J.Forsgren Swedish Military Aircraft 1911-1926 (A Centennial Perspective on Great War Airplanes 68)

Thulin G

  Recognizing the obsolescence of the Farman HF 23, a request for five heavy and four light flying boats was distributed to different manufacturers. AETA put forward offers both for the heavy and light flying boats, with the latter being the Thulin B and D monoplanes. As these types of airplanes were considered insufficient for the MFV’s needs, lacking in engine power and endurance, that contract went to SAF and its H 2.
  For the heavy flying boat contract, a modified 160 h.p. Albatros was offered by AETA. It was expected that five Mercedes engines could be obtained from Germany. In competition with Sodertelge Verkstader, whose cost estimate was five times higher than AETA’s, the AETA offer was accepted. A contract for five Thulin G’s was signed on January 19, 1916. The contract specified a rather modest overall performance, a maximum speed of 100 km/h, an empty weight of 520 kg, a six hour endurance, and a 20 minute climb rate to an altitude of 800 metres(!) The airplane was to be armed with a machine gun, and bomb tubes for 10 and 60 kg bombs. A radio was also to be installed. The first airplane was to be delivered four months after the signing of the contract, followed by one airplane each month.
  Despite many requests, the Mercedes engines were not delivered, eventually being replaced by 150 h.p. Benz engines. However, these engines were not released by Germany until December 16, 1916, with actual delivery taking place in the spring of 1917.
  As a result, the first Thulin G was not launched until July 10, 1917, being flown for the first time the following day. The first two Thulin G’s were not delivered until August 1917. Two more were delivered the following month, with the last one being arriving in October. The five Thulin G’s were issued with the serial number 11 to 15.
  Although initial test flights had shown some promise, it was later found that the Thulin lacked inherent stability, and well as having poor flight and handling characteristics. Modifications included a two-degree wing sweepback, and fitting a considerably enlarged rudder. When the Thulin G’s were fitted with a radio and machine gun, the upper wing had to be moved back seven centimeters in order to maintain centre of gravity. The Thulin G’s were heavily used for maritime reconnaissance. On July 15, 1918, serial number 11 was lost off Lysekil. Both crew, Fritz Netzler and Fredrik Thalin, were never found, with the cause of the crash being unknown. On July 19, 1920, serial number 12, was written off in a crash.
  A third Thulin G, serial number, 14 was destroyed by fire on August 5/6, 1921. The two remaining Thulin G’s were struck off charge in January 1922. One Thulin G, serial number 15, has been preserved.

Thulin G Technical Data and Performance Characteristics
   Engine: 1 x 160 h.p. Benz
   Length: 9,40 m
   Wingspan: 17,20 m
   Height: 4,00 m
   Wing area: 52,00 m2
   Empty weight: 1,340 kg
   Maximum weight: 1,538 kg
   Maximum speed: 118 km/h
   Armament: 1x8 mm machine gun


Preservation

Thulin G

  After being struck off charge in January 1922, Thulin G serial number 15 was donated to the National Maritime Museum in Stockholm. The big flying boat remained in storage until transferred to the adjacent National Museum of Science and Technology, along with other historical airplanes, in the mid-1930’s. Although the fuselage was briefly put on display, it was not fully assembled. Consigned to storage, the Thulin G was roaded to Malmen in 1977. By this time, the airplane had lost its engine and propeller. Formal ownership of the Thulin G was transferred to Flygvapenmuseum in 1997.
  On September 27, 2004, the fuselage and main floats were transported to Tullinge for refurbishment by the Tullinge Group. Upon close inspection, it was discovered that the fuselage was in very good condition, with the few dents being due to damage during storage and transportation. The fuselage was cleaned, with the metal components being treated for corrosion. A new windscreen was constructed, along with an alumunium nose cone. Interestingly, electrical wiring, possibly used for R/T trials were found in the airplane. The floats were also in good condition, with work involving straightening some of the float struts. The paint showed signs of having been subjected to heat, the conclusion being that they had been stored at the Stockholm naval yard during the August 1921 fire.
  In January 2009, the fuselage and floats were trucked to Flygvapenmuseum. Two months later, the wings arrived at Tullinge. Although a great deal of cleaning had to be performed, the wings were in an excellent state of preservation. A Benz Bz III engine (W Nr 20086), possibly having originally been delivered in September 1918 for use in a Friedrichshafen FF.33, subsequently arrived at Tullinge. The engine looked like something from the scrapheap, with a broken crankshaft and many missing parts. The engine was restored to static condition, with a new propeller being built by Mikael Carlson. In 2010, the wings and engine were transported to Flygvapenmuseum, where the Thulin G was assembled for the first time since 1922, and placed on display.


Thulin GA

  With two Thulin G’s having been lost, two replacement airplanes were ordered from AETA. However, there were to be no sixth and seventh Thulin G. Instead, Thulin redesigned the basic Thulin G in order to accomodate a 200 h.p. Curtiss engine, two of which had been delivered to AETA courtesy of the Naval Department. In December 1917, two Thulin GAs were offered to the MFV, a formal order being placed during in early 1918. By March 12, 1918, work on the fuselage drawings commenced, with the first Thulin GA being completed on July 15. The first flight took place five days later, with the pilot, Nils Kindberg, nearly writing off the airplane. This was only the beginning of what seemed to be an almost endless series of problems with the Thulin GA, particularly with regards to the airplane being inherently unstable in flight.
  While the first airplane was being repaired, the second Thulin GA was launched on August 13. Almost exactly one month later, on September 12, the first production Thulin GA was launched for the second time. Protracted tests lasted until early 1919. The pair of Thulin GA’s did not leave the factory until March 18/19, 1919, with the carpenter ’Palle’ Mellbom noting in his diary: ’’Loaded two GA’s, nice feeling after this had been done”.
  Following delivery, the Thulin GA’s were issued with the serial numbers 16 and 17. In late 1920, serial number 16 was fitted with a 200 h.p. Benz engine, flight test commencing in early December. During a test flight, the airplane crashed into Askrikefjarden near Stockholm on January 10,1921. Both crew, Lieutenant Sten G.S. Berthelson and the observer Fritz Pettersson were killed. The airplane was struck off charge in April 1921. The sole remaining Thulin GA was destroyed in the disastrous fire at Galarvarvet on August 5/6, 1921.

Thulin GA Technical Data and Performance Characteristics
   Engine: 1 x 200 h.p. Curtiss
   Length: 9,2 m
   Wingspan: 17,2 m
   Height: 3,65 m
   Wing area: 53,5 m2
   Empty weight: 1,350 kg
   Maximum weight: 1,750 kg
   Maximum speed: 135 km/h
   Armament: -