Editing Junkers Ju 87 (section)

=== Ju 87 D ===
Despite the Stuka's vulnerability to enemy fighters having been exposed during the [[Battle of Britain]], the Luftwaffe had no choice but to continue its development, as there was no replacement aircraft in sight.<ref>{{harvnb|Mondey|1996|p=114}}</ref> The result was the D-series. In June 1941, the RLM ordered five prototypes, the Ju 87 V21–25. A [[Daimler-Benz DB 603]] powerplant was to be installed in the Ju 87 D-1, but it did not have the power of the Jumo 211 and performed "poorly" during tests and was dropped.<ref name="Griehl 2001, p. 87">{{harvnb|Griehl|2001|p=87}}</ref> The Ju 87 D-series featured two coolant radiators underneath the inboard sections of the wings, while the oil cooler was relocated to the position formerly occupied by the single, undernose "chin" coolant radiator. The D-series also introduced an aerodynamically refined cockpit with better visibility and space.{{sfn|Griehl|2001|p=95}} Armour protection was increased and a new dual-barrel 7.92&nbsp;mm (.312&nbsp;in) [[MG 81 machine gun|MG 81Z machine gun]] with an extremely high rate of fire was installed in the rear defensive position. Engine power was increased again, the Jumo 211J now delivering 1,420&nbsp;PS ({{convert|1044|kW|hp|abbr=on|disp=or}}).{{sfn|Griehl|2001|p=95}}
Bomb carrying ability was nearly quadrupled from {{convert|500|kg|lb|abbr=on}} in the B-version to {{convert|1800|kg|lb|abbr=on}} in the D-version (max. load for short ranges, overload condition), a typical bomb load ranged from {{convert|500|-|1200|kg|lb|abbr=on}}.<ref name="Griehl 2001, p. 99">{{harvnb|Griehl|2001|p=99}}</ref>

[[File:Bundesarchiv Bild 101I-329-2984-05A, Russland, Junkers Ju 87 Recolored.png|thumb|Ju 87Ds, Soviet Union, January/February 1943]]

The internal fuel capacity of the Ju 87 D was raised to 800&nbsp;L (of which 780&nbsp;L were usable) by adding wing tanks while retaining the option to carry two 300&nbsp;L drop tanks. Tests at [[Rechlin-Lärz Airfield]] revealed it made possible a flight duration of 2 hours and 15 minutes. With an extra two 300&nbsp;L (80&nbsp;US gal) fuel tanks, it could achieve four hours flight time.{{sfn|Griehl|2001|p=95}}

The D-2 was a variant used as a glider tug by converting older D-series airframes. It was intended as the tropical version of the D-1 and had heavier armour to protect the crew from ground fire. The armour reduced its performance and caused the [[Oberkommando der Luftwaffe]] to "place no particular value on the production of the D-2".{{sfn|Griehl|2001|p=95}} The D-3 was an improved D-1 with more armour for its ground-attack role. Some Ju 87 D-3s were designated D-3N or D-3&nbsp;trop and fitted with night or tropical equipment.{{sfn|Griehl|2001|p=95}} The D-4 designation applied to a prototype torpedo-bomber version, which could carry a {{convert|750|–|905|kg|lb|abbr=on}} [[aerial torpedo]] on a PVC 1006 B rack—this setup would have had the capacity to carry the ''Luftorpedo'' LT 850, the German version of the well-proven Japanese [[Type 91 torpedo#Provision of the aerial torpedo technology to Germany|Type 91 aerial torpedo]] of 848&nbsp;kg (1,870&nbsp;lb). The D-4 was to be converted from D-3 airframes and, in place of the carrier-specific Ju 87C series designs, operated from the aircraft carrier ''{{ship|German aircraft carrier|Graf Zeppelin||2}}''.<ref name="Griehl 2001, p. 97">{{harvnb|Griehl|2001|p=97}}</ref> Other modifications included a flame eliminator and, unlike earlier D variants, two 20&nbsp;mm MG 151/20 cannon, while the radio operator/rear gunner's ammunition supply was increased by 1,000 to 2,000 rounds.<ref name="Griehl 2001, p. 98">{{harvnb|Griehl|2001|p=98}}</ref>

[[File:Duitse Junkers Ju 87 "Stuka" 2157 008308.jpg|thumb|right|A pair of Ju 87Ds following a landing with air brakes still deployed.]]
The Ju 87 D-5 was based on the D-3 design and was unique in the Ju 87 series as it had wings 0.6 metres (2&nbsp;ft) longer than previous variants. The two 7.92&nbsp;mm MG&nbsp;17 wing guns were exchanged for more powerful 20&nbsp;mm MG&nbsp;151/20s to better suit the aircraft's ground-attack role. The window in the floor of the cockpit was reinforced and four, rather than the previous three, aileron hinges were installed. Higher diving speeds were obtained of {{convert|650|km/h|mph|abbr=on}} up to {{convert|2000|m|ft|abbr=on}}. The range was recorded as {{convert|715|km|mi|abbr=on}} at ground level and {{convert|835|km|mi|abbr=on}} at {{convert|5000|m|ft|abbr=on}}.<ref name="Griehl 2001, p. 99"/>

The D-6, according to "Operating instructions, works document 2097", was built in limited numbers to train pilots on "rationalised versions". Due to shortages in raw materials, it did not go into mass production.<ref name="Griehl 2001, pp. 101–102"/> The D-7 was another ground attack aircraft based on D-1 airframes upgraded to D-5 standard (armour, wing cannons, extended wing panels), while the D-8 was similar to the D-7 but based on D-3 airframes.<ref name="Griehl 2001, pp. 101–102">{{harvnb|Griehl|2001|pp=101–102}}</ref> The D-7 and D-8 were both were fitted with exhaust flame dampers, and could conduct night operations.<ref name="Griehl 2001, pp. 101–102"/>

Production of the D-1 variant started in 1941 with 495 ordered. These aircraft were delivered between May 1941 and March 1942. The RLM wanted 832 machines produced from February 1941. The Weserflug company was tasked with their production. From June to September 1941, 40 Ju 87 Ds were expected to be built, increasing to 90 thereafter.<ref name="Griehl 2001, p. 102">{{harvnb|Griehl|2001|p=102}}</ref> Various production problems were encountered. One of the planned 48 was produced in July. Of the 25 the RLM hoped for in August 1941, none were delivered.<ref name="Griehl 2001, p. 102"/> In September did the first two of the planned 102 Ju 87s came off the production lines.<ref name="Griehl 2001, p. 103">{{harvnb|Griehl|2001|p=103}}</ref> The shortfalls continued to the end of 1941. During this time, the WFG plant in Lemwerder moved production to Berlin. Over 165 Ju 87s had not been delivered and production was only 23 Ju 87 Ds per month out of the 40 expected. By the spring of 1942 to the end of production in 1944, 3,300 Ju 87s, mostly D-1s, D-2s and D-5s had been manufactured.<ref name="Griehl 2001, p. 103"/>

In January 1943, a variety of Ju 87 Ds became "test beds" for the Ju 87 G variants. At the start of 1943, the coastal Luftwaffe [[Tarnewitz test site|''Erprobungsstelle'' test centre at Tarnewitz]] tested this combination from a static position. ''Oberst'' G. Wolfgang Vorwald noted the experiments were not successful, and suggested the cannon be installed on the [[Messerschmitt Me 410]].<ref name="Griehl 2001, p. 284">{{harvnb|Griehl|2001|p=284}}</ref> Testing continued, and on 31 January 1943, Ju 87 D-1 W.Nr 2552 was tested by ''[[Hauptmann]]'' [[Hans-Karl Stepp]] near the [[Briansk]] training area. Stepp noted the increase in drag, which reduced the aircraft's speed to {{convert|259|km/h|mph|abbr=on}}. Stepp also noted that the aircraft was also less agile than the existing D variants. D-1 and D-3 variants operated in combat with the {{convert|37|mm|in|abbr=on}} BK 37 cannon in 1943.<ref name="Griehl 2001, p. 284"/>

'''Known prototypes'''
* Ju 87 V 21. Registration D-INRF. W.Nr 0870536. Airframe conversion from B-1 to D-1. First flown on 1 March 1941.
* Ju 87 V 22 ''Stammkennzeichen'' of SF+TY. W.Nr 0870540. Also airframe conversion from B-1 to D-1. First flown on 1 March 1941.
* Ju 87 V 23 ''Stammkennzeichen'' of PB+UB. W.Nr 0870542. Also airframe conversion from B-1 to D-1. First flown on 1 March 1941.
* Ju 87 V 24 ''Stammkennzeichen'' of BK+EE. W.Nr 0870544. Also airframe conversion from B-1 to D-1/D-4. First flown on 1 March 1941.
* Ju 87 V 25 ''Stammkennzeichen'' of BK+EF. W.Nr 0870530. Also airframe conversion from B-1 to D-4 trop. First flown on 1 March 1941.
* Ju 87 V 30, the only known prototype of the Ju 87 D-5. W.Nr 2296. First flown on 20 June 1943.
* Ju 87 V 26-28, Ju 87 V 31, and V 42-47 were experiments of unknown variants.<ref name="Griehl 2001, p. 49"/>