file updated on April 10, 2005
file name: mmn.html
In the beginning of 1940, the Archangelskiy construction bureau
in Zavod 22 aircraft factory worked hard on a perfectioning of the Tupolev
Two steps of development were taken in consideration:
Production tests and operational development proceeded with SB No. 18/206,
using motors M-103 with TK-2 turbosuperchargers.
an aerodynamic improvement of the plane to achiece a top speed of 500 km/h
at 6500 m with M-105 or M-106 engines;
a full redesign of the plane to reach a top speed of 600 km/h.
Zavod 22 was charged to build 3 SB with M-105 TK-2 engines within September
1940, but they found difficulties, and build only two SB-2-M105TK2 that
failed to pass factory tests. One of them was later delivered to NII-VVS
(The Scientific Institute of Air Force) for tests.
To improve the aerodynamics of SB, a new prototype was built.
This was the MMN (modified smaller lifting surface).
In spite of all these efforts, the improvement in performances over the
SB M-103 was neglegible and fully unsatisfactory, while the landing speed
increased to 160 km/h.
new smaller outer wing panels of simplified construction, with a
18.00 m span (instead than 20.33 m) and an area of 48.2 sqm (instead
than 56.7 sqm);
with two further 205 l tanks in the outer wing panels;
a redesigned nose with wider trasparent surfaces and one ShKAS machine
gun (instead of two);
2xM-105 engines of 2x1050 hp (instead than 2xM-103 of 2x960 hp);
VISh-2E 3-blade propellers with starter dog and modified cowling;
dual controls installed on the navigator's cabin;
a dorsal MV-3 turret (instead than TUR-9) with one ShKAS 7.62 mm machine
a ventral MV-2 turret with a ShKAS replaced the LU hatch mounting;
much enlarged flaps;
a lowered vertical tail unit;
a landing light in the leading edge of each wing;
an emergency undercarriage extension system was installed in the cockpit.
The defensive armament was weaker than that of SB.
The prototype was tested in September 1939 by NII VVS.
On the whole, the result was deluding, and the only prototype, called
Shchuka (pike) was allocated to Aeroflot.
However, the State Commission recommanded that many of the new characteristics
of the SB-MMN should have been introduced in the production of SB bombers.