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performance calculations for the De Havilland Gipsy III aircraft engine

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De Havilland Gipsy III

air-cooled 4 -cylinder inverted inline engine 108 [hp](80.5 KW)

introduction : October 1932 country : United Kingdom importance : ***

applications : De Havilland D.H.83 Fox Moth

normal rating : 108 [hp](80.5 KW) at 2000 [rpm] at 0 [m] above sea level

take-off power : 120 [hp] (89.5 [KW]) at 2300 [rpm]

no reduction, direct drive, valvetrain : OHV

general information : Inverted Gipsy II for better view for the pilot over the aircraft

nose. 611 built.

fuel system : Zenith Carburettor fuel type : Petrol (Aviation grade fuel not required)

oil system : engine starter type : Eclipse inertia starter

weight engine(s) dry : 139.0 [kg] = 1.73 [kg/KW]

bore : 114.3 [mm] stroke : 140.0 [mm]

valve inlet area : 19.9 [cm^2] one inlet and one exhaust valve in cylinder head

gasspeed at inlet valve : 33.8 [m/s]

throttle : 85 /100 open, mixture :13.0 :1

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Gipsy III at the Shuttleworth collection

compression ratio: 5.20 :1

stroke volume (Vs displacement): 5.746 [litre]

compression volume (Vc): 1.368 [litre]

total volume (Vt): 7.114 [litre]

calculated engine height : 82 [cm]

engine length: 1.03 [m]

specific power : 14.0 [kW/litre]

torque : 385 [Nm]

engine weight/volume : 24.2 : [kg/litre]

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

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intake manifold absolute pressure (MAP) at 0 [m] altitude Pi : 0.83 [kg/cm2]

mean engine pressure (M.E.P.) at 0 [m] altitude Pm : 6.39 [kg/cm2]

compression pressure at 0 [m] altitude Pc: 6.54 [kg/cm2]

estimated combustion pressure at 0 [m] Pe : 26.11 [kg/cm2]

exhaust pressure at 0 [m] Pu : 3.27 [kg/cm^2 ]

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compression-start temperature at 0 [m] Tic: 355 [°K] (82 [°C])

compression-end temperature at 0 [m] Tc: 527 [°K] (254 [°C])

average engine wall temperature at 0 [m] : 476 [K] (202 [°C])

caloric combustion temperature at 0 [m] Tec: 2098 [°K] (1825 [°C])

polytroph combustion temperature at 0 [m] Tep : 2105 [°K] (1831 [°C])

estimated combustion temperature at 0 [m] Te (T4): 2082 [°K] (1809 [°C])

polytrope expansion-end temperature at 0 [m] Tup: 1156 [°K] (883 [°C])

exhaust stroke end temperature at 0 [m] Tu: 1111 [°K] (838 [°C])

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calculations for take-off/emergency power at sea level

average piston speed : 10.7 [m/s]

gasspeed at inlet valve : 38.8 [m/s]

caloric combustion temperature at sea level Tec: 2121 [°K] (1848 [°C])

emergency/take off rating at 2300 [rpm] at sea level : 121 [hp]

Thermal efficiency Nth : 0.338 [ ]

Mechanical efficiency Nm : 0.775 [ ]

Thermo-dynamic efficiency Ntd : 0.262 [ ]

design hours : 2976 [hr] time between overhaul : 1328 [hr]

dispersed engine heat by cooling air : 1616.23 [Kcal/minuut/m2]

required cooling surface : 2.54 [m2]

weight cooling ribs : 5.29 [kg]

fuel consumption optimum mixture at 2000.00 [rpm] at 0 [m]: 25.12 [kg/hr]

specific fuel consumption thermo-dynamic : 230 [gr/epk] = 308 [gr/kwh]

estimated specific fuel consumption (cruise power) at 0 [m] optimum mixture : 300

[gr/kwh]

specific fuel consumption at 0 [m] at 2000 [rpm] with mixture :13.0 :1 : 312 [gr/kwh]

specific fuel consumption (volume*rpm) at 2000 [rpm] : 403 [gr/kwh]

estimated specific oil consumption (cruise power) : 25 [gr/kwh]

de Havilland – Gipsy III n°3216 - Ailes Anciennes le Bourget

Literature :

Handbook of aeronautics vol.II aero-engines page 7

de Havilland Gipsy - 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 28 November 2021 contact : info.aircraftinvestigation@gmail.com python 3.7.4

notes :