Marinens Flyvebaatfabrikk M.F.7

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Marinens Flyvebaatfabrikk M.F.7
Role Trainer
Manufacturer Marinens Flyvebaatfabrikk
First flight 30 January 1923
Introduction 19 September 1923
Retired 1931
Primary user Royal Norwegian Navy Air Service
Produced 1922–23
Number built 2

The Marinens Flyvebaatfabrikk M.F.7 was a two-seat biplane floatplane built by the Royal Norwegian Navy Air Service aircraft factory Marinens Flyvebaatfabrikk in 1923. The M.F.7 was designed and employed as a trainer aircraft, and functioned as a temporary solution until a better aircraft was designed. Soon after it entered service, the aircraft factory's experience with the M.F.7 led to the construction of the Marinens Flyvebaatfabrikk M.F.8, which remained in service as the main trainer aircraft of the Royal Norwegian Navy Air Service until the German invasion of Norway in 1940.

Floatplane aircraft equipped with floats for operation from water surfaces

A floatplane is a type of seaplane, with one or more slender pontoons mounted under the fuselage to provide buoyancy. By contrast, a flying boat uses its fuselage for buoyancy. Either type of seaplane may also have landing gear suitable for land, making the vehicle an amphibious aircraft. British usage is to call "floatplanes" "seaplanes" rather than use the term "seaplane" to refer to both floatplanes and flying boats.

Royal Norwegian Navy Air Service

The Royal Norwegian Navy Air Service was alongside the Norwegian Army Air Service the forerunner to the modern-day Royal Norwegian Air Force.

Marinens Flyvebaatfabrikk - The Navy's Flying Boat Factory - was the Royal Norwegian Navy Air Service' aeroplane manufacturer. It was established in Horten in 1915 and produced 120 aircraft from then until it ceased to exist in 1940.

Contents

Design and development

By the early 1920s the Royal Norwegian Navy Air Service's main trainer aircraft, the pusher configuration Marinens Flyvebaatfabrikk M.F.4, which had been introduced in 1918, was outdated. The introduction of such new aircraft as the Hansa-Brandenburg W.33 reconnaissance aircraft left the M.F.4 unfit for service as a trainer. The wings of the M.F.4s were also considered to be too weak. This led to a requirement for a new trainer aircraft of the tractor configuration. Until a tractor aircraft could be designed, a final pusher type was built as an emergency measure, in the shape of the Marinens Flyvebaatfabrikk M.F.6. Design and construction of the Marinens Flyvebaatfabrikk M.F.7 began in March 1922. Initial orders from the Royal Norwegian Navy Air Service were for two aircraft, which in the end turned out to be the final number of aircraft built of the type. [1]

Pusher configuration arrangement of propellers on an aircraft to face rearward

In a vehicle with a pusher configuration, the propeller(s) are mounted behind their respective engine(s). According to British aviation author Bill Gunston, a "pusher propeller" is one mounted behind the engine, so that the drive shaft is in compression.

The Marinens Flyvebaatfabrikk M.F.4 was a biplane floatplane built by the Royal Norwegian Navy Air Service aircraft factory Marinens Flyvebaatfabrikk from 1918. The aircraft was the first purpose-built trainer aircraft in Norwegian service and served until retired in October 1924.

Hansa-Brandenburg W.33

Hansa-Brandenburg W.33 was a German two-seat, low-wing single-engined seaplane, which had been designed by Hansa und Brandenburgische Flugzeugwerke during World War I. Although the W.33 was built in relatively small numbers, the design was widely recognized as successful and numerous copies and license built versions were built by the hundreds after World War I.

The M.F.7, powered by a 160 hp (119 kW) Sunbeam engine, had stronger wings than its predecessor, and was initially fitted with floats made out of duralumin alloy imported from Germany. [2]

Sunbeam Motor Car Company automotive and engineering manufacturer

Sunbeam Motor Car Company Limited was a British motor car manufacturer with its works at Moorfields in Blakenhall, a suburb of Wolverhampton in the county of Staffordshire, now West Midlands. Its Sunbeam name had been registered by John Marston in 1888 for his bicycle manufacturing business. Sunbeam motor car manufacture began in 1901. The motor business was sold to a newly incorporated Sunbeam Motor Car Company Limited in 1905 to separate it from Marston's pedal bicycle business; Sunbeam motorcycles were not made until 1912.

Floats are airtight hollow structures, similar to pressure vessels, designed to provide buoyancy in water. Their principal applications are in watercraft hulls and aircraft floats, floating pier and pontoon bridge construction, and marine engineering applications such as salvage.

Duralumin trade name of age-hardenable aluminium alloy

Duralumin is a trade name for one of the earliest types of age-hardenable aluminium alloys. Its use as a trade name is obsolete, and today the term mainly refers to aluminium–copper alloys, designated as the 2000 series by the International Alloy Designation System (IADS), as with 2014 and 2024 alloys used in airframe fabrication.

Soon after test flying began, the imported duralumin-based floats proved troublesome, as they would not plane on water. The metal alloy floats were soon replaced by wooden floats bought by the Marinens Flyvebaatfabrikk after the bankruptcy of the civilian aircraft manufacturer Norsk Aeroplanfabrik. At the same time the carburettors in the aircraft's engines were replaced with newer models. [3] Later the aircraft had their engines replaced with 160 hp (119 kW) Mercedes engines. Built as a trainer, the aircraft carried no armament. [4]

Operational history

The type's first flight took place on 30 January 1923, when First Lieutenant Finn Lützow-Holm took off with M.F.7 F.2 (III) from the Royal Norwegian Navy's main base at Horten. Lützow-Holm test flew the second M.F.7 built on 7 April 1923, when he took off in M.F.7 F.8 (III). After the changes to type's engine and floats had been carried out, test pilot Lützow-Holm declared that the aircraft was ready for service. In his report, Lützow-Holm stated that the aircraft was easy to manoeuvre both on water and in the air, although it was rear heavy and sensitive to gusts of wind. F.8 (III) entered service with the Royal Norwegian Navy Air Service Flying School on 19 September 1923, with F.2 (III) following suit on 15 October 1923. [3] [Note 1]

Finn Lützow-Holm Norwegian military officer

Finn Trond Lützow-Holm was a Norwegian military officer, aviation pioneer and polar explorer.

Horten Municipality in Vestfold, Norway

Horten  is a town and municipality in Vestfold county, Norway—located along the Oslofjord. The administrative centre of the municipality is the town of Horten. The municipality also includes the town of Åsgårdstrand and the villages of Borre, Skoppum, and Nykirke.

Based on its experience with the M.F.7, the Marinens Flyvebaatfabrikk began development of its successor already in October 1923. Among the weaknesses in the M.F.7, which were to be remedied in the Marinens Flyvebaatfabrikk M.F.8, was the low landing speed of only 50 km/h (31 mph). When the work on the M.F.8 was completed in 1924, it was a successful trainer type which remained in Norwegian service until the German invasion in 1940. [6]

The M.F.7 remained in service for several years after the introduction of the M.F.8. M.F.7 F.2 (III) was discarded in January 1930, having flown for a total of 456 hours and 10 minutes. The other M.F.7, F.8 (III), was disassembled in the spring of 1931, having flown for 855 hours and 50 minutes. F.8 (III) was finally discarded on 2 February 1934. [4] Although an interim solution to the Royal Norwegian Navy Air Service's training needs, the aircraft type was considered a success. [7] [8]

Specifications

Data from Hafsten and Arheim [4]

General characteristics

Performance

  • Maximum speed: 120 km/h (75 mph; 65 kn)
  • Cruise speed: 90 km/h (56 mph; 49 kn)
  • Range: 275 km (171 mi; 148 nmi)
  • Rate of climb: 1.39 m/s (274 ft/min)

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References

Notes
  1. Finn Lützow-Holm had a long career in the Royal Norwegian Navy Air Service, rising to command the service from 1938. [5]
Citations
  1. Hafsten and Arheim 2003, pp. 99–101
  2. Hafsten and Arheim 2003, p. 100
  3. 1 2 Hafsten and Arheim 2003, pp. 100–101
  4. 1 2 3 Hafsten and Arheim 2003, p. 224
  5. Larsstuvold, Ulf. "Finn Lützow-Holm". Norsk biografisk leksikon (in Norwegian). Oslo: Kunnskapsforlaget. Retrieved 15 May 2012.
  6. Hafsten and Arheim 2003, pp. 101–102
  7. Arheim 1994, p. 9
  8. Meyer 1977, p. 51
Bibliography