Generate flaps in Gomboc

The current version of Gomboc does not provide any way to edit the shapes. The section profiles have to be done externally. A good and free software for that is XFLR5, which is XFoil with a GUI.Here is the procedure we follow when generating a flap section:

1. Import the base shape to XFLR5
2. Rigth click on the shape and generate a flap for two angles (for example the min and max flap angles).
3. Optional: smooth the pressure distribution (apply low pass to ‘q’)
4. Import the center shape in Gomboc in the Sections Window
5. Open the Section Properties window, and click on the “+” icon to import the two other shapes generated using XFLR5
6. Assign morph values (eg. Flap angle) to each section shape
7. n (right click on a shape –> “Add shapes interpolated with previous/next shape”).
8. Enter the x,y coordinates of the hinge position
9. Run XFoil for all shapes (the icon at the top)
10. Review the generated polars for gap. It’s quite common that XFoil struggles to converge with certain flap shapes with hard kinks. In that case, go back to b) and try to smooth pressure distribution again if having convergence issues
11. Create a “SectionMorphInput“ block in the “Foilboc“ block of the appendage BIC file to associate a “Flap“ channel to each of the element with flaps. In the following example, the 2 elevators of the rudder have flaps.Optionally: create a state block (outside of the “Foilboc“ block) to control the flap angle from the GUI

"RudderFlap": PtSt === "Port" ? BL.State({ Init: 0, Min: -7.5, Max: 7.5, Optimise: true }): "{^.Port.RudderFlap}",
"Rudder": BL.Foilboc({
"SectionMorphInput" : {
"RudderElevatorIB" : {
"InputName" : "RudderFlap",
},
"RudderElevatorOB" : {
"InputName" : "RudderFlap",
},
},
// [...]
}),