USB: the trainer conversion

Updated on 12 June 2018

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When the SB became fully operational, a training version with double commands was needed.

In 1938, Factory n.22 developed a new nose section with an opened cockpit for a flight instructor. This nose section could have been quickly fitted on existing airframes.

In 1938, it produced 29 new USB and 81 conversion sets to be sent to units.


USB prototype




The USB prototype at state tests in March 1938. It was fitted with an unretractable ski gear and, probably, M-100A engines. The variable-pitch propeller without spinner and starter cog.

Nationality marks are visible in standard positions.

The plane looks painted overall matt light grey, apart for Venturi tubes that were usually painted black.


Images from Tupolev SB of M. Maslov, Icarus aviation press

The instructor's cockpit was open and provided with a windshield only.

Images from Tupolev SB of M. Maslov, Icarus aviation press

Details of the front of the canopy and of its left side.

Images from Tupolev SB of M. Maslov, Icarus aviation press


Early USB

USB in light grey finish, with an additional red star with black outline painted on its nose.

The light grey finish suggests that the plane was delivered in mid 1938; later, the painting of SB switched to aluminum up to late 1939.

The early light grey was matt and prone to fading, wearing and peeling off, unlike the AE-9 paint utilized for planes produced in late 1939 and early 1940 that was very gloss and more durable.

Images from Tupolev SB of M. Maslov, Icarus aviation press


USB during the Winter War

Two images of USB 2M-100A in winter 1939/40.

The plane looks in aluminum AE-8 finish, with unretractable ski gear and bays closed by fixed covers.

Note the access to the instructor's cockpit.

Both engines and propellers are protected by adhering covers. The armament of the rear positions appear not installed.

Images from Tupolev SB of M. Maslov, Icarus aviation press



USB 11/3 during the Winter War

An USB M-103A shot down by Finns during the Winter War.

On the rudder, a light (yellow?) 11 outlined in black can be seen, on which a red 3 is overposed.



USB Black 4 of 35 SBAP during Barbarossa

USB 2M103A captured by Germans during operation Barbarossa in summer 1941.

The painting on the tail suggests that it was of 35 SBAP or 50 SBAP.

It wears a glossy light grey AE-9 livery, but the nose appears from a green (A-19f)/blue (a-18f) plane.

Note the VM-3 ball-like turret, probably a refitting.

An elegant black '4' is visible on its rudder.



USB Black 4 of 40 SBAP during Barbarossa




USB n.4 of 48 SBAP left on an airfield captured by Germans invaders in summer 1941.

The arrow, the number and the spinners were painted in colors according to the squadron within the regiment; on this photo, they appear darker than the re star, so they could be lack.

The aluminum finish, typical of planes built in late 1938 and the most part of 1939, is nearly always related to flat-engined SB seen during the Winter war and Barbarossa.


USB 'red 0' during Barbarossa

Another USB with flat cowlings and aluminum livery photographed in summer 1941.

The number 0 on the rudder, presumably red with black outline, suggests that the plane was of an unit commander.


USB 'red 1' with aluminum nose during Barbarossa

These three images depict the same plane.

It is equipped with sharp M-103 A or U engines, and features the 'tall' pilot's windshield of SB 2M-103 and the landing light on the left wing leading edge.

The building of the airframe is datable to late 1939 because of the movable shutters at the cooler's intakes, so it looks likely that it was originally painted in uniform AE-9 light grey as of use on that period; the uppersurfaces were repainted in A-19f alkyd green, and the undersurfaces with A-18f light grey-blue after the summer of 1940 when the painting standard changed.

The installation of the shiny nose, painted in aluminum, was clearly made after this repainting, and is the most prominent characteristic of the plane.

The spinners seem to be painted in grey (or white) and red; a red (?) 1 seems painted on the rudder on all photos.



USB 'red 6' of 72 SBAP of Northern Fleet


USB 2M-100 or 103 of the 72th SAP of the Northern Fleet, autumn/winter 1941.

It features green wavy lines on light grey background, a white rudder tip, a small red (?) 6 on its rudder and probably prewar-style disposition of the red stars

Note the raised windshield..

from Aviamaster 2001/05


USB yellow 3




USB 'yellow (?) 3' photographed during the winter 1941/42.

The number looks as light as the lower part of the fuselage sides, in consideration of the direction of the sun light; one can guess that it was yellow or light blue.

The right engine was removed, but one can suppose that the cowling was of the sharp type, else the edges of the cowling of the engine on the other side should be visible. The color of the spinner is a guess.




USB 'white 34' with gliders tug device


USB 2M-103A with a device to tug gliders.

The red stars on the fuselage were roughly deleted with green paint, and new plain ones, scarcely visible, were painted on the tail to accomplish the directive of the June 1941. The stars over the wings were certainly obliterated in the same way.



USB in a training movie, 1943



This USB 2M-103A was utilized for bailing out tests. It appear to wear a very faded black-green camouflage and large 1943-style stars with red-white outline on the fuselage, tail and undersurfaces.

Images from Tupolev SB of M. Maslov, Icarus aviation press

Aside: screenshots of the same plane from a training movie. The first image shows well the star on the nose.



USB in Soviet far east

USB 2M-100A (the single round window on the side suggests a plane of 1937-38) with a three-shades camo (possibly AMT-4 green, AMT-6 black, AMT-1 light brown), post-1943 stars with white-red outline. The plane features a black (?) 10 (?) and a red trim tab on its rudder.

The photo don't show if the plane was equipped with radio and mast.

Images from Tupolev SB of M. Maslov, Icarus aviation press



Two images of an USB 2M-100 or 103 in the Far East, during the preparation of the war to Japan.

This old plane wears post-1943 red stars with white-red outline, a red 2 outlined in white on its rudder, a small red starlet on its nose, probably a black-green camouflage.

The nose and part of the cowling show discontinuity in colors that suggest the use of pieces from another plane.

Note that some of the soldiers wear helmets of obsolete type.


Images from Aviapark 2010-2


Polish AF USB

The Polish air force received few USB just after the war.

Note that propellers, spinners and perhaps engines were replaced with more modern ones from other planes.

The radio mast looks inclined on the right



Finnish AF USB SB-6






The Finnish Ilmavoimat utilized 24 Soviet-built SB bombers from 1940 up to 1945.

The first eight of these planes were captured during the Winter War (30 November 1939-13 March 1940) after having forcedly landed in Finnish territory because of combat damages or other problems. The were first marked as VP-1 to 8, then recoded as SB-1 to 8

The plane SB-6 was captured in the Winter War, as basic SB-2M103 with fixed coolers intakes, and put into service as an anti-ship plane.

It was converted to USB trainer later, probably after the crash of USB SB-8 in 1944.

Aside and below:

photos of SB-6 as a trainer. Note that the landing light was on the right wing.

The plane appears to have a light grey undersurface, probably as an early Finnish standard; it should have neen repainted in hellblau 65 in late 1942.

For more informations, go to the page on Finnish SB.




Finnish AF USB SB-8



VP-8 was the only Finnish one that had the earlier style of coolers with flat front; anyway, the engines were M-103 as on all the Finnish SBs.

It was later converted into USB on March 1 1943.

The plane crashed soon after the take off from Luonetjarvi on 25 October 1944.



Disclaimer: this work collects a lot of photos and drawings from many sources, not always identified and mentioned.
If someone has rights on the images reproduced here, please don't feel hurted, email to me and I shall provide to remove or to credit them.