Junkers F 13 F 13fe

The F 13's two-letter code explains the variant: f for the long fuselage introduced with the F 13fa, e for the Junkers L5. Together they produced the biggest aircraft in the family, 10.50 m long against the baseline's 9.59 m and spanning 17.75 m against 14.8 m, over 44 m² of wing.

Growth cost weight: 1480 kg empty and 2318 kg loaded, well above the 951 and 1640 kg of the original F 13. In exchange the L5 pushed it to 198 km/h flat out and 170 km/h cruising, and lifted the ceiling to 5090 m — a markedly heavier aeroplane that nonetheless flew faster and higher than the one that had opened the line seven years earlier.

The stretched fuselage did not add seats — the cabin still held four passengers — but it did add volume for freight, mail and baggage, and it eased the centre-of-gravity margins with uneven loads. In a type sold as both an airliner and a mailplane, that margin was what let a single aircraft do both jobs.

The F 13fe represents the end of the type's development before Junkers moved on to the W 33 and W 34, both direct descendants of this airframe. When F 13 production closed in 1932 the design had been in manufacture for thirteen years, with weight and climb performance close to doubled and the original concept left intact.