The Do 217 was the most important aircraft in the series of bombers that began with the Do 17. It was developed to fulfil a 1937 RLM specification that called for a twin engined bomber capable of carrying a heavier bomb load than the Do 17 or He 111 and with the ability to act as a level or dive bomber.
Dornier responded with an expanded version of the Do 17Z. The new design was 3.3 feet wider and 8 feet longer, but retained the slim fuselage of the earlier aircraft. The four man crew were carried in a bulbous nose section very similar to that used in the Do 17Z. The new aircraft was designed to carry a 6,600lb/3000kg bomb load, three times more than could be carried by the Do 17. The original design also included a “petal” type dive brake that would prove to be problematic.
Despite the apparent similarities to the successful Do 17, the first design for the Do 217 was flawed. The first prototype, powered by two 1,075 hp DB 601A engines, flew in August 1938, but in the following month it crashed, killing the two man crew. Tests before the crash indicated that the new aircraft had sluggish controls and poor directional stability, a bad combination.
The search for a suitable engine finally ended on the ninth prototype which used the BMW 801 radial engine. This prototype also features a new fuselage with a deeper cross section and enlarged bomb bay that raised the bomb load of the aircraft to 4,000kg/ 8,818lb. This new fuselage was used on the main production versions of the aircraft, starting with the Do 217E.
The problems with the dive brakes were never solved, and by the summer of 1940 the dive bomber requirements had been removed. The Do 217 was too heavy an aircraft to make a good dive bomber, and although a few early aircraft carried the dive brakes it was not used in that role.
In all 1,541 Do 217 bombers and 364 night fighters were built before production ended in May 1944. It had a largely undistinguished service career, taking part in a series of futile attacks on Britain and achieving its most famous success against the flagship of a former ally.
The A-0 series were pre-production aircraft for a proposed series of reconnaissance aircraft with the original narrow fuselage of the Do 217. Eight were built during 1939-40, and entered service in 1940, flying reconnaissance missions over Russia.
The C-series would have been a bomber using the slim fuselage. One prototype, powered by the Jumo 211 and four pre-production aircraft, powered by the DB 601A, were built, but did not see service. The C-9 could carry a bomb load of 6,614lb/ 3,000kg and carried five 7.9mm machine guns and one 15m MG 151.
The first major production version of the Do 217, the E-1 appeared in the autumn of 1940. It was the first of the deep bodied Do 217s to enter service. The E-1 was similar to the E-0 other than an increase in defensive firepower, which now consisted of a MG 151 15mm cannon in the nose and seven 7.92mm MG 15s.
A modified version of the E-1, the E-3 featured extra crew armour and swapped the 15mm nose cannon for a 20mm MG FF.
The E-4 succeeded the E-2. It was powered by two 1,580hp BMW 801C engines and was equipped with wing leading edge balloon cable cutters. The E-4 was replaced by the K series in the summer of 1942.
The E-5 was a version of the E-4 designed to carry one Henschel Hs 293A missile under each wing. Sixty five were built. The type first saw action in August 1943.
The J-1 was a night fighter and intruder producing my fitting a solid nose to an E-2. The new nose carried four 20mm MG FF cannon and four 7.92mm MG 17 machine guns. Night fighter crews liked the stability and endurance of the Do 217, but not its sluggish handling or slow climb rate, which made it a poor night fighter.
The J-2 was a lighter version of the J-1. The bomb bay was removed, and it was given FuG 202 radar, making it a more potent night fighter, but it was still not popular with the night fighter pilots.
The K-series introduced a redesigned front fuselage, featuring a single glass canopy that curved around the entire front of the aircraft. The new design was similar to that used on the He 177 and later Ju 88s. The only real problem with the new design was the distance from the pilot to the windscreen, which sometimes resulted in distracting reflections. The K-1 was powered by the 1,700hp BMW 801D engine. It appeared in late 1942.
The K-2 was the heaviest genuine Do 217 to see service. It was designed to carry the FX 1400 “Fritz X” guided bomb. The wing span was increased by 18 feet, to 80.38ft, and it was given extra fuel tanks. The K-2 was significantly under powered.
The K-3 was similar to the K-2 but could also carry the Hs 293A guided missile.
The M-series were very similar to the K series, and entered production at the same time in late 1942. The only significant difference at first was the use of the 1,750hp DB 603A inline engine. Both the M-1 and the K-1 had a cruising speed 20mph higher than the E-series.
One M-2 was built to test out the Do 217 as a torpedo bomber. The Ju 88 was chosen to perform this role.
The M-3 was a Dornier proposal for a heavy bomber based on the Do 217, and was not approved by the RLM
The M-4 used a turbo-supercharger. One prototype was constructed.
The M-5 was designed to carry guided missiles but did not enter production.
The M-8 was a second turbo-charged version of the Do 217. One prototype was built and flew in May 1943 but the project was soon cancelled.
The M-3 was similar to the K-2, designed to carry two Fritz-X bombers or two Ms 293 missiles.
The M-10 was a version of the M-1 designed to use reclaimed materials. It did not enter production.
The M-11 could carry one PC 1400 X missile slung under the fuselage.
The N-1 was a second attempt to produce a Do 217 based night fighter. It was powered by DB 603 engines, and was a distinct improvement on the Do 217J, but was still not ideally suited to the night fighter role. It entered service in January 1943.
The N-2 was the best of the Do 217 night fighters. The dorsal turret and lower rear gondola gun were removed, and two tonnes were removed from the weight. The N-2 could reach 310mph, giving it a good chance of catching the British heavy bombers. It was armed with eight forward firing guns – four MG 151s and four MG 17s, and four MG 151s firing upwards at 80 degrees. The N-2 had a very short service career, entering testing in November 1942 and being replaced from early in 1943.
The P series was the most unusual version of the Do 217. It was designed as a high-altitude reconnaissance/ bomber, powered by two 1,750hp DB 603B engines, with a third 1,400hp DB 605T in the rear fuselage to act as a supercharger. The first prototype entered testing in June 1942, but the project was abandoned at the end of 1943 as interest in high altitude flight dwindled.
Do 217R was a designation given to the five Do 317 prototypes when they were used to carry the Hs 293 missile.
The pre-production A-0s were the first Do 217s to see service. In late 1940 they were allocated to a special reconnaissance Gruppe operating as part of the Luftwaffe High Command. Over the winter of 1940-41 they flew a series of reconnaissance missions over Russia, gathering information in advance of the upcoming invasion.
The next unit to receive the Do 217 was II./KG 40, split between bases in Holland and around Bordeaux in western France. This anti-shipping unit received it’s Do 217Es in the spring of 1941, and for the rest of the year was able to carry out relatively successful attacks on British coastal convoys. They were soon joined by KG 2, which was withdrawn from the Russian front in July 1941 to swap its Do 17s for Do 217s. These anti-shipping strikes became increasingly difficult in the first months of 1942 as British defences improved, but they only stopped when Hitler ordered a new bombing campaign over Britain.
This campaign was triggered by one of Bomber Command’s first major raids, against Lübeck on 28 March 1942. This raid destroyed 1,425 buildings and damaged over 10,000. Hitler was predictably furious, and ordered a series of retaliation raids. These became known as the Baedeker raids after a speech in which Hitler promised to destroy every city mentioned as of historical or artistic interest in a Baedeker guide book. These raids hit Bath, Exeter, Norwich, York, Cowes and Canterbury, (as well as Hull and Grimsby, presumably picked for different reasons.) These costly raids only ended in July, after raids against Birmingham and Hull resulted in the loss of 27 aircraft.
The attrition continued in August. During the otherwise disastrous Dieppe raid, the only bright spot for the Allies were the heavy losses inflicted on the Luftwaffe. KG 2 lost 25% of its 80 aircraft in fighting around Dieppe.
For the rest of 1942 KG 2 was restricted to nuisance raids. These involved one or two Do 217s making low level attacks on coastal targets, thus avoiding British radar. Despite gaining some limited successes, these raids were a faded shadow of the aerial armadas of 1940.
These raids increased in intensity in early 1943, with the arrival of the Do 217K and M. Despite the increase in speed offered by these now aircraft, losses were still heavy and results low.
One final manned bombing campaign was to come. At the start of 1944 the Luftwaffe launched Operation Steinbock, for which it was able to muster 500 bombers. The Do 217 was beginning to be phased out by this time, but it still provided 76 of those 500 aircraft. Operation Steinbock lasted from 21 January until May 1944. It achieved little and inflicted heavy losses on the Luftwaffe’s bomber forces just when they needed to gather strength in preparation for the upcoming Normandy landings.
The Do 217’s most notable achievements involved its use as a launch vehicle for guided anti-shipping weapons such as the Hs 293. This was a 1,100lb bomb attached to a rocket motor, and with 10 foot wide wings. It had a range of up to five miles, and was radio controlled. It was designed for use against merchant ships, or lightly armoured warships. In contrast the Fritz-X was an armour piercing bomb with remotely controlled steering fins.
The first unit to use the Hs 293 in action was II./K.G. 100, equipped with the Do 217E. On 25 August 1943 they made the first ever attack with air launched guided missiles – an unsuccessful attack on a Royal Navy escort group. Two days later they went one better, and scored the first victory won by a guided missile, sinking the sloop HMS Egret. The new weapon did not go on to play a major part in the war. It suffered from sabotage at its French bases, where control wires were found to have been cut and then apparently repaired. Once the threat was known, allied fighter escorts made it increasingly dangerous for the Do 217s to linger in the vicinity of their targets – the main weakness of these weapons was that they required the launching bomber to keep the missile in sight until it struck home.
The biggest success for the Fritz-X came on 9 September 1943, the day of the Italian armistice. Under the terms of the armistice the main units of the Italian fleet were to sail to Malta to surrender. III./KG 100, based in southern France and equipped with the Do 217K-2, launched an attack on the Roma, the Italian flagship. The guided bomb scored two direct hits, causing a fire that spread to the forward magazine. The resulting explosion sank the ship. A second Italian battleship, the Italia, was also damaged but did reach Malta.
Attacked on Allied warships off Salerno were less successful. One battleship, the HMS Warspite, and two cruisers were damaged, but not sunk, while the KG 100 suffered serious losses. At Anzio enough Allied fighter cover was provided to keep the Do 217s of KG 100 away from the ships.
The final significant Do 217 bomber operations came in June-August 1944. Attempts to attack the Allied fleets off the Normandy beaches failed with heavy losses, and allied air power over the beaches was overwhelming. On 7 August 1944 III./K.G. 100 took part in a desperate attack on a bridge over the River Selune, at Pontaubault. The attack failed to stop the allied advance and soon afterwards the unit was disbanded. Production of the Do 217 had ended in May 1944. Fuel shortages soon grounded the remaining German bomber units, and although a small number of Do 217s remained in service with reconnaissance units until the end of the war, its front line service as a bomber had come to an end.