The Ju 188 was an improved version of the Ju 88, one of the mainstays of the Luftwaffe during the Second World War. Although the aircraft only entered service in 1943, its basic design was based on an alternative cockpit for the Ju 88 that had been part of the original design for that aircraft in 1936. A prototype of this Ju 88B had flow in 1940, but the advantages of the modified cockpit were not enough to make it worth disrupting production of the already important aircraft. Instead Junkers were to concentrate on the Ju 288, part of the 1939 "Bomber B" competition. Work resumed on the Ju 88B under the new designation Ju 188 in October 1942. It was triggered by the failure of the Bomber B project. Work on the Ju 288 was scaled down in favour of the Ju 188, which as a modification of an existing aircraft would take much less time to enter service. It benefited from the years of development that had gone into improving the Ju 88, with the first prototype originally constructed as Ju 88 V44, (the forty-fourth development aircraft).
The RLM specification for the Ju 188 required it to be capable of acting as either a level or dive bomber. It was to carry the same dive-brakes and automatic pull-out gear as the Ju 88A. It was to be capable of being powered by either Jumo 213 (A series) or BMW 801 (E series) engines, built into a "power egg" that would allow either engine to be installed on the production line. The most obvious change made to the Ju 188 was in the cockpit. The stepped nose of the Ju 88 was replaced by a single canopy that began under the nose then curved up and over the cockpit, ending at the rear dorsal gun position, giving the new aircraft the profile of a tadpole. Changes were also made to the wings, increasing the wingspan by three feet while the tail was also enlarged and the fin made larger.
The standard bomber version carried four guns, all in the main cockpit. These included a 20mm cannon in the nose, an dorsal turret at the top of the cockpit, with either a 13mm or 20mm gun, a rear firing 13mm gun in the rear dorsal position and a rear firing MG 81Z twin machine gun in the ventral position. The normal bomber variant could carry a 3000kg/ 6614lb bomb load. Two prototypes were ready by January 1943, when they began flight tests. The new aircraft was generally popular. It outperformed the already excellent Ju 88, and features a more spacious cockpit with improved visibility. Its biggest weakness was the lack of any effective tail guns, which led to a variety of attempts to fit a rear turret.
The Ju 188 entered service in May 1943 with Erprobungskommando 188, a specialled service test unit, and with KG 6. I./KG 6 would be the first unit to go operational, on 20 October 1943, acting as a pathfinder unit. Only two bomber units (KG 2 and KG 6) would convert entirely to the Ju 188, which was also used by some elements of KG 26 and KG 66. Half of the 1,076 aircraft produced were reconnaissance aircraft, and the type was used by ten reconnaissance units.
The Ju 188 appeared too late to make any significant impact on the war. Of the total production, 283 were built in 1943 and 793 in 1944, by which time the German bomber forces were shrinking. From the summer of 1944 they almost completely disappeared in response to the fuel shortage caused by Allied heavy bombing. Allied control of the air meant that the Ju 188 was unable to achieve much as a reconnaissance aircraft either – the Luftwaffe would be essentially blind until the jet powered Arado Ar 234 entered service. In a somewhat unexpected twist, the Ju 188 was used by the French naval air arm (the Aéronavale) in the immediate post war era.