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performance calculations for the Gnome 7A Monosoupape WWI rotary engine
Gnome 7A Monosoupape air-cooled 7 -cylinder Monosoupape rotary engine 80 [hp](58.8 KW)
introduction : September 1912 country : France importance : *****
applications : Morane Parasol, Caudron G.3, Avro 504A, Bristol Scout C, Sopwith
general information : the atmospheric inlet valves are replaced by apertures in the side of the piston and the base of the cylinder
normal rating : 80 [hp](58.8 KW) at 1200 [rpm] at 0 [m] above sea level
no reduction, direct drive, valvetrain :
weight engine(s) dry : 109.4 [kg] = 1.86 [kg/KW]
bore : 110.0 [mm] stroke : 150.0 [mm]
Mechanical efficiency/mean pressure correction factor : 0.720 [ ]
invloed hoogte > cm : 0.38 [ ]
compression ratio: 0.00 :1
calculated compression ratio : 4.85 : 1
published volume (displacement): 9.980 [litre]
calculated stroke volume (Vs) : 9.978 [litre]
compression volume (Vc): 2.589 [litre]
total volume (Vt): 12.568 [litre]
power / stroke volume (litervermogen Nl): 5.9 [kW/litre]
torque : 468 [Nm]
engine weight/volume : 11.0 : [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 : 5.72 [kg/cm2]
compression pressure at 0 [m] altitude Pc: 7.21 [kg/cm2]
estimated combustion pressure at 0 [m] Pe : 28.85 [kg/cm2]
exhaust pressure at 0 [m] Pu : 3.80 [kg/cm^2 ]
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compression-end temperature at 0 [m] Tc: 571 [°K] (298 [°C])
caloric combustion temperature at 0 [m] Tec: 2197 [°K] (1924 [°C])
polytroph combustion temperature at 0 [m] Te (T4): 2279 [°K] (2005 [°C])
exhaust temperature at 0 [m] Tu: 1253 [°K] (980 [°C])
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emergency/TO rating can be increased with higher [rpm}
(emergency/take off) rating at 1314 [rpm] at sea level : 88 [pk]
Thermal efficiency Nth : 0.326 [ ]
Mechanical efficiency Nm : 0.652 [ ]
Thermo-dynamic efficiency Ntd : 0.213 [ ]
design hours : 1215 time between overhaul : 136
fuel consumption optimum mixture at 1200.00 [rpm] at 0 [m]: 25.65 [kg/hr]
specific fuel consumption thermo-dynamic : 297 [gr/epk] = 404 [gr/kwh]
specific fuel consumption (cruise power) at 0 [m] optimum mixture : 412 [gr/kwh]
estimated sfc (cruise power) at 2000 [m] rich mixture : 422 [gr/kwh]
specific fuel consumption at 0 [m] at 1200 [rpm] optimum mixture : 436 [gr/kwh]
estimated specific oil consumption (cruise power) : 110 [gr/kwh]
Literature :
Warplanes WWI page 58
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 29 February 2020 contact : info.aircraftinvestigation@gmail.com python 3.7.4