Conrad C.III

After having designed two aircraft engines for the German Kaiserpreis aircraft engine competition of 1912/13, Robert Conrad prepared an {{convert|180|hp|kW|abbr=on|0}} six-cylinder aircraft engine for the second Kaiserpreis competition anticipated to take place in 1914–1915. Further improvements on the engine design were done in 1915 by Robert Conrad while he was working for the Deutsche Motorenbau-Gesellschaft. His work resulted in a six-cylinder water-cooled engine with increased bore which was capable of delivering {{convert|185|hp|kW|abbr=on|0}} at 1400 rpm. After a successful type test in February 1916 the engine was assigned the designation C.III (C for Conrad) by the German military.Kyrill von Gersdorff, Kurt Grasmann. Flugmotoren und Strahltriebwerke, Bernard & Graefe Verlag, 1981, {{ISBN|3-7637-5272-2}}

Due to insufficient production capacity at the Deutsche Motorenbau-Gesellschaft, the engine was produced by the Nationale Automobil-Gesellschaft (NAG).

After NAG subsequently adapted the engine, it was uprated to {{convert|210|hp|kW|abbr=on|0}} and successfully type tested in November 1916. The new 210 hp variant however turned out to be unreliable and so subsequent versions of the engine were again rated {{convert|185|hp|kW|abbr=on|0}}, although with various design improvements over the original C.III.

File:NAG C.III MLP 06.jpg in Kraków]]

Engine production was undertaken by NAG under license. Despite various adaptions of the original design all variants had the same bore and stroke.

;C.III: initial design by Deutsche Motorenbau-Gesellschaft (Conrad), license produced by NAG as C.III Nag.Jack Herris. Development of German Warplanes in WWI, Aeronaut Books, 2012, {{ISBN|978-1-935881-08-7}}

;C.III Nag: initial production variant of the C.III engine, license production by NAG, {{convert|185|hp|kW|abbr=on|0}}, wet-sump lubrication system.[http://www.muzeumlotnictwa.pl/digitalizacja_archiwaliow/katalog.php?cz=741 Der NAG-Flugmotor 185 PS - C III NAG], Aircraft engine manual, 1917.

;C.III Nag a: improved production variant, {{convert|185|hp|kW|abbr=on|0}}, improvements over the preceding C.III Nag include revised T-shaped intake manifolds and a dry-sump lubrication system with revised oil sump and oil pump.185 PS NAG Flugmotor Typ C III Nag a, Aircraft engine manual, 1918.

;C.III Nag b: improved production variant, {{convert|185|hp|kW|abbr=on|0}}, improvements over the preceding C.III Nag a include an oil pump fed valvetrain lubrication system, a revised air pump for pressurizing the fuel system and a revised central placement of the two carburettors, along with provisions for mounting a wireless generator on the admission side of the engine.[http://www.muzeumlotnictwa.pl/digitalizacja_archiwaliow/katalog.php?cz=742 185 PS NAG Flugmotor Typ C III Nag b], Aircraft engine manual, 1918.

;C.IIIa: adapted and uprated variant of the initial C.III design, {{convert|210|hp|kW|abbr=on|0}}, only small number of engines produced, turned out to be unreliable.

;C.IIIb Nag: {{convert|185|hp|kW|abbr=on|0}}, no further details given.

;C.IIIav Nag: {{convert|185|hp|kW|abbr=on|0}}, new design, no further details given.

The Conrad C.III (Nag) engine was primarily allocated for training machines because it was found to be too heavy for use in fighter aircraft.P M Grosz. Windsock Datafile No.79, RUMPLER C.I, Albatros Productions, Ltd., 2000, {{ISBN|1-902207-21-1}}

• DFW C.Vc (training aircraft)P M Grosz. Windsock Datafile No.53, DFW C.V, Albatros Productions, Ltd., 1995, {{ISBN|0-948414-70-7}}

• Rumpler C.Ic (Germ) (training aircraft, built by Germania Flugzeug-Werke)

• Gotha G.IV (SSW) (training aircraft, built by Siemens-Schuckertwerke)Peter M Grosz. Gotha!, Albatros Productions Ltd., 1994, {{ISBN|0-948414-57-X}}

• LVG D.III (one prototype aircraft built){{cite book |last=Gray |first=Peter |last2=Thetford |first2=Owen |title=German Aircraft of the First World War |url=https://archive.org/details/germanaircraftfi00thet |url-access=limited |year=1970 |publisher=Putnam |location=London |isbn=0-370-00103-6 |edition=2nd |page=[https://archive.org/details/germanaircraftfi00thet/page/n261 480]}}

• A preserved [http://www.muzeumlotnictwa.pl/zbiory_sz.php?ido=219&w=a NAG C.III engine] is on public display at the Polish Aviation Museum in Kraków

• A [https://ma.as/213309 NAG C.III, serial number 13217], is part of the Museum of Applied Arts & Sciences Barraclough Collection in Sydney

• A preserved [https://areeweb.polito.it/strutture/cemed/museovirtuale/english/memoria/4-02/4-201/float/ac007.htm NAG C.III engine] is part of [https://areeweb.polito.it/strutture/cemed/museovirtuale/english/memoria/4-02/4-201/420103.htm Capetti's Collection] at the Politecnico di Torino

{{pistonspecs

|

|ref=

|type=6-cylinder, inline, water-cooled, piston engine

|bore={{convert|138|mm|in|abbr=on|3}}

|stroke={{convert|190|mm|in|abbr=on|3}}

|displacement={{convert|17.051|L|cuin|abbr=on|0}}

|length=

|diameter=

|width=

|height=

|weight={{convert|332|kg|lb|abbr=on|0}}

|valvetrain=One overhead camshaft, driving two inlet and two exhaust valves per cylinder.

|supercharger=

|turbocharger=

|fuelsystem=Two Pallas carburetters, each serving three adjacent cylinders. Two spark plugs per cylinder, placed horizontally and opposite each other, supplied by two Bosch ZH 6 magnetos.

|fueltype=

|oilsystem=

|coolingsystem=Water-cooled

|power={{convert|185|hp|kW|abbr=on|0}}

|specpower=

|compression=4.6Heinrich Dechamps, Karl Kutzbach. [https://books.google.com/books?id=djLOAAAAMAAJ Prüfung, Wertung und Weiterentwicklung von Flugmotoren], 1921. or 4.8 (C III NAG No. 13176)

|fuelcon=

|specfuelcon=

|oilcon=

|power/weight=

}}

• List of aircraft engines

{{Commonscategory|N.A.G. C.III}}

{{reflist}}

Category:1910s aircraft piston engines