Otto C.I

{{Infobox aircraft | name = C.I | logo = | logo_size = | image = File:Otto-C.I.jpg | alt = | caption = Upturned Otto C.I after an accident near Thessaloniki | long_caption = | other_names = | aircraft_type = Reconnaissance, bomber | aim = | outcome = | related = | national_origin = Germany | manufacturer = Otto Flugmaschinenfabrik | design_group = | designer = Gustav Otto | builder = | issuer = | status = | owners = | primary_user = Bulgarian Air Force | more_users = Luftstreitkräfte | service = | major_applications = | proposals = | prototypes = | number_built = 25 | construction_number = | civil_registration = | military_serial = | radio_code = | requirement = | aircraft_carried = | flights = | total_hours = | total_distance = | construction_date = | introduction = | retired = 1917 | first_flight = 1915 | initiated = | in_service = | last_flight = | expected = | developed_from = | variants = | developed_into = | preservation = | fate = | predecessors = | successors = | concluded = }} The '''Otto C.I''', also known as the '''Otto KD.15''', was a German two-seat biplane reconnaissance and bomber aircraft of the First World War designed and produced by Otto Flugmaschinenfabrik. The C.I was a rare example of an aircraft flown by the Central Powers which had a pusher configuration.

==Design and development== The German aeronautical engineer Gustav Otto designed the C.I as a reconnaissance aircraft for use by the Imperial German Flying Corps. It was an all wooden, fabric covered twin boom design with box-shaped booms. Forward was a large fuselage gondola with two seats, the observer sitting at the fore and the pilot to the rear.<ref name=gray>Gray & Thetford, 1962, p.495</ref> Behind the pilot was a six-cylinder engine driving a pusher propeller.

The unarmed prototype first flew in May or June 1915, named KD.15 and powered by a {{convert|150|kW|hp|abbr=on}} Rapp engine.<ref name=harris163>Harris, 2007 p.163</ref> Production examples were given the official designation C.I and the observer was provided with a single machine gun for defence.<ref name=grosz>Grosz, 1995</ref> The Rapp engine proved unreliable so production aircraft were also equipped with the lower-powered {{convert|120|kW|hp|abbr=on}} Mercedes D.III or {{convert|112|kW|hp|abbr=on}} Benz Bz.III.<ref name=harris163 />

The aircraft was produced in small numbers and proved to be the last made by the company.<ref name=gray /> It is unrelated to the C.II made under license for LVG by Otto.<ref>Gray & Thetford, 1962, p.175</ref>

==Operational history== The C.I entered very limited service with the Imperial German Air Service, serving only with Bavarian ''Feldflieger Abteilung'' like 4b, 8b and 9b.<ref name=harris163/> They were delivered in two batches, each of six aircraft, ordered in August and November 1915 respectively, and served until at least April 1916.<ref name=grosz />

Initially considered "good for nothing" by the Bavarian airmen who first flew them, the aircraft gained a positive reputation during their short careers.<ref name=harris169>Harris, 2007 p.169</ref> They were favourably viewed for their stability and reliability yet were nimble with good handling characteristics both on the ground and in the air.<ref name=nedialkov>Nedialkov, 2001</ref>

The aircraft saw limited export success, being sold to the Bulgarian Air Force in 1915.<ref name=flanagan>Flanagan, 1982, p.156</ref> Thirteen were delivered to Bozhurishte in spring 1916, serving with 2 Aeroplane Otdelenie based at Udovo.<ref name=nedialkov /> The first batch was powered by the Benz engine, while the latter used the slightly more powerful Mercedes inline.<ref name=flanagan/> These aircraft were used in the bombing and reconnaissance role.<ref name=harris168>Harris, 2007 p.168</ref> They served until 1917, when they were replaced by the more capable Albatros C.III.

==Operators== ;{{flag|Kingdom of Bulgaria}} * Bulgarian Air Force ;{{flag|German Empire}} *Luftstreitkräfte

==Specification== {{Aircraft specs |ref=German Aircraft of the First World War<ref name=gray/> |prime units?=met  |crew=2 |length m=9.60 |length ft=31 |length in=6 |length note= |span m=14.50 |span ft=47 |span in=5 |span note= |upper span m= |upper span ft= |upper span in= |upper span note= |mid span m= |mid span ft= |mid span in= |mid span note= |lower span m= |lower span ft= |lower span in= |lower span note= |height m= |height ft= |height in= |height note= |wing area sqm=47 |wing area sqft= |wing area note= |empty weight kg=915 |empty weight lb= |empty weight note= |gross weight kg= |gross weight lb= |gross weight note= |max takeoff weight kg=1500 |max takeoff weight lb= |max takeoff weight note= |fuel capacity=  |eng1 number=1 |eng1 name=Benz Bz.III |eng1 type=six-cylinder, water-cooled, inline engine |eng1 kw=112 |eng1 hp=150 |eng1 note= |prop blade number= |prop name= |prop dia m= |prop dia ft= |prop dia in= |prop dia note=  |max speed kmh=130 |max speed mph=81 |max speed kts=70 |max speed note= |cruise speed kmh= |cruise speed mph= |cruise speed kts= |cruise speed note= |stall speed kmh= |stall speed mph= |stall speed kts= |stall speed note= |never exceed speed kmh= |never exceed speed mph= |never exceed speed kts= |never exceed speed note= |minimum control speed kmh= |minimum control speed mph= |minimum control speed kts= |minimum control speed note= |range km= |range miles= |range nmi= |range note= |combat range km= |combat range miles= |combat range nmi= |combat range note= |ferry range km= |ferry range miles= |ferry range nmi= |ferry range note= |endurance= |ceiling m= |ceiling ft= |ceiling note= |climb rate ms= |climb rate ftmin= |climb rate note= |time to altitude= |sink rate note= |lift to drag= |wing loading kg/m2= |wing loading lb/sqft= |wing loading note= |fuel consumption kg/km= |fuel consumption lb/mi= |power/mass=  |guns= 1 x Parabellum MG 14 machine guns |bombs= 6 × {{convert|10|kg|lb}} bombs for a total of {{convert|60|kg|lb}} }}

==See also== {{aircontent  |related=

|similar aircraft= *Airco DH.1 *AGO C.I *Farman F.40 *Häfeli DH-1 *Voisin VI

|lists= *List of aircraft }}

==References== ===Notes=== {{reflist}}

===Bibliography=== *{{cite journal |last1=Anderson|first1=Lennart|title=La renaissance de l'aviation militair bulgare dans les années vingt|journal=Avions |date=November–December 2019 |issue=232|pages=52–66 |trans-title=The Rebirth of Bulgarian Military Aviation in the Twenties|language=French |issn=1243-8650}} * {{cite journal|last=Flanagan|first=Brian P.|year=1982|title=A History of the Bulgarian Air Force 1892-1919|journal=Cross & Cockade Journal|volume=23|number=2|pages=144–159}} *{{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}} * {{cite journal|last=Grosz|first=Peter M|year=1995|title=Otto B and C type|journal=Windsock|volume=11|number=1}} *{{cite book |last1=Herris |first1=Jack |title=German Aircraft of Minor Manufacturers in WWI: A Centennial Perspective on Great War Airplanes |date=2020 |publisher=Aeronaut Books |location=n.p. |isbn=978-1-935881-86-5|volume=2: Krieger to Union|series=Great War Aviation Centennial Series (50)}} * {{cite journal|last=Herris|first=Jack|year=2007|title=Rare Birds: The Otto C.I|journal=Over the Front|volume=22|number=2}} * {{cite book |last=Nedialkov |first=Dimitar |title=Vŭzdushnata mosht na T︠s︡arstvo Bŭlgarii︠a︡ |script-title=bg:Въздушната мощ на Царство България|trans-title=Air Power of the Kingdom of Bulgaria Part 2|place=Sofia|publisher=Fark|year=2001|language=Bulgarian}}

Category:1910s German military reconnaissance aircraft Category:Aircraft first flown in 1915 Category:Biplanes Category:Single-engined pusher aircraft Category:Twin-boom aircraft