Yermolayev Yer-2 with Klimov M-105 engines 1941

Designed by V. G. Yermolayev, previously a member of the design team concerned with the STAL series of aircraft, the DB-240 long-range bomber prototype was flown for the first time in June 1940. A second prototype followed in September, by which time preparations for mass production at Voronezh were in hand, but the German invasion led to evacuation of the factory in July 1941, by which time 128 examples of the DB-240 had been delivered under the designation Yermolayev Yer-2. An all-metal midwing monoplane of inverted gull-wing configuration and with a twin fin-and rudder tail unit, the Yer-2 had tailwheel landing gear, the main units retracting into the nacelles of its two M-105 engines; accommodation was provided for a crew of four.

By the autumn of 1941 the Yer-2 was in action with two air regiments, making attacks as far distant as Berlin and Konigsberg, but the need for increased range led to experiments with AM-35 engines (April 1942) and a modified wing. Following tests with Charomsky diesels, a new version with ACh-30B engines was approved for production in December 1943 at the Yer-2 factory, which was then established in Siberia. The Soviets experimented extensively with aircraft Diesel engines. Versions of the Pe-8 and Yer-2 were powered by them, but their power-to-weight ratio was too low for modern aircraft, despite their excellent fuel economy. This was the problem all aero-diesels had. The best that was achieved was 2 pounds per horsepower, whereas 1 pound per horsepower was common with gasoline engines.

Some 300 examples of the Yer-2/ ACH-30B were built, forming the backbone of the Soviet long-range bombing force; they also incorporated some improvements, including a revised cockpit, a larger-calibre machine-gun in the ventral position and an enlarged bomb bay accommodating three 1000-kg (2,204-lb) bombs. Maximum speed of this version was 446 km/h (277 mph) and its range 5000 km (3,107 miles), but despite this capability most Yer-2 operations were of necessity carried out at short range on targets behind the front line.

Variants

* Yer-2 production

* Yer-2-ACh-30B

* Yer-2-ACh-30BF

* Yer-2ON (“Osobogo Naznacheniya”, “special purpose”)

* Yer-2 carrier

Specification

Yer-2 (first series)

Type: long-range bomber

Powerplant: two 783-kW (1,050-hp) Klimov M-105 Vee piston engines

Performance: maximum speed 491km/h (305 mph); service ceiling 7000 m (22,965 ft); range 4000 km (2,485 miles)

Weights: empty equipped 6500 kg (14,330 lb); maximum take-off 11920kg (26,279 lb)

Dimensions: span 23.00 m (75 ft 5 ½ in); length 16.34 m (53 ft 7 1/3 in); wing area 72.00 m2 (775.03 sq ft)

Armament: one 12.7-mm (0.5-in) UBT and two 7.7-mm (0.303-in) ShKAS machine-guns, plus a bombload of up to 1000kg (2,204 lb)