Final answer:
Dyna-focal engine mounts reduce engine vibrations caused by individual piston firings in aircraft reciprocating engines by absorbing and dampening the vibrations.
Step-by-step explanation:
A characteristic of dyna-focal engine mounts as applied to aircraft reciprocating engines is that they reduce engine vibrations caused by the thrust of individual piston firings. Dyna-focal engine mounts consist of rubber or elastomer components that connect the engine to the airframe. These mounts absorb and dampen the vibrations generated by the engine, improving overall performance and reducing stress on the aircraft structure.