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performance calculations for the Benz Bz.IIIa WWI aircraft engine

Benz Bz.IIIa liquid-cooled 6 -cylinder inline engine 185 [hp](136.1 KW)

introduction : July 1918 country : Germany importance : **

applications : LFG Roland D.VIb

normal rating : 185 [hp](136.1 KW) at 1450 [rpm] at 0 [m] above sea level

no reduction, direct drive, valvetrain :

weight engine(s) dry : 272.0 [kg] = 2.00 [kg/KW]

calculated bore : 137.2 [mm] calculated stroke : 171.5 [mm]

Mechanical efficiency/mean pressure correction factor : 0.601 [ ]

invloed hoogte > cm : 0.31 [ ]

compression ratio: 0.00 :1

calculated compression ratio : 4.76 : 1

published volume (displacement): 15.200 [litre]

calculated stroke volume (Vs) : 15.200 [litre]

compression volume (Vc): 4.044 [litre]

total volume (Vt): 19.244 [litre]

power / stroke volume (litervermogen Nl): 9.0 [kW/litre]

torque : 896 [Nm]

engine weight/volume : 17.9 : [kg/litre]

average piston speed (Cm): 8.3 [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 : 5.85 [kg/cm2]

compression pressure at 0 [m] altitude Pc: 7.03 [kg/cm2]

estimated combustion pressure at 0 [m] Pe : 28.13 [kg/cm2]

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

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compression-end temperature at 0 [m] Tc: 581 [°K] (308 [°C])

caloric combustion temperature at 0 [m] Tec: 2195 [°K] (1921 [°C])

polytroph combustion temperature at 0 [m] Te (T4): 2317 [°K] (2044 [°C])

exhaust temperature at 0 [m] Tu: 1329 [°K] (1056 [°C])

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

(emergency/take off) rating at 1588 [rpm] at sea level : 203 [pk]

Thermal efficiency Nth : 0.323 [ ]

Mechanical efficiency Nm : 0.800 [ ]

Thermo-dynamic efficiency Ntd : 0.258 [ ]

design hours : 926 time between overhaul : 71

fuel consumption optimum mixture at 1450.00 [rpm] at 0 [m]: 51.49 [kg/hr]

specific fuel consumption thermo-dynamic : 245 [gr/epk] = 333 [gr/kwh]

specific fuel consumption (cruise power) at 0 [m] optimum mixture : 345 [gr/kwh]

estimated sfc (cruise power) at 2900 [m] rich mixture : 357 [gr/kwh]

specific fuel consumption at 0 [m] at 1450 [rpm] optimum mixture : 378 [gr/kwh]

estimated specific oil consumption (cruise power) : 20 [gr/kwh]

Literature :

http://www.theaerodrome.com/forum/showthread.php?t=19017

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

(c) B van der Zalm 23 January 2020 contact : info.aircraftinvestigation@gmail.com python 3.7.4