About AEHS
Piston Engines

Piston engines have powered aircraft since the dawn of powered flight and still power them today. Nearly every noteworthy aircraft performance improvement was the direct result of an engine improvement. Many of these engine improvements ranked among some of the greatest accomplishments of the first half of the Twentieth Century.

This section details piston engine development and use.



Supercharger Development in the U.S. During the Inter-War Period

Twelve-Cylinder Firing Order Display

Air-Cooled Aircraft Engine Cylinders - by George Genevro

Outstanding Compilation of Horizontally Opposed Aero Engine Information - by Jack Erickson

Table of US Engine Details, provided by Larry McClellan (PDF, XLS)

The Air Annual of the British Empire - 1938: British Engine Progress


OX-5, R-3350
OX-5s to Turbo-Compounds:
A Brief Overview of Aircraft Engine Development
by Kimble D. McCutcheon

During the period between the World Wars, aircraft engines improved dramatically and made possible unprecedented progress in aircraft design. Engine development in those days, and to a large extent even today, is a very laborious, detailed process of building an engine, running it to destruction, analyzing what broke, designing a fix, and repeating the process. No product ever comes to market without some engineer(s) having spent many long, lonely, anxious hours perfecting that product. This is especially true of aircraft engines, which by their very nature push all the limits of ingenuity, materials, and manufacturing processes.

- Download Article (712 K PDF) -

No Short Days:
The Struggle to Develop the R-2800
"Double Wasp" Crankshaft

by Kimble D. McCutcheon


Just prior to World War II, engineers at both Pratt & Whitney and Curtiss-Wright worked feverishly to produce the first air-cooled engine capable of more than 2,000 horsepower. The efforts of both teams were nearly thwarted by severe vibration from unexpected sources. This is the story of how the Pratt & Whitney team, through hard labor and persistence, identified and solved the problems with vibration. The result was one of the most successful engines of all times - the R-2800.

1. Introduction (1.28M PDF) 2. Technical background (401K PDF)
3. Torsional Vibration (151K PDF) 4. Linear Vibration (239K PDF)
5. Crankshaft Development (525K PDF) 6. Conclusion (408K PDF)
R-2800 Crankshaft Evolution (66K PDF)