Junkers Ju 252 Passenger / Cargo Transport Aircraft
Intended as a successor to the Junkers Ju 52 tri-motor transport series, the Ju 252 failed in this respect but its design led to the Ju 352 model.
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Junkers of Germany was approached by passenger carrier Lufthansa for a new transport design to succeed their classic Junkers Ju 52 tri-motor series. The entry would be of dimensionally greater size for more internal space and solve issues with both performance and operational range in the process. Like the Ju 52 before it, the new design would rely on a tri-engine configuration with the third engine installed at the nose and the remaining two powerplants residing in the wings. The resultant aircraft became the Ju 252 whose success was largely derailed by the growing German commitment to World War 2 (1939-1945).
The aircraft (project model "EF.77") carried low-set, straight monoplane wings fitted ahead of midships. The fuselage was long and slender, dotted with rectangular viewports along its side. The cockpit was fitted forwards, aft of the nose engine installation, and the empennage was conventional featuring a sole vertical fin and low-mounted stabilizers. A conventional "tail-dragger" undercarriage was featured. Internally, the Ju 252 held the capacity to ferry up to 35 persons in comfort. Power would come from 3 x Junkers Jumo 211F liquid-cooled V12 engines of 1,350 horsepower each. A hydraulically-driven loading ramp (developed in-house by Junkers) was used to level the aircraft when parked (literally lifting the tailwheel from the ground to level the cargo hold), allowing entry and exit of heavy cargo loads.
Heading into 1942, Germany was fully committed to the war and severe material restrictions were placed on the production of any non-military aircraft. The Ju 252 program therefore suffered and only prototypes and those airframes under construction at the time of the directive were allowed to be completed. This netted the series just fifteen total aircraft which went on to serve the German Luftwaffe during the conflict - armed for defensive purposes only through 1 x 13mm MG 131 machine gun in a dorsal turret and 2 x 7.92mm MG 15 machine guns in side beam positions.
The German Air Ministry then returned to Junkers and charged engineers with designing a copy of the Ju 252 that utilized far fewer war materials in its construction. This work then begat the Ju 352 "Herkules" transport which saw considerably more examples produced - fifty. Needless to say, the Ju 252 failed in its attempt to supersede the popular Ju 52 tri-motor line but this was not through any failing of the aircraft directly.
As completed, the Ju 252A production model featured a crew of three to four operating personnel and an overall length of 25 meters, a wingspan of 34 meters and a height of 5.75 meters. Empty weight became 13,130 kg against a Maximum Take-Off Weight (MTOW) of 22,260 kg. Performance specifications included a maximum speed of 440 kmh, a cruise speed of 335 kmh, a range out to 4,000 km and a service ceiling up to 6,300 meters. Rate-of-climb reached 750 feet-per-minute.