06/30/2014. Remarks by Johan Visschedijk: "The increasing need for specialized strategic reconnaissance aircraft possessing higher performance than that offered by the Do 17 P equipping the long-range Aufklärungsgruppen resulted, early in 1940, in the appearance of the Ju 88 D based on the Ju 88 A-4.
The forward bomb-bay was blanked over and used for fuel, no dive brakes were fitted, and aft of fuselage frame No.15 provision was made for either two or three remotely-controlled cameras with the necessary heating installation. The most widely-used installation comprised a single high-altitude Rb 50/30 camera suitable for use up to altitudes of the order of 27,887 ft (8,500 m), and an Rb 20/30 which was not intended to be used above 6,562 ft (2,000 m).
Like the Ju 88 A-4 bomber, it was intended to power the Ju 88 D-1 with the Jumo 211J-1 and 211J-2, but the pre-production Ju 88 D-0 reconnaissance aircraft were delivered with Jumo 211B-1 engines and without the ETC racks beneath the wing centre section, and the non-availability of the Jumo 211J resulted in the initial production model being the Ju 88 D-2 with Jumo 211B-1, 211G-1 or 211H-1 engines, this version being equivalent to the Ju 88 A-5 bomber. The ETC racks were reinstated on the Ju 88 D-2, and for extended-range missions a drop tank was slung beneath each pair of racks.
The crew complement remained four members, but defensive armament was normally restricted to three 0.311 in (7.9 mm) MG 15 machineguns. A tropicalized version, initially known as the Ju 88 D-2/Trop, was later redesignated Ju 88 D-4.
As supply of the Jumo 211J-1 and 211J-2 engines eased, the Ju 88 D-2 gave place on the assembly lines to the Ju 88 D-1 which was identical to the initial model apart from the power plants, although some aircraft had the outboard ETC racks deleted, only the inboard racks being retained for the drop tanks. The tropicalized variant of the Ju 88 D-1 was designated Ju 88 D-3, and a variant standardizing on the tri-camera arrangement of Rb 50/30s and Rb 75/30s employed by some Ju 88 D-2s and manufactured in parallel with the Ju 88 D-1 was designated Ju 88 D-5."