Editing Dornier Do 17 (section)

==Variants==
===Early Daimler-Benz-powered variants===
[[File:Bundesarchiv Bild 101I-565-1407-35A, Italien, Dornier Do 17, Lastensegler DFS 230.jpg|thumb|Dornier Do 17E in Sicily with [[DFS 230]] gliders, 1943]]
The initial production variants were the Do 17E-1 bomber, which was tested with two [[Daimler-Benz DB 600]],<ref name="Dressel and Griehl 1994, p. 26."/> and Do 17F-1 reconnaissance aircraft, powered like the early prototypes with BMW VI engines, which entered production in late 1936. The first Luftwaffe units converted to the Do 17 in early 1937.<ref name="Green v8 p142-144">Green 1967, pp. 142–144.</ref>

The '''Do 17E-1''' was equipped with two BMW VI 7.3D [[Inline engine (aviation)|inline engine]]s of 750 [[Pferdestärke#PS|PS]] each. The crew numbered three. The radio operator manned the two 7.92&nbsp;mm MG 15 machine guns within a ''B-Stand'' pod in the rear cockpit; they had 750 rounds of ammunition. The bomb bay was divided into two compartments. Each had five bomb racks with individual capacity of {{convert|50|kg|lb|abbr=on}}. A single ETC 500/IX bomb rack could be mounted externally underneath the aircraft to carry a 500&nbsp;kg bomb. A Do&nbsp;17&nbsp;E-1 with the designation D-AJUN was tested with an unusual configuration, two [[SC500 bomb|SC 500 bombs]] mounted side by side under the fuselage.{{refn|It appears the single rack could carry an unusual weight of at least one heavy {{convert|450|kg|lb|abbr=on}} bomb. In an unusual trial two SC 500s (500 kg), weighing roughly 1,100 lbs each, appear to have been carried by an ETC 500 rack. This would indicate that the "500" figure in the model name of the rack itself, does not denote maximum load capability{{cn|date=February 2024}}|group="Notes"}} It showed a notable performance reduction due to the increase in weight and drag, this configuration was not used operationally. The E-1 continued to carry low bomb loads into the [[Second World War]]. The performance of the E-1 enabled it to reach a speed of {{convert|330|km/h|mph|abbr=on}} at {{convert|3,000|m|ft|abbr=on}}. Conducting a shallow dive the light frame of the Do 17 could reach {{convert|500|km/h|mph|abbr=on}}. Its maximum ceiling was {{convert|5,500|m|ft|abbr=on}}. Several E-1s were rebuilt as E-2 or E-3, at least three E-2 and one E-3 were used by DVL and Hansa-Luftbild GmbH (Hansa Aerial Photography Ltd) in a secret military reconnaissance role prior to the war.<ref name="Griehl 2005, p. 3">Griehl 2005, p. 3.</ref>

The '''Do 17F-1''' was a long-range reconnaissance aircraft based on field modified Do 17Es. The Do 17 prototype V8 was used to test the configuration of the F-1 and V11 for the F-2. The defensive armament consisted of a MG 15 in the B- and C-Stand (B-Stand - an upper rear firing position, C-Stand — lower gun emplacement). The fuselage had two cameras along with six ejector tubes for flashlight cartridges. The F-1 saw service until replaced by the Do 17 P in 1938. Only one F-2 was ever built, it was designated D-ACZJ and was used by Zeiss-Jena Company as a factory aircraft.<ref name="Griehl 2005, p. 3"/>

Conversion of two E-2 series aircraft with two [[BMW 132F]] [[radial engine]]s led to the '''Do 17 J-1''' and J-2. These aircraft served as flight testing machines to evaluate the BMW 132 for usage in the Do 17. The aircraft were the V18 (''Wrk Nr'', or ''Werknummer'' meaning works/factory number, 2021) and V19 (Wrk Nr 2022) prototypes. Trials began in late 1937. A similar conversion, but with Bramo 323 radial engines, led to the designation Do 17 L-1 and L-2. Two Do 17 (Wrk Nr 2031 and 2032) were renamed as V20 and V21 prototypes and used to evaluate the Bramo 323 for usage in the Do 17. The test was satisfactory and all future production models were equipped with this engine.<ref name="Griehl 2005, p. 3"/>

After seeing the Do 17M V1 at the Zürich air races in 1937, the [[Yugoslav Royal Air Force]] bought license rights for production at the ''Drzavna Fabrika Aviona'' factory in 1938. They equipped it with the more powerful [[Gnome-Rhône Mistral Major|Gnome-Rhône 14 NO]] radial engine.<ref name="Ciglic and Savic 2007, pp. 6-7"/> Dornier designs were delivered to the ''Pomorsko Vazduhoplovstvo'' (Naval Aviation - PV) in 1926, namely the [[Dornier Komet]] and [[Dornier Do Y]] heavy bombers. The Yugoslavs were familiar with Dornier designs, and on 19 November 1935 Yugoslav pilots test-flew the Do 17 V-3 prototype, D-ABIH, ''W.Nr.'' 258. They decided to select the Do 17 for service, despite it being more expensive than any other aircraft, because of the German willingness to deliver them quickly without limitations on numbers.<ref name="Ciglic and Savic 2007, p. 5">Ciglic and Savic 2007, p. 5.</ref>

The '''Do 17L-0''' and '''Do 17M-0''' were developed in parallel as replacements for the earlier E and Fs, the L being the reconnaissance version. Both were designed around the more powerful DB 600A engines, delivering about {{convert|746|kW|hp|abbr=on}}. Two L and one M versions were built as prototypes, both with another MG 15 in the nose.<ref>Nowarra 1990, p. 14.</ref> The first prototype of the revised version, the Do 17M V1 (D-ABVD) was powered by two DB 600s, and demonstrated impressive performance, including a maximum speed of {{convert|425|km/h|mph|abbr=on}}.<ref name="pencil p46">Green and Swanborough 1986, p. 46.</ref>

At the International Military Aircraft Competition at Zürich, Switzerland, in 1937, the Dornier Do 17M V1 proved a leader in its class and was faster than the fastest foreign fighter, the French [[Dewoitine D.510]].<ref name= "Nowarra p. 5"/> The Do 17, along with the [[Messerschmitt Bf 109]], won many prizes, demonstrating the prowess of German aviation design.<ref name="Dressel and Griehl 1994, p. 26."/><ref>Smith 1967, p. 4.</ref>

===Radial variants===
Despite its success, owing to shortages in the supply of the [[Daimler-Benz]] engine, the production Do 17M was fitted with the Bramo 323 engine,<ref name="Green v8 p146">Green 1967, p. 146.</ref> with the corresponding reconnaissance aircraft, the Do 17P, being powered by BMW 132Ns to give better range.<ref name="Green v8 p148">Green 1967, p. 148.</ref>

The supply of the DB 600 remained extremely limited as production was soon switched over to the fuel-injected DB 601, which was reserved for the Messerschmitt Bf 109 and [[Messerschmitt Bf 110]] fighters. Therefore, production versions of the basic Do 17M model airframe were fitted with the new Bramo 323A-1 Fafnir engines of {{convert|670|kW|hp|abbr=on}}, which gave reasonable performance and raised the bomb load to {{convert|1,000|kg|lb|abbr=on}}. The resulting '''Do 17 M-1''' was produced in small numbers and operated until 1941.<ref>Goss 2005, pp. 9–10.</ref>

The prototypes for the M-1 series were Do 17M V1 (Werk Nr 691) and Do 17M V2 (''Werk Nr'' 692) which were tested with bomb loads of a medium bomber. The third prototype, Do 17M V3 was evaluated as a fast bomber. The M V1 was fitted with two Daimler Benz DB 601 inline engines while the M V2 and M V3 had the Bramo 323 A and D respectively. The Ministry of Aviation favoured the widespread use of the DB 601, but demand for the DB 601s in fighter aircraft and the lack of production forced the use of the Bramo.<ref name="Griehl 2005, p. 4">Griehl 2005, p. 4.</ref>

The Do 17 M-1 started its service as a medium bomber and was able to carry {{convert|2200|lb|abbr=on}} of bombs. It was equipped with two [[Air-cooled engine|air-cooled]] Bramo 323 A-1 or A-2. The defensive armament consisted of two, and later three, MG 15 machine guns. The first was operated in an A-Stand pod operated by the navigator through the windshield. The position was allocated 370 rounds of ammunition. The rearward firing B-Stand was operated by the radio operator and allocated 750 rounds. The rear position in the lower fuselage was allocated 375 rounds in a C-Stand pod. The Do 17M could carry a bomb load of either 20 SC50 {{convert|50|kg|abbr=on}} or two [[SC250 bomb|SC250]] {{convert|250|kg|abbr=on}} bombs or 10 SC50 and a single SC250 bomb. The speed of the M was superior to that of the E variant. The Do 17M could reach {{convert|420|km/h|mph|abbr=on}} at altitudes of {{convert|3,500|m|ft|abbr=on}} and could achieve a maximum service ceiling of {{convert|5,790|m|ft|abbr=on}} and a range of {{convert|850|nmi|km}}.<ref name="Griehl 2005, p. 4"/>

[[File:Do-17-2.jpg|thumb|left|Do 17Z in the [[Soviet Union]], winter 1941–42 showing its sleek, pencil-like, outline]]
Reconnaissance aircraft based on the M-1, the under-surfaces of the wing were covered with [[duralumin]] and it had a wider engine axis and longer engine nacelles. The demand for a reconnaissance aircraft based on the M-1 led to the development of the P-1 variant.<ref name="Ciglic and Savic 2007, p. 10">Ciglic and Savic 2007, p. 10.</ref> The L version would not be able to enter production with the DB 600 owing to its use in the Bf 109, and the Bramo engine was rather thirsty on fuel and left the M models with too short a range for reconnaissance use. [[BMW 132]]N radials of 865&nbsp;PS were selected instead, which had lower fuel consumption for better range. Another two prototypes with DB 600 engines were produced as the '''Do 17R-0''', but did not enter production. During reconnaissance missions the P-1 was armed with four MG 15s in the A, B and C—Stands. One machine gun was located in the rear of the cockpit, another in the lower rear ''Bola'' mount, one facing forward through the windscreen and the other in the nose glazing.<ref>Griehl 2005, p. 30.</ref> In earlier variants the B-Stand (the gun position in the upper rear cockpit) was open to the elements, but the P-1 now provided an enclosed bulb-shaped mount protecting the radio operator from the weather.<ref name="Griehl 2005, p. 22">Griehl 2005, p. 22.</ref>

The P variant had similar features to the Do 17M-1, with added blind flying and camera equipment for reconnaissance work. The '''Do 17P-1''' was powered by two BMW 132N radial engines with a maximum performance of 865&nbsp;PS ({{convert|853|hp|kW|abbr=on}} each. The machine was fitted with several radio variations. The FuG IIIaU radio ([[Luftwaffe radio equipment (Funkgerät) of WW II|''Funkgerät'']]), the PeilG V direction finder (PeilG - ''Peilgerät'') and the FuBI 1 radio blind-landing device (FuBI - ''Funkblindlandegerät'').<ref name="Griehl 2005, p. 4"/> The crew of three communicated with each other via the EiV [[intercom]] (EiV -''Eigenverständigungsanlage'').<ref name="Griehl 2005, p. 4"/> The P-1 was equipped with either Rb 20/30 and Rb 50/30 or Rb 20/18 and Rb 50/18 cameras. The P-1/trop was fitted with filters and protection for the cameras.<ref>Smith 1967, p. 5.</ref> The cameras were controlled remotely by the crew from the cockpit.<ref name="Griehl 2005, p. 22"/>

[[File:Bundesarchiv Bild 101I-343-0663-17, Belgien-Frankreich, Dornier Do 17, Instandhaltung.jpg|thumb|A Bramo 323 radial engine is serviced in front of a D 17]]

Due to a shortage of night fighters, at least one Do 17P-1 was assigned to this role. A smooth metal sheet was installed in place of its glass nose and it was armed with three {{convert|20|mm|abbr=on}} MG 151/20 cannons. The machine operated under [[Luftflotte 1|''Luftflotte'' 1]].<ref name="Nowarra 1990, p. 41"/>

The '''Do 17P-2''' was identical to the P-1, with the additional installation of an ETC 500 bomb rack under the fuselage. These aircraft were designed for night reconnaissance. It is assumed that Dornier converted most, if not all, P-2 models from existing P-1 production aircraft.<ref name="Griehl 2005, p. 4"/>

Unlike the P-2, the '''Do 17R-1''' did not see series production. The experiences of the Spanish Civil War proved that unarmed aircraft were easy prey for [[fighter aircraft]]. The R-1 was to be a fast long-range reconnaissance aircraft with two additional fuel cells inside the fuselage aft of the bomb bay. Two variants were suggested, the first (variant I) had a Rb 50/30 and two Rb 20/30 cameras, while variant II had a third fuel cell to replace the rear Rb 20/30. The aircraft had a gross weight of {{convert|7250|kg|abbr=on}} but could be overloaded to {{convert|7500|kg|abbr=on}} in emergencies. The crew usually numbered three, but a fourth was added depending on the missions to be flown.<ref name="Griehl 2005, p. 4"/> To achieve a high performance at increased altitudes two DB 600 Gs were to be used. The power plants were tested in the Do 17R V1 prototype registered D-ABEE. The second, the R V2, registered D-ATJU, received the even more powerful DB 601 Aa engines.<ref name="Griehl 2005, p. 5."/> The power plant of the R-1s that did exist is not known.<ref name="Griehl 2005, p. 11."/>

The lessons from the Spanish Civil War had led Dornier's designers to incorporate more defensive machine guns. Battles with [[Soviet Union|Soviet]]-built fighter aircraft had demonstrated that the Dornier was not as fast and invulnerable as was first thought.<ref name="Griehl 2005, p. 5."/> To cope with this, a completely new pod-like cockpit was designed to give the crew more room and better visibility. The roof was extended upward over the line of the fuselage, sloping down to meet it just in front of the wing. The dorsal gun was moved to the rear of the pod where it had a considerably better field of fire. The floor was dropped under the fuselage as a ''Bola'' casemate-style defensive armament emplacement, and the ventral gun moved to the back of the ''Bola'', allowing it to fire directly to the rear. The changes in the roof and floor made the front of the aircraft much larger and the rest of the airframe remained the same. The new cockpit design was nicknamed ''Kampfkopf'' (German: "battle head").<ref name="Griehl 2005, p. 5."/>

Three S variant prototypes with the DB 600 G inline engines were tested. The S-01 (designation D-AFFY), 03 and 04 were flown.<ref name="Griehl 2005, p. 5."/> The inverted V-12 engines were constructed as the '''Do 17 S-0''' reconnaissance version, but it did not go into production. An additional 15 '''Do 17 U-1''' pathfinder models were built, similar to the S-0 but adding another crewman (taking the total to five) to operate the extra [[radio]] equipment. The U models were to fly ahead of other bombers on night missions, using the radio equipment to locate the target and drop flares on it. They were personally requested by KG 100 as experimental models for this role. The U-1 had a maximum speed of {{convert|265|mph|km/h|abbr=on}} and a combat ceiling of {{convert|4,500|m|ft|abbr=on}}. The U-1 had a cruising speed of {{convert|384|km/h|mph|abbr=on}} and a maximum reachable height of {{convert|5,700|m|ft|abbr=on}}, owing to the "rather low performance of the Bramo 323 A-1 engines". The three prototypes (U-01 - U-03) and twelve production aircraft were built by 1938.<ref name="Griehl 2005, p. 5."/>

===Dornier Do 17Z: The main variant===
[[File:Dornier Do 17 Z (1942).jpg|thumb|Do 17Z of the Finnish Air Force, January 1942]]

The Dornier Do 17Z series was the most recognised and mass-produced variant, and saw more combat service than the E-U types. The type was modified as a result of combat experience during the Spanish Civil War. The forward [[fuselage]] was redesigned, with the cockpit area being "dropped", or extended further to enable a rear firing gunner position to be installed, and the [[Aircraft canopy|canopy]] extended aft, until it was nearly parallel with the [[leading edge]] and [[wing root]].<ref name="Goss 2005, p. 12."/>

To test the design, the Do 17S and Do 17U were produced, both to be powered by the DB 600 power plants. However, a call for all DB 600 series engines to be reserved for fighters led to the variants being fitted with Bramo Fafnir 323 A radial engines. The bomb load was increased to {{convert|1,000|kg|lb|abbr=on}} and a fourth crew member was added. It proved to be underpowered, so Bramo 323 P engines were then fitted. Only three Do 17S and 15 Do 17Us were built. With the updates, the Dornier, with a full bomb load, had a combat radius of {{convert|322|km|mi|abbr=on}}. Later variants, in the Do 17Z-3, Z-4 and Z-5, which were fitted with cameras, dual trainer controls and flotation aids (for maritime operations) respectively, still could not solve the problems with range and bomb load.<ref name="Goss 2005, p. 12."/>

At first, a batch of '''Z-0'''s were built with the Fafnir for testing, the DB 600 again proving to be too hard to obtain. These were quickly replaced with the '''Z-1''' model, which added another gun for the bombardier, but the additional weight of the nose and guns meant the bomb load was reduced to {{convert|500|kg|lb|abbr=on}}. The Luftwaffe, not being satisfied with the test outcome of the Z series, immediately ordered performance and design studies to increase the overall performance of the bomber. These resulted in very optimistic speeds and altitudes for all future Z variants, especially for the Z-5 aircraft. Planned performance altitudes of up to {{convert|7,620|m|ft|abbr=on}} at a maximum speed of {{convert|418|km/h|mph|abbr=on}} with an aircraft weight of {{convert|8,100|kg|lb|abbr=on}} were planned. Unfortunately, production aircraft never reached these optimistic performances during the service career of the Do 17Z. At {{convert|7,740|kg|lb|abbr=on}}, the heavy Do 17Z-1 used two Bramo 323 A-1 engines with self-sealing fuel cells in the fuselage and wings. The crew of four consumed approximately 20 bottles of oxygen during long flights above {{convert|3700|m|ft|abbr=on}}. The Do 17Z-1 had a speed of {{convert|352|km/h|mph|abbr=on}} at {{convert|1,100|m|ft|abbr=on}}. However, the performance of the Bramo 323s did not permit the Do 17 to reach {{convert|416|km/h|mph|abbr=on}} at {{convert|3,900|m|ft|abbr=on}} and level flight when fully loaded. Range of the Z-1 at ground level was {{convert|635|nmi|km|abbr=on}} while at {{convert|4,700|m|ft|abbr=on}} this increased to {{convert|850|nmi|km|abbr=on}}. This gave an average range of {{convert|400|nmi|km|abbr=on}}. The introduction of the Bramo 323P increased subsequent performance in the following sub variants.<ref name="Griehl 2005, p. 5."/>

This was addressed in the major production model, the '''Do 17Z-2'''. The Z-2 mounted the new 323P-1 version of the Fafnir with {{convert|746|kW|hp|abbr=on}}, which was specifically tuned to the performance needs of the Do 17 by decreasing [[supercharger]] power at lower altitudes and thus improving low-level performance. The increase in takeoff power allowed the bomb load to be increased from {{convert|500|to|1,000|kg|lb|abbr=on}}.<ref name="Dressel and Griehl 1994, p. 26."/> However the combat range with a full {{convert|1,000|kg|lb|abbr=on}} bomb load was a very short {{convert|330|km|mi|abbr=on}}.<ref name="Goss 2005, p. 12."/> The armament was further upgraded by adding another pair of guns firing out of the sides of the upper part of the pod, but as the three guns were all fired by a single gunner, only one of them could be fired at a time. From May 1940, 422 Do 17Z-2s flew with ''[[Kampfgeschwader 2]]'' ''Holzhammer'' (Wooden mallet), ''[[Kampfgeschwader 3]]'' ''Blitz (Lightning), ''[[Kampfgeschwader 76]]'' and ''[[Kampfgeschwader 77]]".<ref name="Dressel and Griehl 1994, p. 26."/> The upgrades of the Z-2 had its overall weight increased from {{convert|17,600|to|17,920|lb|kg|abbr=on}}.<ref name="Griehl 2005, p. 6."/> After heavy losses of Do 17s during the [[Battle of Britain]] it was decided to replace the [[MG FF cannon]] with the more powerful [[MG 151 cannon|MG 151/15]]. Losses had mounted in spite of an increase of up to eight machine guns in some Dorniers.<ref name="Griehl 2005, pp. 6-7.">Griehl 2005, pp. 6–7.</ref>

The Z-3 formed part of the bomber versions of the Z series, it was, however, also used as a reconnaissance aircraft by the staff flight of the particular unit. The engines and the general equipment were identical to the Z-2 standard; however two cameras — the Rb 50/30 and Rb 20/30 - were incorporated into the crew entry hatch. A handheld camera was issued to the crew to validate the success during bombing missions. Autopilot equipment was added later. The Z-2 and Z-3 were identical visually, and could only be distinguished from each other by the altered crew hatch on the Z-3. Owing to spacing problems because of the added camera equipment, the ammunition supply was reduced from 44 to 42 magazines.<ref name="Griehl 2005, p. 7.">Griehl 2005, p. 7.</ref> The power plant of the Z-3 was upgraded to the Bramo 323P-2. The Bramo P-2 remained the engine of all the remaining Z series variants.<ref name="Griehl 2005, p. 11."/>

[[File:Bundesarchiv Bild 101I-341-0489-13, Frankreich, Flugzeug Dornier Do 17.jpg|thumb|The Do 17 could carry an internal {{convert|1,000|kg|lb|abbr=on|0}} bomb load, either 20 × {{convert|50|kg|lb|abbr=on|0}} or 4 × {{convert|250|kg|lb|abbr=on|0}} bombs]]
The Z-4 was designed as trainer. Although nearly identical to the Z-2 and Z-3, it featured several equipment changes optimised for blind flying training. The four-seat aircraft had a single control column with dual steering, which was achieved by a jib protruding to the right. Rudder pedals were in front of both seats. The defensive armament and bomb racks were reduced, or in most cases omitted to reduce weight.<ref name="Griehl 2005, p. 7."/> The Z-5 was similar to the Z-3 with a weight of {{convert|19000|lb|abbr=on}}. Designed as an anti-shipping aircraft, the '''Z-5''', was fitted with flotation cells in the fuselage and engine nacelles in case it was forced down on water.<ref name="Dressel and Griehl 1994, p. 26."/><ref name="Griehl 2005, p. 9">Griehl 2005, p. 9.</ref> Usually the flotation devices took the form of inflatable bags stored in the rear of the engine nacelles and in bulges on either side of the nose, just behind the front glazing.<ref name="Goss 2005, p. 14">Goss 2005, p. 14.</ref>

Later variants of the Z model were developed. The Z-6 was to be a reconnaissance aircraft, although it was only built as a prototype. During the war only a few were converted from existing combat variants. The type was selected for weather check flights. It was identical to the Z-1/Z-2 variants, but offensive armament was omitted and extra fuel cells fitted. This increased the fuel load to 2,890 L (578 imperial gallons). As flights required higher altitude, the oxygen supply was increased from 20 to 24 bottles. For long-range flights over water, the larger dinghy of the Z-5 with its updated emergency escape equipment was mandatory during operations.<ref name="Griehl 2005, p. 7."/> The Z-6s were also used for night fighter operations. Some of the few converted Z-6s had the Ju 88C-6 nose installed and were equipped with machine guns and cannons. The nose proved to be unsatisfactory, and it was redesigned. In the tip of the new nose was an [[infrared]] spotlight which was soon made redundant after the introduction of [[Lichtenstein radar]] which was fitted to some of the Z-6.<ref name="Goss 2005, p. 14"/>

[[File:Bundesarchiv Bild 101I-341-0456-04, Frankreich, Flugzeuge Dornier Do 17.jpg|thumb|left|Do 17Z-2s over [[France]], summer 1940<ref>Nowarra 1990, p. 33.</ref>]]
The Z-8 ''Geier'' ([[Vulture]]) was not produced. It was intended as a ground attack aircraft and reached the first planning phase but was given up due to lack of performance and protective armour. An increase in armour would have meant a decrease in speed which would have exposed the aircraft further to enemy fire.<ref name="Griehl 2005, p. 8">Griehl 2005, p. 8.</ref> The Z-9, which was fitted with special bomb release equipment, and delayed release gear for low-level attack missions. Its purpose was to suppress enemy air defences. Therefore, it was designed to fly over anti-aircraft positions and drop [[Butterfly Bomb]]s, an early form of [[cluster bomb]] munitions. This could only be done with [[air superiority]], as the Z-9 was unarmoured. The airframe and equipment was identical to the Z-1/Z-2 version. Only the bomb bay was altered to accommodate 16 bomb-dispenser systems. The maximum weight of the Z-9 was {{convert|7800|kg|abbr=on}}. The design did not reach serial production.<ref name="Griehl 2005, p. 8"/>

After bomber production ended in 1940, the Z model was modified with a "solid" nose from the Ju 88C, fitted with one 20&nbsp;mm [[MG FF cannon]] and three 7.92&nbsp;mm (.312&nbsp;in) [[MG 17 machine gun]]s, to be used as night fighters. Three prototypes were converted from existing Z-series airframes to the '''Do 17Z-7 Kauz I''' ("[[screech-owl]]") configuration. The standard Z-7 was fitted with Bramo 323P-1 radial engines and had a crew of three airmen. In comparison to the standard bomber version, the fuel load arrangement was altered by subdividing into cells. Two cells were in the wings, with a capacity of 770 litres (154 imperial gallons) each. A third cell was placed in the bomb bay within the main fuselage, having a capacity of 895 litres (179 imperial gallons). The oxygen supply for the three man crew was reduced to nine bottles, as intercepts at high altitudes were not anticipated. Add-on armour in the form of heavy steel plates was bolted to the nose bulkhead to protect the crew against frontal fire. Originally, it was planned to completely armour the crew compartment. This idea, was given up again as the increased weight would have reduced flight performance of an already slow aircraft. The ammunition loads for the three 7.92&nbsp;mm MG 17s amounted to 3,000 rounds and 400 rounds of ammunition for the 20&nbsp;mm MG 151 cannon (although some Do 17Z bombers carried a single 20&nbsp;mm for ground attack missions).<ref name="Griehl 2005, p. 7."/><ref>Griehl 2005, p. 45.</ref>

[[File:Lichtenstein radar Do 17.jpg|thumb|Dornier Do 17Z-10 night fighter with [[Lichtenstein radar#FuG 202 Lichtenstein B/C|FuG 202 Lichtenstein B/C]] UHF radar]]
Later, the design was further modified to the '''Do 17Z-10 Kauz II''', the solid nose now containing an infrared searchlight for the ''Spanner Anlage'' infrared detection system.<ref name="Smith 1967, p. 6.">Smith 1967, p. 6.</ref> The infrared lamp in the nose was used to illuminate the target while the display unit in the windshield made the reflection visible to the pilot.<ref>Griehl 2005, p. 44.</ref> The Z-10 was armed with four 7.92&nbsp;mm (.312&nbsp;in) MG 17 machine guns grouped above the IR light and two 20&nbsp;mm MG FF in the lower nose.<ref name="Smith 1967, p. 6."/> The crew could reload the 20&nbsp;mm cannons' [[drum magazine]]s internally. The Z-10 contained an IR searchlight (''Spanner-Anlage'') for the Spanner infrared detection system.<ref>Goss 2005, p. 15.</ref><ref>Nowarra 1990, p. 40.</ref> A single ''Kauz'' II was equipped with and tested the Lichtenstein radar.<ref name="Nowarra 1990, p. 41">Nowarra 1990, p. 41.</ref>

Only 10 of these ''Kauz'' II designs were converted from Z-series airframes. The ''Spanner'' system proved to be essentially useless and many Z-10 were left without any detection system. At least one Z-10, coded CD+PV, was used as a flying test bed to help developing the early low-[[UHF]] band B/C version of the Lichtenstein radar system in late 1941–1942.{{refn|A photograph identifying a Z-10 with the system above the fuselage can be seen at the Luftwaffe test centre at [[Rechlin-Lärz Airfield|Rechlin]], (picture undated).<ref name="Nowarra 1990, p. 41"/>|group="Notes"}} When the Z-10 was stripped of all non-night fighter equipment, it had a maximum weight of {{convert|7300|kg|abbr=on}}. Armament fit was similar to that of the Z-7, with an added MG 17 and an additional 1,000 rounds of ammunition in the nose section. Defensive gun positions included the B and C stand, each equipped with a MG 15.<ref name="Griehl 2005, p. 8"/>