Part 2/2 by Mike Tull

Some years ago I built two 1/4 scale models of the Bristol Mercury MK VIII radial engine. One of the engines was displayed in an 'exploded' format so as to show both the external and internal details. The other engine is fully assembled and one day will become a runner.

The 'exploded' Mercury was mounted on two display stands. One showed the external or outer components. The second display stand showed the internal workings, such as the crankshaft, con rods and pistons. The mechanisms from each of the engine's subsection were able to rotate to demonstrate their function.

The ‘exploded’ Mercury was exhibited at the 2010 Model Engineer Exhibition at Sandown Park. The Bristol Mercury was awarded the Bradbury Winter Trophy and a Gold Medal.

The ‘exploded’ Mercury has been featured on this website before, you can go to Click on any image and it will enlarge, click on it again to zoom right in and see all the detail.

Although the two display stands were an award winner, I was never fully satisfied with them. Two stands required a lot of table space and storage. I also felt they divided the viewer’s attention between the two. So I decided to combine the two display stands into one.

The single display is much more compact and tells the story better than before. It is also so much easier to transport, display and store one item than two. Some of the intricate gear mechanisms are not quite so clearly visible as before, but overall I think it does a better job of displaying the engineering genius of Roy Fedden, the Bristol Aircraft Company and a bygone era of aviation history.

My second Mercury engine, shown below, is now complete and is intended to be a runner and so will require a suitable propeller. A scale, three blade propeller would be 36" in diameter. A propeller of that size is both unwieldy and inconvenient when displaying the engine at exhibitions. Instead, I built a functioning De Havilland variable pitch propeller hub, fitted three short 'stub' blades for exhibition purposes. This propeller hub will be replaced with a wooden two blade propeller when the time comes for the engine to run.

Part one here.

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