This classic primary trainer has one of the world richest aircraft histories. Since the first
series aircraft flight (January 7, 1928) it was widely used for more than 35
years. After death of N.N.Polikarpov U-2 was renamed as Po-2 (Polikarpov,
the second model). Despite retirement of Po-2 started in June 1959, it service continued. Some even were built of spares by
aeroclubs. The F-AZPO is still flying over Belgium with its original engine...
Dozens of production and experimental variants were built. Among them - several agricultural, paramedic and limousine. During
The Great Patriotic War peaceful biplane turned into terrifying night bomber. German fighters were praised with Iron Cross for
shooting down this small plane! All those roles (not planned during aircraft development!) prove superior quality of the design.
As a trainer, it was intended to replace aging U-1 trainer and other old machines used
in this role. As industry recovered from the Civil War wounds, unified primary pilot training schedule became a necessity. Old
120hp M-2 (used on the U-1) was unreliable
and had too short lifetime. But new generation 100hp M-11 was in
production since 1926, specially intended for trainer aircraft.
Requirements to new trainer were formulated by NTK
UVVS under supervision of S.V.Ilyushin.
Aircraft had to be safe to fly, with speed no more than 120km/h. This allowed to exclude non-productive high-speed
taxing on U-1 with 'stripped' wing. After finishing the U-2 courses, pilots had to
perfect advanced P-2 with 300hp engine.
Success came soon, but start was disappointing. First U-2 was built with thick
wing (with high lift at low speed in mind), had very simple and strong airframe. But it turned into failure.
Aircraft was rebuilt. It had numerous similarities to other aircraft designed by
N.N.Polikarpov team. The most distinctive difference was very large rudder. U-2 was
also airdynamically refined compared to its predecessors.
First flight was performed by M.M.Gromov on January 7,
1928. Standard skis from the U-1 were
installed. Later other pilots tried U-2 in air, and everyone was impressed by excellent handling of new aircraft.
U-2 had feature absolutely new for the time - static longitudinal stability. In case of large climb angle and following speed
lose aircraft normally stalled, with risk of lost control and spin. U-2 just dropped nose and than continued steady descent (in
case of low engine power), or accelerated and continue climb. Aircraft could be send into spin only intentionally (and it was not
so easy!). And it was enough to hold controls in neutral position to get out of spin. It was even possible to let U-2 fly without
hands on controls...
In 1928 aircraft was presented on Berlin Airshow. Mass production started
in 1930 at 'Krasnyj Letchik' (The Red Pilot)
factory and ended in 1953, when requirements to primary pilot training changed again. More than 33,000 were build. Actual
number is almost impossible to figure out, because many were built by aeroclubs, repair shops and even enthusiasts. Small scale
production lasted at least until 1959! Undemanding to service, U-2/Po-2 could operate from any sufficient opening.
Monino AF Museum,
by Paul Nann;