What is the primary concern in establishing the firing order for an opposed engine?

The primary concern in establishing the firing order for an opposed engine is to provide balance and eliminate vibration. In an opposed engine configuration, cylinders are positioned opposite each other, and the timing of their firing plays a crucial role in maintaining the engine's balance and minimizing vibrations that can lead to inefficiency and wear.

When firing order is carefully designed, it ensures that the forces generated by the combustion events are counteracted by opposing forces from the opposite cylinder. This counterbalancing helps to smooth out the operation of the engine, leading to less vibration transmitted to the airframe and components, thereby improving overall engine performance and longevity.

Balancing the firing order in this way is critical for opposed engines since their configuration can otherwise produce significant torque and engine vibrations that may compromise performance and comfort during operation. Other concerns such as power output, fuel efficiency, or maximizing RPM become secondary to maintaining a smooth and balanced engine operation.