Fokker F.VII

Fokker F.VII
The Southern Cross, which was the first aircraft to cross the Pacific in 1928
Type:	1- or 3-engine airliner
Design country:	Netherlands
Manufacturer:	Nederlandsche Vfluguigenfabrieken , Atlantic Aircraft Corporation
First flight:	April 11, 1924
Commissioning:	1924
Production time:	1924-1932
Number of pieces:	283 (exact number unknown, probably significantly more)

The Fokker F.VII was a high- wing commercial aircraft from the 1920s. It was built with one or three engines and offered space for two pilots and eight to ten passengers. The development and production was carried out by the Nederlandsche Vendunguigenfabrieken , the aircraft intended for the US market were manufactured by the Atlantic Aircraft Corporation under the name Atlantic C-2 . License versions of the three-engine F.VIIb-3m were developed by other manufacturers for military and civil purposes.

history

The standard cabin of the F.VII with seats and overhead racks for light luggage.

Shortly after the end of the First World War, the idea of ​​an air connection between the Netherlands and their colony, the Dutch East Indies , arose . In December 1923, the head of the KLM airline , Albert Plesman , and the aircraft designer Anton Fokker agreed to develop an aircraft suitable for this long haul. The contract provided for a single-engine high-decker with eight passenger seats and a two-man cockpit with dual controls. The unit price without the engine should be 24,000 guilders. The German designer Walter Rethel was commissioned with the design . When he moved to Arado in 1925 , his compatriot Reinhold Platz took over the further development.

The five machines delivered to KLM from 1924 onwards have been continuously rebuilt and improved. As a result of these attempts, the enlarged version F.VIIa was created from 1925, of which 40 machines could be sold. They were used by various airlines, partly as passenger and partly as cargo planes.

One of these aircraft was equipped with three engines on a trial basis in 1925 in order to ensure safe continued flight in the event of an engine failure. This version, known as the Trimotor , met with great demand. By 1932 more than 150 three-engine aircraft had been sold, mainly in the USA and Europe.

The Fokker F.VII was one of the first commercially successful passenger aircraft and, together with the Ford AT-5 Trimotor, dominated the American aviation market. It wasn't until the Boeing 247 and Douglas DC-2 appeared in the early 1930s that they were slowly being replaced.

The aircraft was later built under license by many other manufacturers. The United States Army Air Corps used eleven copies of the military version Atlantic C-2 as transport machines, four of which were later rebuilt and designated as the Atlantic C-7 . The F.VIIa , built in Poland , were used as bombers by the Polish Air Force .

construction

For the fuselage, the designers used the tubular steel frame and the wooden interior cladding of the Fokker FV , but replaced the wooden outer skin with fabric covering. The span of the cantilevered, completely wooden wings has been increased compared to the previous model and an improved tail skid has been installed. The emergency exit integrated into the roof was provided in the event of an emergency ditching.

In the three-engine versions, the fuselage and wings initially remained almost unchanged. The trunk was not stretched until the last F.VIIa-3m. The F.VIIb-3m also got an enlarged wingspan.

variants

F.VII

Five aircraft were created from the original single-engine version. The drive was a liquid-cooled 12-cylinder V-engine Rolls-Royce Eagle , which was later replaced by the 9-cylinder radial engine Bristol Jupiter .

An in-line F.VII in the Dutch East Indies

The first flight took place on April 11, 1924 in Schiphol . In the same year the prototype was moved to the Dutch East Indies, but returned to the Netherlands after a short period of use. From 1924 three more aircraft were built for the airline KLM. The fifth aircraft, initially powered by a Napier Lion , was initially owned by the manufacturer for advertising purposes before it was purchased by KLM.

Two of these aircraft were later sold to the USA and Australia, respectively.

F.VIIa

The F.VIIa received newly developed wings and a water-cooled 12-cylinder Packard Liberty engine. Small improvements were made to the tail unit and the landing gear. The cabin could be heated for the first time. The first flight took place on March 12, 1925.

In addition to the 36 aircraft built by Fokker, four more were built directly by the KLM airline, which put a total of 15 aircraft into service. Other aircraft went to the French companies CIDNA and STAR , the Swiss Balair , the Polish LOT , the Hungarian Malert and the Danish Det Danske Luftfartselskab, DDL . The machines were often rebuilt and in some cases fitted with controllable pitch propellers, closed cockpits and new engines. Two planes were sold to the United States.

A preserved F.VIIa is now in the Aviodrome Aviation Museum in the Netherlands, a second machine in the Swiss Museum of Transport in Lucerne.

F.VIIa-3m

The first three-engine aircraft was created by converting a half-finished F.VIIa. The mid-engine was replaced by the lighter 9-cylinder radial engine Wright J-4 Whirlwind and two more Whirlwind engines were suspended under the wings. This prototype first flew on September 4, 1925.

In addition to three aircraft designated as C-2 for the US military, 18 other aircraft were built, including one for the British Department of Aviation. The Dutch Air Force received three machines with bomb bays. The final assembly of the aircraft sold in the USA took place at Atlantic Aircraft Corporation. The last aircraft were given a fuselage that was 80 centimeters longer.

F.VIIb-3m

Fokker F.VIIb-3 m (CH-192) of Swissair , flown by Walter Mittelholzer in Kassala (Sudan), February 1934.

The most successful variant was built between 1927 and 1932. It largely corresponded to the stretched version of the F.VIIa-3m, but had a larger span. With the prototype Southern Cross , the pilot Charles Kingsford Smith made the first flight across the Pacific to Australia in 1928. The airline PanAm opened its service in 1927 with two F.VIIb-3m.

A total of around 150 aircraft of this type were built, mostly in the USA by Atlantic Aircraft. In 1929 Avia began license production of 21 aircraft in Czechoslovakia, which were equipped with local Castor engines. The company built 20 civil aircraft and one military version that could be used as a bomber and transport aircraft. This aircraft was used with the 5th Air Regiment. Further civil and military license versions were created in Poland, Belgium, Spain, Italy and as the Avro 618 Ten in Great Britain. The Southern Cross is the only surviving three-engined F.VII in Brisbane, Australia .

Special flight services

From 1926 to 1928, the Australian polar explorer Hubert Wilkins made several flights north of Alaska, including the first trans-Arctic flight by plane. On the Detroit Arctic Expedition he used a single-engine F.VIIa and a three-engine F.VIIb-3m . The attempts with the pilot Carl Ben Eielson were unsuccessful.

The American polar explorer Richard Evelyn Byrd claimed to have flown over the North Pole in an F.VIIa-3m on May 9, 1926 , which is now generally doubted.

From May 31 to June 8, 1928, Charles Kingsford Smith and Charles Ulm crossed the Pacific from Oakland (California) to Brisbane ( Australia ) in an F.VII-3m . They flew a distance of 11,585 kilometers in three sections.

From August 2 to 9, 1929, CD Barnard set a record with an F.VIIa on the England - Karachi route , which he covered in 7 ½ days. The launch took place in Lympne near Folkestone , the landing in Croydon . Also on board were Robert Little as co-pilot and mechanic and the Duchess of Bedford as owner of the aircraft. The aircraft, registered G-ETBS, was powered by a Bristol Jupiter XI .

On January 8, 1930, Walter Mittelholzer was the first to fly over Kilimandjaro in the Fokker F.VIIb-3m CH 190. Among other things, he took aerial photos of the Kibo crater from a height of around 6,500 meters, which were published in magazines and caused a sensation.

Technical data (F.VIIa-3m)

Parameter	Data
crew	2
Passengers	8-10
length	14.35 m
span	19.30 m
height	3.81 m
Wing area	58.5 m²
Empty mass	1950 kg
Takeoff mass	3650 kg
Top speed	185 km / h at an altitude of 1980 m
Service ceiling	2600 m
Range	1160 km
Engines	three 9-cylinder radial engines Wright J-5 Whirlwind with 164 kW (223 PS) each

literature

• The Fokker "Trimotor F VII" Commercial Transport Monoplane . In: National Advisory Committee for Aeronautics (Ed.): Aircraft Circulars . tape 76 , June 1928 ( online [PDF; accessed May 27, 2018]).

Web links

Commons : Fokker F.VII  - collection of images, videos and audio files

Individual evidence

1. ↑ NACA: Aircraft Circulars No. 76 , Figure 4
2. ↑ Vaclav Nemecek: Československá letadla . Naše vojsko, Prague 1968, p. 290/291 .
3. ↑ AERO, issue 16, p. 441.
4. ^ Charles Kingsford Smith and the first trans-Pacific flight, 1928 on the website of the National Museum of Australia. Retrieved December 17, 2014
5. ^ Flight edition August 15, 1929, pp. 878–879
6. ↑ http://blogs.ethz.ch/digital-collections/2012/03/30/eine-weltpremiere-die-erste-uberfliegung-des-kilimanjaro-durch-walter-mittelholzer-8-januar-1930/