Rolls Royce Merlin 24 ratings | aircraft investigation info

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performance calculations for the Rolls Royce Merlin 24 aircraft engine

Rolls-Royce Merlin 24 1,280-hp V12 - Avro York RAF/Dan Air… | Flickr

Merlin 24 built in Avro York

Rolls Royce Merlin 24 liquid-cooled 12 -cylinder V-engine 1175 [hp](876.2 KW)

gear-driven supercharger, constant power to height : 5340 [m] blower ratio : ?? [:1]

introduction : 1943 country : UK importance : ***

applications : Avro Lancastrian, Avro York

normal rating : 1175 [hp](876.2 KW) at 2850 [rpm] at 5340 [m] above sea level

take-off power : 1620 [hp] (1208.0 [KW]) at 3000 [rpm]

reduction : 0.42 , valvetrain : SOHC

weight engine(s) dry with reduction gear : 658.0 [kg] = 0.75 [kg/KW]

General information :

fuel system : fuel type : octane grade no. 81 oil system :

engine starter type :

bore : 137.0 [mm] stroke : 152.0 [mm]

supercharger compression ratio : 2.74 [ ]

valve inlet area : 28.6 [cm^2] one inlet and one exhaust valve in cylinder head

gasspeed at inlet valve : 52.5 [m/s]

blower speed : 114142 [rpm] , mixture :13.0 :1

compression ratio: 6.00 :1

stroke volume (Vs displacement): 27.000 [litre]

compression volume (Vc): 5.378 [litre]

total volume (Vt): 32.265 [litre]

calculated engine height : 101 [cm] engine width :98 [cm]

calculated engine length: 1.23 [m]

specific power : 32.5 [kW/litre]

torque : 2936 [Nm]

engine weight/volume : 24.4 : [kg/litre]

average piston speed (Cm): 14.4 [m/s]

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intake manifold absolute pressure (MAP) at 5340 [m] altitude Pi (ata.) : 1.03 [kg/cm2]

(29.83 [inHg])

mean engine pressure (M.E.P.) at 5340 [m] altitude Pm : 11.62 [kg/cm2]

compression pressure at 5340 [m] altitude Pc: 9.67 [kg/cm2]

estimated combustion pressure at 5340 [m] Pe : 38.64 [kg/cm2]

exhaust pressure at 5340 [m] Pu : 4.04 [kg/cm^2 ]

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compression-start temperature at 5340 [m] Tic: 354 [°K] (81 [°C])

compression-end temperature at 5340 [m] Tc: 547 [°K] (274 [°C])

Rolls Royce Merlin 24 | Rolls royce merlin, Rolls royce, Aircraft engine

average engine wall temperature at 5340 [m] : 476 [K] (202 [°C])

caloric combustion temperature at 5340 [m] Tec: 2262 [°K] (1989 [°C])

polytroph combustion temperature at 5340 [m] Tep : 2185 [°K] (1912 [°C])

estimated combustion temperature at 5340 [m] Te (T4): 2199 [°K] (1926 [°C])

polytrope expansion-end temperature at 5340 [m] Tup: 1179 [°K] (906 [°C])

exhaust stroke end temperature at 5340 [m] Tu: 1145 [°K] (872 [°C])

*********************************************************************************

calculations for take-off/emergency power at sea level

average piston speed : 15.2 [m/s]

gasspeed at inlet valve : 55.2 [m/s]

intake pressure at sea level for Take-off Pi : 1.44 [kg/cm2] (41.70 [inHg])

max. intake pressure (full blower) at sea level for Take-off Pi : 2.83 [kg/cm2] (81.87

[inHg])

high combustion pressure > high loads on pistonrod and crankcase

caloric combustion temperature at sea level Tec: 2361 [°K] (2088 [°C])

high burn temperature > risk of overheating max 2 min max power setting at sea

level

emergency/take off rating at 3000 [rpm] at sea level : 1625 [hp]

Rolls Royce Merlin 23 | The Rolls Royced Merlin was one of t… | Flickr

Merlin 23

Thermal efficiency Nth : 0.361 [ ]

Mechanical efficiency Nm : 0.733 [ ]

Thermo-dynamic efficiency Ntd : 0.265 [ ]

design hours : 745 [hr] time between overhaul : 209 [hr]

dispersed heat by cooling fluids at 2850.00 [rpm] at 5340 [m]: 21.32 [Kcal/minuut/litre]

fuel consumption optimum mixture at 2850.00 [rpm] at 5340 [m]: 207.19 [kg/hr]

specific fuel consumption thermo-dynamic : 227 [gr/epk] = 304 [gr/kwh]

estimated specific fuel consumption (cruise power) at 5340 [m] : 300 [gr/kwh]

specific fuel consumption (volume*rpm at 1 atm MAP) at 2850 [rpm] : 247 [gr/kwh]

estimated specific oil consumption (cruise power) : 12 [gr/kwh]

Literature :

Jane’s fighting aircraft WWII page

Rolls-Royce Merlin - 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

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