The  Dornier Do 17  was a twin-engine  fighter aircraft  manufactured by the German company  Dornier . The model was initially designed as a twin-engine  fast passenger aircraft  and was  used  by the  Luftwaffe during World War II  as  a bomber  and  reconnaissance aircraft  . Later, the aircraft were also used as  tow aircraft  for  cargo gliders  .

The development of the  shoulder-wing aircraft  with double  vertical stabilizer  and retractable  tailwheel landing gear  dates back to a 1932 tender issued by the  Army Ordnance Office  . Its slender fuselage earned it the name “Flying Pencil.”

In 1932, at the suggestion of the  Reich Ministry of Transport , which was acting on behalf of the  Army Ordnance Office  and the  Reichswehr operating in the background  , Dornier began developing an aircraft design officially called an “express mail aircraft”. However, the project already envisaged the creation of a medium bomber in addition to its use as a fast transport aircraft. ^[ 1 ]  The name “express mail aircraft” resulted from the secrecy that was necessary to be able to develop military aircraft in Germany while circumventing the  Treaty of Versailles,  and is also found in similar designs for other   bomber designs that had already been initiated  in the Weimar Republic , such as the He 111 , the  Ju 86  or the  Ju 89. [ ^2 ] This  preparatory work benefited the  Nazi regime  , which  began rearming the Wehrmacht soon after it came to power  in 1933.  The Do Y,  initially offered under the designation Do 15   , was rejected because it was outdated. The concept of the completely redesigned Do 17 was presented on March 17, 1933, and accepted by the newly created  Reich Air Ministry  (RLM), which placed an order for two prototypes on May 24, 1933. The Do 17 A (later Do 17 V2) was designed as a passenger aircraft, while the Do 17 C (Do 17 V1) was already a bomber under the code name “Cargo aircraft (with special equipment)” and its construction was given top priority. The  maiden flight  on November 23, 1934, was completed by Dornier chief pilot Egon Fath in the bomber variant.

Flight tests demonstrated the aircraft’s suitability for military use. From the outset, both  liquid-cooled  V-engines  and air-cooled  radial engines were  planned. The Do 17 MV1—a prototype designed for high-speed flight—won the Alpine Sightseeing Flight for multi-seat military aircraft at the 4th International Air Meeting from July 23 to August 1, 1937, at the  Dübendorf military airfield  near  Zurich  , thus garnering international attention. The deployment of 32 Do 17s in the  Spanish Civil War  (nicknamed ” Bacalao ” or  “Stockfish” ) with the  Condor Legion  in the  88th Experimental Bomber Squadron  and the  88th Reconnaissance Squadron  yielded numerous new insights.

The Do 17 was produced in several variants from August 1936 to October 1940. The first two production versions, the E (bomber) and F (reconnaissance), were powered by  twelve-cylinder BMW VI 7.3 V-engines   , while later versions were equipped with the more powerful nine-cylinder  Bramo 323 “Fafnir” radial engines  , which, thanks to their air cooling, were also more resistant to fire. Of these, the Do 17M was a bomber variant, and the Do 17P a reconnaissance variant. A further reconnaissance variant, the Do 17U, was produced in only 15 units; it had two  Daimler-Benz DB 600 engines .

The Do 17Z, powered by the Bramo 323, produced from 1939 onward, was the most powerful and, with at least 535 aircraft built, also the most frequently built version. The last Do 17 variant, the  Dornier Do 215, was  produced from December 1939 to January 1941. 101 units were produced. This was essentially a modified Do 17Z with liquid-cooled  DB 601 V12 engines  .

Many aircraft were lost in the  Battle of Britain  , and from the end of 1940 onwards the Do 17 was increasingly replaced in bomber units by newer models with higher bomb loads and longer range, such as the  Ju 88  and the  He 111.  The remaining operational aircraft were partly converted into  reconnaissance aircraft  (Z-3),  trainer aircraft  (Z-4), weather reconnaissance aircraft (Z-5) and  night fighters  (Z-7, Z-10, a maximum of nine aircraft) or handed over to allied states ( Bulgaria ,  Finland ,  Romania ).

Some Do 17s were also exported: 33 to Yugoslavia (1937/38), ten to Bulgaria (1940), one to Croatia (1942), ten to Romania (1942) and two to Turkey (1942). Yugoslavia ordered seventy Do 17Ks in 1937, the majority of which were to be built under license. Dornier built 20 of this batch (other sources say 36);  DFA  in  Kraljevo  delivered at least 30 more aircraft before the outbreak of hostilities between the German Reich and Yugoslavia ( Balkan Campaign (from April 6, 1941) ) (experience with the Do 17 later led to the Yugoslav  Zmaj R-1 project ).

Dornier incorporated its experience with the Do 17 into the development of the  Do 217 heavy twin-engine bomber  . Although similar in appearance to the Do 17, it was a new development.

Production of the Do 17 for the  Luftwaffe :

• 
  Second prototype Do 17 A (V2)
• 
  Do 17 V8 (F-1)
• 
  Do 17 MV2
• 
  From 17 E-1
• 
  Do 17 E as a tow aircraft for  DFS-230 cargo gliders of the  Airborne Wing 1 , 1943
• 
  Do 17 M
• 
  Do 17 M-1 of 2./KG 2, in Liegnitz or Gerdauen, 1939
• 
  A Do 17 Z of  Stab/KG 3 , 1940

No museum houses a fully preserved example; only parts of individual aircraft are on display. In the summer of 2007,   a well-preserved wreck of a  Dornier Do 215 B-5 (a variant of the Do 17 Z) was discovered in the Dutch part of the Wadden Sea  .

 In 2008 , the well-preserved remains of a Do 17 Z-2 were discovered in the mud of the  English Channel  near the  Goodwin Sandbanks . ^{[ 3 ] [ 4 ]}  The aircraft with the  squadron identification  5K+AR (7. Staffel, III. Gruppe  Kampfgeschwader 3 , Werknummer 1160) had taken part on 26 August 1940 from  St. Trond airfield  , together with aircraft of  Kampfgeschwader 2 ,  in an attack on the  RAF airfields at  Debden  ( District  Uttlesford ) and  Hornchurch  near  London  , but lost its bearings on approach above the clouds and was separated from the formation. Shortly afterwards, it was attacked by several  Boulton-Paul Defiant fighters of  RAF Squadron 264. The cockpit and both engines were hit, one of which failed and one was damaged. The wounded pilot, Willi Effmert, decided to make an  emergency landing  on the sandbanks and first dropped his 740 kg bomb load. The aircraft touched down on a sandbank at 1:40 p.m. with its undercarriage retracted and overturned. The pilot and observer were able to escape and survived as prisoners of war, while the radio operator and bombardier were killed. Their bodies were later washed ashore in England and the Netherlands and buried there. ^[ 5 ]  In June 2013, the wreckage was recovered and then taken to the  Royal Air Force Museum  in  Cosford  . According to the museum, it will be treated there for two to three years, initially using a new type of preservation process specially developed for this aircraft. ^{[ 6 ] [ 7 ]}  Since October 2013, an exhibition has been on display at the museum in Cosford, parallel to the conservation work, showing the recovery of the wreckage and the history of the aircraft. ^[ 8 ]  An   “Interpretation Zone” at the  RAF Museum in London, sponsored  with £75,000  by the Belarusian  computer game developer  wargaming.net, uses augmented reality  techniques to give   additional visitors access to this historic find.