Although Tupolev and the TsAGI had been requested
to construct a flying boat in 1925, higher priority had
been given to his long-range bomber projects and little
work was done. But in 1930, with Ivan Pogosski as
head, work began in earnest on the ANT-8, which was
given the military designation of MDR-2 (MDR =
Morskoi Dalnii Razvedchik = Naval Long-Range
Reconnaissance).
The designation ANT-8 indicated how long the
TsAGI had held back this project, for shortly after its
first flight, the ANT-14 flew. The flying boat's wings
and tailplane were derived from the ANT-9, and again
an all-metal construction was chosen. The fuselage
was given a lot of attention by the design team, and the
opportunity was taken to make the floats part of
the load bearing structure as well as surface balancing
devices. Power was provided by two BMW-VI pusher
engines mounted on struts over the wings. It was
piloted by S. Riballschuk on its first flight which took
place on 30 January 1931. Armament was two DA-2
machine-guns, and it could carry an underwing bomb
load of 900kg.
Tupolev regarded the ANT-8 as a proof of concept
machine for further development, particularly of hulls.
In fact, it turned out to be a worthwhile design in its
own right, although the Soviet Navy decided not to
proceed with it as it considered the design already
dated and unlikely to meet its developing needs. It
would have to wait another five years for Beriev's
MBR-2. Only the prototype ANT-8 was built;
although several modifications were made to its hull,
it remained essentially a one-off experimental aircraft.