aviation during World War One
WW1 aero engines

Antoinette 8V
Argus As III N
Austro-Daimler AD 6
Benz Bz IIIb
Benz Bz IV
Colombo D 110
Daimler Mercedes D-IV
Fiat A-10
Fiat A-12
Fiat A-12 bis
Fiat A-14
Hispano-Suiza 8BE
Hispano-Suiza HS 44
Hispano-Suiza HS 31
Isotta Fraschini V4 B
Isotta Fraschini V5
Korting Kg IV
Liberty 12-A Engine
Maybach HS D Engine
NAG III Inline 6 Cylinder
Renault 70 CVs


inline Engines

During World War I, rotaries attained tremendous popularity. They were less complex and easier to make than the water-cooled type. They powered such outstanding fighter planes as German's Fokker DR-1 and Britain's Sopwith Camel. They used castor oil for lubrication because it did not dissolve in gasoline. However, they tended to spray this oil all over, making a smelly mess. Worse, they were limited in power. The best of them reached 260 to 280 horsepower (190 to 210 kilowatts).

Thus, in 1917 a group of American engine builders returned to water cooling as they sought a 400-horsepower (300-kilowatt) engine. The engine that resulted, the Liberty was the most powerful aircraft engine of its day, with the U.S. auto industry building more than 20,000 of them. Water-cooled engines built in Europe also outperformed the air-cooled rotaries, and lasted longer. With the war continuing until late in 1918, the rotaries lost favour.

Liberty engine

Curtiss OXX-3 Aero Engine

In this fashion, designers returned to water-cooled motors that again were fixed in position. They stayed cool by having water or antifreeze flow in channels through the engine to carry away the heat. A radiator cooled the heated water. In addition to offering plenty of power, such motors could be completely enclosed within a streamlined housing, to reduce drag and thus produce higher speeds in flight. Rolls Royce, Great Britain's leading engine-builder, built only water-cooled motors.

Inline engines have an advantage of having a small frontal area, thus drag is reduced. Many however use liquid cooling which increases weight and make the aircraft more vulnerable to battle damage.