Aircraft investigation info>>>>>>> HOME PAGE
performance calculations for the RAF 1a WWI aero engine
RAF 1a in the Smithsonian national air and space museum
RAF 1a air-cooled 8 -cylinder V-engine 92 [hp](68.6 KW)
introduction : November 1914 country : United Kingdom importance : *****
applications : RAF BE2c, RAF BE2e, Armstrong Whitworth FK3
normal rating : 92 [hp](68.6 KW) at 1600 [rpm] at 0 [m] above sea level
reduction : 0.5 , valvetrain : SOHC
weight reduction gear : 2.7 [kg]
fuel system : Twin-Claudel Hobson carburettors oil system : sump
weight engine(s) dry without reduction gear : 204.0 [kg] = 2.97 [kg/KW]
bore : 100.0 [mm] stroke : 140.0 [mm]
Mechanical efficiency/mean pressure correction factor : 0.648 [ ]
valve inlet area : 12.8 [cm^2] one inlet and one exhaust valve in cylinder head
gasspeed at inlet valve : 32.3 [m/s]
invloed hoogte > cm : 0.35 [ ]
optimum mixture
throttle : 91 /100 open, mixture :13.0 :1
compression ratio: 4.30 :1
calculated compression ratio : 4.30 : 1
published volume (displacement): 8.800 [litre]
calculated stroke volume (Vs) : 8.796 [litre]
compression volume (Vc): 2.666 [litre]
total volume (Vt): 11.462 [litre]
engine height : 91 [cm] engine width :88 [cm]
power / stroke volume (litervermogen Nl): 7.8 [kW/litre]
torque : 409 [Nm]
engine weight/volume : 23.2 : [kg/litre]
average piston speed (Cm): 7.5 [m/s]
***************************************************************************
intake pressure at 0 [m] altitude Pi : 0.90 [kg/cm2]
mean engine pressure (M.E.P.) at 0 [m] altitude Pm : 5.28 [kg/cm2]
Note the exhaust valve on top with cooling ribs and the 180 degrees upside down inlet valve
compression pressure at 0 [m] altitude Pc: 5.58 [kg/cm2]
estimated combustion pressure at 0 [m] Pe : 22.32 [kg/cm2]
exhaust pressure at 0 [m] Pu : 3.55 [kg/cm^2 ]
**************************************************************************
compression-start temperature at 0 [m] Tic: 369 [°K] (96 [°C])
compression-end temperature at 0 [m] Tc: 520 [°K] (246 [°C])
caloric combustion temperature at 0 [m] Tec: 2002 [°K] (1729 [°C])
polytroph combustion temperature at 0 [m] Tep : 2078 [°K] (1805 [°C])
estimated combustion temperature at 0 [m] Te (T4): 2023 [°K] (1750 [°C])
polytrope exhaust temperature at 0 [m] Tup: 1385 [°K] (1111 [°C])
exhaust end temperature at 0 [m] Tu: 1273 [°K] (1000 [°C])
*********************************************************************************
RAF 1a engine at the USAF national museum
emergency/take off rating at 1800 [rpm] at sea level : 108 [hp]
Thermal efficiency Nth : 0.306 [ ]
Mechanical efficiency Nm : 0.698 [ ]
Thermo-dynamic efficiency Ntd : 0.213 [ ]
design hours : 2003 time between overhaul : 55
fuel consumption optimum mixture at 1600.00 [rpm] at 0 [m]: 28.93 [kg/hr]
specific fuel consumption thermo-dynamic : 282 [gr/epk] = 378 [gr/kwh]
estimated specific fuel consumption (cruise power) at 0 [m] optimum mixture : 382 [gr/kwh]
estimated sfc (cruise power) at 1980 [m] rich mixture : 404 [gr/kwh]
specific fuel consumption at 0 [m] at 1600 [rpm] with mixture :13.0 :1 : 422 [gr/kwh]
estimated specific oil consumption (cruise power) : 36 [gr/kwh]
Literature :
Smitsonian national air and space museum
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 31 May 2020 contact : info.aircraftinvestigation@gmail.com python 3.7.4