Developed from mid 1938 by Dmitrii L Tomashevich
(one of Polikarpov's deputies), the I-180 was originally
conceived with an all-metal structure. Limited all-metal
construction experience, however, led the Polikarpov
OKB to adopt an essentially similar structure to that of
the earlier I-16, with a wooden monocoque fuselage
and a fabric-skinned metal wing. The first prototype,
the I-180.1, was powered by a 1,100hp Tumansky M-88
14-cylinder two-row radial, intended armament being
four 7.62mm guns. This aircraft was lost as a result of
engine failure during its first flight on 15 December
1938. The second prototype, the I-180.2, differed primarily
in having a 1,000hp Tumansky M-87A (later
M-87B) 14-cylinder two-row radial and lengthened
wing outer panels. These increased wing span from
9.00m to 10.05m and area
from 14.68m2 to 16.11m2. First
flown on 19 April 1939, the I-180.2 was lost on its 53rd
flight. A third prototype, the I-180.3 flown on 10
February 1940, featured a redesigned and more
advanced wing structure, a 1,100hp M-88R engine, a
cockpit canopy and an armament of two 12.7mm and
two 7.62mm guns concentrated in the fuselage. Flown
with both wheel and ski undercarriages, the I-180.3
was lost in an accident during State Acceptance Trials.
In the meantime, a pre-series of 10 aircraft based on the
I-180.2 had been under construction as the I-180S
(Seriyny or Series), the first three of these having been
completed in December 1939. The I-180S was powered
by the M-88R and carried an armament of two 12.7mm
and two 7.62mm fuselage-mounted guns, and, like the
I-180.3, featured an enclosed cockpit. The I-180S was
cleared for service trials, but the results of these were
somewhat academic as this fighter had been overtaken
by the more advanced I-185. As a part of the I-185 development
programme, one pre-series I-180S fighter
had the dated triangulated pattern mainwheel legs replaced
with legs of cantilever type, this aircraft being
referred to as the I-180Sh, the suffix indicating Shassi
(chassis). In the event, it was not completed and flown,
the entire I-180 programme having meanwhile been
abandoned.
