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performance calculations for the Hispano Suiza 8Ab WWI aero engine
Hispano Suiza 8Ab liquid-cooled 8 -cylinder V-engine 180 [hp](132.4 KW)
introduction : May 1917 country : Spain importance : **
applications : FBA type H
normal rating : 180 [hp](132.4 KW) at 1800 [rpm] at 500 [m] above sea level
high compression engine : cannot run at full power at sea level,
constant power to height : 500 [m]
no reduction, direct drive, valvetrain :
weight engine(s) dry : 230.0 [kg] = 1.74 [kg/KW]
bore : 120.0 [mm] stroke : 130.0 [mm]
Mechanical efficiency/mean pressure correction factor : 0.634 [ ]
valve inlet area : 15.9 [cm^2] one inlet and one outlet valve in the cylinder head
gasspeed at inlet valve : 39.0 [m/s]
invloed hoogte > cm : 0.29 [ ]
compression ratio: 5.30 :1
calculated compression ratio : 5.30 : 1
high compression engine cannot run with full power/throttle at sea-level (only for short period)
published volume (displacement): 11.760 [litre]
calculated stroke volume (Vs) : 11.762 [litre]
compression volume (Vc): 2.735 [litre]
total volume (Vt): 14.498 [litre]
power / stroke volume (litervermogen Nl): 11.3 [kW/litre]
torque : 702 [Nm]
engine weight/volume : 19.6 : [kg/litre]
average piston speed (Cm): 7.8 [m/s]
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intake pressure at 500 [m] altitude Pi : 0.92 [kg/cm2]
mean engine pressure (M.E.P.) at 500 [m] altitude Pm : 6.67 [kg/cm2]
compression pressure at 500 [m] altitude Pc: 7.80 [kg/cm2]
estimated combustion pressure at 500 [m] Pe : 31.22 [kg/cm2]
exhaust pressure at 500 [m] Pu : 3.67 [kg/cm^2 ]
Above picture shows the 8Ab with reduction gear..to my information all 8A engines did not have a reduction gear, the 8B had a reduction gear
compression-end temperature at 500 [m] Tc: 595 [°K] (321 [°C])
caloric combustion temperature at 500 [m] Tec: 2252 [°K] (1979 [°C])
polytroph combustion temperature at 500 [m] Te (T4): 2373 [°K] (2100 [°C])
exhaust temperature at 500 [m] Tu: 1324 [°K] (1051 [°C])
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compression pressure at sea level Pc: 7.90 [kg/cm2]
estimated combustion pressure at sealevel Pe : 31.60 [kg/cm^2 ]
compression-end temperature at sealevel Tc:595 [°K] (322 [°C])
mean engine pressure at sealevel Pm : 6.76 [kg/cm2]
emergency/TO rating can be increased with higher [rpm}
(emergency/take off) rating at 1971 [rpm] at sea level : 210 [pk]
Thermal efficiency Nth : 0.341 [ ]
Mechanical efficiency Nm : 0.748 [ ]
Thermo-dynamic efficiency Ntd : 0.255 [ ]
design hours : 762 time between overhaul : 62
fuel consumption optimum mixture at 1800.00 [rpm] at 500 [m]: 47.12 [kg/hr]
specific fuel consumption thermo-dynamic : 248 [gr/epk] = 337 [gr/kwh]
specific fuel consumption (cruise power) at 500 [m] optimum mixture : 340 [gr/kwh]
estimated sfc (cruise power) at 2438 [m] rich mixture : 350 [gr/kwh]
specific fuel consumption at 500 [m] at 1800 [rpm] optimum mixture : 356 [gr/kwh]
estimated specific oil consumption (cruise power) : 15 [gr/kwh]
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/photographs/
content please mail to below mail address
(c) B van der Zalm 23 March 2020 contact : info.aircraftinvestigation@gmail.com python 3.7.4