Junkers G 31

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G 31
Junkers G31
Role Airliner
National origin Germany
Manufacturer
Junkers
First flight 1926
Primary user Deutsche Luft Hansa
Number built 13

The Junkers G 31 was an advanced tri-motor airliner produced in small numbers in Germany in the 1920s. Like other Junkers types, it was an all-metal, low-wing cantilever monoplane. In the mid-1920s, the all-metal construction and an aerodynamically 'clean' configuration were remarkable.

Development

Professor Junkers wanted to follow up on the commercial success of the tri-motor G 24 with a new design that would be larger, more comfortable for passengers, and simpler to operate and maintain.[1]

The G 31 was the first Luft Hansa airliner to feature a

flaps that reduced the landing speed by ten percent (Wagner p. 267[1]
).

Professor Junkers originally requested the G 31 have landing gear that would retract into the wings. After extensive wind tunnel experiments Ernst Zindel, the leader of the design team, persuaded Professor Junkers that the gain in speed provided by reduced air resistance, would not outweigh the increased weight, cost, and complexity of either retractable landing gear or simple wheel fairings. The tail skid incorporated a roller, to avoid damage to grass airfields(Wagner p. 262–263[1]).

The intended powerplant was three Junkers L5 engines. When these proved too weak, it was suggested to use the Napier Lion, considered to be the best aero engine at the time ("the best engine for the best plane"). This however was too expensive, especially since it would have had to be paid for in convertible currency, not German Reichsmark. Most G 31s flew with foreign air-cooled radial engines in the 500 hp range, which was license-built in Germany (see list of variants below)(Wagner p. 265–267[1]).

Operational history

Originally, the G 31 had been intended to equip Junkers' airline,

Junkers Luftverkehr, but this venture was merged into Deutsche Luft Hansa in 1926, and the new airline purchased only eight G 31s, beginning operations in May 1928. They were used on the long-range routes of Luft Hansa, particularly to Scandinavia. They continued in this role until 1935, when replaced by the Junkers Ju 52
.

Four other G 31s were sold for freighting cargo in New Guinea. Operated by

Minister for Air's car.[4][5]
Although judged beyond repair by the Air Force, it eventually returned to freighter use in New Guinea for some time after the war.

Unlike the earlier Junkers G 24, the G 31 was not a commercial success, with only 13 being sold, as opposed to 54 civilian G 24s (+30 military derivatives)(Wagner p. 267[1]). Compared to the G 24 it offered passengers more comfort. Compared to the more usual biplane airliners of the 1920s, the G 31 was faster, and its all-metal construction made it safer. However, the purchase price and operating costs were high. Instead of the newly designed G 31, a developed version of the G 24 might have sold better.

Accidents and incidents

September 25, 1928
Deutsche Luft Hansa G 31de (c/n J3004; registration D-1427; named Deutschland) crash-landed and burned due to an engine fire.[6]
December 11, 1928
Deutsche Luft Hansa G 31fi, registration D-1473 and named Rhineland, crashed at Letzlingen due to weather, killing three of four on board.
May 1936
An RLM G 31fo (c/n 3008, D-ABIL) collided with Junkers Ju 52/3m D-APUT.[7][8]

Variants

G 31 Cabin
Junkers G 31 Cabin with beds

Operators

G 31go
Junkers G 31go
 Australia
 Germany

Specifications (G 31fo)

Junkers G.31 3-view drawing from L'Aérophile November,1927

Data from Wagner p. 269[1]

General characteristics

  • Crew: two pilots, one radio operator, and one steward
  • Capacity: 15 day passengers or ten-night passengers
  • Length: 16.50 m (54 ft 1 in)
  • Wingspan: 30.50 m (100 ft 0 in)
  • Height: 6.00 m (19 ft 8 in)
  • Wing area: 102.0 m2 (1,097 sq ft)
  • Empty weight: 5,250 kg (11,590 lb)
  • Gross weight: 8,500 kg (18,760 lb)
  • Powerplant: 3 ×
    Pratt & Whitney Hornet
    , 386 kW (525 hp) each

Performance

  • Maximum speed: 210 km/h (131 mph, 114 kn)
  • Cruise speed: 170 km/h (106 mph, 92 kn)
  • Range: 850 km (528 mi, 459 nmi)
  • Endurance: 5 hours 0 minutes
  • Service ceiling: 4,400 m (14,400 ft)
  • Rate of climb: 3.0 m/s (590 ft/min)

See also

Aircraft of comparable role, configuration, and era

Related lists

References

  1. ^
    ISBN 3-7637-6112-8
    (in German)
  2. ISBN 3-7637-6118-7
    (in German)
  3. ^ Grant 1998, pp. 49–51.
  4. ^ "Junkers G31go VH-UOW – Guinea Airways". The Airways Museum & Civil Aviation Historical Society. Retrieved 17 October 2010.
  5. ^ "RAAF A44 Junkers G31 & W34" Archived 2016-03-03 at the Wayback Machine. ADF Aircraft Serial Numbers. 20 May 2009. Retrieved 17 October 2010.
  6. ^ "Accident Description". Aviation Safety Network. Flight Safety Foundation. Retrieved 4 January 2018.
  7. ^ Ranter, Harro. "ASN Aircraft accident Junkers G.31fo D-ABIL". aviation-safety.net. Retrieved 10 February 2020.
  8. ^ "Civil Aircraft Register - Germany : D-1722". www.airhistory.org.uk. Retrieved 10 February 2020.
  • Grant, James Ritchie (1998). "Corrugated Masterpieces:Junkers Types in Australia and Papua New Guinea".
    ISSN 0143-5450
    .
  • "New Junkers Commercial Monoplane". Flight. 17 March 1927. p. 159. Retrieved 2008-07-30.
  • Taylor, Michael J. H. (1989). Jane's Encyclopedia of Aviation. London: Studio Editions. p. 537.

External links

Wikimedia Commons has media related to Junkers G.31.
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