Marinens Flyvebaatfabrikk M.F.5

Norwegian Navy Floatplane (1919): 9 provided.

The Marinens Flyvebaatfabrikk M.F.5 was a new type of biplane floatplane built in Norway for the Royal Norwegian Navy Air Service, and assembled at Marinens Flyvebaatfabrikk from 1918 based on the Sopwith Baby. The M.F.5 was the first model operated in tractor configuration and remained active for eight years as a primary reconnaissance aircraft (8 deployed from Karljohansvern in Horten), with one retained as a trainer. It was the largest "production" of the manufacturer so far for the Navy but not a success. It was replaced by the MF9 from 1926 (10 manufactured).

Development

Marinens flyvebaatfabrikk was established in May 26, 1915, in Horten (closed its doors 1972) as a Norwegian aircraft factory. No more than a glorified workshop, it only succeeded to deliver 130 aircraft between 1915 and 1940. Co-located with the Royal Norwegian Navy Air Service at Karljohansvern, Horten it was however conventient to access by the staff. Together with the Kjeller Aircraft Factory (Kjeller Flyfabrikk) as mostly land-based models, both formed the core of local aircraft manufacturers. The first model came from Germany in August 1912, converted into a seaplane in 1913 and by 1914, Roald Amundsen donated his French Farman MF.7 seaplane which became the basis for the MF1. The factory was formally established in May 1915 and created a whole lineage until the MF-12. It also produced under license models such as the Sopwith Baby and Hansa-Brandenburg W33...

The factory, which at its peak had about 86 employee in 1938, developed the MF1 (photo) as a copy of the Farman MF.7. It was a biplane pusher with two floats, with a few made, F.2, F.4, F.6, F.8, and F.8(II) after the first crashed. They trained many pilots intended in WW1 for other models and was followed by the MF2, first official recce model from the company, actively used. Only three were made, F10, F10 bis and F12, essentially a modified MF1 with bombs and a machin gun. The last was operational in 1917. Next the MF3 appeared (4 made in 1917: F.14, F.16, F.18, F.20) essentially the same bit powered by a 160 hp Curtiss engine. Next came the MF4 used for training, with 7 made in 1918–24 as a further development of MF1. The MF5 was a completely new model, essentially a licence Sopwith Baby. It was used for reconnaissance. The reat novelty was that it became the first modern model using a pusher engine configuration.

Indeed, the Maurice Farman MF.7, designed in 1912 and introduced in 1913 (3,310 made by France) was powered by a 70 to 100 hp engine, and declined into 5 versions, also used by Britain (13 squadrons), nown locally as the "longhorn", as well as Austrlia, Italy and Belgium. From the MF1 to the MF4, the Norwegian produced some 20 until 1917, some used for training and others for recce. However by 1917 given the rapid pace of aviation technology, the MF.7 appeared obsolete and had been already replaced by new models in the entente. To keep pace with the technology of the time, the naval air branch decided to go for a completely new model, fresh in 1917, the Sopwith Baby.

The Sopwith Baby was a fighter aircraft equipped with floats, based on the Sopwith Schneider race model, further developed as a fighter and sharng some characterics with the Pup. It had however a powerful engine, the 110 hp, 9-cylinder Clerget 9A rotary and was fitted to receive on demand, machine guns, bombs, even rockets. Some 195 were manufactured total by Blackburn and a further 105 with a 130 hp Clerget 9B engine.

Design specifics

Thus, in 1917, the Royal Norwegian Navy Air Service purchased ten of these. They came with a licence for local production. Thus, an additional seven could be built at the aircraft factory in Horten. The adoption of this model was based on the experience with this type by the director and Captain Halfdan Gyth Dehli. Work on this first tractor in Norwegian history started in 1917 but it occupied all the space at the Marinens Flyvebaatfabrikk from 1918. Halfdan Gyth Dehli was a businessman and aviator, at the head Marinens Flyvebaatfabrikk from 1916 to 1918. He essentially transformed a 1-seat fighter floatplane into a 2-seater scout. A total of nine of these seaplane scouts were produced in 1918, plus another two planned, but never completed as better models were available.

General conception

The MF5 was much larger than the original one-seater Baby (23 ft (7.01 m), long wingspan 25 ft 8 in (7.82 m) height 10 ft 0 in (3.05 m), weight 1,226 lb/556 kg, gross 1,715 lb/778 kg). Indeed, given the second seat, it had not only a longer fuselage and added wingspan. Indeed the MF5 measured 10 meters overall (32 ft 10 in), for a wingspan ported to 15 m (49 ft 3 in), height of 3.66 m (12 ft). Its empty weight was 1,200 kg (2,646 lb) and its gross weight reached 1,580 kg (3,483 lb). However the entire structure remained the same, metallic tubes for the fuselage, wrapped in doped canvas and a mix of metal and wooden frames for the wings, tail and ailerons. The general design recalled more the Short 184 than the Baby by a long shot.

The general outlook was however very different indeed: First off the fuselage was lenghtened, the engine was now inline and thus completely changed the nose shape, the wings were much elongated instead of the original stubby ones, the tail was triangular, the ailerons had a more geometric, triangular shape, and the main wings were unequal, with the upper one a bit wider making for a sesquiplane configuration. Plus they were attached by three sets of "H" bay struts. If the general float configuration was about the same, with two main, one axial under the tail, the main floats were reinforced to deal with ice, larger, and attached by inverted W struts.

Engine

Instead of the original Clerget 9Z 9-cylinder air-cooled rotary piston engine rated for 110 hp (82 kW) and drving a wooden 2-bladed, later 4-bladed fixed-pitch propeller, the MF5 was powered by a more potent 160 hp (120 Kw) 16-cylinder Sunbeam water-cooled engine, imported, but they did not perform as well as hoped. The Norwegians tried to return the engines, and this led to an agreement reducing the cost on 12 out of 16 imported engines. Still, they never functioned well, even to the point of being rebuilt several times over the years, causing four crashes, including the prototype. The last M.F.5s manufactured had instead the more powerful 240 hp 6-cylinder Siddeley Puma water-cooled engine. The MF5 managed to reach 132 km/h (82 mph, 71 kn) as max speed, for a cruise speed of 115 km/h (71 mph, 62 kn). Range was 500 km (310 mi, 270 nmi), more than the Baby, but the rate of climb was also better than the Baby at 1.19 m/s (234 ft/min).

Armament

Armament on the original Baby consisted of a single Lewis machine gun in the fuselage and synchronised to fire through the propeller, but the Norwegian replaced it by a Madsen. However it was only for a short time, as later the Lewis were back. It could also carried a 40 kgs mine, or five 40 kgs bomblets. It seems the machne gun was synchonized and placed in front of the pilot of the left side. The observer had no additional defensive ring mount MG.

⚙ MF5 specifications
Light Weight	1,200 kg (2,646 lb)
Gross Weight	1,580 kg (3,483 lb)
Lenght	10 m (32 ft 10 in)
Wingspan	15 m (49 ft 3 in)
Height	3.66 m (12 ft)
Wing Area	Unknown
Engine	Sunbeam 6-cyl. piston engine, 120 kW (160 hp)
Top Speed	132 km/h (82 mph, 71 kn)
Cruise Speed	115 km/h (71 mph, 62 kn)
Range	500 km (310 mi, 270 nmi)
Climb Rate	1.19 m/s (234 ft/min)
Ceiling	Unknown
Armament	Madsen machine gun, 40 kgs mine or 5 bomblets.
Crew	1 pilot, 1 observer in tandem open cockpits

Service

The MF5 completely missed the war. Its first flight took place on 19 November 1918, just after the armistice. This was M.F.5 F.22. However after two weeks of training it was lost on 4 December after an engine stoppage. It entered into a non-recoverable spin, crashing in Horten harbour. This spared the life of the two on board, which suffering injuries and were hospitalised at the Royal Norwegian Navy's hospital in Horten. F.22 by that time only cranked up 1 hour and 55 minutes of flight.

By the winter of 1922, the F.22 (II) powered by a 240 hp Siddeley Puma multiplied successful test landings and take-offs, with new reinforced "ski-floats" designed to work both on snow and ice. Tests on ice were made at Karljohansvern naval base, Horten, and on snow nearby Lake Borrevannet. Not having the same buoyancy as proper floats, they remained optional for winter operation. The MF5 over its eight years of service developed a poor reputation: Six out of the nine provided were lost in accidents. Three had been caused by engine failure and the remainder, pilot error for two crashes. One, M.F.22 (II) just lost balance after a sudden burst of wind while takeing-off on 29 May 1922. However there was no fatality. All these trained pilots went into more modern model. Still the attrition rate of the M.F.5 was abysmal. All but one crashes were around the main base at Karljohansvern, Horten. F.32 crashed however off the port city of Kristiansand. Between the speed and water, it was survivable.

The three surviving M.F.5s were retired on 5 August 1926. F.26 clocked a total of 55 hours over seven years, which was not stellar. Although designed as scouts and reconnaissance model, a single one wasretained for training all thes eyears, F.34. It was stuck at the Royal Norwegian Navy's flying school until lost to pilot error, on 19 September 1921. They were replaced in their role by the MF9.