Wright J-6-9 Whirlwind | aircraft investigation

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performance calculations for the Wright R-975 J-6-9 Whirlwind aircraft engine

Wright J-6-9 (R-975) Whirlwind Radial Engine 2 | Photographp… | Flickr

Wright R-975 J-6-9 Whirlwind air-cooled 9 -cylinder radial engine 300 [hp](223.7 KW)

gear-driven supercharger, constant power to height : 1000 [m]

introduction : 1927 country : U.S.A. importance : ***

applications : Ford 4AT Trimotor, Fokker F.VIIb/3m

normal rating : 300 [hp](223.7 KW) at 2000 [rpm] at 1000 [m] above sea level

no reduction, direct drive, valvetrain : pushrod-actuated

fuel system : oil system :

weight engine(s) dry : 306.0 [kg] = 1.37 [kg/KW]

bore : 127.0 [mm] stroke : 140.0 [mm]

valve inlet area : 24.6 [cm^2] one inlet and one exhaust valve in cylinder head

gasspeed at inlet valve : 33.7 [m/s]

throttle : 90 /100 open, mixture :13.0 :1

compression ratio : 6.19 : 1

high compression engine cannot run with full power/throttle at sea-level (only for short period)

published volume (displacement): 15.930 [litre]

calculated stroke volume (Vs) : 15.961 [litre]

compression volume (Vc): 3.073 [litre]

total volume (Vt): 19.034 [litre]

diam. engine : 105 [cm]

engine length: 0.25 [m]

specific power : 14.0 [kW/litre]

torque : 1068 [Nm]

engine weight/volume : 19.2 : [kg/litre]

average piston speed (Cm): 9.3 [m/s]

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intake pressure at 1000 [m] altitude Pi : 0.95 [kg/cm2]

mean engine pressure (M.E.P.) at 1000 [m] altitude Pm : 6.91 [kg/cm2]

compression pressure at 1000 [m] altitude Pc: 9.28 [kg/cm2]

estimated combustion pressure at 1000 [m] Pe : 37.09 [kg/cm2]

exhaust pressure at 1000 [m] Pu : 3.73 [kg/cm^2 ]

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compression-start temperature at 1000 [m] Tic: 351 [°K] (78 [°C])

compression-end temperature at 1000 [m] Tc: 543 [°K] (269 [°C])

average engine wall temperature at 1000 [m] : 476 [K] (202 [°C])

caloric combustion temperature at 1000 [m] Tec: 2218 [°K] (1945 [°C])

polytroph combustion temperature at 1000 [m] Tep : 2167 [°K] (1894 [°C])

estimated combustion temperature at 1000 [m] Te (T4): 2168 [°K] (1895 [°C])

polytroph expansion-end temperature at 1000 [m] Tup: 1149 [°K] (876 [°C])

exhaust stroke end temperature at 1000 [m] Tu: 1097 [°K] (824 [°C])

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emergency/take off rating at 2200 [rpm] at sea level : 320 [hp]

Thermal efficiency Nth : 0.366 [ ]

Mechanical efficiency Nm : 0.760 [ ]

Thermo-dynamic efficiency Ntd : 0.278 [ ]

design hours : 1663 [hr] time between overhaul : 49 [hr]

dispersed engine heat by cooling air : 4594.67 [Kcal/minute/m2]

required cooling surface : 11.91 [m2]

weight cooling ribs : 129.28 [kg]

fuel consumption optimum mixture at 2000.00 [rpm] at 1000 [m]: 67.62 [kg/hr]

specific fuel consumption thermo-dynamic : 216 [gr/epk] = 290 [gr/kwh]

estimated specific fuel consumption (cruise power) at 1000 [m] : 305 [gr/kwh]

estimated sfc (cruise power) at 2400 [m] rich mixture : 308 [gr/kwh]

specific fuel consumption at 1000 [m] at 2000 [rpm] with mixture :13.0 :1 : 302 [gr/kwh]

estimated specific oil consumption (cruise power) : 18 [gr/kwh]

Literature :

Wikipedia

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/

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