C.Owers Hansa-Brandenburg Aircraft of WWI Vol.2: Biplane Seaplanes (A Centennial Perspective on Great War Airplanes 18)

Type W.13 (Austro-Hungarian K Flying Boat)

   The W.13 was another large flying boat built for production in Austro-Hungary by Phonix and UFAG, and later by Oeffag, as a Type K boat.(5) The prototype was constructed in Germany but none were used by the German air services.
   The first W.13 for the kuk Kriegsmarine was K305 that arrived at Pola in March 1917. This machine crashed on 25 April during trials. The second Brandenburg-built machine, K306, did not arrive until 6 March 1918, indicating problems at the Brandenburg factory at Briest. In the meantime the type had entered active service, with K366 attacking the Italian barracks at Palmanova in August 1917.
   K307 was found by an Italian Torpedo boat on 28 September 1917, having alighted due to engine failure, and was recovered in almost perfect condition. "She appeared to be brand new, well-built, and nicely finished off, a great contrast to K222, captured on 11th August 1917, which was rather cheaply built." The report published by the British noted that the wings were of deep section and large camber. The interplane struts were of 44 mm streamlined steel tubing and inclined inwards from bottom to top. The fin was a hollow three-ply structure built onto the hull that was constructed of three-ply throughout.
   The wings were attached by steel extensions of the main spars that passed through the deck of the hull. The pilot sat on the left side with the observer on the right. He could pass to the front cockpit by means of a sliding door without climbing over the top. The engine was reported to be a 12-cylinder Vee-type Austro-Daimler of 345-hp. Twin Bosch magnetos were fitted, each supplying 12 cylinders. Twin carburettors were fitted on the starboard side, each supplying six cylinders. Starting was achieved by means of a starting crank (removable) on the end of the crank shaft and a standard Bosch starting magneto. The engine was supported on steel bearers.
   The two-bladed propeller had brass tips and was of mahogany except for the central lamination that was of ash. Fuel for eight hours was carried in two tanks located in the hull under the engine. The forward tank held 170 litres, while the aft tank held 590 litres. A gravity tank located in the starboard top plane was fed by air pressure from the main tanks. Full supply also could be made from the main tanks. A hand pump and two mechanical pumps driven off the cam shaft could be used to supply fuel.
   The aileron controls were led from the hull through the wings. Rudder and elevator control runs were along the top of the boat. No controls were duplicated. "The rudder control bar is fitted with rests for both feet, and must be unusually comfortable for a long flight."
   Armament comprised a single machine gun in the front cockpit, the gunner standing to operate the gun. K307 was fitted to carry two 155 kg bombs and fourteen 20 kg bombs. One 155 kg bomb was carried against the hull under the main planes on each side. The bombs could not be released except in a live condition as the fusing wire was operated by the bomb-dropping lever. Fourteen 30 kg bombs could be carried in two "more or less" streamlined boxes mounted on the lower main planes. The bombs could be dropped separately or by turning the lever swiftly, in a box together.(6)
   Despite the "Kappa" having a good record in service, 59 of the 134 known to have been constructed were placed directly into storage, mainly due to the lack of suitable engines.
   After the end of the war, when the French left the Austro-Hungarian seaplane base at Kumbor, the Royal Yugoslav Navy obtained 22 abandoned Austro-Hungarian marine aircraft. There were four Brandenburg W.18 flying boats, five Brandenburg K, and five Brandenburg W.13 boats, together with a Friedrichshafen FF49C, two Rumpler 6B2 floatplanes, and five Lohner TL boats. Some of these, including the Brandenburgs, were pressed into service, mostly as trainers.(7)
   The USN received a number of Austro-Hungarian naval aircraft post-Armistice. On 23 October 1919, it was reported that the Commander, US Naval Forces, Eastern Mediterranean, had arranged with Italian authorities to obtain two ex-Austrian seaplanes from the Naval Air station at Pola. UFAG-built W.13 K405, with a 12-cylinder 450-hp Daimler engine, was shipped to the US by the USS Mars in October 1919, along with UFAG-built FB K248 with a 250-hp Hiero engine,(8) both boats being reported at the Naval Aircraft Factory (NAF) on 1 October 1920. K405 was restored to flight status with a Liberty engine by the NAF. On 4 January 1921, it was reported that the bottom of the hull was weak and old and should be replaced. Whether this was done or not is unknown; however, the flying boat was shipped by air to Hampton Roads, where the USN had its experimental facility, on 27 May 1921. It underwent testing at Hampton Roads with the Bureau No. A-5806. On 18 May 1922, Hampton Roads put in a Trouble Report that noted that the hull had depreciated to such an extent that the machine was no longer safe to fly and as it was beyond economic repair, it was recommended that it be stricken from the list of naval aircraft, this being carried out on 16 June 1922.

(5) The K class of flying boat was introduced to supplement the L Class and to have a greater load and defensive power with a crew of three and a machine gun in the forward cockpit. The types were most often flown with a crew of only two.
(6) UKNA AIR1 /716/27/19/32. "Austrian Flying Boat"K.307."
(7) Why the W.13 boats were listed separately from K boats is not explained. Source: Isaic,V. and Frka, D. Naval Aviation at the Eastern Coast of the Adriatic Sea 1918-1941 (Volume 1), TKO ZNA ZNA, Zagreb, 2010.
(8) NARA RG72 Box 2, File O-ZS-21.


Brandenburg W.13 Production
Serial Manufacturer Notes
K305 - K319 Brandenburg Short hulls. 350-hp Austro-Daimler.
K320 - K364 Brandenburg Long hulls. 350-hp Austro-Daimler. 40 delivered without engine.
K365 - K422 UFAG 350-hp Austro-Daimler. K417 - K421 destroyed in fire at factory.
K425 - K452 Phonix Long hull. Only first 10 delivered, 7 without engine (See below).
K431 & K434 Oeffag 350-hp Austro-Daimler. Possibly sub-contract from Brandenburg.

M.Dusing German Aviation Industry in WWI. Volume 1 (A Centennial Perspective on Great War Airplanes 84)

Hansa und Brandenburgische Flugzeugwerke AG (Brand)

Aircraft Development:

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  Late in the year a redesigned version of the Type W.18 was built for the Austro-Hungarian Navy. This machine was powered with the 350 hp Austro-Daimler engine Dm345 and was generally referred to as the Type “KG”. 60 aircraft were eventually delivered from Brandenburg, 60 from UFAG and 8 from Phonix. In early 1918 OEFFAG constructed three modified machines, and these were designated Class "T".
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E.Hauke, W.Schroeder, B.Totschinger Die Flugzeuge der k.u.k. Luftfahrtruppe und Seeflieger 1914-1918

Kampfflugboote
K 305 - K 322 Type Brandenburg W.13/Hansa Brandenburg Dm 350
K 323 - K 364 Type Brandenburg W.13/Hansa Brandenburg ohne Motor
K 365 - K 388 Type Brandenburg W.13/UFAG Dm 350
K 389 Type Brandenburg W.13/UFAG, dort durch Brand zerstört
K 390 Type Brandenburg W.13/UFAG, dort durch Brand zerstört
K 391 - K 397 Type Brandenburg W.13/UFAG Dm 350
K 398 - K 405 Type Brandenburg W.13/UFAG Dm 350
K 406 Type Brandenburg W.13/UFAG ohne Motor
K 407 Type Brandenburg W.13/UFAG Dm 350
K 408 - K 416 Type Brandenburg W.13/UFAG ohne Motor
K 417 - K 422 Type Brandenburg W.13/UFAG. dort durch Brand zerstört
K 425 Type Brandenburg W.13/Phönix Dm 350
K 426 - K 430 Type Brandenburg W.13/Phönix ohne Motor
K 431 Type Brandenburg W.13/Phönix Dm 350
K 432 - K 434 Type Brandenburg W.13/Phönix ohne Motor