Tag Archives: transport

Yakovlev Yak-10

USSR flag USSR (1946)
Multipurpose Aircraft – 41 Built

An impressive photo of freshly produced Yak-10 sit on the Dolgoprudny airfield awaiting delivery. [Yefim Gordon]
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.

History

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.

Yak-10 Blueprint Drawing

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.

The Yak-10 prototype, still known as the Yak-14 at the time this photo was taken. [Yefim Gordon]
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.

Design

A Yak-10 flies over the Moskva River near the Moscow suburbs. [Yefim Gordon]
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 same Yak-10 above parked at the Chkalovskaya AB during state acceptance trials at NII VVS. [Yefim Gordon]
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.

Variants

  • 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.

Operators

  • 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.

Yakovlev Yak-10 Specifications

Wingspan 39 ft 4 ½ in / 12.0 m
Length 27 ft 8 ⅝ in / 8.45 m
Wing Area 237 ft² / 22 m²
Wing Airfoil Clark YH Airfoil
Thickness / Chord Ratio 11%
Engine 1x 5-cylinder air-cooled Shvetsov M-11FR-1 radial engine (160 hp)
Propeller 1x two-blade aluminum VISh-327 propellers
Empty Weight 1,746 lb / 792 kg
Normal Loaded Weight 2,535 lb / 1,150 kg
Maximum Loaded Weight 2,712 lb / 1,230 kg
Fuel Weight 207 lb / 94 kg
Oil Weight 31 lb / 14 kg
Climb Rate 3,280 ft / 1,000 m in 5.5 minutes
Maximum Speed 124 mph / 200 kmh – Normal Loaded Weight

122 mph / 196 kmh – Maximum Loaded Weight

Landing Speed 49 mph / 79 kmh – Normal Loaded Weight

52 mph / 84 kmh – Maximum Loaded Weight

Takeoff Distance 853 ft / 260 m – Normal Loaded Weight

1,115 ft / 340 m – Maximum Loaded Weight

Landing Distance 919 ft / 280 m – Normal Loaded Weight

984 ft / 300 m – Maximum Loaded Weight

Range 358 mi / 576 km
Maximum Service Ceiling 11,155 ft / 3,400 m
Crew 1x Pilot
Load Capacity 3x Passengers

Yakovlev Yak-10S Specifications

Wingspan 39 ft 4 ½ in / 12.0 m
Length 27 ft 8 ⅝ in / 8.45 m
Wing Area 237 ft² / 22 m²
Wing Airfoil Clark YH Airfoil
Thickness / Chord Ratio 11%
Engine 1x 5-cylinder air-cooled Shvetsov M-11FR radial engine (160 hp)
Propeller 1x two-blade aluminum VISh-327 propellers
Empty Weight 1,808 lb / 820 kg
Normal Loaded Weight 2,579 lb / 1,170 kg
Maximum Loaded Weight 2,756 lb / 1,250 kg
Fuel Weight 207 lb / 94 kg
Oil Weight 31 lb / 14 kg
Climb Rate 3,280 ft / 1,000 m in 5.5 minutes – Normal Load Weight
Maximum Speed 128 mph / 206 kmh – Normal Load Weight
Landing Speed 45 mph / 73 kmh – Normal Load Weight
Takeoff Distance 748 ft / 228 m – Normal Load Weight
Landing Distance 633 ft / 193 m – Normal Load Weight
Range 376 mi / 605 km
Maximum Service Ceiling 11,483 ft / 3,500 m
Crew 1x Pilot
Load Capacity 2x Stretchers + Injured Personnel

1x Doctor

Gallery

Illustrations by Haryo Panji

Yakovlev Yak-10 – Standard Model
Yakovlev Yak-10 – Standard Model in Alternate Livery
Yakovlev Yak-10 – Air Ambulance
Yakovlev Yak-10 – Float Variant

The prototype Yak-10G floatplane variant sits in a river awaiting flight trials. [Yefim Gordon]
A Yak-10 flies over the Moskva River near the Moscow suburbs. [Yefim Gordon]
A white painted Yak-10S ambulance variant. The port hatch for loading stretchers is visible beside the cross. [Yefim Gordon]

Credits