View source for Dornier Do 217

{{short description|1940 bomber aircraft family by Dornier}}
{{Use dmy dates|date=August 2019}}
{{Infobox aircraft
| name = Do 217
| image = File:Do 217E-2 NAN15Jul43.jpg
| caption = Do 217 E-2
| type = [[Medium bomber]]<br />[[Heavy bomber]]<br />[[Night fighter]] <br /> [[Reconnaissance aircraft]]
| manufacturer = [[Dornier Flugzeugwerke]]
| designer = 
| first_flight = 4 October 1938<ref name="Griehl 1991, p. 21.">Griehl 1991, p. 21.</ref>
| introduction = 1941
| retired = 1945
| status = 
| primary_user = ''[[Luftwaffe]]''
| more_users = 
| produced = 1940–1943
| number_built = 1,925<ref name="German military archive, Freiburg">German military archive, Freiburg</ref>
| unit cost = 
| developed_from = [[Dornier Do 17]]
| variants = 
| developed_into = [[Dornier Do 317]]
}}

The '''Dornier Do 217''' was a [[bomber]] used by the [[Nazi Germany|German]] ''[[Luftwaffe]]'' during World War II. It was a more powerful development of the [[Dornier Do 17]], known as the ''Fliegender Bleistift'' (German: "flying pencil"). Designed in 1937–1938 as a [[heavy bomber]] but not meant to be capable of the longer-range missions envisioned for the larger [[Heinkel He 177]], the Do 217 design was refined during 1939 and production began in late 1940. It entered service in early 1941 and by the beginning of 1942 was available in significant numbers.

The Dornier Do 217 had a much larger bomb load and a much greater range than the Do 17. In later variants, [[dive bombing]] and maritime strike capabilities using glide bombs were experimented with, considerable success being achieved. Early Do 217 variants were more powerful than the contemporary [[Heinkel He 111]] and [[Junkers Ju 88]], having a greater speed, range and bomb load. Owing to this it was called a heavy bomber rather than a [[medium bomber]]. The Do 217 served on all fronts in all roles. On the [[Eastern Front (World War II)|Eastern Front]] and [[Western Front (World War II)|Western Front]] it was used as a [[strategic bomber]], [[torpedo bomber]] and reconnaissance aircraft. It was also used for tactical operations, either direct ground assault or anti-shipping strikes during the [[Battle of the Atlantic]] and [[Battle of Normandy]]. The Do 217 was also converted to become a [[night fighter]] and saw considerable action in the [[Defence of the Reich]] campaign until late in the war.

The type also served in anti-shipping units in the Mediterranean, attacking Allied convoys and naval units during the [[Battle of the Mediterranean]]. In 1943, the Do 217 was the first aircraft to deploy [[precision-guided munition]]s in combat, when [[Fritz X]] radio-guided bombs sank the Italian [[battleship]] ''[[Italian battleship Roma (1940)|Roma]]'' in the Mediterranean. After the end of the war, at least one Dornier Do 217 continued in military operational service with the [[Swiss Air Force]] until 1946.
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==Development and design==

===Early designs and marine plans===
[[File:Bundesarchiv Bild 101I-342-0603-25, Belgien-Frankreich, Flugzeuge Dornier Do 17.jpg|thumb|The Dornier Do 17. The Do 217 was to be a larger, improved version in all areas.]]

At the beginning of 1938, Dornier issued manufacturing specification No. 1323, recognising the need for a twin-engine bomber or long-range [[Aerial reconnaissance|reconnaissance]] aircraft powered by [[Daimler-Benz DB 601]]B engines.<ref name="Griehl & Griehl 1994, p. 54">Dressel & Griehl 1994, p. 54.</ref> In February 1938 the ''[[Reichsluftfahrtministerium]]'' (RLM/German Aviation Ministry) authorized a testing program.<ref name="Dressel & Griehl 1994, p. 53">Dressel & Griehl 1994, p. 53.</ref>
Dornier worked on a version of the Do 17M with the all round vision cockpit of the Do 17Z and a fuselage with a large bomb bay capable of holding a maximum of two {{convert|500|kg|lb}} and ten {{convert|50|kg|lb}} bombs. For reconnaissance an Rb 50/30 movie camera was fitted ahead of the front [[spar (aviation)|spar]] of the wing, and an Rb 20/30 was mounted in the second bomb bay.<ref>Dressel & Griehl 1994, pp. 53–54.</ref> Jettisonable fuel tanks were carried in the forward bomb bay. For smoke-laying, the aircraft could be fitted with two Type S200 smoke generators. Dornier also envisaged the Do 217 as a naval [[dive bomber]], in which case it was to be fitted with twin floats. In April and May 1938, the Do 217 WV1 and WV2 prototypes were produced.<ref name="Griehl & Griehl 1994, p. 54"/><ref name="Griehl 1991, pp. 15-16">Griehl 1991, pp. 15–16.</ref>

The wing span was to be one metre greater than that of the Dornier Do 17, giving an overall span of {{convert|19|m|ftin}}. Under the wing a retractable diving [[Air brake (aircraft)|air brake]] was to be installed. To power the aircraft the Dornier office at Manzell favoured two DB 601B engines, which could generate 1175&nbsp;PS (1159&nbsp;hp, 864&nbsp;kW) for take off. The [[Jumo 211]], [[Bramo]] 329 and BMW 139 (forerunner to the [[BMW 801]]) were also considered. Whichever power plant was selected, the RLM expected the aircraft to have a maximum speed of {{convert|520|km/h|kn}} and weigh {{convert|10200|kg|lb}} fully loaded.
On 5 June 1938 Dornier's overview of its design submitted to the Technical Bureau (''Technisches Amt'') highlighted some structural differences from the Do 17. In particular, the proposed increase in the bomb load to {{convert|1500|kg|lb}} had to have been a vital factor in the design's acceptance. The fuselage was to be not only bigger but also stronger.<ref name="Griehl 1991, p. 16">Griehl 1991, p. 16.</ref>

The RLM also had other requirements for Dornier to satisfy. Since 1933 the ''[[Kriegsmarine]]'' had pressed for the formation of a Naval Air Arm. In January 1938 the Naval Air Arm Inspectorate of the Luftwaffe presented its requirements for a multi-role twin-engined all-metal aircraft which could also conduct maritime operations. On 5 February 1938 it was agreed with the [[General Staff]]. The ineffectiveness of horizontal bombing of ship targets had already been noted. At the ''Erprobungsstelle [[Travemünde]]'' military aviation test centre at Greifswald, training units together with a few naval air units practiced bombing the ship ''Zähringen'' with concrete bombs. The results were a two percent hit rate. [[Junkers Ju 87]] dive bombers repeated the assault with a 40% hit rate. The superior accuracy of dive bombing was clearly demonstrated. The Luftwaffe also wanted a machine that could operate as a [[fighter aircraft]] to combat enemy aircraft. Essentially they wanted a "sea ''[[Stuka]]''" (Junkers Ju 87).<ref name="Griehl 1991, pp. 16-17">Griehl 1991, pp. 16–17.</ref> The aircraft was to have floats and a range of {{convert|1500|km|mi}} and a maximum speed of {{convert|400|km/h|kn}}.<ref name="Griehl 1991, p. 17">Griehl 1991, p. 17.</ref>

Dornier set about designing a floatplane. For hitting targets in the air and sea surface, four [[automatic weapons]] would be fitted in the nose. The armament would consist of two [[MG 17 machine gun]]s (500 rounds of ammunition each) and two MG 204 (aka Lb 204) 20mm autocannon (200 rounds of ammunition) as part of the Dornier Do P.85 project (in German sources these were all classified as "machine guns", since the Luftwaffe considered anything 20mm or lower a "machine gun", rather than a cannon like Western nations, hence the "MG" designation).<ref name="Griehl 1991, p. 17"/> Heavy weapons consisted of one 500&nbsp;kg or two 250&nbsp;kg bombs for assaulting enemy [[warship]]s. Dornier faced competition from [[Heinkel]] and [[Junkers]] who were developing the [[Junkers Ju 88]] and [[Heinkel He 115]].<ref name="Griehl 1991, p. 17"/>
Instead of MG 204s, MG 151 or MG FF was installed instead. Defensive armament was to consist of MG 15s to cover the aft approach. In addition the payload could be modified to one {{convert|500|kg|lb}} and eight {{convert|50|kg|lb}} bombs or even two [[SC 500 bomb|SC 500]] bombs. The floats had a volume of {{convert|8100|L|impgal}} and were broken into compartments for safety reasons. Each float was to contain a fuel tank with a capacity of {{convert|500|L|impgal}}. The tail was to consist of the same twin stabilizer configuration as the Do 217, although a single fin was planned.<ref name="Griehl 1991, p. 18">Griehl 1991, p. 18.</ref>

For dive bombing capability a dive brake was installed underneath the wing. The power plants were to reflect the speed requirements. It was envisaged as having two DB 601G engines, generating {{convert|1300|hp|kW}}, or two Jumo 211s. The fuel tanks were located in the wing and fuselage which had a capacity for {{convert|2000|L|impgal}} of fuel and {{convert|190|L|impgal}} of oil. At full weight the Dornier would reach {{convert|360|km/h|kn}} and its effective range was expected to be {{convert|1880|km|mi}}. Its optimum range at an average cruising speed of {{convert|270|km/h|kn}} at an altitude of {{convert|4000|m|ft}}, was {{convert|2800|km|mi}}. The specifications were dated 8 March 1938.<ref name="Griehl 1991, p. 18"/>
The Do 217 lost out in the naval aircraft race to the Ju 88 and [[Blohm & Voss Ha 140]], as the ''Luftwaffe'' favoured these designs owing to the Do 217 failing to live up to the specifications given.<ref name="Griehl 1991, p. 18"/>
Although specifically ordered to cease development of the naval version of the Do 217,<ref name="Griehl 1991, p. 19">Griehl 1991, p. 19.</ref> Dornier unofficially pursued the project and produced the Do 217W V1 and W V2 prototypes.<ref name="Griehl 1991, p. 20">Griehl 1991, p. 20.</ref>

By the summer, 1940 the Luftwaffe had been using the [[Dornier Do 18]], [[Heinkel He 115]], [[Heinkel He 59]], [[Heinkel He 111]] and [[Junkers Ju 88]] in maritime operations in the [[Baltic Sea|Baltic]]. At this point, the Ju 88 and He 111 equipped units were ordered to cease providing maritime support en masse. Instead, the Luftwaffe returned to the idea of the Do 217 and its floatplane version as a specialized naval attack aircraft. At the same time more plans were in place to produce extremely long-range aircraft (probably for operations deep in the Soviet Union). It is possible that the data sheet which Dornier gave the designation Do 217G was a part of that project. Unlike the ''Sea Stuka'', a floatplane, the G was to carry an MG 151 mounted in the nose and three MG 15s fitted for defence. The G was expected to reach {{convert|14900|kg|lb}}. It was still designed for a crew of four and equipped with sprung floats which would allow the aircraft to land in rough open seas. The G could also carry the entire variation of the E-1 bomb load it could carry a load twice that of the Do P.85 aircraft. However, the Do 217&nbsp;E-1s performance was favoured. Nevertheless, the Gs design features figured and influenced the E-4 which went into production as the aircraft that was envisaged to be the backbone of the Luftwaffe's bomber fleet in the [[Battle of the Atlantic]].<ref name="Griehl 1991, p. 20"/>

===Focus on a heavy bomber===
[[File:3sd Do 217E NAN15Jul1943.jpg|thumb|left|Outline of the Do 217E]]

At the end of August 1938 arguments against the floatplane version were made and proposing a land based aircraft to serve as a torpedo bomber, with more potential applications, were accepted. At the beginning of January 1939 the RLM stopped all work on the marine dive bomber version, as its estimated performance was not adequate.<ref name="Griehl & Griehl 1994, p. 54"/>
On 8 July 1939 Dornier issued a manufacturing specification for a glide bomb-deploying version for full maritime use. It was to be equipped with [[Kraftei|unitized]] BMW 801 engines. The Do 217 E had a new nose and the nose, cockpit rear, and ventral positions carried one MG 15 each. It was to carry a maximum bomb load of two SC 500 and two [[SC 250 bomb|SC 250]] bombs. It was also possible to carry an aerial mine or torpedo,<ref name="Griehl & Griehl 1994, p. 54"/> for which the bomb bay had been substantially extended rearwards, nearly 70% longer than that of the earlier Do 17Z.
A "clamshell"-like [[dive brake]] was fitted aft of the tail, with rear-hinged single dorsal and ventral panels. These features increased the design's weight to {{convert|10500|kg|lb}}. Dornier had intended the speed to be in the region of {{convert|530|km/h|kn}}.<ref name="Griehl & Griehl 1994, p. 54"/>
 
Superficially a bigger [[Dornier Do 215]], and initially powered by the same engines, the Do 217 was actually considerably larger and totally different in both structural and aerodynamic design.<ref name="Green v9 p12">Green 1967, p.12.</ref> The first prototype (the '''Do 217 V1''') flew on 4 October 1938, but crashed seven days later during a single-engine flying test.<ref name="Dressel & Griehl 1994, p. 53"/>{{Sfn | Munson | 1960 | p =  17}}  The aircraft had been piloted by Rolf Koeppe, a flight commander at [[Rechlin-Lärz Airfield|the central ''Erprobungsstelle'' facility at Rechlin]]. A Dornier mechanic, Eugen Bausenhart was also on board.<ref name="Dressel & Griehl 1994, p. 21">Dressel & Griehl 1994, p. 21.</ref> It was found to be underpowered and was not manoeuvrable when compared with contemporary bombers.<ref name="Green v9 p15-7">Green 1967, pp. 15–17.</ref> Instability was a problem at first, but modifications such as fixed [[Handley-Page]] [[leading edge slot]]s along the [[leading edge]]s of the vertical stabilizers helped to improve flight stability.<ref name="Price Aero p60">Price ''Aeroplane'' March 2009, p. 60.</ref>

The second prototype flew on 5 November 1938. After arriving at [[Friedrichshafen]] in June 1939, further evaluations were scheduled to take place. Plans were made to install unitized [[Daimler-Benz DB 603]] engines to enable the aircraft for high-altitude reconnaissance. This meant the fitting of a pressurized cabin. When Daimler-Benz failed to supply the engines, development came to a standstill. On 29 October the RLM ordered the aircraft to be scrapped, or a new use found for it.<ref name="Griehl 1991, p. 23">Griehl 1991, p. 23.</ref>

[[File:Me110.jpg|thumb|Bf 110 using standard 900-litre drop tanks, tested for the Do 217]]
A third prototype flew on 25 February 1939 with Jumo 211A engines in place of the DB 601s.<ref name="Griehl & Griehl 1994, p. 55">Dressel & Griehl 1994, p. 55.</ref> On 15 August 1939 and 23 January 1940, the aircraft was flown to Rechlin, where it was tested in night flying trials. A number of the flights were to assess the performance of the new [[Siemens]] navigation aids under development. At the same time, Dornier also carried out fuel jettisoning and drop tank trials using the standardized 900&nbsp;L capacity, vertical-finned drop tanks pioneered by the [[Messerschmitt Bf 110#Early variants|Bf 110D]] extended-range heavy fighter. As with the Do&nbsp;17, the test team tried several tail configurations with the Do&nbsp;217&nbsp;V3. single, [[Twin tail|double]] and triangular-planform assemblies were tried. These designs were used in the Do&nbsp;217&nbsp;M-3, M-9 and [[Dornier Do 317]].<ref name="Griehl 1991, p. 23"/>

The same units were used on the fourth prototype V4 which flew in April 1939 at Friedrichshafen and [[Rechlin]]. The Jumo proved to be superior, and the designers deemed them to be essential if the desired performance was to be achieved.<ref name="Griehl & Griehl 1994, p. 55"/> In February 1941, the V4 began trials with the dive brake which was installed in the tail. This was to satisfy a demand for the Do 217 to conduct dive bombing missions. It also was fitted with a brake parachute to test the ability of the Dornier to conduct short landings. The parachute brake was also considered in use as a dive brake.<ref name="Griehl 1991, p. 23"/> The V5 prototype was fitted with them and flew in June 1939. Later it was retested with DB 601s and was the third of six aircraft given the official designation Do&nbsp;217&nbsp;A-0.<ref name="Griehl & Griehl 1994, p. 55"/> The Jumo 211 B-1 was used in the V5 prototype. But in September 1939 the water pump and entire cooling system failed. On 28 April 1940 the DB 601 A-1s were fitted.<ref name="Griehl 1991, p. 25">Griehl 1991, p. 25.</ref>

The V6 prototype was powered by Jumo 211B engines, but was also tested with DB 601s. The V7 was tested with BMW 139 engines, but as these had been abandoned for use in the Fw 190 fighter [[Focke-Wulf Fw 190#Later prototypes (BMW 801)|as early as 1939]], use of the unpopular BMW 139 powerplants was never taken beyond the prototype stage. The V8 was given BMW 801 engines, which became the fixture for the entire E series. The Do 217A and C series were only built in small numbers. Owing to this the following D and F types never advanced beyond the design stage.<ref name="Griehl & Griehl 1994, p. 55"/>

There was a desire for the Do 217 to be capable of performing dive bombing, so it was therefore fitted with the aforementioned, tail-mounted dive brakes, with dorsal and ventral panels that were hinged, "clamshell"-fashion, at the extreme rear of the tail extension they emerged from. This could not be made to function adequately in the early models however, and was omitted until the Do 217 E-2 entered service. When this mark reached service, use of the dive brake was found to sometimes overstrain the rear fuselage, so it was often removed.<ref name="Green v9 p24-5">Green 1967, pp.24–25.</ref>

The production specifications were ratified on 8 July 1939, with the ultimate goal of the Do 217 having the capability of flying maritime and land operations armed with glide bombs. The four-seat aircraft was adaptable to both land and maritime operations wherein the tactical emphasis was on bombing from a 50-degree dive angle, and it had a maximum speed of {{convert|680|km/h|kn}}. In contrast with earlier specifications for a modified version of the Do 17M, the proposed Do 217E had a new nose section design in which the A-Stand position was armed with a MG 15 machine gun. Additional MG 15s were to be located in the B and C-Stand gun emplacements. The design teams configured the bomb bay to carry two SC 500 and 250 bombs or four SC 250 bomb loads. In addition a LMB II aerial mine, or an [[F5 Torpedo]] could be loaded. Instead of the dive brakes being installed under the wings as on the R variant, it was placed on the tail of the aircraft. The design was tested in the E-1 and became the blueprint for all subsequent sub-variants.<ref name="Griehl 1991, p. 19"/> The E-1 carried strengthened wing and tail structures to deal with the upgraded armament, which increased the aircraft's weight.{{Citation needed|date=January 2021}}

==Basic design (Do 217 E-2)==

===Wing===
The Do 217 was a shoulder-wing cantilever monoplane. Its two-spar wing was built in three sections: the centre section, incorporating part of the fuselage, and two outer wing sections with very little taper on the leading and trailing edges, leading out to a pair of broad, semi-circular wing tips. The stress bearing [[Skin (aircraft)|skin]] was riveted to spars and ribs. Owing to its future use as a dive-bomber, stressed skin construction was employed with the use of Z-section frames and [[Stringer (aircraft)|stringer]]s. Slotted ailerons were fitted to the outer wing sections. The inner split flaps were electrically operated and had a maximum flap angle of 55°. The ailerons were linked to the flap system to permit partial operation as [[flaperon]]s, meaning if the flaps were lowered the ailerons drooped down.<ref name="Price Aero p58">Price ''Aeroplane'' March 2009, p. 58.</ref>
The design of the rear and front spar attachments revealed the flanges of the spar were flushed with the wing surface making the most efficient structure. The outer wing leading edges were double-skinned.<ref name="Price Aero p58"/> In the wing space, a hot air feed was fitted, using heat pumped through lagged pipes from the engines to warm up and de-ice the wings. The ducts were located just forward of the front spar flanges and in between the main spars where they could escape into the wing. The hot air could escape through the apertures at the aileron hinges.<ref name="Price Aero p58"/> A diversion pipe was also installed in the [[engine nacelle]], which could shut down the hot air flow to the ducts and divert the air out through bottom end of the nacelle if de-icing was not required.<ref name="Price Aero p59">Price ''Aeroplane'' March 2009, p. 59.</ref>
The fuel and oil tanks were located in the wing and centre section. The two outer fuel tanks were located next to the outer side of the engine nacelle. The outermost fuel tank contained a {{convert|160|L|impgal}} fuel capacity, while the tank closest to the engine could accommodate {{convert|44|impgal|L}} of [[oil]].<ref name="Price Aero p58"/> Both were sandwiched in between the main and rear main spar. Between the fuselage and inner side of the engine nacelle, the {{convert|795|L|impgal}} main tanks were located.<ref>Dornier Do 217 E-1/E-3 manual, October 1941</ref> In the centre section a {{convert|1050|L|impgal}} fuel tank was installed forward of the bomb bay.<ref name="Price Aero p58"/>

===Fuselage===
The fuselage was an all-metal structure built in three main sections: the nose section, which accommodated the crew; the section including the wing centre section; and the rear fuselage. The main structure had a conventional stringer and former framework, to which [[stressed skin]] was riveted.<ref name="Price Aero p58"/>
The centre and rear sections were divided in the horizontal plane to within a couple of metres of the tail. The lower half of the fuselage contained the bomb cells, while the remainder and upper parts contained the bracing frames which supported and kept the bomb load secure.<ref name="Price Aero p58"/>
In the lower half of the fuselage the bomb bay extended past the trailing edge [[wing root]]s to nearly a quarter of the way down the rear fuselage. Extra doors were added for [[torpedo]] operations against Naval targets. The extreme rear of the fuselage contained stowage space for anti-shipping weapons.<ref name="Price Aero p59"/>
In the upper fuselage, directly above the forward bomb cells in the centre section, just aft of the cockpit, the 242 gallon fuel tank was located. This had a jettison pipe which was attached to the roof of the fuselage and extended to behind the tail wheel.<ref name="Price Aero p59"/>
Above the two rear bomb cells in the centre section there was an armoured dinghy stowage place. Either side of the dinghy, aft of the {{convert|242|impgal|L}} fuel tank, and directly above the rear bomb bay, were the oxygen bottles.<ref name="Price Aero p59"/>

The tail wheel was retractable and had its own folding doors. The tip of the fuselage could be removed to allow quick access to the jack mechanism which controlled the tail plane [[angle of incidence (aerodynamics)|incidence and pivot]].<ref name="Price Aero p59"/> The tail incidence was automatically changed when the landing flaps were lowered; it could also be adjusted manually.<ref name="Price Aero p60"/>
This tip would be replaced by [[dive brake]]s in the event the Dornier was required to attack precision targets.<ref name="Price Aero p59"/>
The [[horizontal stabilizer]] surfaces were conventional, as part of a [[twin tail]] empennage with "endplate" vertical fin/rudder units, as on the previous production Do 17 airframes. The [[rudder]] contained a balance tab while the [[Elevator (aircraft)|elevators]] contained an elevator balance tab and an automatic dive pull-out tab, in the event of a dive-bombing mission.<ref name="Price Aero p59"/> The stabilisers were fitted with fixed slats, with the trailing edges of the slats positioned inside of the fins. The rudders had very narrow horn balances (the amount of rudder or active control surface forward of the rudder-stabilizer [[hinge]]) which allowed for better balance, and the trimming tabs extended the full length of the stabilizers trailing edges. The stabilizers also had the [[Handley-Page]] [[leading edge slot]]s installed on the inboard side.<ref name="Price Aero p60"/>

===Powerplants===
[[File:BMW801 front.jpg|thumb|The BMW 801 series powered the Do 217E variants.]]

All the Do 217E variants were fitted with  [[Kraftei|unitized]], [[BMW 801]]A [[Engine cooling|air-cooled]] 14-cylinder [[radial engine|radial]] [[aircraft engine]].<ref name="Dressel & Griehl 1994, p. 58">Dressel & Griehl 1994, p. 58.</ref><ref name="Griehl 1991, p. 27">Griehl 1991, p. 27.</ref> The early E-series variants were intended to be fitted with a BMW 801B engine on the port side to give [[counter-rotating propellers]]. The engines  were mounted on welded [[steel]] tube mountings at the extremities of the wing centre section. The oil coolers were integral to the front lower section of the BMW-designed [[cowling]]s, as used in all twin and multi-engined aircraft that used BMW 801 radials for power. The machine had two oil and five fuel tanks which were protected with rubber and self-sealing coverings. In an emergency, [[Carbon dioxide|CO<sub>2</sub>]] could be released into the tanks to extinguish fires. The engines had three-blade, light [[alloy]] VDM propeller units.<ref name="Price Aero p60"/> Flame dampers were also fitted in the form of "fish tail" exhaust pipes.<ref name="Price Aero p59"/> Such a configuration gave a speed of {{convert|470|km/h|kn}} (282&nbsp;mph) at [[sea level]] and {{convert|530|km/h|kn}} (318&nbsp;mph) at {{convert|6700|m|ft}}. It enabled a service ceiling of {{convert|7300|m|ft}} when fully loaded and {{convert|8200|m|ft}} when lightly loaded. The Do 217's range was a much more impressive {{convert|3900|km|mi}}, (compared with the other German bomber types).<ref name="Price Aero p60"/>

The engines and their supporting [[strut]]s were positioned well forward of the leading edge, allowing plenty of room for the [[Landing gear|undercarriage]] and other components. In the upper forward part of the nacelle the de-icing tank was located. The undercarriage was the main structure in this part of the aircraft. Each main unit comprised two oleo legs and a single wheel. It was retracted electrically via the crew in the cockpit.<ref name="Price Aero p60"/>
The adoption by the Luftwaffe midway through the war, of a general system of unitized powerplant installations for twin and multi-engined combat aircraft incorporating as many of the engine's auxiliary components (radiator and oil cooler, and all fluid and mechanical connections) into a single, easily interchangeable unitized "bolt-on" package, known as the ''Kraftei'' ([[power-egg]]) concept, was being widely adopted by the time of the Do 217's initial frontline appearance. The Junkers Jumo 211 was one of the first engines to be unitized as seen on the [[Junkers Ju 88|Ju 88A]], with the BMW 801 radial and Daimler-Benz DB 603 following not long afterwards, as both the BMW radial and the DB 603 inline engines were to be used in such a "unitized" format to power the frontline models of the Do 217.{{Citation needed|date=January 2021}}

===Cockpit===
The Do 217 usually carried a crew of four. Included were a pilot, an observer/[[bomb aimer]]/forward gunner, [[Air gunner|dorsal gunner]]/radio operator and a [[flight engineer]]/ventral gunner. As with the Dornier Do 17, the crew were positioned in the cockpit cabin forward of the engines and leading edge. The pilot sat on the port side, with a spectacle-type [[control column]] mounted on a swinging arm centred in the [[Flight instruments|instrument panel]]. The entire arm could be swung 180 degrees to starboard, placing the yoke in front of the bombardier, in case of emergencies. In the later Do 217K and M with stepless windscreen, the centre pivot was mounted on a rocking control arm or pedestal, rather than a sliding piston, since the instrument panel itself was eliminated (replaced with smaller panels holding the gauges, hung from the edge of the fuselage wall and from the glazing frames above the yoke, respectively.)<ref name="Price Aero p60"/> The bomb aimer sat on his immediate right, slightly below and behind. In combat he could move forward into the nose and operate the bomb release gear or aim the forward machine gun (or 20&nbsp;mm cannon). On the right side of the nose, the bomb aimer's window penetrates the cockpit and is visible as a bulge on the exterior. Back-to-back with the bombardiers seat, the flight engineer/ventral gunner sat on the port side, his seat facing to the rear. The seat of the ventral gunner/flight engineer was next to the radio operator facing forward, behind the bomb aimer. During operations the ventral gunner/engineer would lie on his stomach facing aft, his post as a gunner taking immediate and first priority.<ref name="Price Aero p60"/>
The radio-operator/dorsal gunner sat in a pivoting seat in the extreme rear, above the ventral gun position. His head was inside the B-Stand gun position, and the instruments mounted in a semi-circle around his torso level. The pilot had a curved shield of [[Armour plating]], 8.5&nbsp;mm thick, placed behind his seat. His seat had a further 5mm ({{frac|1|4}} in) of armour and another 5mm ({{frac|1|4}} in) plate above his head, installed in the top of the cockpit roof.<ref name="Price Aero p58-0">Price ''Aeroplane'' March 2009, pp. 58–60.</ref> The dorsal gunner was also protected by armour plating.<ref name="Price Aero p59-0">Price ''Aeroplane'' March 2009, pp. 59–60.</ref>
The ''[[Luftwaffe radio equipment (Funkgerät) of WW II|Funkgerät]]'' or FuG radio communication device compartments were located in the extreme rear of the cockpit, near the leading edge. The [[Autopilot|automatic pilot panel]] was located next to the FuG boxes. In the right-rear of the cockpit the piping that was also attached to the de-icing ducts in the wings also entered the cockpit, as part of a single heating system to emit warm air to heat the cabin if needed.<ref name="Price Aero p59"/>
The FuG X, 16, navigational direction finder ''PeilG V'' [[direction finder]] (PeilG – ''Peilgerät'') and the FuG 25 IFF and FuBI 2 blind landing devices were used in the E-2.<ref name="Griehl 1991, p. 54">Griehl 1991, p. 54.</ref>

===Armament===
The defensive armament consisted of an A-Stand (forward firing machine gun position) in the nose with a [[MG 15 machine gun]]. In the C-Stand (lower rear gun emplacement) at the rear end of the undernose ''Bola'' gondola – a standard feature on many German twin-engined bombers – and a B-Stand position (rear-upper gun post) at the rear of the cockpit glazing, the crew were provided with MG 15 (E-1) or [[MG 131 machine gun]]s (E-2). In the side of the cockpit, two MG 15s were mounted (one on each side) on bearings. As well as the manual machine gun positions, the E-2 was equipped with a ''Drehlafette'' DL 131 rotating turret armed with a 13&nbsp;mm machine gun.<ref name="Griehl 1991, p. 53.">Griehl 1991, p. 53.</ref> In some instances, a moveable 20&nbsp;mm cannon was fitted in the nose and a fixed 15&nbsp;mm weapon was installed in the floor of the nose. The weapons could be controlled by the pilot, via a firing button located on the yoke. To assist in acquiring his target, a Revi C12/C was installed in the cockpit.{{citation needed|date=January 2025}}

The maximum permissible bomb load of the E-series without sacrificing fuel load was {{convert|3500|kg|lb}} of bombs of which a maximum of 3,000&nbsp;kg could be carried internally.<ref>Do 217 E-1/E-2 Kennblatt, Berlin 1941</ref> To have the maximum load of 4,000&nbsp;kg, part of the {{convert|1050|L|impgal}} fuselage fuel tank had to be sacrificed. If long-distance operations had to be flown, drop tanks could be fitted under the wings, which affected speed.<ref name="Griehl 1991, pp. 53-54.">Griehl 1991, pp. 53–54.</ref> Beside the bomb load a LT F5 Torpedo could be carried in its long bomb bay, as well as three aerial mines (the E-1 did not carry the mine load of the E-2).<ref name="Dressel & Griehl 1994, p. 58"/>

==Level and dive bomber variants – radial-engined==

===Do 217 E===
[[File:Rocket Henschel Hs 293 A front.jpg|thumb|Henschel Hs 293 missile with added "Kopfring" (lit. "head ring") on the nose<ref>{{cite web | url = http://www.ibiblio.org/hyperwar/USA/ref/TM/pdfs/TM9-1985-2-German.pdf | title = U.S. Army Technical Manual#TM 9-1985-2, German Explosive Ordnance | author = <!--Staff writer(s); no by-line.--> | publisher = ibiblio.org/hyperwar | page = 15 | access-date = 1 August 2013}}</ref> for nautical targets. It was first tested with the E variant.]]

The E series was the initial major production variant, based on V9 prototype, and powered by two BMW 801 radial engines. Deepened fuselage with larger bomb-bay, entered production in 1940.<ref name="Price variants p116-7">Price 2002, pp. 116–117.</ref><ref name="Green v9 p18-9">Green 1967, pp. 18–19.</ref>
The V9 had been planned as the prototype for the E-1 variant. The V9 had a fixed MG 151 with 250 rounds of ammunition while the MG 204 was to be installed in the nose. The type was fitted with a dummy run of Lofte 7 and BZA 1 bombing systems. The main armament was to be a single torpedo of either SD 1000 or SC 1800 standard. When the mock up had been given the green light for technical development construction began in the spring, 1940. During September 1940 engine vibration problems were experienced but fixed quickly. During flight tests it was discovered the air brake caused a speed loss of {{convert|2|m/s|mph}}. The V9 underwent heavy tests and was withdrawn to Rechlin, where it acted as a prototype until at least October 1943. During this time it also had trials with BMW 801A and BMW 801G engines.<ref name="Griehl 1991, p. 32">Griehl 1991, p. 32.</ref>

====Do 217 E-0 and E-1====
The E-0 was a pre-production bomber/reconnaissance version of Do 217E. It was powered by BMW 801A engines and armed with one forward firing 15&nbsp;mm [[MG 151 cannon]] and five 7.92&nbsp;mm [[MG 15 machine gun]]s on gimbal mounts.<ref name="Price variants p116-7"/> It entered production and service in late 1940.<ref name="Green v9 p19-20">Green 1967, pp. 19–20.</ref> Continued development led to the Do 217 E-1. The Do 217 E-1 first flew on 1 October 1940. Full production level bomber/reconnaissance variant, similar to the E-0, and followed it into production and service in late 1940, 94 were built.<ref name="Price variants p116">Price 2002, p.116.</ref> Additional armament consisted of a 20&nbsp;mm cannon fitted in the nose. Its power plants were BMW 801s of 1,560 [[Horsepower#PS|PS]] ({{convert|1539|hp|kW}}). The aircraft could carry an internal bombload of 2,000&nbsp;kg. Alternatively, it could carry a load of two LMW aerial mines or one torpedo. The E-2 could carry three mines.<ref name="Dressel & Griehl 1994, p. 58"/>

In late 1940, testing under operational conditions began. By March 1941, 37 217s had been built and test flown. Many of the E-1 variants, now being built in increasing numbers, were selected for conversion to the new improved fighter variants; the planned 217H, P and R series. A large number of these "fighter/bomber" aircraft were put through severe testing runs between July and September 1941. Dornier was able to gain valuable knowledge for the future improvement of the armament and bomb jettisoning systems. Of the first six prototypes, two (the third and sixth) were delivered to operational units. The third, Wrk Nr. 1003 was lost on 22 May 1941 (at Rechlin) and 1006, the sixth prototype, was severely damaged on 11 April 1941 whilst with ''[[Kampfgeschwader 40]]''.<ref name="Griehl 1991, p. 42"/>

====Do 217 E-2====
The E-2 was designated as a level and dive bomber, which could be fitted with a clamshell-type dive brake mounted on the fuselage aft of the elevator's trailing edge, with rear-end-hinged dorsal and ventral panels opened and closed by a jackscrew. It was powered by BMW 801L engines and armed with forward firing 15&nbsp;mm MG 151, a single [[MG 131 machine gun]] in the dorsal turret, an MG 131 flexibly mounted at the rear of the ventral  gondola and three MG-15 machine guns{{clarify|mounted where?|date=November 2024}}. The E-2 entered production slightly later than the E-3 level bomber, and was produced in parallel, a total of 185 being built and entering service from the summer of 1941.<ref name="Price variants p116"/><ref name="Green v9 p23-4">Green 1967, pp. 23–24.</ref>

The ''Luftwaffe'' continued to develop the E series. Not satisfied with the E-1, it perfected a modified version it designated the E-2. Testing was not complete until March 1942.  Improvements were added to existing E-1s, which were already being produced by late 1940, and to the prototypes V2 and V4 which would serve as the prototypes for the E-2. The V2 was given the DB 601 engines and a third aircraft, designated V4, was tested with Jumo 211s. Studies of the aircraft began on 15 August 1939, running concurrently with the development of the E-1s. Level, dive and torpedo carrying roles were all examined. Emphasis was also placed on developing a reliable reconnaissance type. These developments were significant as the trials undertaken by the E-1 prototype had ''not'' shown any negative characteristics. Level bombing tests were very positive. Only glide-bombing attacks using interception control, and with dive-brakes open, did not quite match the stringent specifications set some four years earlier.<ref name="Griehl 1991, p. 42">Griehl 1991, p. 42.</ref> According to the test pilots, the aircraft performed well with either the DB 601A, Jumo 211A/B, or even the BMW 801A-1 engines. Pleasing the designers, the test pilots also noted that with all auxiliary bomb racks removed test flights showed at an altitude of 6,000 metres, the Do 217 was quite capable of making an operational range of 2,400&nbsp;km. With the addition of two 900-litre tanks, it increased to 3,700&nbsp;km.<ref name="Griehl 1991, p. 43">Griehl 1991, p. 43.</ref>

The BMW 801 was the preferred powerplant, and although it had been tested by the summer of 1942, the lack of replacements, low production and their use in the [[Focke-Wulf Fw 190]] series prevented large-scale operational testing under combat conditions. In September 1941 flame dampeners were fitted and testing completed.  Further innovations were made regarding the installment of reconnaissance equipment, namely the standard Rb 20/30 cameras. During this final phase, plans to construct and designate an E-1b with MG 131 turret was explored, but later shelved.<ref name="Griehl 1991, p. 46">Griehl 1991, p. 46.</ref> Modifications were also made on the already operational E-1s before the E-2 entered service. One such modification was the installation of MG FF 20&nbsp;mm cannons, the installation of a hand-held MG 131 in the forward-facing glazing of the cockpit and a MG 131 turret facing aft in the B position (rear cockpit covering the rear). De-icing systems were also installed in the cabin and tailplane for high altitude operations.<ref name="Griehl 1991, p. 46"/>

Production of the E-2 began in March 1942. About twelve of the 280 produced at [[Friedrichshafen]] were used as testbeds to keep pace with the constantly changing series specifications. Two, Wrk. Nr. 1221 and 1228, served as testbeds for the BMW 801 L-2 engines as well as flights to assess the installation of auxiliary 300-, 900- and 1,200-litre fuel tanks. During this time, an E-2 equipped with lattice-type airbrakes appeared. It had been designed in June 1940. Its weaponry consisted of a fixed MG 151 in its nose and a MG 15 and the A position. Three rotating positions were put in the B and C stand positions. The machine resembled the [[Junkers Ju 188]]. Later it was installed with ''Kutonase'' (cable cutting equipment).<ref name="Griehl 1991, pp. 49-50">Griehl 1991, pp. 49–50.</ref> The Do 217 E-1 and E-2 could reach 535&nbsp;km/h at 5,300 m and none had a problem with maintaining altitude with BMW 801s, even with weapons, dive-brakes and dampers added, provided it had an all-up-weight of less than twelve tonnes. Machines over thirteen tonnes were difficult to handle and needed experienced pilots at the controls.<ref name="Griehl 1991, p. 51">Griehl 1991, p. 51.</ref>

The failure of the [[Heinkel He 111]], [[Dornier Do 17]], and [[Junkers Ju 88]] during the [[Battle of Britain]] and [[the Blitz]] led the OKL to see the Do 217 as the only heavy bomber with the range, bombload and defences for long-range bombing. The E-2 had incorporated all the new design features such as the ''Drehlafette'' DL 131 turret and a modified bomb bay which allowed to hold 3,000&nbsp;kg of bombs. The E-1s originally were given the FuG X, 16, 25 and PeilG V and FuBI 1 radio sets and navigation aids. The E-2 was given the FuBI2. In the next two variants, the E-3 and E-4, the Siemens FuG 101 radio altimeter was also added enabling the pilot to conduct more accurate and safer low-level attacks. The E-1 had ''Rüstsätz'' /R1 racks for 1,800&nbsp;kg of bombs, the /R2 wing rack and /R3s for 50&nbsp;kg of bombs. Dornier wanted to increase the strength of the racks to increase the size of external loads. A specialist company which had often collaborated with Dornier, Technischer Aussendienst, developed the /R20 rack which enabled heavier loads to be carried. The /R20 enabled fixed MG 81Zs to be installed in the tail cone. The previous lattice air brake was removed; the drag was too much and it bent the fuselage out of shape, making the aircraft unsafe and hastening metal fatigue.<ref name="Griehl 1991, p. 55">Griehl 1991, p. 55.</ref>

====Do 217 E-3 to E-5====
In the E-3, additional armour was fitted to protect crew. Armed with forward firing 20&nbsp;mm [[MG FF cannon]] and seven MG 15 machine guns. (Despite the large number of machine guns, the defensive weight of fire was light, with five of the gimbal mounted machine guns to be operated by the radio-operator, who could only use one at a time).<ref name="Price variants p116-7"/><ref name="Green v9 p21">Green 1967, p.21.</ref>

The E-4 was similar to the E-2, which it replaced in production, but with the dive brakes removed. It was fitted with ''Kuto-Nase'' [[Barrage balloon|barrage-balloon]] cable cutters in the leading edge of the wings. 258 E-3 and E-4 were built.<ref name="Green v9 p25">Green 1967, p.25.</ref><ref name="Price variants p117">Price 2002, p.117.</ref> The E-4 was identical to the E-2, with the exception of the heavy MG FF in the nose. Five of the six positions were flexible, with only one fixed gun; the MG FF installed along the floor, just off centre. The cannon in the nose could be moved.<ref>Griehl 1991, p. 103.</ref> Both were powered by BMW 801L engines.<ref name="Dressel & Griehl 1994, p. 58"/>

The E-5 was a modified version of E-4 for anti-shipping operations. It was fitted with a bomb carrier for a [[Henschel Hs 293]] [[glide bomb]] or a drop tank under each of the outer wings, and carried the appropriate ''Kehl'' series radio guidance and control transmitter system for the missile. It was usually operated with a missile under the starboard wing and a drop tank under the port wing. Sixty-seven were new-built with additional 34 converted from E-4 airframes.<ref name="German military archive, Freiburg"/>

Testing with glide bombs was halted as the electrics were too sensitive to moisture, rockets prone to icing and the radio valves in the control units (in the aircraft) were disrupted by vibrations. By May 1942, hit rates were just 50 percent. In April 1942, the first E-5 reached the test centres at Peenemünde. Various test were made with aircraft with anywhere from 15.4 and 16.5 tonnes in all up weight. Often these tests were made to assess flight characteristics when carrying glide bombs such as the Hs 293.<ref name="Griehl 1991, p. 106"/> The E-5 was given heating units to keep the cold from the heat-sensitive glide bombs' electrics. With external ETCs, but without Glide bombs and auxiliary fuel tanks, the E-5 could attain of a speed of 480&nbsp;km/h at 5,000 m. With two external stores, its speed was reduced to 445&nbsp;km/h and its weight, including 4,300 litres of fuel, was 16.85 tonnes. The Do&nbsp;217&nbsp;E-2/U1 was used as an E-5 prototype. Whether an E series Do 217 ever launched a Hs 294 glide bomb is unclear. The only known fact is that a Do 217 flew a Hs 294 to Berlin-Schonefeld in May 1943. The first launch of the missile was done from a [[Messerschmitt Bf 110]], and thereafter was taken over by the [[Heinkel He 177]] equipped with the [[Kehl-Strasbourg radio control link|FuG 203 ''Kehl'' transmitter]] to control the missile. Only the Do 217, He 177 and [[Focke-Wulf Fw 200]] could carry a Hs 293/4 or Fritz X missile.<ref name="Griehl 1991, p. 106">Griehl 1991, p. 106.</ref>

===Do 217 K===
[[File:Bundesarchiv Bild 101III-Pachnike-041-24A, Flugzeug Dornier Do 217, PK-Filmberichter.jpg|thumb|Do 217K-1, with the K-version's standard "stepless cockpit"]]

To replace the Do 217, the RLM planned for the He&nbsp;177&nbsp;A-3 and A-5 to be the long-range carrier aircraft for missiles, owing to the lack of BMW engines to power the Dornier but problems with the [[Heinkel He 177#Engine difficulties|engine reliability]] of the He 177A led to the failure of the plan. The [[Battle of Stalingrad]] used up more and more aircrew which prevented them retraining on the Do 217 for glide bomb operations. Owing to the problems with the He 177A, Air Inspector General [[Erhard Milch]] returned his attention to the Do 217 and demanded a greater number of improved variants for [[Precision-guided munition]] (PGM) operations.<ref>Griehl 1991, p. 110.</ref>

In early 1942, tests on a new and improved, completely glazed cockpit for the Do 217 series had been underway at the ''Hamburger Schiffbauanstalt'' (Hamburg Shipbuilding Institute). E-2s were fitted with a new streamlined "[[stepless cockpit]]" following its conceptual debut in January 1938 for the [[Heinkel He 111#He 111P|He 111P]], as this design philosophy became the standard for almost all German bombers later in World War II, which eliminated the separate windscreen panels for the pilot of earlier versions of the Do 217. The lower nose of the K-version also retained the ''Bola'' inverted-casemate gondola for a rearwards-aimed ventral defensive armament emplacement, with its forward end fully incorporated with the new nose glazing design. The testing for this new well-framed cockpit glazing format for the later models of the Do 217, was carried out at the Shipbuilding Institute in Hamburg. The design of the cockpit was put to the test using water pressure to simulate a speed of 700&nbsp;km/h. Only a few of the glass panels failed, caused by inadequate mounting. The cabin design passed the tests easily.<ref name="Griehl 1991, p66">Griehl 1991, p.66.</ref> Initial flights took place on 31 March 1942 after teething problems had been resolved. The Do&nbsp;217&nbsp;K&nbsp;V1 flew with BMW 801A-1s from Löwenthal and [[Rechlin-Lärz Airfield|''Erprobungsstelle'' Rechlin]]. This was followed by the ten-airframe pre-production batch, Do 217 K-01 to K-010. Mass production of the Do&nbsp;217&nbsp;K-1 began at the Dornier factory at Wismar.<ref>Griehl & Dressel 1994, p. 65.</ref>

The first prototype, a modified E-2 flew on 31 March 1942,<ref name="Dressel and Griel p65">Dressel and Griel 1994, p.65.</ref> with the aircraft showing higher maximum speed owing to reduced drag. The Do 217 K entered production from September 1942.<ref name="Price variants p120">Price 2002, p.120.</ref> BMW believed that the type could reach an operational ceiling of 7,000 m, notwithstanding a [[Maximum takeoff weight|MTOW]] of 16.8 tonnes. Tests at Peenemünde in June and July 1943 showed that while the Do 217K could carry and deploy a Fritz-X PGM, it was still controllable.<ref>Griehl 1991, pp. 110–111.</ref>

====Do 217 K-1====
The Do 217 K-1 was a night bomber version with the 1560 PS BMW 801L engine.<ref>Do 217 K-1 manual, January 1943</ref> It carried the same crew of four in the "stepless cockpit" crew compartment with a revised defensive armament of a twin-barreled 7.92&nbsp;mm [[MG 81 machine gun|MG 81Z machine gun]] in the nose, two single MG 81s or twin-barrelled MG 81Z in beam positions, a MG 131 in the B stand position dorsal turret, the DL 131/1C, and another in a ventral position inserted in a ''Walzenlafette'' WL 131/1 cylindrical carriage at the rear of its ''Bola'' gondola.<ref name="Griehl 1991, p. 130">Griehl 1991, p. 130</ref> 220 were built.<ref name="German military archive, Freiburg"/> It had an average flying weight of 12,700&nbsp;kg, this aircraft achieved speeds of 520&nbsp;km/h at 5,200 m.{{Citation needed|date=January 2021}}

The K-1 was equipped with [[GM 1]] nitrous oxide boost, which increased its maximum speed by 84&nbsp;km/h at 8,000 m at a rate of 100&nbsp;g/s. With 50&nbsp;g/s the aircraft's operational ceiling could be extended from 8,400 to 9,800 metres. Failure rates of the GM 1 were very high and attention was shifting to other Do 217 variants and the use of GM 1 soon stopped.<ref name="Griehl 1991, p. 130"/> Serious shortages of the BMW 801 led to the cancellation of the K series but tests with BMW 801ML ''Motoranlage'' unitized-mount format radial engines, added a supplementary command unit to the usual 801 ''Kommandogerät'' [[engine control unit]] for each radial, which could engage the booster switch, ignition timing and the weak-rich mixture control automatically, which made the 801L powerplants easy to operate. Oil pressures also triggered operation of the VDM propellers, which on the K-1 subtype were 3.9 m in diameter. A smaller, 3.8 meter diameter wood-bladed propeller could be used as an alternative, though with a slight loss of speed. The standard 2,165-litre fuel tank could be supplemented by two fuselage tanks with 700-litre capacity or with either the standardized Luftwaffe 300-litre [[drop tank]] used on many German front-line military aircraft or fin-stabilized 900-litre drop tank as the Bf 110D used. An all-up-weight of 15 to 16.5 tonnes could be expected. The K-1 would need some 850 to 1,110 m to get airborne. Taking off from a grass strip, an altitude of 20 m was reached after 1,500 m and from a concrete runway it was 1,300. With two auxiliary tanks its speed dropped by 4.5 percent, and with bombs, by 6 percent. Flame-damper equipment also caused serious speed reductions; 7 percent in level flight and 9 percent when at operational ceiling.<ref name="Griehl 1991, p. 129">Griehl 1991, p. 129.</ref>

====Do 217 K-2====
This was a specialised anti-shipping version based on the K-1, intended to carry the [[Fritz X]] guided bomb, being fitted with pylon-faired hardpoints to allow carriage of two Fritz Xs inboard of the engines and the  FuG 203 ''Kehl'' guidance system. It had longer-span wings (24.8&nbsp;m (81&nbsp;ft {{frac|4|1|2}}&nbsp;in) compared with 19&nbsp;m (62&nbsp;ft 4&nbsp;in) for the K-1) to give better high-altitude performance when carrying the heavy Fritz-X bombs. 50 were converted from K-1 airframes.<ref name="German military archive, Freiburg"/> The wing area was expanded by a total of 67&nbsp;m<sup>2</sup>, but most of the K-2s internal equipment was the same as the K-1.<ref name="Dressel & Griehl 1994, p. 65">Dressel & Griehl 1994, p. 65.</ref> The increase in area was to increase high-altitude performance.<ref name="Griehl 1991, p. 130"/> Some of the K-2s had a rigid tail MG 81Z which was not especially effective.<ref name="Dressel & Griehl 1994, p. 66">Dressel & Griehl 1994, p. 66.</ref> It was loaded with 350 rounds and controlled by the use of a rear-facing telescope mounted in the forward section of the canopy left of the pilot. Either the gunners or pilot could fire the weapon, which could be jettisoned in case of an emergency to reduce weight.<ref name="Griehl 1991, p. 130"/>

====Do 217 K-3====
The next variant was the Do 217 K-3. A revised anti-shipping version, the Do 217 K-3 was similar to the K-2 but fitted with improved FuG 203-series ''Kehl'' missile guidance equipment for Fritz-X glide-bombs or Hs 293 missiles. 40 were converted from M-1 airframes.<ref name="German military archive, Freiburg"/> It was given the K-2s larger wings. When fitted with external ETC weapons racks it was named the K-3/U1. It had improved armament, a MG 81Z and MG 81 J in the nose.<ref name="Dressel & Griehl 1994, p. 66"/> The K-3 did not roll off the production lines until the beginning of 1944. The Dornier Do 217 M-11, its intended successor as the standard missile platform, was only produced in small numbers owing to lack of production capacity.<ref name="Griehl 1991, p. 117">Griehl 1991, p. 117.</ref>

==Level and dive bomber variants – inline-engined==

===Do 217 M===
As the BMW 801 radial engine used by the Do 217K was in great demand for the Fw 190 fighter, the Do 217M, a version powered by ''Kraftei''-unitized installation versions of the [[Daimler-Benz DB 603#Specifications (DB 603A)|largest displacement inverted V12]] then in service, the 44.5-litre displacement [[Daimler-Benz DB 603]] liquid-cooled inverted [[V12 engine]], was developed in parallel with the 217K. It shared the new forward fuselage of the 217K, with the first prototype flying on 16 June 1942.<ref name="Price variants p110">Price 2002, p.110.</ref><ref name="Dressel and Griel p66">Dressel and Griel 1994, p.66.</ref>
According to RLM plans, production of the M model, which was powered by DB 603 A-1s was due to commence with two aircraft in May 1942 and 10 M-1s in the summer. By March 1943 a production target of 42 aircraft per month was to be achieved. The DB 603 A-3 was chosen as the increased performance handed the aircraft improved characteristics. However, it had not been fully tested and a number of technical problems arose. A Do 217H (a glider-bomber for land operations with E-2 airframe) would be used for endurance testing. This would provide [[Dornier Do 217#Do 217H, L and R|useful testing evaluations]] for the M-1.<ref name="Griehl 1991, p137">Griehl 1991, p.137.</ref>

The M V1 was to be the first prototype. It was an E-2 conversion with altered cockpit and DB 603 engines and operated from the central Luftwaffe ''Erprobungstelle'' aircraft test centre at [[Rechlin-Lärz Airfield|Rechlin]] from September 1942. During the winter, the prototype performed long-range and high-altitude flights. On 16 November it was forced landed for unstated reasons. Different engine-cooling systems were tried and flame retarders added, although the addition of the dampers caused a reduction in speed of 15 to 25&nbsp;km/h depending on altitude. The first production prototype series M-0 aircraft (M-01) crashed in Lake Müritz, just north of the Rechlin test base, on 9 September 1942, while on an engine test. The M-02 was given wing reduction to 59&nbsp;m<sup>2</sup>, which became the predecessor of the M-3. The M-03 refined the design with DB 603 A-1 engines but crashed after a mid-air collision with a [[Dornier Do 215]] on 14 May 1943. Six 0-series aircraft (Wrk Nr. 1241 to 1245) were manufactured.<ref name="Griehl 1991, p142">Griehl 1991, p.142.</ref> Rechlin log books included frequent references to a M-04 from December 1942 to May 1943. This aircraft was apparently used for de-icing and cabin heating tests as well as high-altitude testing with DB603s. Some M-0s were used to evaluate performance with glide bombs (Wrk Nr. 1244 and 1245). These aircraft were named M-0/U1. Each had an ETC 2000 XII, under the fuselage.<ref name="Griehl 1991, p143">Griehl 1991, p.143.</ref>

====Do 217 M-1====
The M-1 night bomber version, equivalent to Do 217 K-1 but with DB603A engines, carried similar armament and bomb load to K-1.<ref name="Green v9 p28-9">Green 1967, pp. 28–29.</ref><ref name="Price variants p121">Price 2002, p.121.</ref> [[Daimler-Benz DB 601]]s were also used on some variants to keep the airframes in service (the shortage of powerplants made this difficult).<ref name="Griehl 1989, p15">Griehl 1989, p.15.</ref> Mostly though, DB603A-1 engines were used on the M-1, its only major difference from the K series. The M-1/''Umrüst-Bausätze'' 1 (abbreviated "/U1") incorporated the M defensive armament and the lattice air brake of the E-2. The MG 81Z and 131 were to be replaced by the MG 151 in the A-stand position. Problems with the air brakes prevented serial conversions. By November 1943 the M-1/U1 had matured into a night bomber with anti-glare protection in the cabin. The machine was equipped with a MG 131 in the nose, two MG 81Js in the cabin windows and two MG 131s in the B and C stand.<ref name="Griehl 1991, p143"/> Some M-1/U2s were fitted for deployment of German PGM guided ordnance with the required FuG 203d ''Kehl IV'' guidance transmitter, and rear-looking FuG 216 ''Neptun R'' radar equipment.<ref name="Griehl 1991, pp143-145">Griehl 1991, pp.143–145.</ref> 438 M-1 were built by Dornier in Munich and Wismar.<ref name="German military archive, Freiburg"/>

====Do 217 M-2 to M-11====
[[Torpedo-bomber]] version of Do 217M. Only a single prototype was built, the [[Junkers Ju 88]] being chosen as a torpedo-bomber instead.<ref name="Dressel and Griel p66"/> The M-5 series was a modified version of M-1 fitted with Hs 293 missile recessed under fuselage. Only one prototype was built.<ref name="Price variants p121"/> The last in the M series was the M-11. It was a revised anti-shipping version of M-1, with extended wings of K-2 and provision for one Fritz-X or Hs-293 under fuselage. 37 M-11 were converted from M-1 airframes.<ref name="German military archive, Freiburg"/>

====Do 217 R====
In 1941, Dornier worked out a derivative of the Do 217M with dive brakes, a greater wing area, and increased defensive armament, designated '''Do 217R'''. Three Do 217R versions were planned, the baseline Do 217R-0 powered by either DB 603As or BMW 801ML, the Do 217R-1 dive bomber/torpedo bomber, and the Do 217R-2 dive bomber. Four Do 217R prototypes were converted from existing airframes, the first of which flew on August 6, 1942, but the Do 217R did not go into production.<ref name="Griehl 1991,
pp156-158">Griehl 1991, pp. 156-158.</ref>

==Night fighter variants==

===Do 217 J===
[[File:Lichtenstein radar Do 17.jpg|thumb|Nose of prototype Do 17 Z-10 ''Kauz II'' night fighter, similar to that of the Do 217 J, equipped with ''Matratze'' (mattress) 32-dipole radar antenna for its UHF-band early model [[Lichtenstein radar|''Lichtenstein BC'']] AI radar gear]]

In 1941, with Germany under increased night-time attack by [[RAF Bomber Command]] and with shortages of the [[Messerschmitt Bf 110]] and the preferred Junkers Ju 88C night fighters, it was decided to supplement the night-fighter force with a version of the Do 217 E, despite its much greater size and 15-ton weight.<ref>Regnat 2006, p. 16.</ref> This aircraft, the Do 217 J, was fitted with a new "solid" nose, similar to that used by Dornier in night fighter versions of the Do 17 and Do 215, with four forward firing 2&nbsp;cm MG FF cannon and four 7.92&nbsp;mm machine guns.<ref name="Price variants p120"/><ref name="Price variants p110"/> By October 1940, the production of heavy night fighters and night fighters such as the Do 217 and Ju 88, had been discussed comprehensively and by 5 November 1941 these discussions had been concluded. On 23 November the ''Technische Amt'' (T.A.) had ordered the Dornier bomber fleet to be withdrawn in accordance with a decision made earlier that year on 23 May. Dornier designated the subject of their new project the "Do 217 Z", later renamed the Do 217 J.{{Citation needed|date=January 2021}}

The [[Japanese Imperial Navy]] and [[Japanese Army Air Force]] had also taken an interest in license building the type in mid-1942, demonstrating the type's potential. The ''Luftwaffe'', however, had no intention of delivering the Do 217 to Japan, and none were ever exported.<ref name="Griehl 1991, p. 83">Griehl 1991, p. 83.</ref> Dornier encountered many problems in procuring the BMW 801 engines required for the night fighter versions. Junkers had also struggled with BMW deliveries, its Ju 88C variants were to be powered by the BMW as the initial Jumo 211B/F engine plan had been abandoned.<ref name="Griehl 1991, p. 83"/> The Do 217s competitor, the Ju 88 C, had only four fixed guns, whereas the Dornier could hold eight. In most cases, the Ju 88 C carried only one 2&nbsp;cm MG FF and three 7.92&nbsp;mm MG 17s.<ref name="Griehl 1991, p. 83"/>

In January 1941 Junkers concentrated on the C variant designs. It planned on producing 60 C-4s and 374 C-6s powered by Jumo 211s. It later transpired to Dornier that Junkers also wanted the BMW 801 to power the C-6. The power plants would also be supplemented with [[GM-1]] nitrous oxide injection engine performance boosters for greater performance or alternatively, using the new, more powerful Jumo 213. The Ju 88s weaponry was improved by the addition of one or two MG FFs in the fuselage. Both the Do 217 and Ju 88 used the FuG 202 Lichtenstein B/C sets, but later Ju 88s were given FuG 212 Lichtenstein C-1s and later FuG 220s. The equipment of the Dornier did not change. Against this competition Dornier needed to improve the types' abilities as a night fighter.<ref name="Griehl 1991, p. 83"/>
The first problem Dornier attempted to overcome was long and short range capabilities. A modified E-1, (Wrk Nr. 42) was used to test the equipment for the forthcoming Do 217 J. During testing the characteristics of the various types [[fire extinguisher]] hardware were carried out. Performance trials were carried out in January 1942 using an E-2, Wrk Nr. 1122 which was put through its paces at the Löwenthal testing facility.<ref name="Griehl 1991, p. 83"/>

Dornier intended the prototype to ready by February 1942. The machine, Wrk Nr. 1134, was a modified E-2 and equipped with FuG 202 and a ''Spanner-Anlage'' Infrared gun sight. These systems enabled the Dornier to detect the heat signature of enemy aircraft. Heat seeking detection at limited range making the Dornier a good proposition for the [[Defence of the Reich]] campaign. Testing was set back as the prototype crashed owing to engine failure. The continuing slow development of the IR equipment precluded its use in the J-1. Work on the IR program was sped up until late 1943. Modified IR equipment appeared in 1945 and was installed in the Ju 88 G-6.<ref name="Griehl 1991, p. 84">Griehl 1991, p. 84.</ref>

Delays of BMW 801 engine deliveries forced the project to be temporarily abandoned. In November 1941 the directive for the design team had been a J-1 with a Spanner IR system, and a J-2 with Lichtenstein radar. In 1942 the directive changed slightly, and the J-2 was to be fitted with AI radar. Specifically, the Dornier was to be armed with four MG FF fuselage mounted cannon and machine guns for bomber assault, and one MG 131 each in the B-Stand and C-Stand positions for defence from RAF night fighters. Curiously, the night fighter version was ordered to be able to carry eight 50&nbsp;kg bombs<ref name="Griehl 1991, p. 85">Griehl 1991, p. 85.</ref> so the type could act as a night fighter and intruder over enemy territory.<ref name="Griehl 1991, p. 88">Griehl 1991, p. 88.</ref>

The electronic equipment to be installed was listed as the FuG X, 16, 25 Peil G V air-to-ground communications and blind landing devices. The FuB1.1 was also listed as a potential piece, and if possible a FuG 101 radio equipment was to be fitted as standard. It was intended to equip J-1 with the Lichtenstein FuG 202, which had an effective range of 4,000-metre, with three tubes. The weight of the equipment would reduce the performance of the J-1 by 30 – 40&nbsp;km/h so in January 1942, Dornier opted to install the IR spanner equipment instead of the Lichtensten.<ref name="Griehl 1991, p. 85"/> A rear braking system had also been in the original plan, but it was deemed unnecessary.<ref name="Griehl 1991, p. 85"/> The design was declared ready on 5 January 1942 and first flew later that month. The prototype was delivered to the [[Tarnewitz test site|Tarnewitz test facility]] where gunnery trials took place with MG FF and MG 17 weapons. Satisfied with the performance, series production began in March 1942.<ref name="Griehl 1991, p. 87">Griehl 1991, p. 87.</ref>

====Do 217 J-1====
The operational Dornier night fighter, redesignated J-1, before entering operations was powered by BMW 801L engines. It was fitted with a revised crew compartment housing a crew of three, with a solid nose housing four fixed 7.92&nbsp;mm [[MG 17 machine gun]]s, with four 20&nbsp;mm MG FF/M cannon in the forward part of the ventral gondola. It retained the MG 131s in a dorsal turret and ventral position of the bomber, and could carry eight {{convert|50|kg|lb}} bombs in the rear bomb-bay, with a fuel tank in the forward bomb-bay.<ref name="Complete fighter p186">Green and Swanborough 1994, p.186.</ref><ref name="Green v1 p85">Green 1960, p.85.</ref>

Production had commenced in March 1942, during which eight J-1s were built. In April, 13 followed and 55 were built in May. Despite this start production declined in June and this trend continued until November 1942, when only four were built. Dornier had been ordered to withdraw Dornier airframes for unspecified reasons. Owing to this, by 31 December 1942, only 130 J-1s had been completed.<ref name="German military archive, Freiburg"/>
Dornier kept a production run of 19 aircraft for evaluating equipment. These were to be used when [[Josef Kammhuber]], General of the Night fighters demanded the J-1 to have a modified fuselages made available for upward firing cannon installed within the dorsal areas of the fuselage, above the wing roots. This armament configuration was called ''[[Schräge Musik]]'' ("slanted" or "oblique" Music). A prototype was given four MG 151s in place of its MG FFs and named J-1/U1.<ref name="Griehl 1991, p. 87"/> The prototype was modified in September 1942 and sent to the Tarnwitz Experimental Establishment on 14 October for tests on gunnery performance. The guns delivered 125,000 rounds during tests without problems. The concept was available for adoption, although Dornier had some reservations about the slow firing pattern of the MG 151/20.<ref name="Griehl 1991, p. 87"/>

The Dornier appeared to be a very effective night fighter with significant hitting power. However it attracted strong criticism from the ''Luftwaffe''. After the first J-1 was delivered to 4./''[[Nachtjagdgeschwader 1]]'', in March 1942, the crew complained it was too heavy, and criticised its takeoff and landing characteristics. The pilot complained it had "too little performance reserve". The aircraft's high service loading and its poor manoeuvrability in aerial combat did not enhance its performance reputation.<ref name="Griehl 1991, p. 87"/> Part of the types performance issues lay with the fact the MG 131 defensive guns and bomb release mechanisms had remained, and been built into the J-1 to allow for its use as a bomber. With eight machine guns mounted in the fuselage and the supporting ammunition, the weight was increased and outweighed the Do 217E by 750&nbsp;kg.<ref name="Griehl 1991, p. 87"/>

====Do 217 J-2====
The J-2 night-fighter version of Do-217J was fitted with [[Lichtenstein radar#FuG 202 Lichtenstein B/C|FuG 202 Lichtenstein]] [[radar]] in the nose, and had the rear bomb-bay plated over. The MG FF/M of the J-1 were replaced by 20&nbsp;mm MG 151 cannons.<ref name="Complete fighter p186"/> The J-1 was withdrawn from intruder duty following an order stopping night intruder raids against England,<ref name="Complete fighter p186"/> while the J-2 proved disappointing as a night fighter, showing poor performance and manoeuvrability,<ref name="Price variants p110"/><ref name="Donald p39">Donald 1994, p.39.</ref> although they were used for early trials of the ''Schräge Musik'' arrangement of upward firing cannon, three Js being used for tests in July 1942.<ref name="D&G fighter p93">Dressel and Griel 1993, p.93.</ref> The J-2 was only converted from J-1s.<ref name="German military archive, Freiburg"/>

There was little difference in design between the J-1 and J-2, save for the FuG 202 Lichtenstein C1 radar fitted to the later. The first C-1 had been used in the Dornier Do 17 Z-10. Production of the C-1 began in full only after the Do 217J production had ceased. FuG 202 Lichtenstein radar continued to be used in Dorniers, although historian Manfred Griehl points out this was only according to the manuals.<ref name="Griehl 1991, p. 88"/>

Complaints were made by crews about the performance of the Dornier in comparison to other German types. On 12 May 1942 Erhard Milch ordered that Dornier cease all night fighter design. It was decided that the Ju 88 series only (Ju 88 C-6) would continue to be developed and serve as a heavy night fighter. Strangely, the order was not passed onto the Dornier design team who continued to produce the N variant.<ref name="Griehl 1991, p. 88"/>

===Do 217 N===
[[File:Do217Nightfighter.jpg|thumb|Do 217N-1, captured at [[Straubing]], May 1945]]

The end of the J series did not mean the end of the Dornier night fighter. One of the few German fighter pilots to side with the type against its critics was ''[[Hauptmann]]'' [[Rudolf Schoenert]] of ''III./[[Nachtjagdgeschwader 3]]''. Schoenert suggested to his Commanding officer, in July 1942, that trials be made of weapons slanting upwards at an angle of 70° (later known as ''Schräge Musik'') in the fuselage in the hope of increasing the efficiency of his Do 217. This entailed mounting four to six MG 151/20 autocannon in the centre of the fuselage. At ''Technisches Amt'', two Do 217s, one with four and the other with six MG/151/20 cannon were ready for inspection on 5 August 1942 and testing in September.<ref name="Griehl 1991, p. 90">Griehl 1991, p. 90.</ref> The idea of the upward firing cannon had originally come from an engineer, Dr. Poppendieck, in June 1942.<ref name="Griehl 1991, p. 90"/> Nevertheless, Schoenert built on it, and with the introduction of the IR ''spanner'' and headlight, the bomber could approach from below a British bomber and avoid exposure to its powerful powered turrets guarding its tail, nose and upper fuselage by attacking from behind or head-on. Unlike the [[B-17 Flying Fortress]] or [[B-24 Liberator]], the British bombers did not have a ventrally located [[ball turret]], and the new Dornier design attempted to take advantage.<ref name="Griehl 1991, p. 90"/> It was decided, due to cost, to limit the upward-firing armament to four guns. Other tactical improvements involved fitting a semi-rigid brake parachute in October 1942, allowing the Dornier to adjust to the speed of the bomber before firing on its target. The prototypes J-1/U2 and J-1/U4 were tested under these conditions.<ref name="Griehl 1991, p. 90"/>

These designs were to be carried forward into the new variant, the Dornier Do 217 N. The BMW 801 that powered the Do 217 J proved underpowered, so a night-fighter using the more powerful DB 603 A-1<ref name="Griehl 1991, p. 93">Griehl 1991, p. 93.</ref> engines was produced, with the first prototype flying on 31 July 1942.<ref name="Donald p39"/> While it had much improved performance, it was still unpopular due to its poor agility and climb rate,<ref name="Price variants p110"/> and was prone to engine problems.<ref name="D&G fighter p93"/>
Ten pre-production series N variants were designated as test beds. Trials began in the summer of 1942. On 16 August the second prototype Do 217, N&nbsp;V2, entered trials,. The N&nbsp;V1 and N&nbsp;V2 were the main testbeds, and the DB 603 A-1s they were powered by were tested at high altitude. On 11 October 1942 the N&nbsp;V1 crashed after [[Stall (flight)|stall]]ing with its landing gear down and crashing into [[Müritz|Müritz Lake]], killing the crew.
On 21 December 1942, 100-hour engine endurance trials began at Rechlin with the DB engines. The [[piston]]s became useless after 91 hours. Testing of DB 603 A-2 inline engines was carried out between 28 April and 8 May 1943, but the programme was beset by continual breakdowns and the project was abandoned. There was no further record of the N variant prototypes after 20 June 1943.<ref name="Griehl 1991, p. 93"/>

In April 1943, the four MG FF guns had started but were not completed until the late summer. The third prototype, N-1/U was fitted with MG 151/20 and unspecified aerodynamic refinements. The machine was used in high-altitude de-icing tests, and the aircraft was tested with ''Lichtenstein BCR'' and ''Bernhardine'' radar. In August ten of these aircraft were constructed, and between 27 and 31 August, they were fitted with their ''Schräge Musik'' at [[Tarnewitz test site|''Erprobungsstelle Tarnewitz'']] and Wismar Testing Facilities. The tenth N variant, designated N-0, underwent radio trials. The machine was tested with the Peil G VI/APZ 6, a later and more sophisticated variant automatic direction-finding equipment. On 2 December further tactical trials were carried out with infrared target-illuminating equipment. These trials were carried out with DB 601 powered J-1s.<ref name="Griehl 1991, p. 94">Griehl 1991, p. 94.</ref>

====N-1 and N-2====
[[File:Dornier Do 217N night fighter in 1945.jpg|thumb|A Dornier Do 217 N-2 night fighter without radar]]
After testing was satisfied the two variants, the N-1 and N-2, which had two sub-variants, were fitted with FuG 202. The N-1 variants were given two sub-variants which were to follow the design of the E-2/E-4 and the J-1/J-2 with emphasis on range and endurance. Extra fuel tanks were added to the empty bomb bay. For operations over water the heavy night fighters were fitted with lifeboats and radio transmitters. The FuG X with TZG 10 and FuG 16. IFF equipment was the FuG 25s. The N also had the FuG 101 radio [[altimeter]], blind flying equipment FuB1 2 and PeilG V. AI search radar was the FuG 202. The no longer needed bomb release gear remained, bringing the aircraft up to {{convert|15000|kg|lb}} on take-off, so it was barely able to reach {{convert|7400|m|ft}}. Fuel consumption lightened the load, and the Dornier could reach a maximum operational ceiling of {{convert|8400|m|ft}}. The speed of the N was a maximum of {{convert|500|km/h|kn}} at {{convert|6000|m|ft}}. The N-2 was much improved, as it was much lighter and refined.<ref name="Griehl 1991, p. 94"/>

Overall the N-1 was an initial production of the J-1 version. Powered by a DB 603 it had similar armament to Do 217 J-2, retaining defensive armament. Entered service in April 1943.<ref name="Price variants p121"/> Some modified with dorsal and ventral guns replaced by wooden fairings as '''Do 217 N-1/U1''', conversion with ''Schräge Musik'' arrangement of four upward-firing 20&nbsp;mm MG 151s as '''Do 217 N-1/U3'''. About 240 built.<ref name="Price variants p121"/>

The Do 217 N-2 was a new build equivalent of Do 217 N-1/U1; some were fitted with two or four cannon in ''Schräge Musik''  installation. About 95 were built<ref name="Price variants p122">Price 2002, p.122.</ref> until it was retired from front line use in mid-1944.<ref name="Donald p40">Donald 1994, p.40.</ref>

The N-2 was originally not to have the ''Schräge Musik'' armament configuration or a brake parachute, but it was then decided to fit the armament set for tactical reasons. A semi-rigid brake parachute was also installed for unspecified reasons. The N-2 prototype was a converted E-1, serial 0174, code PE+AW. Communications were improved on the FuG 16 ZY and FuG 214. The B and C cupolas were removed and the positions fared over with Plexiglas and wood. The MG FF guns were replaced by MG 151/20 cannon. The MG 17s in the nose were to be abandoned with more powerful armament, but this was never carried out. To kill the excess weight that had plagued earlier types, the bomb bay, its doors, and the bomb release gear were removed, and changes were made to the control panels. The gaps were replaced by lighter wood parts which reduced weight, allowing heavier armour protection for the crew. The N variant was the most heavily armoured Dornier variant.<ref name="Griehl 1991, p. 95">Griehl 1991, p. 95.</ref>
The improvements enabled a top speed of {{convert|525|km/h|kn}} (an increase of {{convert|25|km/h|kn}}) and a reduction from {{convert|15000|kg|lb}} to {{convert|12500|kg|lb}}, which increased ceiling height to {{convert|9500|m|ft}}.<ref name="Griehl 1991, p. 95"/>

==Projects, minor production variants==

===Do 217A===
The A variant was a pre-production reconnaissance version, with original shallow fuselage and powered by DB 601A engines. Armed with three MG 15 machine guns. Nine were built, entering service in late 1940, and used for secret reconnaissance missions over the then-neutral Soviet Union.<ref name="Price variants p116"/><ref name="Green v9 p17">Green 1967, p.17.</ref>
Although the specifications had originally envisaged a multi-role aircraft which could perform bombing missions, it was to function in reconnaissance roles. The fuselage had to be extended to accommodate the two cameras which could be "accessed directly by the crew" (presumably in flight).<ref name="Griehl 1991, p. 26">Griehl 1991, p. 26.</ref>
Dornier was ordered to produce three A-0 series machines up to the E variant. This changed to six as the number of reconnaissance machines was inadequate for the military's need. The small production run would consist of six aircraft. The original power plants, the DB 601Fs, could not be installed in time and the lower performance DB 601B engines were assigned to the type instead for the short term. As in the Dornier Do 17, Rb 20/30 and 50/30 cameras were to be installed. The 20/30 would be fitted in the fuselage while the 50/30 camera was to be placed in the cockpit and be jettisonable. For emergencies the aircraft was to have a fuel transfer unit control installed to move fuel from one tank to another.<ref name="Griehl 1991, p. 26"/>
The first four A-0 aircraft were powered by DB 601Bs while the last two were given DB 601N engines in January 1940.<ref name="Griehl 1991, p. 26"/> The tests were problem free. However the RLM requested a B variant design which would have a fairing in which the film footage would be stored. Dornier reported that the A-0s were not getting the power plants they required for high altitude reconnaissance sorties so construction had to be delayed. The Do 217B program was suspended, as it turned out, altogether.<ref>Griehl 1991, pp. 26–27.</ref>

Dornier completed work on the V6 prototype, the fourth A-0 aircraft. On 15 October 1939 it was flown successfully. The bomb bay had been enlarged and continued testing various weaponry until 1941. It had DB 601P engines installed and its wing was enlarged in early 1941. The DB 601Ps could operate a maximum altitude of 5,800 m and would use high octane C3 aviation fuel. It should have been ready to fly by March, but problems with the engines slowed progress.<ref name="Griehl 1991, p. 27"/>
At that time Dornier was working on additional features, in particular a new [[pressurization|pressurised cabin]] for the A variant. It also hoped to introduce [[GM-1]] booster units to increase performance at extreme altitudes. The first trial of this aircraft took place on 23 April 1940.<ref name="Griehl 1991, p. 27"/>

The RLM had stated it wanted the A prototypes to be tested by May 1940 with its high altitude engines. Owing to unresolved engine complications testing was delayed. Finally, on 1 October 1941 RLM ordered Dornier to return the aircraft to its original condition and abandon high altitude modifications. In January 1942 Dornier was ordered to prepare the two Do 217A aircraft fitted with DB 601Fs for immediate combat operations in both transport and bomber roles. The conversion was to be complete by February but the aircraft were not operational. Finally one machine was made ready and began operations with DB 601F engines on 30 December 1942, some ten months later. The other machine was sent to Löwenthal in July 1940 and had undergone trials with autopilot controls. From March 1941 it had been fitted with BMW 801A-1s and later A-2 engines for greater reliability on long-range sorties. In the summer of 1942 BMW 801G-1 engines were installed while later it had trials with BMW 801G-2 engines which had [[GM-1]] boosters fitted in January 1943 for high performance at altitude.<ref name="Griehl 1991, p. 30">Griehl 1991, p. 30.</ref>
A number of the A prototypes served as test beds through the war. The last (V7) flew testing improvised de-icing systems at altitudes of 9,000 metres. In December 1944 the Dornier projects were halted owing to lack of fuel.<ref name="Griehl 1991, p. 30"/>

In 1940–1941 the A-0s that were allocated to combat units saw service mainly in [[Western Europe]] serving in ''[[Kampfgeschwader 2]]'' from bases in the Netherlands.<ref name="Griehl 1991, p. 32"/>

===Do 217C===
The C series was a pre-production bomber powered by DB 601A engines and original shallow fuselage. It had five MG 15 machine guns installed and {{convert|3000|kg|lb}} bombs as its main offensive armament. Five were built and used as test beds.<ref name="Price variants p116"/><ref name="Green v9 p17"/>
The V9, which had acted as a prototype for the E variant was also used for the C-0 series. The C-0 was a three crew combat aircraft powered by Jumo 211B engines and had a four-bladed 3.8&nbsp;m airscrew. The RLM found no faults with the new machine in a June 1939 inspection. The only minor complaint was the limited view from the pilots' seat. Apart from the same engines and small fuselage space inherent in C-series aircraft, externally the C looked like the A-0 series.<ref name="Griehl 1991, p. 32"/>
On 12 November 1940 Dornier increased the number of the crew to four to enable the five MG 15 weapons in the A, B and C-Stand positions to operate with the maximum protection. The bomb bay had also been modified to take four SC 500 or multiple SC 50 bomb loads. The Do 217 C-0 was equipped with a Lotfe 7A bomb aiming system and a Revi 12C sight for the pilot. For high-altitude flight sixteen 32-litre oxygen bottles were installed. The C-0 was capable of achieving a maximum speed of {{convert|475|km/h|kn}} at an altitude of {{convert|5600|m|ft}}. Carrying a full operational load, its maximum speed was reduced by {{convert|20|km/h|kn}}.<ref name="Griehl 1991, p. 34">Griehl 1991, p. 34.</ref>

The first Do 217 series aircraft, Wk Nr. 2710 flew on tests between September 1940 and March 1941. It crashed on 2 July 1942 at Rechlin. The second C-0 prototype was fitted with dive brakes on the under side of the wings but this configuration was abandoned in January 1941 and replaced by a brake parachute installed in the tail. The third prototype flew on 6 September 1940 and four further machines flew between September and November 1940. The final machine, 2716, flew on 6 November 1940. The eight machines remained at Rechlin in various test bed roles until at least July 1942. The C series project was abandoned and its variants never entered mass production.<ref name="Griehl 1991, p. 35">Griehl 1991, p. 35.</ref>

===Do 217H, L and R===
The Do 217 H was a conversion of a Do 217E with DB 601 engines fitted with experimental [[Twincharger|turbo-supercharger]]s.<ref name="Price variants p120"/> The H&nbsp;V1 to H&nbsp;V3 prototypes were designed as unarmed bombers with DB engines with 3.8 m VDM propellers. Bombs, Recon cameras, and dive brakes were all dispensable. The H&nbsp;V1 was delivered in September 1941 but crashed soon after as a result of propeller failure. After the evaluation of the flight, the wings were expanded to 67 m<sup>2</sup>. In September 1943, after nearly two years of constant delays, the H&nbsp;V1 was fitted with DB603G prototype engines. It is unknown how these tests developed. The H&nbsp;V2 also crashed on 25 October 1942, severely injuring the crew. The cause was the propellers. The H&nbsp;V3 tested a variety of DB603s until November 1944. On 9 June 1942 it successfully tested at high altitude. It also proved successful testing twin exhausts and pulse jets. Later, in October three and four-bladed duralumin propellers were used. Because of better vibration characteristics, the four-bladed VDM was judged the best performer.<ref name="Griehl 1991, p139">Griehl 1991, p.139.</ref> On 11 October 1942 the first flight was made at 8,000 m. After, 9,000 m flights were reached. In September 1943 the DB603E had improved superchargers, giving better high-altitude performance. The H series continued as test beds for the M series until October, when they were cancelled for lack of fuel.<ref name="Griehl 1991, p141">Griehl 1991, p.141.</ref>

The L was a variant of the Do 217K with revised cockpit layout and armament. Only two prototypes were built.<ref name="Green v9 p28">Green 1967, p.28.</ref> The R was a [[Dornier Do 317]] with cabin pressurisation systems removed and modified to carry Hs 293 missiles. Only five built.<ref name="Green v9 p34">Green 1967, p.34.</ref>

===Do 217P===
High altitude reconnaissance/bomber version with two DB 603B engines supercharged by a single [[Daimler-Benz DB 605]]T engine, in a so-called ''Hohen-Zentrale Anlage'' (HZ-Anlage) installation in the central fuselage, as one example of the [[Henschel Hs 130]]E had been fitted with, solely for powering a shaft-driven centrifugal supercharger. Three prototypes, plus three pre-production '''Do 217P-0''' aircraft, armed with six MG 81s. Ceiling of {{convert|16200|m|ft}}.<ref name="Price variants p122"/><ref name="Green v9 p31-34">Green 1967, pp. 31–34.</ref>

==Variant list==
* '''Do 217 A-0:''' Pre-production series with two 1,100&nbsp;PS ({{convert|809|kW|hp}}) [[Daimler-Benz DB 601|DB 601]]B inline engines, used for reconnaissance missions. Only eight aircraft were built.
* '''Do 217 C-0:''' Pre-production bomber, DB 601B engines, increased defensive armament. Only four built.
* '''Do 217 E-0:''' Pre-production bomber with deepened fuselage and powered by two 1,560&nbsp;PS {{convert|1147|kW|hp}} [[BMW 801]]A engines.
* '''Do 217 E-1:''' Production bomber with five 7.92&nbsp;mm (.312&nbsp;in) [[MG 15 machine gun]]s and one 15&nbsp;mm [[MG 151 cannon]] for defence.
* '''Do 217 E-2:''' Bomber with dive bombing capabilities, with three 7.92&nbsp;mm MG 15s, two 13&nbsp;mm (.51&nbsp;in) [[MG 131 machine gun]]s, one 15&nbsp;mm MG 151, and a {{convert|4000|kg|lb}} bombload.
* '''Do 217 E-3:''' Level bomber, seven 7.92&nbsp;mm (.312&nbsp;in) MG 15s and one forward-firing 20&nbsp;mm [[MG FF cannon]].
* '''Do 217 E-4:''' BMW 801L engines.
* '''Do 217 E-5:''' E-4 with extended [[wingspan]], modified on production line with added ''Kehl'' [[radio control]] gear to launch [[Henschel Hs 293]] missiles.
* '''Do 217 G:''' In January 1940 Dornier produced a data sheet for a Do 217 G with BMW 801 engines with the same airframe as a Do 217 E-1. None were built.
* '''Do 217 H:''' Conversion of a Do 217 E with DB 601 engines fitted with experimental [[Twincharger|turbo-supercharger]]s.
* '''Do 217 K:''' Bomber with redesigned forward fuselage with stepped windscreen eliminated, a common World War II German bomber cockpit design concept adopted just before the start of World War II initially on earlier Heinkel bombers (He 111 P and He 177 A). Two 1,560&nbsp;PS BMW 801L radial engines.
* '''Do 217 K-1:''' Standard bomber version.
* '''Do 217 K-2:''' Extended wingspan with ''Kehl'' radio gear to carry Fritz X bombs on underwing racks.
* '''Do 217 K-3:''' Similar to K-2, but capable of carrying both Henschel Hs 293 or Fritz X.
* '''Do 217 M:''' Bomber; Do 217 K with 1,750&nbsp;PS {{convert|1287|kW|hp}} [[DB 603]]A inline piston engines.
* '''Do 217 M-1:''' Equivalent to the K-1.
* '''Do 217 M-3:''' DB 603A-engined equivalent to the K-3.
* '''Do 217 M-5:''' ''Kehl'' radio gear-equipped Henschel Hs 293 carrier with a single missile mounted semi-externally beneath the fuselage.
* '''Do 217 M-11:''' Similar to the K-2 with extended wingspan, ''Kehl'' control gear and Fritz X bombs.
* '''Do 217 J:''' Night fighter based on the Do 217 E. Solid nose with four 7.92&nbsp;mm (.312&nbsp;in) [[MG 17 machine gun]]s and four 20&nbsp;mm MG FFs.
* '''Do 217 J-1:''' Night intruder version.
* '''Do 217 J-2:''' Dedicated night fighter. Bomb bays removed.
* '''Do 217 L:''' Modified version of the Do 217 K with rearranged cockpit and defensive armament. Only two built.
* '''Do 217 N:''' Night fighter based on the Do 217 M. Armament similar to Do 217 J but with improved 20&nbsp;mm MG 151/20 cannons replacing the 20&nbsp;mm MG FFs plus the addition of four 20&nbsp;mm MG 151/20s as ''[[Schräge Musik]]''.
* '''Do 217 N-1:''' Similar to J-2.
* '''Do 217 N-2:''' N-1 with defensive gun turret and bomb bay equipment removed to reduce weight.
* '''Do 217 P:''' High-altitude reconnaissance aircraft with two 1,860&nbsp;PS {{convert|1368|kW|hp}} DB 603B [[supercharged]] by a DB 605T in the fuselage (the ''Höhenzentrale'', or "HZ" system) with a ceiling of {{convert|16155|m|ft}}. Three '''Do 217 P-0''' pre-production aircraft only.
* '''Do 217 R:''' Dive bomber with increased wing area, greater defensive armament, and dive brakes. Four prototypes built.<ref name="Griehl 1991,
pp156-158"/>

==Production==
The production of the Do 217 lasted until December 1943. Between January and August 1944 conversions only took place. Below is a list of the numbers produced.<ref>Griehl 1991, p. 50.</ref>

Quarterly production 1939–1944:
{| class="wikitable sortable" style="font-size: 9pt; text-align:center"
! Quarter !! Year !! Bombers !! Night fighters
|-
| Fourth || 1939 || 1 || 0
|-
| First || 1940 || 1 || 0
|-
| Second || 1940 || 4  || 0
|-
| Third || 1940 || 3 || 0
|-
| Fourth || 1940 || 12 || 0
|-
| First || 1941 || 47 || 0
|-
| Second || 1941 || 52 || 0
|-
| Third || 1941 || 105 || 0
|-
| Fourth || 1941 || 73 || 0
|-
| First || 1942 || 99 || 8
|-
| Second || 1942 || 164 || 75
|-
| Third || 1942 || 160 || 46
|-
| Fourth || 1942 || 141 || 28
|-
| First || 1943 || 187 || 70
|-
| Second || 1943 || 181 || 64
|-
| Third || 1943 || 135 || 73
|-
| Fourth || 1943 || 1 || 0
|}

==Flying the Do 217 M-1==
In October 1945 British Captain [[Eric Brown (pilot)|Eric Brown]] undertook full handling trials with a Do 217 M-1 WNr 56158 at [[RAF Farnborough]]. He recalled a distinctly "underwhelming" experience.<ref name="Price Aero p70">Price ''Aeroplane'' March 2009, p. 70.</ref>
Brown recalled that he took off with full power of some 2,700 rpm and the lightly loaded Do 217 M left the runway at {{convert|160|km/h|abbr=on}}. Brown held a shallow climb, waiting to reach {{convert|200|km/h|abbr=on}} before retracting the undercarriage. Brown timed the time it took to retract, which was between 30 and 40 seconds.<ref name="Price Aero p70"/>
At {{convert|150|m|abbr=on}} he reduced power to 2,500 rpm and raised the [[Flap (aircraft)|flap]]s at about {{convert|230|km/h|abbr=on}}. With the flaps up a climbing speed of {{convert|230|km/h|abbr=on}} was established giving a rate of "very moderate proportions".<ref name="Price Aero p70"/>

While in cruising mode, Brown took the Dornier to {{convert|5500|m|abbr=on}} and with the tail at +2&nbsp;degrees [[angle of incidence (aerodynamics)|angle of incidence]], gave it a top speed of {{convert|523|km/h|abbr=on}}, [[true air speed]].<ref name="Price Aero p70"/>
Brown stated the aircraft was very stable about all three axes, and the controls were well harmonised and effective, and not unduly heavy for bomber operations. At the other end of the speed range, stall occurred at {{convert|154|km/h|abbr=on}}, and was characterised by a gentle nose-down pitch.<ref name="Price Aero p70"/>
At this stage Brown tried the Dornier's single-engine performance and this "proved decidedly unimpressive". It underlined that the aircraft was underpowered. Above {{convert|1500|m|abbr=on}}, height could not be maintained at 2,300 rpm and its ceiling was barely {{convert|7600|m|abbr=on}}.<ref name="Price Aero p70"/>
Brown reverted to "normal power", and decided to "chance his arm" (risk) on a dive-bombing procedure in what he described as a "ponderous aeroplane".
Brown made a straight dive to {{convert|700|km/h|abbr=on}}, the maximum permitted below {{convert|3000|m|abbr=on}} in order to get a feel for the controls, which began to stiffen considerably. The engine revolutions built to 2,750 during the dive causing a lot of noise. Brown pulled the aircraft out of its dive though it called for a "good full-blooded heave" on the control column.<ref name="Price Aero p70"/>

After climbing to regain the height lost, Brown decided to test the tail-mounted, clamshell-like dive brake and automatic pull-out equipment. The Dornier entered the dive automatically when the dive switch was selected and soon attained its "braked condition", limiting the airspeed to {{convert|575|km/h|abbr=on}}. The pull-out was initiated by hitting the bomb-release stick on the control column or selecting the "level flight" switch, which also retracted the dive-brake. Brown stated, "All very sedate and totally unimpressive as a precision weapon".<ref name="Price Aero p70"/>

The landing procedure began at an air speed of {{convert|250|km/h|abbr=on}}. The oil coolers were opened fully and the radiator hatches opened to 30 degrees. At {{convert|240|km/h|abbr=on}} the undercarriage was lowered, which again took 30 to 40 seconds. Flaps were lowered to their start position at {{convert|235|km/h|abbr=on}} and fully deployed at {{convert|220|km/h|abbr=on}}. The tail had to be trimmed to 4 degrees incidence (tail heavy).<ref name="Price Aero p70"/>
Final approach was made at {{convert|200|km/h|abbr=on}} and touchdown occurred at about {{convert|160|km/h|abbr=on}}. Landing weight was roughly {{convert|13000|kg|abbr=on}}. The control column had to be held back beyond the neutral to keep the tail wheel locked until the landing run was complete.<ref name="Price Aero p70"/>

==Operational history==
<!--{{Main|Operational history of the Dornier Do 217}}-->

The first deliveries of Do 217s to operational units of the Luftwaffe was the pre-production Do 217A-0 reconnaissance aircraft, which entered service with the ''Aufklärungsgruppe der Oberbefehlshaber der Luftwaffe'' to carry out clandestine reconnaissance missions over the [[Soviet Union]].<ref name="Price AI p145">Price ''Air International'' September 1993, p. 145.</ref><ref name="Green 3rd p144">Green 1970, p. 144.</ref> Deliveries of the Do 217E started late in 1940, with some aircraft joining another reconnaissance unit, 2 ''Staffel'' of ''Fernaufklärungsgruppe 11'', which was also involved in spyflights over the Soviet Union from bases in [[Romania]].<ref name="Green 3rd p145">Green 1970, p. 145.</ref><ref name="Price variants p108-9">Price 2002, pp. 108–109.</ref>

===Western Europe===
{{Main|Dieppe raid|Battle of the Atlantic|Operation Steinbock|Operation Overlord}}
The first bomber unit to receive the Dornier Do 217 was II ''Gruppe'' of ''[[Kampfgeschwader 40]]'' (II/KG 40) in March 1941, followed by [[KG 2]] later that year.<ref name="Green 3rd p145,154">Green 1970, pp. 145, 154.</ref><ref name="Price variants p109">Price 2002, p. 109.</ref> At first these units, based in the [[Netherlands]], were used to carry out [[Naval mine|minelaying]] and anti-shipping operations over the [[North Sea]].<ref name="Price variants p109"/><ref name="Green p154">Green 1970, p. 154.</ref><ref name="Price AI p146">Price ''Air International'' September 1993, p. 146.</ref> On the night of 24/25 April 1942, however, Dornier Do 217s of KG 2 took part in an attack on the city of [[Exeter]], the first raid of what was to become known as the [[Baedeker Blitz]]. {{Not a typo|KG 2}}'s Dorniers were heavily deployed during the Baedeker raids, against British provincial cities which were less heavily defended than London, which continued until July that year.<ref name="Price Aero p61-2">Price ''Aeroplane'' March 2009, pp. 61–62.</ref>

The Do 217 squadrons had little time to recover as on 19 August 1942 the Allies launched an amphibious raid on [[Dieppe Raid|Dieppe]] in Northern France, with KG 2 launching almost its entire strength of 80 aircraft in response, losing 20 over Dieppe. It had suffered serious losses of trained personnel during operations during 1942, with the number of combat ready crews in KG 2 falling from 88 at the start of the year to 23 by September.<ref name="Price Aero p62">Price ''Aeroplane'' March 2009, p. 62.</ref>

The Dornier Do 217-equipped bomber units spent most of the rest of 1942 recovering from these losses and re-equipping with the more capable Do 217K and M. Night attacks against Britain re-commenced in January 1943, and continued sporadically throughout the year, often suffering heavy losses. As an example the Do 217 equipped KG 2 lost 26 complete crews during March 1943.<ref name="Price Aero p63">Price ''Aeroplane'' March 2009, p. 63.</ref> The pace of bombing attacks against Britain increased again in January 1944 with the launch of [[Operation Steinbock]], with the Do 217 equipped I and III KG/2 and I/KG 66 being involved, these attacks continuing until
May, with the bomber units again taking heavy losses.<ref name="Price Aero p63-5">Price ''Aeroplane'' March 2009, pp. 63–65.</ref><ref name="Hooton p276-7">Hooton 1997, pp. 276–277.</ref>

Two ''Gruppen'' of the anti-shipping ''[[Kampfgeschwader 100]]'' (KG 100) equipped with Do 217s in 1943, with II/KG 100 receiving the Do 217E-5, equipped to carry the [[Hs 293]] guided missile and III/KG 100 the Do 217K-2, with the [[Fritz-X]] guided bomb.<ref name="Price AI p150">Price ''Air International'' September 1993, p. 150.</ref> II/KG 100 made its combat debut against Royal Navy warships in the [[Bay of Biscay]] on 25 August 1943, when it near missed the sloop [[HMS Landguard|HMS ''Landguard'']], while on 27 August, a second attack by 18 Do 217s sank the sloop [[HMS Egret (L75)|HMS ''Egret'']] and badly damaged the destroyer [[HMCS Athabaskan (G07)|HMCS ''Athabaskan'']].<ref name="Price AI p150"/> This attack lead to a temporary withdrawal of [[Royal Navy]] surface ships from the Bay of Biscay until the guided weapon equipped aircraft were transferred to the Mediterranean following the [[Allied invasion of Italy|allied landings at Salerno]].<ref name="Hooton p58">Hooton 1997, p. 58.</ref>

The final actions of Do 217 equipped units over Western Europe was against the allied [[Invasion of Normandy]] in June 1944, when the remaining Do 217 equipped bomber units, II/KG 2 and III/KG 100 were thrown into action against the Allied landings. Losses were heavy, with III/KG 100 losing 8 of 13 servicible Do 217s in 10 days of operations.<ref name="Price AI p151">Price ''Air International'' September 1993, p. 151.</ref><ref name="Price Last p58-60">Price 1991, pp. 58–60.</ref> As American forces broke out of the bridgehead at the end of July, III/KG 100 sent its remaining Do 217s to carry out attacks on bridges over the Rivers [[Sée]] and [[Sélune]] with Hs 293 missiles. They managed a single hit on one of the bridges, which remained in use, while seven Dorniers were lost.<ref name="Price Last p63">Price 1991, p. 63.</ref><ref name="Price variants p114">Price 2002, p. 114.</ref>

===Mediterranean and Italy===
{{see also|Battle of the Mediterranean|Operation Torch|Allied invasion of Sicily|Italian Campaign (World War II)}}

Twelve Do 217 J-1 and J-2 variants were acquired by Italian ''[[Regia Aeronautica]]'' between September 1942 and June 1943 for night fighter operations.<ref name="Dimensione Cielo 1972, p. 47">Dimensione Cielo 1972, p. 47.</ref> One Italian unit was equipped: 235a ''Squadriglia'' of 60° ''Gruppo'' (41° ''Stormo''). Based at Treviso San Giuseppe, then at [[Lonate Pozzolo]], the unit performed poorly. The unit shot down only one enemy aircraft, and lost one of their own, after nearly a year of activity.<ref name="Dimensione Cielo 1972, p. 53">Dimensione Cielo 1972, p. 53.</ref><ref name="Dimensione Cielo 1972, p. 54">Dimensione Cielo 1972, p. 54.</ref>

When the [[Armistice between Italy and Allied armed forces|Italian Armistice with the Allies]] was announced on 9 September 1943, the Italian Fleet was instructed to sail to Malta to surrender. III/KG 100, based at [[Marseille]] launched an attack from its base at comprising 11 Do 217s armed with Fritz-X guided bombs against Italian warships near Corsica, sinking the [[battleship]] [[Italian battleship Roma (1940)|''Roma'']] and damaging the battleship [[Italian battleship Littorio|''Italia'']].<ref name="Price Aero p67-8">Price ''Aeroplane'' March 2009, pp. 67–68.</ref> The Dorniers were then deployed against the Allied landings at Salerno, damaging the cruisers [[USS Savannah (CL-42)|USS ''Savannah'']] and [[HMS Uganda (66)|HMS ''Uganda'']] and the battleship [[HMS Warspite (03)|HMS ''Warspite'']] with Fritz X bombs.<ref name="Price AI p150"/>

The Dorniers of KG 100 continued to be deployed against convoys in the Mediterranean, but by the time of the [[Operation Shingle|Anzio landings]] in January 1944, heavy allied fighter cover and jamming reduced the effectiveness of the attacks, although Hs 293 missiles sank the cruiser [[HMS Spartan (95)|HMS ''Spartan'']] and several destroyers and merchant ships.<ref name="Price AI p150-1">Price ''Air International'' September 1993, pp. 150–151.</ref><ref name="Price Aero p68-9">Price ''Aeroplane'' March 2009, pp. 68–69.</ref>

===Defence of the Reich===
{{see also|Defence of the Reich}}
{{Expand section|date=December 2009}}
Deliveries of the Dornier Do 217J-1 started in March 1942, with night-fighter pilots being unimpressed, considering the type to have poor manoeuvrability and speed. The J-1 was relegated to the training role by summer that year, replaced by the radar equipped J-2 in front-line units.<ref name="Green 3rd p149">Green 1970, p. 149.</ref> Despite the aircraft's faults, the Do 217 was widely used, being used by 11 night-fighter ''Gruppen'', although it did not completely equip any unit, usually being operated in conjunction with the more popular [[Messerschmitt Bf 110]].<ref name="Green 3rd p149"/><ref name="Smith&Kay p136"/> The Luftwaffe deployed the Do 217 night-fighter over Italy and the Eastern front as well as in direct defence of Germany, but the type had been phased out of service by mid-1944.<ref name="Green 3rd p150">Green 1970, p. 150.</ref>

==Operators==
;{{flagcountry|Nazi Germany}}
* ''[[Luftwaffe]]''<ref name="Smith&Kay p136">Smith and Kay 1972, p. 136.</ref>
** ''[[Nachtjagdgeschwader 1]]''
** ''[[Nachtjagdgeschwader 2]]''
** ''[[Nachtjagdgeschwader 4]]''
** ''[[Nachtjagdgeschwader 5]]''
** ''[[Nachtjagdgeschwader 6]]''
** ''[[Nachtjagdgeschwader 100]]''
** ''[[Kampfgeschwader 2]]''
** ''[[Kampfgeschwader 6]]''
** ''[[Kampfgeschwader 40]]''
** ''[[Kampfgeschwader 100]]''
** ''[[Kampfgeschwader 200]]''
;{{flagcountry|Kingdom of Italy}}
* ''[[Regia Aeronautica]]'' (Italian Royal Air Force) operated six Do 217-J-1 and six J-2<ref>''Dimensione Cielo: Caccia Assalto 3, Aerei Italiani nella 2a Guerra Mondiale'' 1972, p. 47.</ref>
;{{SUI}}
* [[Swiss Air Force]] operated a single Do 217N-2, interned after landing at [[Basel]] in 1944 or 1945 and was in use until at least 1946.<ref>Griehl 1991, p. 98.</ref>

==Surviving aircraft==
A total of 1,925 Do 217s were produced, however no complete aircraft survives. The largest known relic of this aircraft, a large piece of the rear fuselage, can be found at the [[Italian Air Force]] Museum in Rome.<ref>{{cite web|url=http://www.preservedaxisaircraft.com|title=Classic Wings Magazine|website=www.preservedaxisaircraft.com}}</ref> One remnant of a Do 217 in the United States is one of the ''Motoranlage'' unitized BMW 801ML (BMW 801L) radials, still fully cowled, at the [[New England Air Museum]] that used to power a Do 217.<ref>{{cite web|url=http://neam.org/index.php?option=com_content&view=article&id=1072|title=New England Air Museum|website=neam.org}}</ref> The remains of two aircraft then based at [[Toulouse]] that crashed over the [[Pyrenées]] in July 1944, were being recovered in 2013.<ref>{{cite news|url=https://www.bbc.com/news/magazine-24159975|title=A French Dornier surfaces bit by bit|first=Chris|last=Bockman|work=BBC News |date=22 September 2013}}</ref>

==Specifications (Do 217 M-1)==
{{Aircraft specs
|ref=Aircraft of the Third Reich Volume one,<ref name="Green">{{cite book |last1=Green |first1=William |title=Aircraft of the Third Reich Volume one |date=2010 |publisher=Crecy |location=London |isbn=9781900732062 |pages=258–285}}</ref> German Aircraft of the Second World War<ref name="German Aircraft">{{cite book |last=Smith |first=J.R. |author2=Kay, Antony L. |title=German Aircraft of the Second World War |year=1972 |publisher=Putnam |location=London |isbn=978-0-85177-836-5 |pages=127–136}}</ref>
|prime units?=met
<!--
        General characteristics
-->
|crew=4
|length m=17
|span m=19
|height m=4.97
|wing area sqm=57
|aspect ratio=<!-- sailplanes -->
|airfoil=<!--'''root:''' [[NACA airfoil|NACA]]; '''tip:''' [[NACA airfoil|NACA]]<ref name="Selig">{{cite web |last1=Lednicer |first1=David |title=The Incomplete Guide to Airfoil Usage |url=https://m-selig.ae.illinois.edu/ads/aircraft.html |website=m-selig.ae.illinois.edu |access-date=16 April 2019}}</ref>-->
|empty weight kg=9065
|empty weight note=
* '''Empty equipped weight:''' {{cvt|10950|kg}}
|gross weight kg=
|max takeoff weight kg=16700
|fuel capacity={{cvt|2960|L|USgal impgal}} in fuselage tank and four wing tanks
|more general=
<!--
        Powerplant
-->
|eng1 number=2
|eng1 name=[[Daimler-Benz DB 603A]]
|eng1 type=V-12 inverted liquid-cooled piston engines
|eng1 kw=1305
|eng1 note= for take-off
:::{{cvt|1379|kW}} at {{cvt|2100|m}}

|prop blade number=3
|prop name=VDM constant-speed propellers
|prop dia m=<!-- propeller aircraft -->
|prop dia ft=<!-- propeller aircraft -->
|prop dia in=<!-- propeller aircraft -->
|prop dia note=
<!--
        Performance
-->
|max speed kmh=475
|max speed note=at sea level
:::{{cvt|560|km/h|mph kn}} at {{cvt|5700|m}}
|cruise speed kmh=400
|cruise speed note=at optimum altitude
|stall speed kmh=
|never exceed speed kmh=
|minimum control speed kmh=
|range km=2180
|range note=with maximum internal fuel
|combat range km=
|ferry range km=2500
|ferry range note=with auxiliary fuel tank
|endurance=<!-- if range unknown -->
|ceiling m=9500
|ceiling note= without bomb load
::: {{cvt|7370|m}} with maximum internal bomb load
|g limits=<!-- aerobatic -->
|roll rate=<!-- aerobatic -->
|climb rate ms=3.5
|time to altitude={{cvt|1000|m}} in 3 minutes 18 seconds
:::{{cvt|2000|m}} in 6 minutes 42 seconds
|wing loading kg/m2=
|fuel consumption kg/km=
|power/mass=
|thrust/weight=

|more performance=
<!--
        Armament
-->
|guns=<br />
:*2 × {{cvt|7.92|mm|3}} [[MG 81 machine gun]] with 500 rpg in the nose
:*2 × {{cvt|7.92|mm|3}} [[MG 81 machine gun]] with 750 rpg in lateral positions
:*1 × {{cvt|13|mm|3}} [[MG 131 machine gun]] with 500 rounds in ventral step
:*1 × {{cvt|13|mm|3}} [[MG 131 machine gun]] with 500 rounds in dorsal position
|bombs= maximum bomb load {{cvt|4000|kg}} ({{cvt|2520|kg}} internally)
|rockets=
|missiles=
|hardpoints=
|hardpoint capacity=
|hardpoint rockets=
|hardpoint missiles=
|hardpoint bombs=
|hardpoint other=

|avionics=
}}

==See also==
{{aircontent
|related=
* [[Dornier Do 17]]
* [[Dornier Do 215]]
* [[Dornier Do 317]]
|similar aircraft=
* [[Junkers Ju 188]]
* [[Martin B-26 Marauder]]
* [[Mitsubishi Ki-67]]
* [[North American B-25 Mitchell]]
* [[Tupolev Tu-2]]
* [[Vickers Wellington]]
|lists=
* [[List of aircraft of World War II]]
* [[List of bomber aircraft]]
* [[List of military aircraft of Germany]]
}}

==References==
===Citations===
{{reflist|30em}}

===Bibliography===
* {{cite book |title=German Aircraft and Armament |date=2001 |publisher=US Army Air Force 1944, Brassey's republished in 2000 |isbn=1-57488-291-0}}
* {{cite book |title=Dimensione Cielo Aerei italiani nella 2° guerra mondiale ''CACCIA ASSALTO 3'' |location=Roma, Italy |publisher=Edizioni Bizzarri |year=1972}}
* {{cite book |last=Dressel |first=Joachim |author2=Griehl, Manfred |title=Fighters of the Luftwaffe |publisher=Arms and Armour Press |year=1993 |isbn=1-85409-139-5}}
* {{cite book |last=Dressel |first=Joachim |author2=Griehl, Manfred |title=Bombers of the Luftwaffe |publisher=Arms and Armour |year=1994 |isbn=1-85409-140-9}}
* {{cite book |editor-last=Donald |editor-first=David |title=Warplanes of the Luftwaffe |location=London, UK |publisher= Aerospace Publishing |year=1994 |isbn=1-874023-56-5}}
* {{cite journal |last1=Garello |first1=Giancarlo |title=La chasse de nuit italienne (3): la méthode scientifique |journal=Avions: Toute l'Aéronautique et son histoire |date=September 2001 |issue=102 |pages=9–16 |trans-title=Italian Night Fighters: The Scientific Method |language=fr |issn=1243-8650}}
* {{cite book |last1=Goss |first1=Chris |title=Dornier Do 217: A Combat & Photographic Record in Luftwaffe Service 1841–1945 |date=2022 |publisher=Classic |location=Manchester, UK |isbn=978-1-90653-758-6}}
* {{cite book |last=Green |first=William |title=War Planes of the Second World War: Volume One, Fighters |publisher=Macdonald |location=London, UK |year=1960}}
* {{cite book |last=Green |first=William |title=War Planes of the Second World War: Volume Nine, Bombers and Reconnaissance Aircraft |publisher=Macdonald |location=London, UK |year=1967}}
* {{cite book |last=Green |first=William |title=The Warplanes of the Third Reich |publisher=Doubleday & Co. |location=New York, US |year=1970}}
* {{cite book |last=Green |first=William |author2=Swanborough, Gordon |title=The Complete Book of Fighters |publisher=Smithmark |location=New York, US |year=1994 |isbn=0-8317-3939-8}}
* {{cite book |last=Griehl |first=Manfred |title=Do 217-317-417: An Operational Record |publisher=Airlife |year=1991 |isbn=1-85310-072-2}}
* {{cite book |last=Griehl |first=Manfred |title=German Twin-Engine Bombers of World War II |publisher=Schiffer Publishing |year=1989 |isbn=0-88740-191-0}}
* {{cite book |last=Hooton |first=E.R. |title=Eagle in Flames: The Fall of the Luftwaffe |publisher=Arms & Armour Press |location=London, UK |year=1997 |isbn=1-85409-343-6}}
* {{cite book |last = Munson |first = Kenneth |title = Enemy Aircraft (German and Italian) of World War II |location = London, UK |publisher = Ian Allan Ltd |year = 1960 }}
* {{cite book |last = Munson |first = Kenneth |title = German Aircraft Of World War 2 in colour |location = Poole, Dorset, UK |publisher = Blandford Press |year = 1978 |isbn = 0-7137-0860-3}}
* {{cite book |last=Olrog |first=Mikael |title=Dornier Do 215: From Reconnaissance Aircraft to Nightfighter |publisher=Classic |location=Manchester, UK |year=2017 |isbn=978-1-90653-752-4}}
* {{cite journal |last=Price |first=Alfred |title=Database: The Dornier Do 217 |journal=[[Aeroplane Monthly]] |volume=37 |issue=3 |date=March 2009 |issn=0143-7240 |pages=53–70}}
* {{cite journal |last=Price |first=Alfred |title=Dornier's Welterweight Bomber |journal=[[Air International]] |volume=45 |issue=3 |date=September 1993 |issn=0306-5634 |pages=145–151}}
* {{cite book |last=Price |first=Alfred |title=The Last Year of the Luftwaffe: May 1944 to May 1945 |publisher=Wren's Park Publishing |location=Ashcroft, UK |year=1991 |isbn=0-905778-74-X}}
* {{cite journal |last=Price |first=Alfred |title=Variant File: Dornier Do 217: The 'Baedeker' bomber |journal=International Air Power Review |volume=5 |date=Summer 2002 |pages=108–123 |isbn=1-880588-44-7}}
* {{cite book |last=Regnat |first=Karl-Heinz |title=Vom Original zum Modell: Dornier Do 217 |publisher=Bernard & Graefe Verlag |location=Bonn, Germany |year=2006 |isbn=3-7637-6037-7}}
* {{cite book |last=Smith |first=J.R. |author2=Kay, Antony L |title=German Aircraft of the Second World War |publisher=Putnam |location=London, UK |year=1972 |isbn=0-85177-836-4}}

==External links==
{{Commons category|Dornier Do 217}}
* [https://books.google.com/books?id=-iYDAAAAMBAJ&pg=PA81 ''Tail Brake on Do-217E Controls Its Diving Speed'', November 1942, Popular Science]

{{Dornier aircraft}}
{{RLM aircraft designations}}
{{Authority control}}

[[Category:Dornier aircraft|Do 217]]
[[Category:1940s German bomber aircraft]]
[[Category:1940s German fighter aircraft]]
[[Category:High-wing aircraft]]
[[Category:Aircraft first flown in 1938]]
[[Category:Twin piston-engined tractor aircraft]]
[[Category:Twin-tail aircraft]]
[[Category:Aircraft with retractable conventional landing gear]]