Editing Dornier Do 17 (section)

===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"/>