WWI aero engine performance calculations

FIAT A-12

liquid-cooled 6 -cylinder inline engine 260 [hp](191.2 KW)

introduction : February 1917 country : Italy importance : ***

applications : Pomilio PE , Savoia-Pomilio S.P.2

normal rating : 260 [hp](191.2 KW) at 1630 [rpm] at 750 [m] above sea level

high compression engine : cannot run at full power at sea level,

constant power to height : 750 [m]

no reduction, direct drive, valvetrain :

weight engine(s) dry : 415.0 [kg] = 2.17 [kg/KW]

bore : 160.0 [mm] stroke : 180.0 [mm]

Mechanical efficiency/mean pressure correction factor : 0.645 [ ]

invloed hoogte > cm : 0.30 [ ]

compression ratio: 4.50 :1

calculated compression ratio : 4.50 : 1

published volume (displacement): 21.700 [litre]

calculated stroke volume (Vs) : 21.715 [litre]

compression volume (Vc): 6.204 [litre]

total volume (Vt): 27.919 [litre]

power / stroke volume (litervermogen Nl): 8.8 [kW/litre]

torque : 1120 [Nm]

engine weight/volume : 19.1 : [kg/litre]

average piston speed (Cm): 9.8 [m/s]

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intake pressure at 750 [m] altitude Pi : 0.87 [kg/cm2]

mean engine pressure (M.E.P.) at 750 [m] altitude Pm : 5.43 [kg/cm2]

compression pressure at 750 [m] altitude Pc: 5.98 [kg/cm2]

estimated combustion pressure at 750 [m] Pe : 23.94 [kg/cm2]

exhaust pressure at 750 [m] Pu : 3.48 [kg/cm^2 ]

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compression-end temperature at 750 [m] Tc: 569 [°K] (296 [°C])

caloric combustion temperature at 750 [m] Tec: 2158 [°K] (1885 [°C])

polytrope combustion temperature at 750 [m] Te (T4): 2271 [°K] (1998 [°C])

exhaust temperature at 750 [m] Tu: 1328 [°K] (1055 [°C])

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compression pressure at sea level Pc: 6.40 [kg/cm2]

estimated combustion pressure at sealevel Pe : 25.61 [kg/cm^2 ]

compression-end temperature at sealevel Tc:567 [°K] (293 [°C])

mean engine pressure at sealevel Pm : 5.81 [kg/cm2]

(emergency/Take Off) rating at 1630 [rpm] at sea level : 278 [pk]

Thermal efficiency Nth : 0.313 [ ]

Mechanical efficiency Nm : 0.756 [ ]

Thermo-dynamic efficiency Ntd : 0.237 [ ]

design hours : 894 time between overhaul : 58

fuel consumption optimum mixture at 1630.00 [rpm] at 750 [m]: 77.28 [kg/hr]

specific fuel consumption thermo-dynamic : 267 [gr/epk] = 363 [gr/kwh]

specific fuel consumption (cruise power) at 750 [m] optimum mixture : 365 [gr/kwh]

estimated sfc (cruise power) at 2500 [m] rich mixture : 368 [gr/kwh]

specific fuel consumption at 750 [m] at 1630 [rpm] optimum mixture : 404 [gr/kwh]

estimated specific oil consumption (cruise power) : 15 [gr/kwh]

notes :

Literature :

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/photograps/content please mail to below mail address

(c) B van der Zalm 13 december 2018 contact : bvanderzalm@ziggo.nl python 3.4.1