Blohm & Voss BV 138

The Blohm & Voss BV 138 Seedrache (Sea Dragon) was a trimotor flying boat designed and built by the German aircraft manufacturer Blohm & Voss. It served as the Luftwaffes primary seaborne long-range maritime patrol and naval reconnaissance aircraft operated by the Luftwaffe during the Second World War.

The BV 138 was a pre-war design by Dr Richard Vogt, originally developed under the company name of Hamburger Flugzeugbau, and thus it was initially designated Ha 138 instead. It had an uncommon appearance due to its combination of unusual design features, such as its twin boom tail unit, short hull, and trimotor engine configuration. In reference to the side-view shape of its fuselage, the aircraft was often referred to via the nickname Der Fliegende Holzschuh ("Flying Clog"). Originally designed to be powered using two engines, the trimotor configuration was adopted prior to flight testing due to engine difficulties. Development would be protracted due to multiple redesigns being enacted.

Shortly after the maiden flight of the first prototype (D-ARAK) on 15 July 1937, identified instabilities necessitated a redesign of the hull and tail booms to improve both hydrodynamic and aerodynamic properties. The first production-standard aircraft, designated BV 138A-1, performed its first flight during April 1940, by which point Germany was at war with multiple neighbouring nations. By December 1940, it has been introduced as a military naval reconnaissance aircraft by the Luftwaffe. Despite concerns as to its structural strength, which was improved over time, it was adapted into various roles, including as a radar-equipped anti-shipping aircraft, an austere troop transport, and as an airborne aerial countermeasure to naval mines. The definitive BV 138C-1 was introduced to service during March 1941. A total of 297 BV 138s were built between 1938 and 1943.

Development

During the early 1930s, the Blohm & Voss shipbuilding company in Hamburg was suffering financial hardship due to a prolonged downturn in orders amid the Great Depression affecting global demand; company officials opted to diversify via the creation of a new subsidiary company, Hamburger Flugzeugbau, which specialised in the design and manufacture of aircraft. The BV 138, which was originally designated as the Ha 138, originated out of the new company's interest in creating its first flying boat; the endeavour was considered a natural fit for the firm, being owned by a shipbuilding company meant that many staff already had good knowledge of the maritime environment and suitable construction practices thereof, while the company's main complex was sited on the Elbe, permitting direct access to a large body of water.

Design studies into various configuration were performed; one, referred to as P.12, was selected for further development as a long range reconnaissance aircraft. A longer and reshaped hull was adopted along with stronger tail booms. A total of five pre-production aircraft, which were capable of carrying multiple defensive machine guns, were completed during the late 1930s.

During April 1940, the first production-standard aircraft, designated BV 138A-1, performed its first flight; shortly thereafter, it was rapidly introduced into Luftwaffe service in response to pressing wartime demands.

The strength of the structure was only fully addressed via the introduction of the improved BV 138C-1 in March 1941; this model became the definitive version of the aircraft. To address vibration-related concerns on the earlier models, the central engine of the BV 138C-1 drove a four-bladed propeller, while the other two engines were fitted with broader three-bladed counterparts; the central engine's radiator arrangement was also revised. In addition to its use in the maritime reconnaissance role, several aircraft were specially adapted to sweep naval mines; designated BV 138MS, this role necessitated the deletion of all conventional armaments and the installation of a large (roughly diameter) dural hoop mounted horizontally under the wings, powered by an auxiliary motor generating an electric field which detonated magnetic mines. Early built aircraft often had issues related to insufficient structural strength.

In March 1941, the most successful variant of the aircraft, designated BV 138C-1, entered Luftwaffe service.

Some BV 138s served with the specialist KG200, where they would often carry up to 10 fully armed infantry troops in place of a bombload.

In preparation of a repeat of Operation Wunderland in 1943, the U-boat U-255 was sent to the East coast of Novaja Zemlya where it teamed up with a BV 138. The U-255 refuelled the BV 138 four times for reconnaissance flights over the Kara Sea, up to the Vilkitsky Strait. The BV 138 could not find any shipping however, that would make a mission for the German cruiser Lützow worthwhile, so the operation was cancelled.

The BV 138 was tested with the Walter HWK 109-500 Starthilfe RATO jettisonable rocket pod, used in pairs, for shorter takeoff performance. All rocket units were jettisoned after use; fitted with parachutes, they could be recovered after landing. The wrecks are stored at the National Museum of the Romanian Navy in Constanța.

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 WWII German seaplane harbour in Indre Billefjord.

Another wreckage of a BV 138 was identified by the Norwegian Mapping and Cadastre Authority on the seabed near Svalbard in 2022.

Blohm & Voss BV 138

Development

Specifications (BV 138C-1)

See also

References

Notes

Citations

Main sources

Secondary sources

External links