Originally Posted by
gtippin
The crank shaft was bolted to the firewall and the prop was bolted to the engine making them one unit.
You learn something every day!
Digging in deeper;
Notably, the fuel was mixed and sprayed into the center of the engine through a hollow crankshaft, and then into the cylinders through the piston itself, a single valve on the top of the piston let the mixture in when opened.The valves were counter balanced so that only a small force was needed to open them, and releasing the force closed the valve without any springs. The center of the engine is normally where the oil would be, and the fuel would wash it away. To fix this, the oil was mixed in liberal quantities with the fuel, and the engine spewed smoke due to burning oil. Castor oil was the lubricant of choice, its gum-forming tendency being irrelevant in a total-loss lubrication system. The result is that the engines threw a mist of unburnt fuel and castor oil; the pilot's scarf being used to wipe this from their goggles. Finally, the Gnôme had no throttle or carburetor. Since the fuel was being sprayed into the spinning engine, the motion alone was enough to mix the fuel fairly well.