G.38
Role	Transport
Manufacturer	Junkers
First flight	6 November 1929
Primary users	Lufthansa Luftwaffe
Number built	2
Variants	Mitsubishi Ki-20

The Junkers G.38 was a large German four-engined transport aircraft which first flew in 1929.^[1] Two prototypes were constructed in Germany. Both aircraft flew as a commercial transport within Europe in the years leading up to World War II.

During the 1930s, the design was licensed to Mitsubishi which constructed and flew a total of six aircraft, in a military bomber/transport configuration, designated Ki-20.^[2]

The G.38 carried a crew of seven. On board mechanics were able to service the engines in flight^[1] due to the G.38's blended wing design which provided access to all four power plants.

Design and development [edit]

Junkers G 38s.

Structurally the G38 conformed to standard Junkers' practice, with a multi-tubular spar cantilever wing covered, like the rest of the aircraft in stressed, corrugated duraluminium. The biplane tail, found in other large aircraft of the time was intended to reduce rudder forces; initially there were three rudders with only a central fixed fin. The undercarriage was fixed, with double tandem main wheels that were initially enclosed in very large spats. The wing had the usual Junkers "double wing" form, the name referring to the full span movable flaps which served also as ailerons in the outer part.

The first Junkers prototype - 3301 and marked as D-2000 - first flew on 6 November 1929 with four diesel engines: two L55 12-cylinder V-motors and two 294 kW L8 6-cylinder inline motors with combined power rating of 1470 kW (1971 hp).^[3] The Reich Air Ministry purchased the D-2000 for demonstration flights,^[4] and took delivery on 27 March 1930. In flight tests, the G.38 set four world records including speed, distance and duration for airplanes lifting a 5000 kg payload.^[1] On 2 May 1930 Lufthansa put the D-2000 into commercial service for both scheduled and chartered flights.

On 2 February 1931 the Leipzig-based Junkers' yard re-engined the D-2000 with two L8 and two L88 motors giving a total power rating of 1764 kW (2366 hp) and increasing passenger capacity from 13 to 19.^[3]

The G.38, during its early life, was the largest land plane in the world.^[1] Passenger accommodation was sumptuous by today's standards and was meant to rival that found on the competing Zeppelin service offered by DELAG. The plane was unique in that passengers were seated in the wings, which were 1.7 m (5 ft 7 in) thick at the root.^[5] There were also two seats in the extreme nose. The leading edge of each wing was fitted with sloping windscreens giving these passengers the forward-facing view^[1] usually available only to pilots. There were three 11 seater cabins, plus smoking cabins and wash rooms.

In design terms the G-38 foreshadowed the Blended Wing Body design currently being developed by both NASA and Boeing as an alternative to traditional tube and wing aircraft configurations.

First prototype at Berlin Tempelhof Airport showing spatted tandem main wheels, the aileron section of the "double wing" and - most unusually - retractable oil and water radiators

Operational history [edit]

On 1 July 1931 Lufthansa initiated regularly scheduled service between Berlin and London on flights carrying up to 13 passengers.^[1] This London-Berlin service was halted in October 1931 to retrofit the aircraft and expand the passenger cabin of the D-2000. Construction lasted from this time until the summer of 1932, during which a second deck was built within the D-2000's fuselage - enabling an increased cargo capacity and seating for up to 30 passengers. Additionally the D-2000's engine were again upgraded to four L88s, giving a combined power total of 2352 kW (3154 hp). Also at this time the D-2000's certificate number was changed to D-AZUR.

Meanwhile, a second G.38 - factory number 3302 and c/n D-2500, later changed to D-APIS - was built with a double deck fuselage and capacity for 34 passengers. Six passengers were carried in two compartments in the leading edge of each wing and the remaining 22, on two levels, in the fuselage. Lufthansa used D-APIS on a scheduled service covering the cities Berlin, Hanover, Amsterdam and London. This aircraft was named the General Feldmarschall von Hindenburg.

In 1934 D-2000/D-AZUR had its engines upgraded, this time with Jumo 4 engines, giving a total power rating of 3000 kW (4023 hp).^[6]

Both planes were in service simultaneously until 1936, when D-AZUR crashed in Dessau during a post-maintenance test flight. Lufthansa had to write off this aircraft due to the extensive damage, but test pilot Wilhelm Zimmermann survived the crash, and there were no other casualties.

The second G.38 - marked D-2500 and later D-APIS - flew successfully within the Lufthansa fleet for nearly a decade. With the outbreak of World War II the D-2500/D-APIS was pressed into military service as a transport craft by the Luftwaffe. It was destroyed on the ground during an RAF air raid on Athens on 17 May 1941.^[1][7]

Specifications (G.38 1929) [edit]

General characteristics

• Crew: Seven
• Capacity: 30 (D-2000/D-AZUR) and 34 (D-2500/D-APIS) passengers^[3]
• Length: 23.21 m (76 ft 2 in) ^[3]
• Wingspan: 44 m (144 ft 4 in)
• Height: 7.2 m (23 ft 7 in) ^[1]
• Wing area: 290 m² (3,100 sq ft) ^[1]
• Empty weight: 14,920 kg (32,893 lb) ^[3]
• Gross weight: 24,000 kg (52,911 lb)
• Max takeoff weight: 21,240 kg (46,826 lb) ^[1][3]
• Powerplant: 2 × Junkers L55 V-12 water-cooled piston engines inboard
• Powerplant: 2 × Junkers L8a six-cylinder, water-cooled, in-line piston engines, 308 kW (413 hp) each at take-off, outboard
• Propellers: 2-bladed wooden fixed pitch propellers outboard, 4-bladed wooden fixed pitch propellers inboard

Performance

• Maximum speed: 225 km/h (140 mph; 121 kn) ^[5]
• Cruising speed: 175 km/h (109 mph; 94 kn)
• Range: 3,460 km (2,150 mi; 1,868 nmi) ^[5]
• Service ceiling: 3,690 m (12,106 ft) ^[5]

Operators [edit]

•  Weimar Republic
  • Lufthansa
•  Nazi Germany
  • Luftwaffe

See also [edit]

• Junkers
• List of RLM aircraft designations

Related development

• Mitsubishi Ki-20

Aircraft of comparable role, configuration and era

• Tupolev ANT-20
• Burnelli CBY-3

References [edit]

Notes [edit]

Bibliography [edit]

Wikimedia Commons has media related to: Junkers G.38

External links [edit]

• Movie of the first test flight of the G38 D-2000
• "Huge Plane Carries Passengers In Wings" Popular Mechanics, February 1930
• "Huge Plane Takes Crew Under Its Wing", January 1931, Popular Mechanics article includes photo and cutaway drawing
• "Giant Of The Air - The Latest German Liner", January 1933, Popular Mechanics cutaway drawing of G.38 better than 1931 article
• Photo of D-APIS in Greece in 1941