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performance calculations for the Armstrong Siddeley Serval III aircraft engine

Armstrong Siddeley Serval III air-cooled 10 -cylinder double-row radial engine 340

[hp] (253.5 KW)

gear-driven supercharger, constant power to height : 1219 [m] blower ratio : [:1]

introduction : 1930 country : UK importance : ***

applications : Armstrong Whitworth AW.15 Atlanta

normal rating : 340 [hp](253.5 KW) at 2000 [rpm] at 1219 [m] above sea level

take-off power : 380 [hp] (283.4 [KW]) at 2200 [rpm]

no reduction, direct drive, valvetrain : overhead poppet valves

weight engine(s) dry : 324.0 [kg] = 1.28 [kg/KW]

General information : developed from the Mongoose, by fitting two Mongoose engines

on one single crankcase

fuel system : fuel type : octane grade no. 77 oil system :

engine starter type : viet gas # herzmark

bore : 127.0 [mm] stroke : 139.7 [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]

blower speed : [rpm] , mixture :13.0 :1

compression ratio: 5.25 :1

stroke volume (Vs displacement): 17.700 [litre]

compression volume (Vc): 4.164 [litre]

total volume (Vt): 21.861 [litre]

overall engine diameter: 116.0 [cm]

calculated engine length: 97.54 [m]

specific power : 14.3 [kW/litre]

torque : 1211 [Nm]

engine weight/volume : 18.3 : [kg/litre]

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

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intake manifold absolute pressure (MAP) at 1219 [m] altitude Pi (ata.) : 0.96 [kg/cm2]

(27.86 [inHg])

mean engine pressure (M.E.P.) at 1219 [m] altitude Pm : 6.91 [kg/cm2]

compression pressure at 1219 [m] altitude Pc: 7.64 [kg/cm2]

estimated combustion pressure at 1219 [m] Pe : 30.54 [kg/cm2]

exhaust pressure at 1219 [m] Pu : 3.78 [kg/cm^2 ]

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compression-start temperature at 1219 [m] Tic: 350 [°K] (77 [°C])

compression-end temperature at 1219 [m] Tc: 519 [°K] (245 [°C])

average engine wall temperature at 1219 [m] : 476 [K] (202 [°C])

caloric combustion temperature at 1219 [m] Tec: 2167 [°K] (1894 [°C])

polytroph combustion temperature at 1219 [m] Tep : 2071 [°K] (1798 [°C])

estimated combustion temperature at 1219 [m] Te (T4): 2095 [°K] (1821 [°C])

polytrope expansion-end temperature at 1219 [m] Tup: 1158 [°K] (885 [°C])

exhaust stroke end temperature at 1219 [m] Tu: 1105 [°K] (832 [°C])

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calculations for take-off/emergency power at sea level

average piston speed : 10.2 [m/s]

gasspeed at inlet valve : 37.1 [m/s]

intake pressure at sea level for Take-off Pi : 1.06 [kg/cm2] (30.78 [inHg])

caloric combustion temperature at sea level Tec: 2257 [°K] (1983 [°C])

insufficient cooling, can run max 2 minutes at this power before overheating

emergency/take off rating at 2200 [rpm] at sea level : 380 [hp]

Thermal efficiency Nth : 0.339 [ ]

Mechanical efficiency Nm : 0.747 [ ]

Thermo-dynamic efficiency Ntd : 0.253 [ ]

design hours : 2006 [hr] time between overhaul : 539 [hr]

dispersed engine heat by cooling air : 4987.77 [Kcal/minuut/m2]

required cooling surface : 9.41 [m2]

weight cooling ribs : 27.49 [kg]

fuel consumption optimum mixture at 2000.00 [rpm] at 1219 [m]: 79.38 [kg/hr]

specific fuel consumption thermo-dynamic : 237 [gr/epk] = 318 [gr/kwh]

estimated specific fuel consumption (cruise power) at 1219 [m] : 325 [gr/kwh]

specific fuel consumption (volume*rpm at 1 atm MAP) at 2000 [rpm] : 395 [gr/kwh]

estimated specific oil consumption (cruise power) : 15 [gr/kwh]

Literature :

Handbook of aeronautics vol.II aero-engines page 6

Aero engines page 18

Armstrong Siddeley Serval - 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/

content please mail to below mail address

(c) B van der Zalm 22 January 2022 contact : info.aircraftinvestigation@gmail.com python 3.7.4

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