Fokker F.III
The Fokker F.III[1] was a straightforward development of the F.II. A widened cabin allowed all five passengers to sit within; in the earlier aircraft, one passenger sat alongside the pilot in his exposed cockpit. The pilot now sat alongside the engine, which was offset laterally by about 100 mm (4 in); whether to port or starboard depended on the type of engine installed. Although this unusual arrangement meant that pilots were "burned on one side and frozen on the other," they had a much better view than from the F.II. The view was further improved by a cut-out in the wing leading edge for the pilot's head, allowing his seat to be raised. The external wing struts of the F.II were removed, leaving a clean cantilever wing. The trapezoidal windows seen in the Grulich built F.IIs were standard on the F.III.
Like its predecessor, the F.III was initially powered by a readily available, war surplus 138 kW (185 hp) BMW IIIa engine, but once again KLM re-engined theirs with the 172 kW (230 hp) Armstrong Siddeley Puma.
The F.III was first used by KLM when they re-opened their Amsterdam-London service on 14th April 1921 (they did not, at this time operate over winter). Soon, F.IIIs were also flying on routes to Bremen, Brussels, Hamburg and Paris. They proved to be very reliable aircraft. KLM received 14 F.IIIs from Fokker's German factory at Schwerin during 1921 and built two more itself from spares in the following year. This final pair used 268 kW (360 hp) Rolls-Royce Eagle VIII engines, with the pilot on the left.
Another operator of new F.IIIs was Deutsch-Russiche Luftverkehrs Gesellschaft (Deruluft) who used nine aircraft on their Berlin-Konigsberg-Moscow route from May 1922. These machines, partially built in Schwerin and finished in the Netherlands at Veere, had Eagle engines. One was a Fokker-Grulich.
Deutsche Aero Lloyd gained a licence to build F.IIIs as they had for F.IIs and the company, with its southern subsidiary built and operated eighteen of these Fokker-Grulich F.IIIs. Most of these used BMW engines, typically the 186 kW (250 hp) BMW IV in preference to the 138 kW (185 hp) BMW IIIa. Some of these were re-engined with the 239 kW (320 hp) BMW Va, and were designated F.IIIc.
Another operator from new was the Hungarian airline Malert, who received six Dutch built aircraft for their Budapest-Vienna-Belgrade service from 1922 to 1929. These initially had BMW IIIa motors, but later ran with 172 kW (230 hp) Hiero IVs. They had larger wings, increased in area by about 14 percent. Deutsche Luft-Reederei also operated two, originally intended for KLM. Four F.IIIs probably went to the United States
Later F.IIIs changed ownership frequently as airlines went bankrupt or merged. They were still flying commercially in Germany until about 1936.
Operators
Denmark               Det Danske Luftfartselskab
Weimar Republic Deutsch-Russiche Luftverkehrs Gesellschaft (Deruluft)
                               Deutsche Aero Lloyd
                               Deutsche Aero Luft
                               Deutsche Luft-Reederei
                               Sud-deutsche Luft Hansa
Hungary                Malert
Netherlands          Koninklijke Luchtvaart Maatschappij (KLM)
Type
1 + 5 seat airliner
Engine
1 Armstrong Siddeley  Puma
Dimensions
Length 11,07 m , height 3,20 m ,  span 17,68 m , wing area  45,65 m2 ,
Weights
Empty 1200 kg, loaded  1905 kg 
Performance
Max.. speed  , cruising speed 135 km/h , range 1000 km , endurance  , service ceiling   , climb