The production of the first prototype aircraft began in February 1940, four months before receiving an order from the Ministry of Aviation. To work out some solutions in the field of aerodynamics before the flight of experimental aircraft on the Junkers, they decided to use Ju.88-V2 (D-AREN) and Ju.88-V5 (D-ATYU). They installed nose sections similar to the Ju.288, as well as a two-keel plumage based on its model. Tunnel spinners were installed on the engines, surface capacitors were installed in the leading edge of the wing, and the outer section of the flaps received lattice air brakes.

Flight tests of two converted Ju.88s began in the late spring of 1940 under the direction of flask-captain Holzbauer with the participation of test pilots Joop and Preuschen. Pilot reports were favorable. Comparative tests of lattice air brakes and spoilers were carried out. The latter were called "comb" and were several vertical plates produced on the upper and lower surfaces of the wing at 35% of the chord. Since the tests did not show the advantages of any particular type of airbrake, this made it necessary to postpone the final choice until the flight of Ju.288.

Static tests of gliders were carried out in Dessau in the autumn of 1940. At the end of January 1941, after prolonged ground tests, the first experimental Ju.288-V1 (D-AOTF) finally took off. Even before that, it became obvious that bringing the Jumo-222 to the flight model would take much more time than it was planned according to the program of bomber "B". Work on the Jumo-223 was stopped almost immediately, and the first Ju.288 had to install a 14-cylinder air-cooled engine VMW-801. These were the most powerful engines available at that time, having a slightly larger diameter than the Jumo-222. The Ju.288-V1 was equipped with two VMW-801MAs with a takeoff power of 1600hp and 1380hp at an altitude of 4600m. The defensive armament was modeled after the first EF-73 project. On it were models of towers on the upper and lower surfaces of the fuselage.

In the early spring of 1941, the second experimental Ju.288-V2 (D-ABWP) flew, which was distinguished by the installation of spoilers instead of lattice air brakes on the first experimental aircraft. The VZ, which flew at the beginning of the summer, also had spoilers. At the same time, work began on another series of prototypes, the first of which was the Ju.288-V4 (D-AACS).

The Ju.288-V4, like its predecessors, was equipped with BMW-801MA engines, but did not have air brakes. During one of the first flights during the landing approach, a fire broke out in the left engine. The fire was so strong that during the landing it burned the spars and almost completely destroyed the forward fuselage. Despite severe damage, the aircraft was restored and resumed flights in November. Later, new landing gear shock absorbers were tested on it, while the take-off weight of the aircraft reached 11800 kg, and the wing load - up to 220 kg / m².

Armament. Upper and lower remote controlled turrets with pairs of 13 mm MG-131 machine guns; up to 3000kg of bombs in the bomb bay, including 3x1000kg or 3x500kg + 6x250kg

By mid-July 1941, the program was suspended pending the delivery of the first Jumo-222A/B to be installed on the Ju.288-V5. By this time, the decision to increase the combat load forced again to increase the wingspan from 18.3 to 20.2 m, and the area from 54 to 59 m². The production model "A" had a wing span of 22m and an area of ​​60m². Two serial models were supposed: Ju.288a-1 with large side blisters and without periscopes and Ju.288a-2 - with small blisters and periscopes. The crews of both variants were to consist of three people, the normal takeoff weight was estimated at 17215kg, and the maximum - 18500kg, the maximum bomb load weight - 5000kg. According to these estimates, three experimental V6, V7 and V8 were ordered. The enlarged wing received new ailerons. It was purged in March 1941. A monthly release of 80 Ju.288a was planned for the Junkers, and another 300 for the Arado, ATG, Dornier, Heinkel, Henschel and Siebel. However, the Technical Department again changed the requirements, including a fourth person. All plans for the production of the Ju.288a had to be rejected in favor of the Ju.288b with a wider cabin and a new wing of even greater area and scope.

Problems with the supply of Jumo-222 engines delayed the readiness of the Ju.288-V5 until the end of September 1941. The first flight of the fifth prototype took place on 8 October. Until the end of the month flew and V6. On the V6, the wing span was 22.7 m and an area of ​​64.6 m². The readiness of the V7 was delayed until the spring of 1942. It was similar to the V6, but due to a lack of engines, the Jumo-222 was equipped with BMW-801C engines. He clearly lacked power, and soon the plane was seriously damaged by fire. As a result, the third prototype of the A series - Ju.288-V8, released shortly after the V7, was equipped with Jumo-222 engines and a larger empennage, which was planned for the B series. Later, the V7 received similar plumage.

Meanwhile, on Lake Trebbihau near Dessau, studies were carried out on the tightness of the bow section of the Ju.288a, which was towed submerged, and the Ju.288-V2 and V3 were used in the work on fine-tuning the chassis. From the very beginning, the depreciation of the Ju.288 chassis turned out to be unsatisfactory, and lengthy refinements and numerous changes in its design were required. During the winter of 1941-42, comparative tests of the Ju.288-V2 and Ju.88-V16 were carried out on snow-covered runways. The characteristics of the first one turned out to be unsatisfactory. Additional improvements were required. During October 1941, the Ju.288-V3 (VK+HS) was tested with a specially reinforced chassis. But these problems haunted Ju.288 throughout the entire test program.

During the summer of 1942, the Ju.288-V3 was fitted with an MG-151/15 remote-controlled cannon in the tail section, but shortly after that, the aircraft was wrecked when both landing gear collapsed during landing.

Bibliography

• Wings of the Luftwaffe (warplanes of the Third Reich)/William Green/
• Bombers "B"/Wings of the Motherland Yuri Borisov/