What percentage of thrust is produced by the ducted air around the engine?

The correct percentage of thrust produced by the ducted air around the engine is 80%. This value represents a significant aspect of the design of ducted engines, such as those found on the CRJ550.

In a ducted fan engine, the airflow created by the fan not only contributes to thrust but is also more efficient due to the guided flow around the engine. This high percentage highlights the effectiveness of ducted engines in harnessing the air's kinetic energy, resulting in better fuel efficiency and performance compared to other engine types.

The other percentages reflect less efficient designs or engines that do not utilize ducting to the same extent. In a typical high bypass ratio engine like the CRJ550’s, the substantial thrust produced by the ducted air is critical for optimizing performance, maximizing thrust while minimizing fuel consumption, and enhancing overall operational efficiency.