This feature is accessed from the Compare button on the Airfoil Polar GraphAirfoil_Polar_Graph Tab or from the Lift Graph TabLift_Graph_Tab  on the Airfoil ListAirfoil_List screen.

This feature provides the ability to ;

Select Reynolds numbers for Polar and Lift Graphs for a selected Airfoil.

Compare an Airfoil against another selected Airfoil and Reynolds number.

Compare an Airfoil against a number of airfoils with the data for the same Reynolds number. 

When the Compare button is pressed the Graph Properties screen will displayed.  

To select one or multiple Reynolds numbers to graph for either the Polar or Lift Graph;

Click on one or more  Reynolds numbers in the Select Reynolds Number list and then click on the Ok button. Do not click on the Compare check box if you wish to select more than one Reynolds number.

To compare with other Airfoils;

Click on the Compare check box.  Click on the Show all Airfoils to select an Airfoil from the list of all Airfoils in the database with performance data. If you choose this option you must select an Airfoil for the comparison and a Reynolds number. Click on the Show Airfoils option to select an Airfoil for comparison which has data that matches the selected Reynolds number. You must then select an Airfoil then a Reynolds number. If you also click on the Cycle checkbox then there is no need to select an Airfoil for the comparison or Reynolds number. Winfoil will automatically cycle through each matching airfoil. The Pause textbox is the delay in seconds between redrawing the graph for each Airfoil comparison. 

If the Cycle checkbox is selected then when the Ok button is clicked and the Graph is displayed the an additional toolbar will be displayed to control the cycle.

The buttons on this toolbar perform the following actions;

Pause

Pauses the cycle to allow the user to Save the displayed graph as a bitmap or Print the graph or take a note of the airfoils being compared.

Cycle

Restarts the cycle process.

End

Ends the cycle process and returns to the Graph screen. You must click on this button so that you can continue using Winfoil and to exit this special mode.

Save

This button is used to save the currently displayed graph as a bitmap. This button is only enabled after the Pause button is pressed.

Print

This button is used to print the currently displayed graph. This button is only enabled after the Pause button is pressed.