Tab 3 - Engine

Engine calculations for either a Turbojet or Turbofan cycle can be performed.

This tab is not displayed by default.
Click the view menu and choose engine, this will display the Engine Tab between the Flight and Nozzle tabs

With the aim of calculating an NPR this is automatically entered into the NPR text entry of the Nozzle page, which is greyed out when the Engine Tab is selected.

By default this is set to calculate a Turbojet cycle therefore the Fan section is empty.
Go to Tools Options and within the Options Tab choose the Turbofan radio button to enable this section.