The Blohm & Voss BV 138 Seedrache (Sea Dragon), but nicknamed Der Fliegende Holzschuh ("flying clog", from the side-view shape of its fuselage) was a World War II German trimotor flying boat that served as the Luftwaffe's main seaborne long-range maritime patrol and naval reconnaissance aircraft.
Design and development
A total of 297 BV 138s were built between 1938 and 1943. The aircraft was unusually powered by three engines, with one mounted high above the centerline driving a four-blade propeller, and one on each wing driving three-blade propellers. The pre-production prototypes and the BV 138 A-01 to BV 138 A-06, were powered by various makes of engines ranging from 485–746 kW (650–1,000 hp). The first standardized version, BV 138 B-1, was powered by three 880 PS (868 hp, 647 kW) Junkers Jumo 205D aircraft diesel engines. The unusual appearance of the aircraft was due to several things. The aircraft's semi-anachronistic trimotor configuration, with the central engine mounted high over the center wing, was unique, not helped by the mismatched numbers of propeller blades. Even the engine cowlings themselves had an atypical appearance due the to unique nature of the two-stroke, opposed-piston diesel engines used. The general appearance of the cowlings was similar to the engine cowling on an typical 4 or 6-cylinder inverted inline engine, due to the similar shape of the engines. Such engines were unusual on aircraft of this size, being more commonly found on smaller civil and utility aircraft. Protruding from the rear of the outer engine nacelles were the slab-sided booms of the twin boom tail unit, while the (also slab-sided) hull unit that was slung underneath reputedly bore a certain resemblance to a wooden shoe (earning the Bv 138 its popular nickname "The Flying Clog"). For hydrodynamic reasons, there was also a distinct "turn-down", or "beak" at the stern, like the fuselage had been bent. All these features combined to give the aircraft a highly distinctive and unique appearance, as well as ungainly lines. Not helping were the prominent enclosed powered gun turrets at the bow and stern — the bow turret closely resembling the forward dorsal turret on the Focke-Wulf Fw 200C-3/U1 four-engined patrol aircraft — each mounting a single MG 151/20 autocannon, as well as a fully open Scarff ring-like emplacement behind the central engine containing a 13mm MG 131 heavy machine gun, which had the appearance of being added on as an afterthought to cover the fields of fire that were obstructed from the 20mm cannon by the horizontal stabilizer; the contrast echoed the mismatched propeller blades on the engines. These features together produced the aircraft's ungainly appearance, but inspired a certain affection among its crew and mechanics.
The first of the 227 standard service variant, BV 138 C-1, began service in March 1941. Although various versions of the aircraft carried a variety of armament, the standard included two 20 mm MG 151/20 cannons, one in a power-operated bow turret and one in a power-operated stern turret, up to three 7.92 mm MG 15 machine guns, and a 13 mm (.51 in) MG 131 machine gun in the aft center engine nacelle. It could carry up to 500 kg (1,100 lb) of bombs or depth charges (under the starboard wing root only) or, in place of these, up to 10 passengers. Several were later fitted with FuG 200 Hohentwiel low-UHF band search radar for anti-shipping duties. Some were converted for the minesweeper role, as the BV 138 MS variant, with the "MS" suffix signifying Minensuch (German for mine-clearing, literally mine-search), carried a circular ring-shape degaussing device, a hoop with the same diameter as the length of the fuselage (encircling the entire hull), and field-generating equipment, instead of weapons.
Developed under Hamburger Flugzeugbau designation
- Ha 138 V1 (D-ARAK) – First flight on 15 July 1937
- Ha 138 V2 (D-AMOR) – First flight in August 1937
- Ha 138 V3 – Construction abandoned due to redesign.
- BV 138 A-01 to 06 – Operational testbeds
- BV 138 A-1 – Flew reconnaissance during Operation Weserübung (The invasion of Norway)
- BV 138 B-0 – Officially entered service in October 1940
- BV 138 B-1 – Entered service in November 1940
- BV 138 B-1/U1
- BV 138 C-1, also had minesweeper variant
- BV 138 C-1/U
- BV 138 MS – Minesweeping version.
No complete BV 138s remain in existence. However, the wreck of one aircraft, sunk after the war in a British air show, was raised from the seabed of the Øresund Sound in 2000, and is on display at the Danish Technical Museum in Helsingør.
On 27 June 2012, two divers (Pascale Roibu and Iulian Rusu) found a Heinkel He 114 seaplane in Siutghiol Lake near Mamaia, Constanta, Romania. During that time, the two divers also found pieces of a Blohm & Voss BV 138 seaplane.
In June 2013, a vessel from the Norwegian Geological Survey filmed a Blohm & Voss BV 138 at a depth of 35 m in Porsangerfjorden, Norway, not far from the WW2 German seaplane harbour in Indre Billefjord.
- Nowarra 1997, original German title of the Schiffer book.
- NRK Nordnytt 14 June 2013
- Green, William. Warplanes of the Second World War, Volume Five: Flying Boats. London: Macdonald & Co.(Publishers) Ltd., 5th impression 1972. ISBN 0-356-01449-5.
- Green, William. Warplanes of the Third Reich. London: Macdonald and Jane's Publishers Ltd., 4th impression 1979. ISBN 0-356-02382-6.
- Ledwoch, Janusz. Bv 138 (Wydawnictwo Militaria 64) (in Polish). Warszaw, Poland: Wydawnictwo Militaria, 1998. ISBN 83-7219-015-1.
- Nowarra, Heinz J. and Don Cox, (transl.) Blohm & Voss Bv 138 (Schiffer Military History). Atglen, Pennsylvania: Schiffer Publishing Ltd., 1997. ISBN 0-7643-0296-5.
- Smith J. Richard and Anthony Kay. German Aircraft of the Second World War. London: Putnam & Company Ltd., 1972 (3rd impression 1978). ISBN 0-370-00024-2.
- Wagner, Ray and Nowarra, Heinz. German Combat Planes: A Comprehensive Survey and History of the Development of German Military Aircraft from 1914 to 1945. New York: Doubleday, 1971.
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