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performance calculations for the Wright R-3350-C18-BA3 Duplex-Cyclone aircraft engine
Wright R-3350-C18-BA3 Duplex-Cyclone air-cooled 18 -cylinder double row radial engine 1800 [hp](1342.3 KW)
gear-driven supercharger, constant power to height : 4260 [m] blower ratio : 8.81 [:1]
introduction : 1945 country : USA importance : ***
applications : Lockheed L-049 Constellation
normal rating : 1800 [hp](1342.3 KW) at 2400 [rpm] at 4260 [m] above sea level
take-off power : 2200 [hp] (1640.5 [KW]) at 2800 [rpm]
reduction : 0.4375 , valvetrain : overhead valves, pushrod operated
weight engine(s) dry with reduction gear : 1212.0 [kg] = 0.90 [kg/KW]
General information :
fuel system : Chandler-Evans downdraft carburettor fuel type : octane grade no.
100/130 ROB oil system : dry sump
engine starter type :
bore : 155.6 [mm] stroke : 160.2 [mm]
valve inlet area : 37.0 [cm^2] one inlet and one exhaust valve in cylinder head
gasspeed at inlet valve : 46.4 [m/s]
blower speed : 21144 [rpm] , mixture :13.0 :1
compression ratio: 6.85 :1
high octane fuel needed tp prevent detonation
stroke volume (Vs displacement): 54.862 [litre]
compression volume (Vc): 9.373 [litre]
total volume (Vt): 64.206 [litre]
overall engine diameter: 141.7 [cm]
calculated engine length: 119.50 [m]
specific power : 24.5 [kW/litre]
torque : 5341 [Nm]
engine weight/volume : 22.1 : [kg/litre]
average piston speed (Cm): 12.8 [m/s]
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intake manifold absolute pressure (MAP) at 4260 [m] altitude Pi (ata.) : 1.07 [kg/cm2] (30.99 [inHg])
mean engine pressure (M.E.P.) at 4260 [m] altitude Pm : 11.00 [kg/cm2]
compression pressure at 4260 [m] altitude Pc: 11.86 [kg/cm2]
estimated combustion pressure at 4260 [m] Pe : 47.37 [kg/cm2]
exhaust pressure at 4260 [m] Pu : 4.19 [kg/cm^2 ]
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Low intake temp. > risk of ice forming
compression-start temperature at 4260 [m] Tic: 352 [°K] (79 [°C])
compression-end temperature at 4260 [m] Tc: 561 [°K] (288 [°C])
average engine wall temperature at 4260 [m] : 476 [K] (202 [°C])
caloric combustion temperature at 4260 [m] Tec: 2382 [°K] (2109 [°C])
polytroph combustion temperature at 4260 [m] Tep : 2242 [°K] (1969 [°C])
estimated combustion temperature at 4260 [m] Te (T4): 2282 [°K] (2009 [°C])
polytrope expansion-end temperature at 4260 [m] Tup: 1180 [°K] (907 [°C])
exhaust stroke end temperature at 4260 [m] Tu: 1138 [°K] (865 [°C])
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calculations for take-off/emergency power at sea level
average piston speed : 15.0 [m/s]
gasspeed at inlet valve : 54.1 [m/s]
intake pressure at sea level for Take-off Pi : 1.08 [kg/cm2] (31.39 [inHg])
rich mixture 11.5 : 1 applied for cooling > carburettor adjustable in flight by the pilot
caloric combustion temperature at sea level Tec: 2122 [°K] (1849 [°C])
insufficient cooling, can run max 2 minutes at this power before overheating
emergency/take off rating at 2800 [rpm] at sea level : 2200 [hp]
Thermal efficiency Nth : 0.382 [ ]
Mechanical efficiency Nm : 0.742 [ ]
Thermo-dynamic efficiency Ntd : 0.283 [ ]
design hours : 830 [hr] time between overhaul : 332 [hr]
dispersed engine heat by cooling air : 20318.35 [Kcal/minuut/m2]
required cooling surface : 27.79 [m2]
weight cooling ribs : 86.13 [kg]
fuel consumption optimum mixture at 2400.00 [rpm] at 4260 [m]: 419.16 [kg/hr]
specific fuel consumption thermo-dynamic : 212 [gr/epk] = 284 [gr/kwh]
estimated specific fuel consumption (cruise power) at 4260 [m] : 286 [gr/kwh]
specific fuel consumption (volume*rpm at 1 atm MAP) at 2400 [rpm] : 277 [gr/kwh]
estimated specific oil consumption (cruise power) : 8 [gr/kwh]
time between engine failure : 415 [hr]
can continue fly on 3 engines, low risk for emergency landing for PUF
writing off per paskm : 0.038 [eur]
insurance per paskm : 0.001 [eur]
maintenance cost per paskm : 0.137 [eur]
direct operating cost per paskm : 0.238 [eur]
direct operating cost per tonkm (max. load): 0.910 [eur]
direct operating cost per tonkm (normal useful load): 2.038 [eur]
Literature :
Jane’s fighting aircraft WWII page 318
ENGINE COLLECTION | The Hangar Flight Museum (thehangarmuseum.ca)
Wright R-3350 Duplex-Cyclone - Wikipedia
Aero engines – Bill Gunston page 200
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 22 January 2022 contact : info.aircraftinvestigation@gmail.com python 3.7.4