Here we have sleek and fast heavy fighter/ground attack airplane from Polikarpov in the form of the ITP M-1 prototype.

AG-1 - 20mm ShVAK cannons
AG-2 - 37mm Sh-37 cannon

History:
The ITP was designed around two unproven water-cooled inline engines; the 1,650 hp Klimov M-107 and the 1,400 hp Mikulin AM-37. Two prototypes were built, the M-1 powered by the M-107P and the M-2 powered by the AM-37, but both engines proved to be unreliable.

The ITP was a low-wing monoplane, with a wooden monocoque fuselage and metal wings. The wing was made up of a centre section and two outer panels (the same configuration as on the Polikarpov I-16), and was fitted with flaps and automatic slats. The centre section contained honeycomb radiators, with the air intakes in the wing leading edge and the exhausts towards the back of the upper wing surface. The exhaust outlets could be used to provide some extra thrust.

The prototype M-1 was armed with one engine mounted 37mm Sh-37 cannon and upper-cowling mounted 20mm cannon, justifying its name - Istrebitel Tyazhely Pushechny or Fighter, Heavy Gun. Later, the 37mm cannon was replaced with a 20mm cannon on the port side of the nose. The aircraft could also carry four 100kg bombs or eight RS-82 rockets under the wings.

The M-1 prototype made its maiden flight on 23 February 1942 at Novosibirsk. The unreliable M-107P engine repeatedly disrupted the test programme, and towards the end of the year was replaced with the M-107A. The modified aircraft was then used for static tests and structural testing, so never flew again. The aircraft had an estimated top speed of 382mph or 400mph with the extra boost from the exhaust.

Three-view drawing of ITP (M-1).

Three somewhat-grainy photos of M-1 prototype.

Uncowled M-107P engine of M-1 prototype. 37mm cannon barrel
can be seen extending through propeller hub at far right.

M-107P engine with cowling on.

Armoured seat for ITP pilot.