Wright 20hp

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performance calculations for the Wright no.3 WWI aero engine

Just over the pilot's legs, you can see the four combustion chambers on the left side of the engine. These ran exceedingly hot. When the engine of the Flyer III was built in 1904, it produced just 16 horsepower. But the Wrights continued to tweak it until by September 1905, it was producing 24. The engine ran at about 1300 rpm. The small gears on the crankshaft and the large gears on the propeller shafts reduced this so the props turned at just 450 rpm.

Wright no.3 liquid-cooled 4 -cylinder inline engine 24 [hp](17.9 KW)

introduction : May 1905 country : USA importance : ****

applications : Wright Flyer III

max. continuous(take-off) rating : 24 [hp](17.9 KW) at 1300 [rpm] at 0 [m] above sea

level

reduction : 0.346 , valvetrain : SOHC

weight reduction gear : 7.2 [kg]

fuel system : oil system : splash system

weight engine(s) dry without reduction gear : 111.9 [kg] = 6.25 [kg/KW]

bore : 108.0 [mm] stroke : 110.0 [mm]

Mechanical efficiency/mean pressure correction factor : 0.737 [ ]

valve inlet area : 14.9 [cm^2] one inlet and one exhaust valve in cylinder head

gas speed at inlet valve : 20.5 [m/s]

rich mixture - additional cooling due vaporizing fuel

throttle : 99 /100 open, mixture :11.6 :1

calculated compression ratio : 3.65 : 1

stroke volume (Vs) : 4.031 [litre]

compression volume (Vc): 1.521 [litre]

total volume (Vt): 5.552 [litre]

engine width : 74 [cm]

power / stroke volume (litervermogen Nl): 4.5 [kW/litre]

torque : 131 [Nm]

engine weight/volume : 28.0 : [kg/litre]

average piston speed (Cm): 4.8 [m/s]

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intake pressure at 0 [m] altitude Pi : 1.00 [kg/cm2]

mean engine pressure (M.E.P.) at 0 [m] altitude Pm : 4.34 [kg/cm2]

compression pressure at 0 [m] altitude Pc: 4.99 [kg/cm2]

estimated combustion pressure at 0 [m] Pe : 18.94 [kg/cm2]

estimated combustion pressure at 0 [m] Pe : 20.32 [kg/cm2]

exhaust pressure at 0 [m] Pu : 3.71 [kg/cm^2 ]

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The original Wright Flyer III is preserved in the Wright Brothers Aviation Centre at Carillon Historic Park in Dayton, Ohio. Here you can see a close-up of the engine

compression-start temperature at 0 [m] Tic: 384 [°K] (110 [°C])

compression-end temperature at 0 [m] Tc: 509 [°K] (236 [°C])

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

caloric combustion temperature at 0 [m] Tec: 1901 [°K] (1628 [°C])

polytroph combustion temperature at 0 [m] Tep : 1930 [°K] (1657 [°C])

estimated combustion temperature at 0 [m] Te (T4): 1900 [°K] (1627 [°C])

polytrope expansion-end temperature at 0 [m] Tup: 1153 [°K] (880 [°C])

exhaust stroke end temperature at 0 [m] Tu: 1088 [°K] (814 [°C])

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emergency/take off rating is equal to max.continuous rating : 24 [hp](17.9 KW)

the note on the wooden mount for the magneto says "Found near Kill Devil Hills Aug 6 '08. This part and many others were recovered from souvenir hunters on the Outer Banks.

Thermal efficiency Nth : 0.266 [ ]

Mechanical efficiency Nm : 0.620 [ ]

Thermo-dynamic efficiency Ntd : 0.165 [ ]

design hours : 384 [hr] time between overhaul : 19 [hr]

much heat generated, risk of over heating the engine > for this reason the wright brothers installed a 2^nd radiator in the Flyer III, also the fuel mixture was rich for extra cooling

fuel consumption optimum mixture at 1300.00 [rpm] at 0 [m]: 13.17 [kg/hr]

specific fuel consumption thermo-dynamic : 365 [gr/epk] = 490 [gr/kwh]

estimated specific fuel consumption (cruise power) at 0 [m] optimum mixture : 680 [gr/kwh]

estimated sfc (cruise power) at 100 [m] rich mixture : 715 [gr/kwh]

specific fuel consumption at 0 [m] at 1300 [rpm] with mixture :11.6 :1 : 736 [gr/kwh]

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

Literature:

https://www.wrightexperience.com/the-engine/

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/

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