Anti-Vibration Mounting of Aircraft Power Plants

THE elastic members used in flexible engine mountings are nearly always made of rubber, cither natural or synthetic, bonded or unbonded. The reason for this is that although metallic springs could be designed to have the required stiffness properties they have very little natural damping and would allow very large amplitudes to build up at resonant conditions unless some external damping device such as friction disks or oil dashpots were employed. Also it is a difficult matter to anchor a metallic spring in such a way that fretting will not occur at the fixing point. Rubber on the other hand has considerable damping properties and it is this (plus its high specific resilience) which has largely determined its pre-eminence in this field.