Predecessor of the Pe-8/TB-7.
The project was launched in 1934 in response to specifications requesting
for strategic four-engine bomber with optimal altitude 8,000m. The aircraft took off on December 27,
1936. Later (1937) the fifth
engine was fitted in central fuselage to drive the centralized supercharger. This solution was also used on the second prototype.
Production Pe-8/TB-7 did not inherit this oddity thanks to new powerplant
Military Parade magazine,
article in November/December issue;
Enzo Angelucci, Paolo Matricardi "Combat Aircraft Of World War II" Vol. IV, 1940-1941, ISBN 0-517-56843-8;