The aircraft did not show its true potential until the end of 1941, after the Soviet Air Force had a chance to regroup after the German onslaught during the Winter. The Pe-2 quickly proved itself to be a highly capable aircraft, able to elude the Luftwaffe??'?s interceptors and allowing their crews to develop great accuracy with their bombing.
The records of the 16th and 39th BAPs of the Western Front Air Force note that the Pe-2s crews had the greatest success in repelling the attacks of enemy fighters in June and July 1941. On 1 July, for example, six Pe-2s fended off attacks by four Messerschmitt Bf 109s, shooting down two of them. A week later a group of Pe-2s was attacked by four Bf 109 and again brought down two of the attackers. On both occasions the Petlyakovs suffered no losses. On the southern front, a bombing mission against Ploesti, in Romania, by six Pe-2s, led by Capt. A. Tsurtsulin, was a great success: 552,150 lb of petroleum were burnt in the raid. The Romanian information agency claimed that at least 100 Soviet planes had bombed Ploesti. A German pilot shot down by a Petlyakov over Bobruysk, Maj. A. Mudin of JG 51, affirmed that the Pe-2 was the best Soviet aircraft: "It is a fast aircraft, with good armament, and it is dangerous to enemy fighters." The Pe-2 regiments' operations were not always successful and crews complained about insufficient defensive armament and survivability: there was a great risk of fire and insufficient armour protection, especially for the navigators and gunners. German pilots soon discovered the limited sighting angles of the ventral gun mounting and its poor reliability. The Ammunition belt of the UBT machine-gun often jammed after the first burst of fire when shooting in extreme positions. The navigator and the radio operator were poorly protected. On average, ten Pe-2 gunners were wounded for every pilot, and two or three were killed for the loss of one pilot. Throughout 1942 the design was steadily refined and improved, in direct consultation with pilots who were actually flying them in combat. Improved armour protection and a fifth ShKAS machine-gun were installed and fuel tanks modified. Despite anecdotal reports by Soviet fliers, which were often exaggerations and unconfirmed or "over claims" for which the Soviets were well known, Pe-2s were a daylight bomber, often crewed by comparative novices in the early years of the war, and took significant losses, even when well protected by fighters. In December 1942 General Turkel of the Soviet Air Force estimated the life expectancy of a Pe-2 was 30 combat flights. An example of loss rates after the Soviets gained the upper hand can be gained by the losses suffered by the 1st and 2nd BAK. The former started the month of July 1943 with 179 machines, and lost 52 that month, and 59 the next, ending August with 156 bombers after receiving replacements. The 2nd BAK started July with 122 Pe-2s, with monthly losses of 30 and 20, ending August 1943 with 114 Pe-2s after replacements arrived. Most of these losses were at the hands of the thinly stretched German fighter groups, which continued to inflict significant losses when present in strength, even in the closing months of the war. For example, in the Baltic where JG54, "the Green Hearts," were the main opposition, and greatly outnumbered, the Soviet 1st Gv BAK lost 86 Pe-2's shot down (another 12 to other causes), mostly to German fighters between July 23, 1944 and February 8, 1945. Western sources use mark Pe-2FT for production series after 83 (where FT stands for Frontovoe Trebovanie (Frontline Request)), although Soviet documents do not use this identification. Final versions Pe-2K (transitional version of Pe-2I) and Pe-2I were produced in small numbers, due to the unwillingness of Soviet industry to decelerate production numbers.