Junkers Ju 252/352

https://en.wikipedia.org/wiki/Junkers_Ju_252

https://en.wikipedia.org/wiki/Junkers_Ju_352

The Junkers Ju 252 was a German cargo aircraft that made its first flight in
late October 1941. The aircraft was planned as a replacement for the Junkers Ju
52/3m in commercial airline service, but only a small number were built as cargo
aircraft for the Luftwaffe.

The original Ju 252 came about after talks between Junkers and Deutsche
Lufthansa in December 1938. Lufthansa requested a new design that would replace
the Ju 52, but offer much greater loads, seating, range and performance. Junkers
responded with the EF.77 design with a pressurized fuselage with seating for up
to 35, making it one of the larger airliners in the world at that time. It was
powered by three Junkers Jumo 211F engines, in nacelles almost identical in
appearance, each complete with annular radiator and possibly as Kraftei unitized
"power-egg" modular engine installations, to those on Jumo 211-powered versions
of the Junkers Ju 88, replacing the BMW 132 of the Ju 52, which dramatically
improved performance. Compared to the Ju 52, the Ju 252 was twice as heavy
(13,100 kg vs. 5,600), was over 100 km/h faster (440 km/h vs. 305), and had
dramatically improved range (3980 km vs. 1300) when fully loaded. Design was
headed by Konrad Eicholtz.

By the time the prototype was ready to fly in October 1941, the war was already
in progress and the Luftwaffe took over development. Like earlier tail-dragger
designs, the Ju 252 would normally be difficult to load when parked, owing to
the sloping floor. Junkers had already pioneered - with the earlier Junkers Ju
90's fifth and sixth prototype airframes during 1939 - a unique solution to this
problem, the Trapoklappe, a hydraulically powered ventral rear loading ramp that
possessed powerful enough operating mechanisms to lift the plane off its
tailwheel, leveling the floor and allowing oversized cargo to be loaded directly
forward into the fuselage. Even though cargo aircraft of all nations since World
War II have used nosewheel landing gear undercarriage designs, the Trapoklappe
concept of a rear loading ramp that forms the opening rear ventral panel of the
fuselage of a cargo aircraft, is a ubiquitous feature of most military airlift
cargo aircraft to the present day.


Role
Transport

National origin
Germany

Manufacturer
Junkers

First flight
1 August 1942

Introduction
January 1943

Primary user
Luftwaffe

Number built
15

Variants
Junkers Ju 352

Although the Ju 252 was a vast improvement over the Junkers Ju 52/3m, the
situation at that time did not permit any disruption of the existing production
lines, and the Reich Air Ministry (RLM) was of the opinion that any replacement
for the Junkers Ju 52/3m must make minimum demands on supplies of strategic
materials and use power plants not required by combat aircraft. Junkers was then
instructed to investigate the possibility of redesigning the Ju 252 in order
that a considerable portion of wood could be included in its structure,
simultaneously replacing the Junkers Jumo 211F engine with the BMW Bramo 323R
engine of which surplus stocks existed. The result was the Junkers Ju 352.
Production of the Ju 252 was restricted to already completed prototypes plus
those for which major assemblies had already been semi-completed, thus only
fifteen transports of this type were completed before production was switched to
the Junkers Ju 352.


Specifications (Ju 252A)

General characteristics
Crew: 3-4
Length: 25.11 m (82 ft 4¼ in)
Wingspan: 34.10 m (111 ft 10? in)
Height: 5.75 m (18 ft 10? in)
Wing area: 122.6 m² (1,320 ft²)
Empty weight: 13,127 kg (28,880 lb)
Loaded weight: 22,257 kg (49,560)
Max. takeoff weight: 24,050 kg (52,911 lb) (overload)
Powerplant: 3 × Junkers Jumo 211F liquid-cooled inverted V12 engines, 1,007 kW
(1,350 hp) each

Performance
Maximum speed: 438 km/h (237 knots, 272 mph) at 5,800 m (19,030 ft)
Cruise speed: 335 km/h (181 knots, 208 mph) (econ cruise)
Range: 3,981 km (2,150 nmi, 2,473 mi) with maximum payload, 6,600 km (3,565 nmi,
4,100 mi) with 2,000 kg (4,400 lb ) payload
Service ceiling: 6,300 m (20,670 ft)
Rate of climb: 12.5 m/s (748 ft/min)

Armament

Guns:
1 x 13 mm MG 131 machine gun in dorsal turret
2 x 7.92 mm MG 15 machine guns in side windows

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Specifications (Ju 352A)

General characteristics
Crew: 3–4
Length: 24.60 m (80 ft 8½ in)
Wingspan: 34.20 m (112 ft 2¾ in)
Height: 5.74 m (18 ft 10¼ in)
Wing area: 128.20 m² (1,379.90 ft²)
Empty weight: 12,500 kg (27,561 lb)
Max. takeoff weight: 19,600 kg (43,216 lb)
Powerplant: 3 × BMW Bramo 323 R-2 Fafnir 9-cylinder radial engine, 735.5 kW,
(986 hp,)1,000 PS 883 kW (1,200 PS, 1,184 hp) with MW-50 each

Performance
Maximum speed: 370 km/h (230 mph) at 5,050 m (16,565 ft)
Cruise speed: 241 km/h (150 mph)
Range: 1,800 km (1,120 miles)
Service ceiling: 6,000 m (19,685 ft)

Armament

Guns: 1 x MG 151 cannon in dorsal turret
2 x MG 131 machine guns in side windows




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