was ready. The second flight had identical circumstances as the first flight (same pilots, destination, fuel load, etc). Interestingly enough, both flights concluded with enough fuel for four more hours of flight, attesting to the Yer-2’s long-range capabilities. A third Yer-2ON was converted at an unspecified time, but details of its tests (if it performed any at all) are unknown. Some internet sources claim that a fourth example was completed on May 10th of 1945, but this cannot be confirmed and disagrees with most publications.
Despite the Yer-2ON performing relatively well and passing the manufacturer’s flight tests, the aircraft was never used for its intended role of government VIP passenger transportation. This was likely the result of the project being deemed as low priority within the Sukhoi OKB firm. At the time, Sukhoi was invested in other more pressing projects which led to the Yer-2ON being eventually canceled. Joseph Stalin himself was reputed to have aviophobia (a fear of flying) and the Yer-2ON not entering service did not appear to have consequences for the Sukhoi OKB. Nonetheless, the Yer-2ON project was dropped some time post-war and the three manufactured prototypes were likely scrapped as a result.
The Yermolayev Yer-2ON was a two engine VIP passenger transport aircraft based on the Yermolayev Yer-2 bomber aircraft, powered by two liquid-cooled Charomskiy ACh-30B V-12 diesel engines capable of producing 1,500 hp each. The Yer-2ON was identical to the standard Yer-2 bomber in most respects, though armaments and turrets were removed and the bomb bay was converted to a passenger compartment with seats for 9 passengers and 1 flight attendant. The crew would have consisted of a commander pilot, a co-pilot, a navigator, a radio operator, and a flight attendant. In the passenger compartment, the left side (aircraft facing forward) had 5 seats while the right side had 4. The flight attendant’s seat was located behind the last seat on the right side, and was retractable. A luggage compartment was also provided. Another notable feature was the addition of a toilet compartment, as the aircraft’s long-distance travel routes required such a feature. Several windows were installed on the side of the fuselage for the passengers.
Soviet Union – The Yer-2ON was intended to be used as a passenger transport aircraft for government VIPs traveling in and out of the country to attend meetings.
* – Statistics taken from “OKB Sukhoi: A History of the Design Bureau and its Aircraft” by Dmitriy Komissarov, Sergey Komissarov, and Yefim Gordon
Nazi Germany (1945)
Rocket Interceptor Trainer – 1 Built
The Messerschmitt Me 163S (Schulflugzeug / Training Aircraft) Habicht (Hawk) was an unarmed two-seat training glider based off of the famous Messerschmitt Me 163 Komet. Originally designed for the purpose of training novice pilots for landing, the Habicht ultimately never saw active service with the Germans and only a single example was produced through the conversion of a serial Me 163B-1. With the sole example captured by the Russians after the war, the Habicht underwent extensive testing by the Soviet Air Force which helped them understand the flying characteristics of the Komet and prepared Soviet pilots for flying the powered Komets. The Habicht undoubtedly played a part in helping Soviet engineers understand the Komet and thus played a part in the future development of Soviet rocket aircraft.
The Messerschmitt Me 163 Komet was one of Nazi Germany’s most famous aircraft produced during the Second World War. Although bearing the title of the world’s first mass-produced rocket-powered interceptor, the Komet did have its fair share of flaws, such as the volatile and sometimes dangerous Walter HWK 109-509 rocket engine, which prevented it from becoming an effective weapon against the Allies.
As the Komet was designed to have a limited amount of fuel to engage Allied bombers, pilots were expected to glide the Komet back to friendly airfields once they disengaged from combat. With gliding landings as a potential problem for the less experienced pilots, one of the ideas proposed by Messerschmitt designers in 1944 was to introduce a dedicated trainer variant of the Komet which would have a student pilot accompanied by an instructor pilot. Designated as the Messerschmitt Me 163S (Schulflugzeug / Training Aircraft) Habicht, the trainer glider differed from the production model with the addition of an instructor’s cockpit behind the forward cockpit. This addition was accompanied by the removal of the Walter HWK 109-509 rocket engine and the Habicht would have to be towed by another aircraft in order to get airborne. Another interesting addition to the Habicht was a second liquid tank behind the instructor’s cockpit for counterbalancing. All the liquid tanks would be filled with water for weight simulation and ballast. A total of twelve examples were planned for production, but only one was produced due to wartime production constraints.
The sole example of the Habicht was built by converting an earlier Me 163B-1 production model. Due to the scarcity of information regarding the Me 163S, it is unknown exactly when the Habicht was produced and what sort of testing it may have undergone during German possession. However, it is known that the Soviet Union was able to capture the only example during the final stages of the World War II’s Eastern Front. The sole Habicht was sent to the Soviet Union along with three Me 163B Komets during the Summer of 1945 for thorough inspection and testing. In historian Yefim Gordon’s book “Soviet Rocket Fighters – Red Star Volume 30”, he claims that in addition to the three Komets, seven Habicht trainer models were also captured. This, however, remains quite dubious as there is no evidence that more than one Habicht existed, and all current photographic material, research materials, and books all suggest that only a single example was produced.
As the Soviets were particularly interested in rocket propulsion aircraft, the State Defence Committee issued a resolution which called for the thorough examination of the Walter 109-509 jet engine and the Me 163 Komet along with captured German documents on rocket propulsion. The three Me 163B Komets, of which only one was airworthy, and the Me 163S Habicht were sent to the Flight Research Institute (LII), the Valeriy P. Chkalov Soviet Air Force State Research Institute (GK NII VSS), and the Central Aerohydrodynamic Institute (TsAGI). The Habicht and Komets saw extensive testing in Soviet hands, undergoing several structural, static and wind tunnel tests. During the initial flight testing period, the Komet only flew as a glider as Soviet pilots and engineers were unsure of whether or not the Walter rocket engine was ready for use since bench tests were not completed. Securing the T-Stoff and C-Stoff propellants for the rocket engine was also a problem. In order to understand the handling characteristics of the Komet, the Habicht was flown numerous times at different altitudes, as was the unpowered Komet. A Tupolev Tu-2 bomber was responsible for towing the Habicht to these altitudes. Under Soviet ownership, the Habicht was given the nickname of “Карась” (Karas / Crucian Carp) due to the glider’s distinct silhouette. The test pilot responsible for flying the Habicht was Mark Lazarevich Gallaj. In general, the Habicht was considered relatively easy to handle by the Soviet test pilots. It is unknown how many test flights the Habicht underwent, but the aircraft certainly aided Soviet pilots in understanding the handling characteristics of the Komet. The Habicht’s service came to an end once the Soviet state trials of the Komet concluded. The sole example was scrapped sometime in 1946, along with seemingly all the other Komets.
If the Me 163S was able to be mass produced and flown with the Luftwaffe, the aircraft would have been a valuable tool to train German pilots. Landing the Komet was a problem for some pilots and in some cases resulted in fatalities but, with the use of the Habicht, the number of accidents would have certainly decreased.
The Messerschmitt Me 163S Habicht was a semi-monocoque aluminum based two-seat training glider developed off the standard tailless Messerschmitt Me 163B-1 Komet. The sole example was converted from a production Komet, which meant dramatic modifications had to be made to the aircraft. The Walther HWK 109-509 rocket engine was removed and in its place was a cockpit for an instructor. The fuel tanks in the airframe were all filled with water to simulate fuel weight while another water tank was added behind the instructor’s cockpit for ballast purposes. There was no armament fitted to the glider. There was a small transparent section between the student pilot’s cockpit and the instructor pilot’s cockpit, presumably for the purpose of communication. As there are no known German documents on the Habicht and Russian documents are scarce, not much is known on the other differences the Habicht may have had. Detailed specifications of the Habicht are unknown, but theoretically it should have been identical to the standard Me 163B-1 Komet except for possibly weight, air drag and center of gravity.
Nazi Germany – The intended operator and producer of the Me 163S Habicht.
Soviet Union – The main operator of the Me 163S Habicht. A single Habicht was captured and tested by the Soviets after the war. The Habicht was scrapped in 1946.
*Editor’s note: As noted above, the exact specifications of the Me 163S Habicht are unknown. However they are presumed to be similar to that of the Me 163B-1 Komet.
The Yak-23 emerged as the final step of the Yak-15 and Yak-17 development series. It made its first flight in mid-1947, powered, ironically, by a British Rolls-Royce Derwent jet-engine. By the time it entered production, the engine was changed with a Soviet-built copy. Over 300 were built, but as more advanced planes were ready for service the Yak-23s were sold to several Eastern Bloc countries. There they remained in service until replaced with the MiG-15 in the mid-1950s.
History of the Yak-23 predecessor
The Soviets began developing jet powered aircraft in the 1930s, but the process was slow with no major progress. However, by the end of World War 2, the Soviets managed to come into possession of large quantities of German war technology, engines as well as experimental and operational jet aircraft.
In April 1945, by orders of the National Defense Committee of the Soviet Union, work on a new generation of jet-powered aircraft began. In the case of jet fighters, the minimum requirement was that it had to achieve a maximum top speed of 500 mph (800 km/h). As there were a number of captured German Junkers Jumo 004B1 and BMW 003 jet engines, it was proposed to try to use them in Soviet designs. These received the new Soviet designation RD-10 Reaktinyi Dvitagatel, which is Russian for “jet engine.” The design and work on the first power plant was given to the OKB-117 Experimental Design Bureau, under the designer Vladimir Y. Klimov in late April 1945. A few months later, a second order was given to develop a new RD-20 jet engine based on the German BMW 003 jet engine. As the Soviet scientists were not familiar with this technology, the entire development ran quite slowly. The first series of these engines was ready in 1946, but the performance turned out to be limited and almost useless.
The work on the new jet fighter program was also slow and largely fruitless. Projects like the MiG-13, La-7R and Yak-3RD were built in limited numbers and proved to be unsuccessful. One of the main reasons for so many failed projects was the fact that the Soviet designers used captured and complicated German jet technology as an inspiration. There had to be a change in the way the Soviet designers and engineers approached these technologies and developments. Since time was crucial, the designers were forced to adopt simpler solutions.
Several new projects resulted from these decisions, one of which was the A.S.Yakovlev Yak-Jumo project. It was based on Yakovlev’s own analysis of German technology, especially the light weight, stepped fuselage and the forward position engine design. His first idea was to try to take advantage of the already existing piston engine-powered fighters and, if possible, install one or more jet engines on them. He reused one Yak-3 fighter and modified it to mount one rocket engine instead of the piston engine. Most parts of the Yak-3 were reused, wings, including the whole fuselage, tail surfaces, undercarriage and most in-built systems and equipment. The new engine was fitted in the forward part of the fuselage, but tilted at a 430’ angle with respect to the plane’s axis. Besides this, it was necessary to redesign the whole fuel system. A new redesigned cockpit was installed and the armament would consist of two 23 mm NS-23K autocannons each with 60 rounds of ammunition located above the engine. The German Jumo 004 engine was used and thus the project name was Yak-Jumo or Yak-3 Jumo (depending on the source).
The first prototype was completed and ready by late 1945. During its first several ground tests, many problems were reported. One of them was the excessive heating of the rear lower fuselage caused by the engine exhaust gases. A second complete and improved prototype was built in December 1945. It was equipped with the Soviet-built RD-10 which was a direct copy of the Jumo 004. Tests on the second prototype plane began during the second half of 1946. During these tests, several complaints were noted and the aircraft was returned to the factory in order to resolve these issues. By that time, this plane received a new military designation, the Yak-15.
On 12th September, 1946, an order for a limited production run was given by the Ministry of Aircraft Production. The Yak-15 and MiG-9s were first presented to the public during a military parade held in Moscow’s Red Square of that year.
Due to the rapid development of Western jet aircraft, Soviet military authorities demanded improved and more advanced jet planes. The new fighters had to be able to reach a maximum speed of 620 mph (1,000 km/h), but mostly due to lack of adequate jet engines this was only successfully implemented in later, much more improved models like the MiG-17. This was the reason why some jet fighters were put into production despite much lower top speeds.
Due to obsolescence and new problems discovered during the Yak-15’s service, most were modified to be used as advanced trainers, but some were operated as standard fighters. Yakovlev was again tasked with the development of an improved jet fighter. It was required to have a significantly better aerodynamic layout and was to be powered by an RD-10 engine. Estimated maximum speed was to be around 527 mph (850 km/h) at an altitude of 16.400 ft (5,000 m). Besides this, a novelty was the installation of an ejection seat and armored glass plate for the windscreen. By September 1946, the first Yak-17 was ready for testing. These tests were considered successful, especially by the pilots who considered it to have good flying performance. Serial production was to start in the autumn of 1947. The Yak-17 would be built in relatively small numbers as more advanced designs would replace it in the following years, designs like the Yak-23.
History of the Yak-23
Later development of new Yakovlev aircraft was characterized by several different methods of approaching development. One of the many Yakovlev design teams, lead by Leonid L. Selyakov, worked on a completely new design that would later lead to the Yak-25. The main goal of this project was to build a completely new aircraft. In addition to this team, a second team advocated for the improvement of the already existing Yak-15 and Yak-17 designs.
The second team’s design was a lightweight and with highly maneuverable jet fighter. This new fighter was to be powered by an RD-500 jet engine, which itself was based on a British Rolls-Royce Derwent 5 turbojet engine. The whole aerodynamic concept was taken from the older Yak-17, but improved with an all-metal construction. The new plane was a lightweight mid-wing monoplane, but with unswept wings and rear tail. The cockpit was placed at the middle of the fuselage and equipped with an ejection seat. To save weight, some modifications were done such as the omission of air brakes, the armor plate being removed, fuel tank capacity lowered, no pressurization fitted to the cockpit and decrease of the wing thickness. The calculated weight with these modifications was about 4,725 lbs (1,902 kg). By the time it entered production, there was a slight increase of weight. The main armament was also relatively light, as it consisted of only two 0.9 in (23 mm) cannons, with some 90 rounds for each cannon.
The work on this project began in the early 1947. Plant No.115 was tasked with the construction of the first operational prototype. On 17th June, 1947 the prototype, designated Yak-23-1 was completed. The first factory test flight was made on 8th July, 1947 by the test pilot M.I. Ivanov. The results of these first flights showed that the Yak-23-1 had a high rate of climb and excellent maneuverability. The maximum speed achieved was 578 mph (932 km/h) at low level. Some issues that were noted during these first flights were solved in time.
In September the same year, on the insistence of the Minister of Aircraft Production, Mikhail V. Khruniche, the Yak-23 was accepted for additional test trials. For this purpose, a second prototype was built, named Yak-23-2. For the series of new test flights, besides G.A.Sedov, the main test pilot, many more pilots were also chosen to test the Yak-23, such as A.G. Proshakov, Valentin, I. Khomvakov among others. By March 1948, these test flights were successfully completed. The Yak-23 displayed great maneuverability during flights. In contrast to other models, like Su-9 and MiG-9, the Yak-23 proved to have much better climb rate. But it was not without its problems: during acceleration, the forward fuselage tended to suddenly rise and the lack of air brakes made potential dog-fighting very difficult. At higher speeds it took a lot of time to slow down and the lack of a pressurized cockpit made the Yak-23 incapable of operating at high altitudes. The second prototype was lost on 14th July, 1948, during one of the many flight exercises for the planned military parade to be held at Tushino. During these exercises, an unknown object struck the wing of Yak-23-2 flown by M.I. Ivanov, which caused the wing to break and fall off. The pilot lost control and crashed to the ground. Ivanov died immediately and the aircraft was totally destroyed. A subsequent investigation found that the main culprit was a balance tab that was torn from the tail of one of the Tu-14 bombers that was flying above the Yak-23.
Despite these problems, the Yak-23 was considered a successful aircraft worthy of production. Plant No.31 was chosen for manufacturing. By mid-1949, the production began, however, at first, the process was slow due the lack of RD-500 engines. The first batch was not ready until October 1949. In the period of January to March 1950, some 20 aircraft were used to conduct more tests. These trials revealed that the Yak-23 had a few more problems to be worked out, such as smoke in the cockpit, among other small issues.. As these problems were considered minor and did not endanger the production of the Yak-23 at the time.
The Yak-23 was designed as a lightweight, all-metal, mid-wing monoplane with unswept wings and tail surfaces. The long front fuselage was designed and constructed so that it could be easily changed or removed for ease of maintenance.
The external fuselage was made of 0.039 in (1 mm) thick duralumin sheets (D16AWTL) and the inner part was made of 0.031 in (0.8 mm) sheets. To protect the main landing wheels, a special cover was installed close to the exhaust nozzle. The lower part of the Yak-23 fuselage was covered with a specially designed heat resistant plate in order to protect the plane’s inner structure from any potential thermal damage. The two unswept wings were made of 17 ribs that were covered in 0.05-0.07 in (1.3-1.8 mm) duralumin panels. At the wing’s trailing edges, ailerons and flaps were fitted. The wings were made mostly of duralumin sheet metal. The wing ends were flat and it was possible to mount two external fuel tanks that were ejectable. The rear tail had a tapered design and was made of metal covered with duralumin sheets. There were no air brakes installed and this caused the Yak-23 to have some problems with maneuvering. This would be a major problem in any potential dogfight with other fighters.
The main engine was the RD-500 turbojet engine with 3,500 lbs (1590 kg) of thrust that was fitted with a single centrifugal compressor and nine cylindrical shaped combustion chambers. The engine had a diameter of 3.58 ft (1.09 m) and 6.76 ft (2.06 m) long. It was angled downwards by 4°30’ with respect to the plane’s centerline. This was not a perfect design choice as when the pilot accelerated the plane, it tended to suddenly pitch up. The main jet fuel was kerosene, stored in five large tanks mounted in the fuselage with a capacity of 240 gallons (910 liters) and two smaller 50 gallon (190 liters) tanks located in the wings. With this fuel capacity, the maximum operational range was around 640 mi (1,030 km). The Yak-23’s flight endurance was very low, with only one hour of operational flight. With this engine, the maximum speed achieved was 606 mph (975 km/h) with a climb rate of 6,693 ft (2,041 m) per minute. The air intake was located at the front, which split into two symmetrical ducts that passed under the cockpit. There was a headlight located in the air intake to help during landings.
The landing gear was a tricycle design typical of jet planes of the era. The front nose wheel retracted forward, while the larger rear wheels retracted into the fuselage sides. A built in shock absorber mechanism with double rebound system was used for the landing gear.
The cockpit was located at the center of the upper fuselage. The cockpit was designed with a fixed windscreen with an armored glass panel and a rear sliding hood with non-armored glass. For the pilot to enter his seat, he had to climb on top of the wings. The Yak-23 was equipped with an ejection seat that could be used by the pilot in case of emergency. The ejection seat with parachute was activated with a command handle located next to the armrest of the seat’s right side. A small explosive charge was used to catapult the seat from the plane. The main command instruments were in the standard configuration. All instruments were placed ahead of the pilot and the rudder pedals were mounted at the floor. The pilot’s instrument panel was divided into three sections. In the central section were the main and most important flying instruments: M-46 Mach meter, PDK-45 compass, AGK-47A artificial horizon, and engine control indicators. Secondary controls were located at sides of the main control panel. An oxygen supply system with a capacity of 2.11 gal (8 l) with a KM-16 model mask was fitted in the cockpit. Electric power was provided by 1.5 kW GSK-1500 generator and 12A-10 type battery. For communication, a RSI-6K radio set and a RPKO-10M radio-direction finder/semicompass were used. Also, the SCh-ZM IFF (Identification Friend or Foe) system was used.
The offensive weapon load consisted of only two 0.9 in (23 mm) NR-23 cannons placed in the lower forward part of the fuselage. Available ammunition for these two cannons was limited with only 90 rounds per gun. The main weapons were aimed by the semi-automatic gyro gun sight placed above the pilot’s instrument panels. Additional offensive armament could consist of two 123 lb (60 kg) bombs attached in the place of the external fuel tanks.
Beside the Yak-23 fighter aircraft, a trainer version, the Yak-23 UTI, was developed. One Yak-23 (serial number 115001) was converted for this purpose. A second instructor cockpit was installed at the rear of the pilot’s seat. The prototype was tested from March to September of 1949, but this modification was ultimately deemed unsuccessful. A new attempt was made with the redesigned Yak-23 UTI-II. The fuselage was stretched by some 7.8 inches (200 mm) to the front, and this time the instructor was moved to the front. A special periscope was installed to allow the instructor to see what the pilot was doing in the rear seat. The armament was reduced to only one 0.5 in (12.7 mm) machine gun. Many more changes were made, which resulted in the third version, Yak-23 UTI-III. By this time, the more impressive MiG-15 UTI was entering production and so the Yak-23 UTI project was canceled.
Despite its good flying characteristics the Yak-23, also known by its NATO designation “Flora,” was built in small numbers, 310 planes in total. Its operational service life in the Soviet Union was very limited, as it was operated by only a few fighter regiments located in the Caucasus and Volga military districts. As more modern planes were becoming available, the Yak-23 would be sold off to Eastern bloc countries such as Czechoslovakia, Bulgaria, Romania and Poland.
In Czechoslovak Service
Czechoslovakia had extensively negotiated with Soviet military officials in the 1950s about the purchase of new jet-powered fighters. These negotiations had been preceded by earlier ones, from which Czechoslovakia received one older Yak-17 under designation S-100. This sole aircraft was to be used as a basis for future local production. However, since this plan went nowhere, the Yak-17 was sent to a military museum and it was never used operationally. An agreement was made in November 1950 for a possible license production of the Yak-23 under a new name, S-101, and also for the engine under the M-02 name. The first group of 12 Yak-23s arrived in Czechoslovakia in late 1950. Their first public appearance of nine planes were used in a military parade on 6th May, 1951, the anniversary of the liberation of Czechoslovakia by the Soviet Red Army in WW2. A second group of 9 Yak-23s was allegedly received, possibly in 1951 or 1952, but precise information is lacking.
The Yak’s were first used by the 3rd Fighter Division, but as the more advanced MiG-15 arrived, the Yak-23s were given to the 11th Fighter Regiment, part of the 5th Fighter Division, from June to August 1951. By early 1952, this unit had 11 operational Yak-23s in total. One Yak-23 was lost in an accident on 16 October, 1952. In 1953, all available Yaks were given to the 51st Air Regiment, which was renamed as the 7th Air Regiment in October. By early 1954, there were 12 Yak-23s reported in service, of which 11 were operational.
Due to the purchase of newer types of aircraft, the Czechoslovakian military authorities thought that the Yak-23 plane was inadequate and outdated and so the original plans for a license production were dropped. By 1956, a decision was made to withdraw all Yak-23s from operational service. Only a small number of Yak-23s where ever used by the Czech Air Force, thought to be around 21, but the exact number is unknown. Most of these were sold, 10 to Poland in 1953, possibly 7 to Bulgaria, with one given to a military museum and at least one was lost in an accident.
In Bulgarian Service
Bulgarian military officials purchased several Yak-17 UTI training variants and 12 Yak-23s from the Soviet Union in early 1951. These were used to form the 19th Fighter Regiment in March 1951. The first pilot to fly on one of the Yak-23s was Major Vasil Velichkov. On his first take-off, the engine suddenly stopped working and he was forced to land in a field near the airfield. Because it was necessary to train new pilots to fly the Yaks, some planes were supplied to the 2nd Training Combat Air Regiment, located at the Georgi Benkovski Flying School. In order to increase the number of units equipped with the Yak-23s, some 72 new planes were purchased from the Soviet Union in 1952. Around 7 Yak-23s were sold to Bulgaria by Czechoslovakia in early 1956. As in Czechoslovakia, the Yak-23 would not stay long in service, and by 1959 all were retired.
In Romanian Service
After the Second World War, the Romanian Military leadership had great plans for the revival of their shattered air force and acquiring modern jet planes. Some 60 Yak-23s were bought from the Soviet Union during the fifties, with the first 12 planes reaching Romania in early 1951. The total number of planes used is not known. As the more modern MiG-15 was received during 1953, the Yak-23 was considered obsolete and only small numbers were ever used. One Yak-23 was modified by the Romanian air engineers of the AEMV-2 (Atelierele de Reparații / Material Volant) to be used as a dual-command trainer aircraft. A new instructor cockpit was installed. This new modified plane was designated as Yak-23 DC (Dublă Comandă / double command), but only a single prototype was built.
On the 24th June, 1953, Romanian pilot Mihail Diaconu escaped to Yugoslavia in Yak-23, where he sought asylum. Not long afterwards, another pilot flying a MiG-15 flew over and later landed onto Yugoslav territory, most likely due to a navigation error. Both planes were thoroughly researched and tested. Pilots Todorović and Prebeg both flew the Yak-23 with more than 4 flight hours. Beside the flying performance, the weapon systems were also tested during 1954. According to the agreement between US and Yugoslav military officials (code name ‘Zeta’), the Yak-23 was disassembled and sent to the Wright-Patterson Air Force Base in order to test the progress of Soviet aviation technology. Test flights were conducted on 4th November and, by 25 November, it was ready to be sent back to Yugoslavia. The Yak-23 was disassembled, and loaded onto a C-124 and later flown to Pančevo airfield. The whole operation was a complete success as it remained a secret for nearly 40 years. After several months, this Yak-23 was returned to Romania, without the Soviets ever realizing where it was the whole time.
In Polish Service
After the Second World War, Poland was economically and militarily devastated. It took several years before the beginning of the renewal of Polish military power. The new Polish military leadership wanted to built up the shattered air force and, despite their plans to acquire a new jet fighter by 1948, this was not possible. The process of acquiring new jet fighters began only in the spring of 1950. The first negotiations with the Soviet Union focused on the acquisition of Yak-15s, but this was later changed to the Yak-17. Due to outbreak of the Korean war, Soviet authorities decided to supply their allies with larger numbers of newer jet fighters. On 6th January, 1951, Poland received its first Yak-23 planes. The planned production of the older Yak-17s was suspended in favor of the Yak-23 under the Polish designation G-3.
Besides the 1st Fighter Aviation Regiment (PLM for short in Polish) which had some 16 Yak-23, a second unit, the 2nd PLM was also supplied with this plane. To train the new pilots, Yak-17 UTI training planes were used. In mid-1952, all operational Yaks were used by five Fighter Regiments: 2nd PLM with 26, the 39th PLM with 19, the 40th PLM with 19, the 26th PLM with around 11 and the 29th PLM with 14 Yak-23. From 1953 onwards, according to the new Polish military strategy, the first line fighter units would be equipped with the new MiG-15, while second-line units received all available Yak-23s.
In the early fifties, the Western Allies were eager to examine and spy on the military power of the East. A simple way to do this was by using various types of balloons. They were used for propaganda, meteorological, and reconnaissance duties. The Polish Air Force was heavily engaged with shooting down these balloons.
The final fate of Polish Yak-23s was sealed by the start of licenced production of the MiG-15 (under the name Lim-1). The remaining Yak-23s were gradually phased out of service. All operational Yak planes were allocated to training units at Radom, where they were used for training new officers and pilots. Some Yak-23s were temporarily used as reconnaissance aircraft in the 21st PLZ (21st Scout Aviation Regiment). By late August 1954, all Yak-23s were moved to Radom. The ones that were not operational were cannibalized for spare parts. On 1st September, 1959, the remaining 39 Yak-23s were removed from the Polish Air Force and a few would be used as memorials. During its operational service in the Polish Air Force, several planes were lost in crashes but, in most cases, the pilots escaped without any injuries.
Albanian Air Force allegedly operated a unknown number of Yak-23. Possibly bought from Poland sometime after 1951, according to author Yefim G.
Hungary and the Yak-23
Hungary allegedly also used the Yak-17 and 23, but there is no documentation or any information to confirm this (Source Marian M.). But according to author Yefim G. an unknown number of Yak 23 were operated by the Hungarian Air Force during the 1955 to 1956. But this author does not specify the number of planes used nor describes in more detail operational service life.
Production and modifications
A relatively small number of planes of this type were ever produced. As more advanced planes were becoming rapidly available, there was no need to continue the production of the old Yak-23. Most of the Yak-23s produced would be later sold to Eastern bloc countries.
In total, 310 aircraft plus three prototypes were built by Plant No.31. The plant produced these in twelve series, with 25 to 26 aircraft in each batch. Production was stopped by the end of 1950.
Yak-23 – Main production aircraft
Yak-23 UTI – One Yak-23 was modified to be used as a fighter trainer. It did not enter production.
Yak-23 DC (Dublă Comandă) – Romanian experimental dual control trainer, only one tested.
Bulgaria – Used over 70 Yak-23s
Soviet Union – Operated only two fighter regiments equipped with the Yak-23
Romania – Some 60 Yak-23 were bought from the Soviet Union during the fifties
Poland – Used around 101 planes, under the designation G-3
Czechoslovakia – Operated around 21 aircraft (possibly more) under the designation S-101
Yugoslavia – Used one Romanian interned plane for experimenting with flying performance and weaponry
USA – Briefly tested one aircraft that was supplied by Yugoslavia
Hungary – Allegedly used this type of aircraft, but proof is lacking
Albania – Possibly operated a small numbers of Yak-23
The Yak-23, despite proving that it had good flying performance and good handling, had a rudimentary design and was produced too late to have any great impact or role in the Soviet fighter force. Due to the rapid development of jet technology, more advanced planes were soon ready for service like the La-15 or MiG-15. The Yak-23 finished its career in service with many Eastern Block air forces.
Although its operational service life was short and its significance was negligible, the Yak-23 was an example of how, with only a short time and using limited resources, a solid jet fighter could be designed and built by the Soviets.
Yakovlev Yak-23 Specifications
28 ft 7 in / 8.73 m
26 ft 7.8 in / 8.12 m
10 ft 10.3 in / 3,31 m
145.32 ft² / 13.5 m²
One Klimov 3,505 lbs/1,590 kg thrust RD-500 turbojet engine