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performance calculations for the Liberty L-12 WWI aero engine
Indicated on the sign : Bore 5 in.(127mm), stroke 7 in. (178 mm) displacement 1649 cubic inch, 449 hp at take-off, 400 hp continues, 21 lbs per HP, weight 845 lb (383 kg)
Liberty L-12 liquid-cooled 12 -cylinder V-engine 400 [hp](294.2 KW)
introduction : July 1918 country : United States of America importance : ****
applications : Airco D.H.9A, Curtis HS-2L, DH.4 Liberty plane
normal rating : 400 [hp](294.2 KW) at 1750 [rpm] at 0 [m] above sea level
take-off rating, max.power : 449 [hp] at 2000 rpm
no reduction, direct drive, valvetrain : One intake and one exhaust valves per
cylinder operated via a single overhead camshaft per cylinder bank
weight engine(s) dry : 383.0 [kg] = 1.30 [kg/KW]
bore : 127.0 [mm] stroke : 178.0 [mm]
Mechanical efficiency/mean pressure correction factor : 0.634 [ ]
valve inlet area : 17.8 [cm^2] one inlet and one outlet valve in the cylinder head
gasspeed at inlet valve : 51.9 [m/s]
invloed hoogte > cm : 0.39 [ ]
compression ratio: 5.40 :1
calculated compression ratio : 5.40 : 1
high compression engine cannot run with full power/throttle at sea-level (only for short period)
published volume (displacement): 27.030 [litre]
calculated stroke volume (Vs) : 27.058 [litre]
compression volume (Vc): 6.150 [litre]
total volume (Vt): 33.208 [litre]
power / stroke volume (litervermogen Nl): 10.9 [kW/litre]
torque : 1605 [Nm]
engine weight/volume : 14.2 : [kg/litre]
average piston speed (Cm): 10.4 [m/s]
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intake pressure at 0 [m] altitude Pi : 0.73 [kg/cm2]
mean engine pressure (M.E.P.) at 0 [m] altitude Pm : 6.27 [kg/cm2]
compression pressure at 0 [m] altitude Pc: 6.39 [kg/cm2]
estimated combustion pressure at 0 [m] Pe : 25.58 [kg/cm2]
exhaust pressure at 0 [m] Pu : 2.94 [kg/cm^2 ]
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compression-end temperature at 0 [m] Tc: 618 [°K] (345 [°C])
caloric combustion temperature at 0 [m] Tec: 2281 [°K] (2007 [°C])
polytroph combustion temperature at 0 [m] Tep : 2471 [°K] (2198 [°C])
estimated combustion temperature at 0 [m] Te (T4): 2344 [°K] (2071 [°C])
polytrope exhaust temperature at 0 [m] Tup: 1455 [°K] (1181 [°C])
exhaust temperature at 0 [m] Tu: 1159 [°K] (886 [°C])
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Thermal efficiency Nth : 0.344 [ ]
Mechanical efficiency Nm : 0.753 [ ]
Thermo-dynamic efficiency Ntd : 0.259 [ ]
design hours : 527 time between overhaul : 37
Major Henry H. "Hap" Arnold with the first Liberty V12 engine completed
fuel consumption optimum mixture at 1750.00 [rpm] at 0 [m]: 111.38 [kg/hr]
specific fuel consumption thermo-dynamic : 244 [gr/epk] = 332 [gr/kwh]
specific fuel consumption (cruise power) at 0 [m] optimum mixture : 336 [gr/kwh]
estimated sfc (cruise power) at 2552 [m] rich mixture : 351 [gr/kwh]
specific fuel consumption at 0 [m] at 1750 [rpm] optimum mixture : 379 [gr/kwh]
estimated specific oil consumption (cruise power) : 14 [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 28 March 2020 contact : info.aircraftinvestigation@gmail.com python 3.7.4