Abstract: A model helicopter includes a body and an engine mounted in the body. A rotor is connected to the engine through a substantially vertical primary shaft. A radial fan cools the engine while a lateral opening is provided on a tail boom connected to the body. Air is sucked in from outside of the body by a radial fan in the body, with the air flowing through the lateral opening and being directed to the tail boom through a channel. This air imparts a torque on the body that counter-acts the torque transmitted by the drive for the rotor on the body. The radial fan includes two impellers, which are coaxially mounted on the primary shaft. The air displaced by the second impeller flows through the engine, while flowing through the body, and dissipating the heat from the engine. A separation wall is provided between the two impellers of the radial fan.