Oberursel U.I rating | aircraft investigation info

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performance calculations for the Oberursel U.I WWI aero engine

German mechanics posing around a Oberursel U.I rotary engine | with finger prints for forensic research

Mechanics of a Marine flieger abteilung posing with a Oberursel U.I rotary engine. Whose fingerprints are on the picture ?

Oberursel U.I air-cooled 9 -cylinder atmospheric inlet-valve rotary engine 100 [hp](73.6 KW)

introduction : September 1915 country : Germany importance : ***

applications : Fokker E.III, Fokker D.II

general information : License built Gnome Delta engine

normal rating : 100 [hp](73.6 KW) at 1200 [rpm] at 0 [m] above sea level

no reduction, direct drive, valvetrain :

weight engine(s) dry : 139.7 [kg] = 1.90 [kg/KW]

bore : 124.0 [mm] stroke : 150.0 [mm]

calculated compression ratio : 3.70 : 1

published volume (displacement): 16.280 [litre]

calculated stroke volume (Vs) : 16.303 [litre]

compression volume (Vc): 6.049 [litre]

total volume (Vt): 22.352 [litre]

power / stroke volume (litervermogen Nl): 4.5 [kW/litre]

torque : 585 [Nm]

engine weight/volume : 8.6 : [kg/litre]

average piston speed (Cm): 6.0 [m/s]

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intake pressure at 0 [m] altitude Pi : 0.95 [kg/cm2]

mean engine pressure (M.E.P.) at 0 [m] altitude Pm : 4.62 [kg/cm2]

compression pressure at 0 [m] altitude Pc: 5.08 [kg/cm2]

estimated combustion pressure at 0 [m] Pe : 20.33 [kg/cm2]

estimated combustion pressure at 0 [m] Pe : 21.22 [kg/cm2]

exhaust pressure at 0 [m] Pu : 3.80 [kg/cm^2 ]

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compression-end temperature at 0 [m] Tc: 527 [°K] (254 [°C])

caloric combustion temperature at 0 [m] Tec: 2019 [°K] (1745 [°C])

front and side view drawing of a 100 p.s. Oberursel U.I rotary engine

polytroph combustion temperature at 0 [m] Te (T4): 2101 [°K] (1827 [°C])

exhaust temperature at 0 [m] Tu: 1226 [°K] (953 [°C])

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emergency/TO rating can be increased with higher [rpm}

(emergency/take off) rating at 1314 [rpm] at sea level : 110 [pk]

Thermal efficiency Nth : 0.279 [ ]

Mechanical efficiency Nm : 0.618 [ ]

Thermo-dynamic efficiency Ntd : 0.172 [ ]

design hours : 1464 time between overhaul : 167

fuel consumption optimum mixture at 1200.00 [rpm] at 0 [m]: 44.18 [kg/hr]

specific fuel consumption thermo-dynamic : 367 [gr/epk] = 499 [gr/kwh]

specific fuel consumption (cruise power) at 0 [m] optimum mixture : 515 [gr/kwh]

estimated sfc (cruise power) at 1800 [m] rich mixture : 569 [gr/kwh]

specific fuel consumption at 0 [m] at 1200 [rpm] optimum mixture : 601 [gr/kwh]

estimated specific oil consumption (cruise power) : 85 [gr/kwh]

Oberursel U.I 110HP inside view

Oberursel U.I on display in Deutsches museum Munchen

Literature :

The aerodrome

Marek Mincbergr

Flugmotoren von Herman Dorner und Walther Isendahl, Berlin, Richard Carl Schmidt & Co., 1918 :

Oberursel U.I rotary engine cylinder diagram

DISCLAIMER Above calculations are based on published data, they must be

regarded as indication not as facts.

Calculated performance and weight may not correspond with actual weights

and performances and are assumptions for which no responsibility can be taken.

Calculations are as accurate as possible, they can be fine-tuned when more data

is available, you are welcome to give suggestions and additional information

so we can improve our program. For copyright on drawings/photographs/

content please mail to below mail address

Oberursel U.I 110HP cylinder head with valve close-up