In April 1939, the RLM asked Junkers for a further development of the Ju 90 for military transport purposes.
The Ju 90V5 and V6 were the prototypes of this military design.
They got a new wing with a straight inner section leading edge, of greater span (19%) and area (11%).
The landing gear was strengthened with twin main wheels and the fins were more rounded, lacking the characteristic horn balance nick of the earlier models.
The windows were replaced by 10 small portholes a side.
The Ju 90 V5 flew first on 5 December 1939.
A special feature of both the V5 and V6 was a powered boarding ramp in the floor of the rear section of the fuselage for loading cars and larger cargo freight.
This Trapoklappe ramp, when lowered, was powerful enough to raise the fuselage to the horizontal flying position.
Both aircraft were retroactively fitted with the much more powerful, unitized Kraftei-mount 1,200 kW (1,600 hp) BMW 801MA radials, with the first suffix letter “M” signifying the initial Motoranlage format of unitized powerplant installation design promulgated by the RLM. Ju 90s were also used as tugs for heavy gliders.
The two last prototypes – the V7 and V8 – fed directly into the Ju 290 development program.
The former had a fuselage extension of 1.98 m (6 ft 6 in) and the addition of dihedral to the tailplane to solve a yaw instability.
A reconnaissance prototype aerodynamically similar to the V7, the V8 was armed, however, with two 20 mm MG 151/20 cannons and up to nine 13 mm (.51 in) MG 131 machine guns in two dorsal, one ventral, and one tail position.
Ju 290 / 390 development
Some of the Ju 90s were converted into prototypes of the bigger Ju 290 transport and reconnaissance aircraft.
The more powerful engines and other modifications to the Ju 90 V5 and V7 were steps in this direction and the latter was converted into the Ju 290 V3.
The Ju 90 V8 became the second prototype Ju 290 V2.
An uncompleted 11th A-series machine was turned into the Ju 290 V1.
The Ju 90 V6 airframe was used in the construction of the Junkers Ju 390 V1.
Numbers and survivors
In the end, only 18 Ju 90s of all versions were completed.
Just two survived the war to fall into Allied hands, but both were scrapped soon afterwards.
26.3 m (86 ft 3 in)
35.02 m (114 ft 11 in)
7.5 m (24 ft 7 in)
184 m2 (1,980 sq ft)
19,225 kg (42,384 lb)
33,680 kg (74,252 lb)
4 × BMW 132 H-1 9-cylinder air-cooled radial piston engine, 610 kW (820 hp) each