Aircraft investigation >>>>>>> HOME PAGE
performance calculations for the De Haviland Gipsy Major I aircraft engine
The Gipsy Major was a reliable engine, in 1937 it was approved for a TBO of 1000 hours.
introduction : 1933 country : United Kingdom importance : ***
applications : De Havilland DH84 Dragon, De Havilland DHA-3 Drover
normal rating : 122 [hp](91.0 KW) at 2100 [rpm] at 0 [m] above sea level
take-off power : 145 [hp] (108.1 [KW]) at 2550 [rpm]
no reduction, direct drive, valvetrain : OHV
General information : Inverted configuration had the advantage to give the pilot in a single-engined aircraft a better view over the nose while having the propellor shaft at a high position to keep the propellor turning clear from the ground. Initial disadvantage was the high oil consumption, up to 4 pints/hour (= 2.72 litre/hour), later this improved by the use of modified piston rings. Total production reached 14615 units.
fuel system : Downdraught Hobson A.I.48 H3M (Mk 1C and Mk 7) or H1M (others) octane no. 71 oil system : Dry sump, gear-type pump
weight engine(s) dry : 136.0 [kg] = 1.49 [kg/KW]
bore : 118.0 [mm] stroke : 140.0 [mm]
valve inlet area : 21.3 [cm^2] one inlet and one exhaust valve in cylinder head
gasspeed at inlet valve : 35.5 [m/s]
throttle : 86 /100 open, mixture :13.0 :1
compression ratio: 5.25 :1
stroke volume (Vs) : 6.124 [litre]
compression volume (Vc): 1.441 [litre]
Gipsy Major engine installed in a DHA-3 Drover
total volume (Vt): 7.565 [litre]
engine height : 86 [cm]
calculated engine length: 0.00 [m]
specific power : 14.9 [kW/litre]
torque : 414 [Nm]
engine weight/volume : 22.2 : [kg/litre]
average piston speed (Cm): 9.8 [m/s]
***************************************************************************
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 : 6.45 [kg/cm2]
compression pressure at 0 [m] altitude Pc: 6.61 [kg/cm2]
estimated combustion pressure at 0 [m] Pe : 26.42 [kg/cm2]
exhaust pressure at 0 [m] Pu : 3.27 [kg/cm^2 ]
**************************************************************************
compression-start temperature at 0 [m] Tic: 352 [°K] (79 [°C])
compression-end temperature at 0 [m] Tc: 524 [°K] (251 [°C])
average engine wall temperature at 0 [m] : 476 [K] (202 [°C])
caloric combustion temperature at 0 [m] Tec: 2099 [°K] (1826 [°C])
polytroph combustion temperature at 0 [m] Tep : 2094 [°K] (1821 [°C])
estimated combustion temperature at 0 [m] Te (T4): 2076 [°K] (1803 [°C])
polytrope expansion-end temperature at 0 [m] Tup: 1150 [°K] (877 [°C])
exhaust stroke end temperature at 0 [m] Tu: 1105 [°K] (832 [°C])
*********************************************************************************
calculations for take-off/emergency power at sea level
emergency/TO max rpm : 2550 [rpm]
average piston speed : 11.9 [m/s]
gasspeed at inlet valve : 43.1 [m/s]
intake pressure at sea level Pi : 0.86 [kg/cm2]
compression-end temperature at sealevel max rpm Tc:527 [°K] (254 [°C])
caloric combustion temperature at sea level Tec: 2099 [°K] (1826 [°C])
mean engine pressure at sealevel max rpm Pm : 6.64 [kg/cm2]
emergency/take off rating at 2550 [rpm] at sea level : 143 [hp]
Thermal efficiency Nth : 0.339 [ ]
Mechanical efficiency Nm : 0.784 [ ]
Thermo-dynamic efficiency Ntd : 0.266 [ ]
design hours : 2330 [hr] time between overhaul : 1005 [hr]
dispersed engine heat by cooling air : 1795.19 [Kcal/minuut/m2]
required cooling surface : 2.77 [m2]
weight cooling ribs : 6.00 [kg]
fuel consumption optimum mixture at 2100.00 [rpm] at 0 [m]: 28.09 [kg/hr]
specific fuel consumption thermo-dynamic : 226 [gr/epk] = 303 [gr/kwh]
estimated specific fuel consumption (cruise power) at 0 [m] optimum mixture : 300
[gr/kwh]
At first the inverted cylinder arrangement gave a high oil usage, later this was improved
specific fuel consumption at 0 [m] at 2100 [rpm] with mixture :13.0 :1 : 309 [gr/kwh]
specific fuel consumption (volume*rpm) at 2100 [rpm] : 400 [gr/kwh]
estimated specific oil consumption (cruise power) : 23 [gr/kwh]
Literature :
de Havilland Gipsy Major - 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 :
