This big fellah is really something. The Bristol Hercules engines were used to power a myriad of airplanes over the span of their life and these are not the typical radial engine as they are a slide valve motor, meaning that the sleeves that the pistons travel up and down in actually move to expose the valves for intake and exhaust rather than just having them in the head itself. Pretty wild, right? Nearly 60,000 Bristol Hercules engines were built starting in the late 1930s.
The sleeve valve setup was used because engineers thought that it would be better at making power than a traditional two valve head. Apparently they were unable to create the four valve head they they really wanted and this was a compromise. It was an effective one and these things make some power. Displacing just shy of 39 liters, the most powerful versions of the engine made more than 1,700hp and were used in groups to power bombers and freighters. Most famously, England’s Lancaster bombers used these engines.
Like all radial engines this thing cacks and bellows like crazy when it fires off. It also fires off with the traditional plume of smoke from the bottom cylinders. The funniest part of this whole program is the dude running it just gets blaster with wash from the clipped propellor as well as dirt, sand, grass, and whatever else gets stirred up and sent into the air.
We’re envious as hell that he owns and restored this awesome engine, though. Big fun!