Staff Writer (Updated: 5/18/2016):
Entering the war, the Soviets and Germans stood as Allies. When Germany invaded neighboring Poland in September of 1939, it began what would become a year's long struggle for the world. Weeks later, Soviet forces arrived to effectively divide Poland in two. The Germans then turned on the Soviets for, in June of 1941, Hitler enacted "Operation Barbarossa" - the invasion of the Soviet Union - and officially began the East Front. While gains were initially excellent for the Germans and losses horribly bad for the Soviets, the ensuing winter and strained supply lines slowed the Germans just outside of Moscow. Regrouping, the Soviets then began their monumental push westwards until the entire Axis war machine was destroyed at Berlin in April of 1945.
Prior to the war in 1937, aeronautical engineer Vladimir Petlyakov was serving a prison sentence at a Soviet camp when he and others were charged with designing a new high-altitude fighter to serve as escort for a new bomber. His team developed the VI-100, a two-seat, twin-engine speedster featuring a pressurized cabin for the high-altitude requirement and modern all-metal construction. Progress then produced the initial prototype form which was fitted with 2 x Klimov M-105 V-12 turbocharged engines of 1,100 horsepower. First flight was recorded on May 7th, 1939 and the design showcased a maximum speed nearing 390 miles per hour. A second prototype was later added and testing proved so successful and the design so promising that the aircraft was ordered for production by the Soviet Air Force.
By this time, however, the Germans had begun their "blitzkrieg" campaigns in Europe and showcased the value of concentrated, well-coordinated attacks involving dive bombers (primarily the Junkers Ju 87 "Stuka"). As all nations observed the progress of what was now modern warfare, many searched to copy this battlefield success and adopted similar platforms in turn. For the Soviets, the Petlyakov-led design was selected for revision into a dive bomber form.
Work began immediately and the turbochargers were dropped with the adoption of the M-105K series engines (high-altitude capability was lost which led to a now-unpressurized crew cabin and lower fighting ceiling). Dive brakes of a lattice design type were installed to retard the dive of the aircraft while dihedral was added to the tail plane to promote increased stability. A glazed nose assembly was instituted as was a third crew member (now consisting of a pilot, bombardier and dedicated machine gunner. For its dive bomber role, the aircraft was granted defensive armament in the way of a 7.62mm ShKAS machine gun in a dorsal position and another 7.62mm machine gun was added to a ventral, rear-facing, gun position- this aimed through a periscope by the gunner. General armament included 2 x 7.62mm ShKAS machine guns in fixed, forward-firing positions in the nose to be controlled by the pilot. These were (later) substituted for a 1 x 7.62mm ShKAS and 1 x 12.7mm UBT heavy machine gun arrangement for greater firepower. Similarly, the dorsal gun position could be substituted for the larger-caliber 12.7mm machine gun. Maximum bomb load for the aircraft totaled between 2,650lbs to 3,500lbs (depending on variant) and consisted of conventional drop ordnance held in an internal bomb bay or externally.
With the changes, the VI-100 was evolved into the "PB-100" prototype and it was this design that was officially adopted by the Soviet Air Force as the Petlyakov "Pe-2". Two prototypes featuring the changes were completed and tested. Externally, the aircraft exhibited a conventional twin-engined design form. The engines were held in extended nacelles at each wing leading edge. The wings were straight appendages with rounded tips and mounted just ahead of midships. The cockpit, despite its heavy framing, was seated well-forward in the design, offering generally excellent visibility for an aircraft of this type. The three crew were seated in line and protected by 9mm of armor plating. The fuselage was long and well-streamlined, tapering at the empennage. The tail unit consisted of a split-rudder configuration extended outboard by individual horizontal planes along the aft fuselage sides. The undercarriage was wholly retractable and of the "tail-dragger" arrangement consisting of two single-wheeled main legs and a tail wheel. This gave the aircraft a pronounced "nose-up" appearance when at rest.