:Friedrichshafen FF.31
{{Short description|German maritime reconnaissance floatplane}}
{{good article}}
{{Infobox aircraft
|name = FF.31
|image = Friedrichshafen FF.31 Q 67766.jpg
|caption =A FF.31 with axles installed underneath its floats
|type = Two-seat maritime reconnaissance floatplane
|manufacturer = Flugzeugbau Friedrichshafen
|designer =
|first_flight = 12 April 1915
|introduction =
|retired =
|status =
|primary_user = Imperial German Navy
|more_users =
|produced =
|number_built =2
|unit cost =
|developed_from =
|variants =
}}
The Friedrichshafen FF.31 was a two-seat prototype German maritime reconnaissance floatplane built by Flugzeugbau Friedrichshafen during the First World War. Although primarily intended for reconnaissance duties, the aircraft was provided with a machine gun to engage other aircraft. Although it was satisfactory for its intended mission, it lacked the performance necessary for use as a fighter. A pair of aircraft were built in 1915 and it was not accepted for production by the Imperial German Navy's ({{lang|de|Kaiserliche Marine}}) Naval Air Service ({{lang|de|Marine-Fliegerabteilung}}).
Background and description
Developed from the prewar Friedrichshafen FF.27 maritime reconnaissance floatplane, the FF.31 was fitted with a machine gun for the observer who had an excellent field of fire from his position in the front cockpit. The aircraft was intended by Flugzeugbau Friedrichshafen to be able to intercept enemy aircraft in addition to its primary reconnaissance mission, but its lack of speed and poor rate of climb made this difficult at best. Furthermore, by this time, the vulnerability of pusher-configuration aircraft to attacks from the rear had been realized. The first prototype flew on 12 April 1915 and was deemed an acceptable maritime patrol aircraft, but its poor performance as a fighter caused the Naval Air Service to reject it for service.Boruztzki, p. 62
The FF.31 was a twin-boom biplane with a central nacelle with the {{convert|160|PS|adj=on|lk=on}} Maybach Mb.III straight-six engine mounted at its rear. Two open-frame booms extended aft from the wings to carry the tail structure. It was fitted with two open cockpits in the nacelle. The observer was armed with a {{convert|7.92|mm|adj=on}} Parabellum MG14 machine gun on a flexible mount. The two forward floats were attached to the lower wing by four pairs of V-shaped struts while the third float was connected directly to the tail. To speed construction of the aircraft, the wings and floats from the Friedrichshafen FF.29 reconnaissance aircraft were used. A version of the FF.31 with conventional landing gear and a {{cvt|150|PS}} Benz Bz.III engine was designated the FF.37, but it was also rejected for service.
Variants
- FF.31: Two prototypes built.Borzutzki, p. 104
- FF.37: FF.31 with conventional landing gear and a Benz Bz.III engine. One prototype built.Gray & Thetford, p. 369Borzutzki, p. 123
Specifications (FF.31)
{{Aircraft specs
|ref=Flugzeugbau Friedrichshafen GmbH: Diplom-Ingenieur Theodor Kober;Borzutzski, pp. 104–105 Friedrichshafen Aircraft of WWI: A Centennial Perspective on Great War AirplanesHerris, p. 34
|prime units?=met
|genhide=
|crew=2
|capacity=
|length m=10.15
|span m=
|upper span m=16.85
|mid span m=
|lower span m=15.8
|width m=
|height m=3.7
|wing area sqm=60
|aspect ratio=
|airfoil=
|empty weight kg=1063
|gross weight kg=1535
|max takeoff weight kg=
|fuel capacity=
|more general=
|eng1 number=1
|eng1 name=Maybach Mb.III
|eng1 type= water-cooled straight-six engine
|eng1 hp=160
|power original=Originally measured as {{cvt|160|PS|0}}.
|prop blade number=2
|prop name=
|prop dia m=
|prop dia ft=
|prop dia in=
|prop dia note=
|max speed kmh=98
|max speed mach=
|cruise speed kmh=
|stall speed kmh=
|never exceed speed kmh=
|minimum control speed kmh=
|range km=500
|combat range km=
|ferry range km=
|endurance=
|ceiling m=
|climb rate ms=
|time to altitude={{cvt|500|m}} in 9 minutes 30 seconds; {{cvt|800|m}} in 16 minutes
|wing loading kg/m2=
|fuel consumption kg/km=
|power/mass=
|thrust/weight=
|more performance=
|guns= 1 × {{cvt|7.92|mm|3}} Parabellum MG14 machine gun
}}
See also
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|related=
|similar aircraft=
|lists=
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References
{{reflist}}
Bibliography
- {{cite book |last1=Borzutzki |first1=Siegfried |title=Flugzeugbau Friedrichshafen GmbH: Diplom-Ingenieur Theodor Kober |date=1993 |language=de |publisher=Burbach |location=Berlin |isbn=3-927513-60-1|trans-title=Friedrichshafen Aircraft Company: Diploma-Engineer Theodore Kober |ref=none}}
- {{cite book|author1-last=Gray|author1-first=Peter|title=German Aircraft of the First World War|orig-year=1970|year=1987 |publisher=Putnam |location=London|isbn=0-85177-809-7|edition=2nd|author2-first=Owen|author2-last=Thetford|name-list-style=amp |ref=none}}
- {{cite book |last1=Herris |first1=Jack |title=Friedrichshafen Aircraft of WWI: A Centennial Perspective on Great War Airplanes |date=2016 |publisher=Aeronaut Books |location=n.p. |isbn=978-1-935881-35-3|series=Great War Aviation Centennial Series|volume=21 |ref=none}}
{{Friedrichshafen aircraft}}
Category:1910s German military reconnaissance aircraft