Thread: Interesting, Odd or Funny Pics II.

Originally Posted by johntins

34. The 'rotary' engine one threw me, and then I remember the Yanks use that word to describe what I always called 'radial'.
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Rotary and radial are not the same thing. They look similar, but in a radial, the cylinders stay still while the crankshaft rotates, but in a rotary the crankshaft stays still while the cylinders and crankcase rotate. The rotary usually has a hollow crankshaft, and the intake valves in the pistons, and runs a petroil mixture like a two stroke. It has the advantage that all the heavy moving components travel in perfect circles, just with different centres, so there is almost nil vibration, and there is no cooling issue (radials had serious cooling issues until years were spent on development). This meant rotaries could be much lighter (cylinders were typically steel rather than cast iron, turned from solid, and with paper-thin cooling fins). There were two major problems - firstly, the large flywheel that the cylinders made meant a noticeable gyroscopic effect when an aircraft turned rapidly, and powers over about 150hp had serious problems getting enough mixture through the crankshaft, and made multi-row engines impractical. Radials eventually grew to four or even more rows, with powers well over 2,000hp.

Sopwith Camel comes to mind when talking about the gyroscopic effect on rotary engines. It turned slower to the left than the right, with the wing rising on left turns and dropping on right. Often quoted as saying it was quicker to go left by turning right instead.

Simons?

Sopwith Camel comes to mind when talking about the gyroscopic effect on rotary engines. It turned slower to the left than the right, with the wing rising on left turns and dropping on right. Often quoted as saying it was quicker to go left by turning right instead.

That is why Fairey Gannets had twin counter-rotating props.

Originally Posted by donh54

Including Aussie M113 APCs

Landing craft too for that matter. They are widely used in the Maritime industry. All of the ex RAN 40 Foot work boats are powered by 671s, many small tugs and work boats and even one of the tugs I use at work. Our organisation also has boats with 471s and a tug with 2x 1271s, although the latter two are not green, but they do leak.

Another confusing aspect is that many people refer to Wankel Engines as Rotary Engines.

Landy Semi.jpg

Originally Posted by cuppabillytea

Another confusing aspect is that many people refer to Wankel Engines as Rotary Engines.

As opposed to people who drive them who are just wankels?