Abstract: The invention relates to a fuel supply device for model aircraft. To produce an excess pressure in the fuel tank in order to force the fuel into the engine, the fuel tank is connected to an excess pressure chamber (4) of an exhaust constructed in the form of a silencer. The casing (1) of the exhaust is subdivided by partitions (5, 6) into a number of chambers lying axially one behind the other. The excess pressure chamber (4) and the chamber (3) disposed therebehind in the direction of flow and directly connected to the exhaust gas outlet (9) are interconnected via a valve arrangement (16-18) which so operates after the fashion of a non-return valve that the valves are throttled in dependence on the inclined position of the exhaust. During climbing throttling is particularly heavy, so that a heavier excess pressure is formed in the chamber and therefore higher delivery pressure acts on the fuel in the tank. In this way the engine is supplied with enough fuel even during climbing.