Le Rhône 9J

The Le Rhône 9J is a nine-cylinder rotary aircraft engine produced in France by Gnome et Rhône. Also known as the Le Rhône 110 hp in a reference to its nominal power rating, the engine was fitted to a number of military aircraft types of the First World War. Le Rhône 9J engines were produced under license in Great Britain by W.H. Allen Son & Company of Bedford, and in Germany by Motorenfabrik Oberursel.

In common with other Le Rhône series engines, the 9J featured highly visible copper induction pipes and used a single push-pull rod to operate its two overhead valves. The main visual difference between the 9J and the earlier, less powerful Le Rhône 9C engine is that the copper intake manifold tubing (with round section lower ends) on the 110 hp 9J is attached to the crankcase behind the cylinders, whereas on the 9C (80 hp) the intake manifolds (with rectangular lower ends) are fully visible from the front.

The engine was manufactured under license in Germany by Motorenfabrik Oberursel and sold as the Oberursel UR.II.