Aviation of Word War II

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Do-217J

Night Bomber

Dornier

Do-217J

At the very beginning of the war, it was recognized that the best aircraft acceptable for offensive and defensive missions of fighter aviation was the Ju88 - a durable and stable aircraft capable of carrying crushing small arms, with excellent flight characteristics and flight duration required for long-distance raids behind enemy lines. and patrolling. Unfortunately, for night groups of night fighters, this aircraft was required in large numbers for other purposes, and by the end of 1940. the Luftwaffe received only 62 Ju 88C-2 fighters out of a total of 2,184 Ju 88s built this year. Kammhuber, who was promoted to Major General and Commander of Night Bomber on October 16, 1940, petitioned in vain for a Ju88 for night fighter groups, but the situation did not improve. In 1941, of the 2619 aircraft of this type adopted by the Air Force, only 66 were assembled as fighters, and most of them ended up in heavy fighter squadrons. Even in 1942, when 3,094 Ju88s rolled off assembly lines in a year, only 257 were built as fighters, and few were equipped for night operations.

                                                                                                                                 

And then the Do 17 and Do 215B gave way to the assembly of the Do 217 heavy bomber. Although the use of the heavy bomber as a base for creating a night fighter was in question, the Dornier project, proposed in early 1941, had some merit. The improvised fighter was based on the Do 217E-2. Despite its size and weight, the Do 217 was relatively maneuverable, but somewhat under-armed in thrust. It had flight characteristics acceptable for an "offensive" night fighter - it had a more than satisfactory flight duration, which could be further increased by using bomb bays for additional fuel, and could carry powerful weapons. While not an ideal base for a fighter jet, due to the lack of sufficient supplies, the coveted Ju 88 could at least be a pretty decent transition aircraft. The Dornier project for reworking the Do 217E-2 was adopted along with a parallel proposal to develop a future version with DB 603A engines simultaneously as a bomber and a night fighter.

Do 217J-1 The first version of the converted Do 217E-2 bomber was named Do 217J-1. It was specially designed for raids over enemy territory, while retaining the rear bomb bay, which could accommodate eight 50-kg SC50X bombs. The front compartment was occupied by an additional 1160 liter tank, bringing the standard internal fuel supply to 2960 liters. The nose cone was re-controled and lengthened to accommodate four 7.92 mm MG 17 machine guns with 1,000 rounds of magazines. The forward fuselage was also redesigned to accommodate four 20mm MG FF-M cannons, located in two pairs under the cockpit. The top pair was moved to the starboard side. An ammunition reserve of 350 rounds per barrel was provided. The upper turret with an electric drive, in which a 13-mm MG 131 machine gun with a stock of 500 rounds and a machine gun in the ventral ledge with a stock of 1000 rounds were mounted, were preserved.

On October 12, 1941, shortly before the prototype of the Do 217J-1 fighter began flight tests, the Fuehrer issued a decree prohibiting further operations of night fighters over Great Britain. Since the original offensive mission for which the aircraft was conceived was replaced by a defensive mission even before the prototype took off, the focus in further development was shifted from the Do 217J-1 to the radar-equipped Do 217J-2, which could not be used for offensive purposes. The rework at the Do 217E-2 factory into the Do 217J-1 had already reached the final stages when the Fuehrer's decree appeared. However, these vehicles were delivered as J-1s, since the Liechtenstein radars needed to convert them into J-2s were not received due to the fact that Bf110 production had priority in their delivery.

Combat trials of the Do 217J-1 began in March 1942 at II / NJG1 in Gilse-Reyen. The large night fighter, the largest of all in service at the time, was negatively compared to the Do 215B-5 by the pilots of the 4th squadron due to the high wing loading and poor take-off characteristics of the engines, which were said to severely limit the number of sites from which the Do 217 could be safely operated. Since the Dornier night fighter was no longer intended for raids on the enemy, the advantages of the long flight duration were now of purely academic interest. The Himmelbett night air defense system did not require long flight times from the fighters used in it, but clearly wanted more speed and maneuverability than those possessed by the Do 217.

"Himmelbett" or "four-layer" (the name reflected the four components of the system - the Freya early warning radar, two Würzburg control radars and the Seeburg tablet table) was a system of sectors, the radius of which was determined by the tracking range of the Würzburg station "that followed the invading planes and directed the fighters to targets within the sector. Poorly suited for Himmelbett operation, the Do 217J-2 was accordingly given low priority in the supply of the A1 radar and other equipment.

A small number of Do 217J-1s supplied to the Luftwaffe were used mostly for training purposes. Do 217J-2s began to enter combat units in the summer of 1942, when the Luftwaffe command began to attach increasing importance to Germany's night air defense. Great efforts by the British Royal Air Force Bomber Command resulted in the replacement of the slow and poorly armed twin-engine bombers in night raids with significantly more powerful heavy aircraft such as the Lancaster, which debuted in the skies over Germany on the night of 10-11. March 1942 A month later, the first 3629 kg bomb was dropped on Essen. All doubts about the importance of night fighter aircraft were dispelled on the night of 30/31 May, when the British launched Operation Millennium, the first "raid of a thousand bombers" targeting Cologne.

Do 217J-2 Do 217J-2 differed from its predecessor only by the absence of a rear bomb bay and by the fact that a Liechtenstein VS was mounted in the nose with its Matratzen antenna. Having a dry weight with equipment of 9350 kg and a normal loaded 13,180 kg, the Do 217J-2 was actually only slightly heavier than the fighter version of the Ju88, but two 14-cylinder BMW 801ML air-cooled radial engines, which gave 1580 hp at takeoff. with., and at an altitude of 4600 m - 1380 liters. with., could not give the desired ratio of thrust to weight, and the maximum speed at 5500 m was only 489 km / h.

Specification
Do217K-1 Do217M-1 Do217J-2 Do217N-1
Dimensions
Length, m 17.12 17.12 17.67* 17.67*
Wing span, m 19.0
Wing area without a fus., m² 48.5
Wing area,including a fus., m² 56.7
Height in line of flight, m 4.8
Weight, kg:
Empty weight, kg - 9065 8730 10270
Loaded weight - 16790 13180 13200
Powerplant
Engine (two) BMW 801D DB603A BMW 801ML DB603A
Power, hp takeoff 1700 1750 1580 1750
at alt 1440 1620 1380 1850
m 5700 5700 4600 2100
Performance
Max speed, km/h at alt 515 560 489 515
m 4000 5700 5500 6000
Cruise speed, km/h at alt - 400 465 470
m -     5400
Rate of climb min - 6.7 3.5 9
to alt, m - 2000 1000 4000
Ceiling, m - 7350 9000 8900
Range, km - 2150 2050 1755
Armament
7.92-mm machine guns 3** 3** 4 4
13-mm machine guns 2/3 2/3 2 2
15/20-mm cannon no no 4 4
Internal bomb load, kg 2500 2500 no 400
Bombs, kg 4000 4000 no 400

* - without radar antennas.

** - the nose 7.9-mm twin MG 81Z machine gun was quite often replaced with 13-mm MG 131.

- no data


Combat use. Although 157 Do 217 night fighters had been assembled by the end of 1942, reports from the Luftwaffe chief of staff indicated that only 55 of them were used in combat, mainly due to difficulties with the supply of the necessary equipment for night operations, including the Liechtenstein radar, which was increasingly used in night fighter aircraft. The Reich Ministry of Aviation, which at the beginning of 1942 promised to supply the Italian Air Force as soon as possible with enough Do 217Js to arm a fully night fighter group, began to struggle with the slow delivery of fully equipped Do 217J-1s. On August 15, 1942, not a single Dornier had yet reached Italy. An Italian commission arrived in Germany to speed up deliveries to its air force. The Commission was given the opportunity to test the Do 217J-2 and had favorable impressions of its capabilities, although it was somewhat embarrassed, as recorded in a subsequent report, by the "complexity" of the aircraft.

In fact, only two Do 217J-1s could be immediately dispatched to the Italians. They were handed over to the Italian Air Force on September 10, 1942 and immediately drew a protest from the Italian ambassador, who said that these second-hand aircraft were "defective and lacking the promised radar." However, on October 21, 1942, two Do 217J-1s were handed over to 235 Squadron (Group 60, 41 Division) at Treviso San Giuseppe. Two additional Do 217J-1s were delivered to this unit towards the end of the year, when, in addition to the four Dorniers, the squadron used three Bf 110s, one Fiat CR 42CN and one captured Bristol Beaufighter. In early February 1943, two more Do 217J-1s plus one equipped with a Do 217J-2 radar were flown to Italy by a group of Italian pilots who were trained on night fighters at NJG3. They were followed by five more Do 217J-2s. 235 Squadron was assigned to patrol a very large area covering Liguria, Piedmont, Lombardy and Emilia. Although several victories were recorded, the number of aircraft was too small to provide anything other than the appearance of cover. The Dornier's suitability for service was poor, mainly due to a lack of spare parts. Radars "Liechtenstein" constantly junk due to inadequate training of service personnel. There were also problems with the Do 217 chassis. The unit, as a rule, could exhibit no more than 50% of its composition. For example, on July 31, 1943, in the 235th squadron of 11 Do 217 fighters (one was decommissioned as a result of an accident after a chassis failure), three were under repair, and three were not operational due to a lack of spare parts.

Photo Description
Do 217J-2 The Do 217J-2 crew prepares for a combat mission

Bibliography

  • "Aviation of Luftwaffe" /Viktor Shunkov/
  • "Encyclopedia of military engineering" /Aerospace Publising/