To run successfully an engine relies on several separate and at the same time often related systems.

1)   Mounting System

The engine must be mounted so it is held securely and maintains it's correct position in flight. Rubber mounts work only if the resonant frequency is not in the operating range of the engine and if the model is subjected to high 'G' forces then rubber mounting is going to be difficult, as the mass of the engine will flex the mounts till they support the load, the higher the force the greater the change in the engine thrust line and therefore the trim of the model will be. Generally we will require a good stiff mount, nose structure and wing mounting. As it is the wing that supports the model in the air I like to think of how well I am attaching the engine to the wing when I am building a model.