Fin Set Dialog

The Edit Fin Set Dialog in SpaceCAD 7 allows users to configure the rocket’s fins, which are crucial for stability and control during flight. This dialog provides two main views: one for defining the fin form and another for setting up the fin tab, which ensures proper attachment to the rocket body. Users can define the fin shape, material, number of fins, and placement. While the table in the dialog shows the fin’s key points for reference, most editing of the free fin form should be done using the visual editor in the main window, where users can move the fin points with their mouse.

Key Fields and Features:

1. Fin Set Name

• Editable field where users can specify the name of the fin set.
• Example: “Fin Set” or “Main Fins.”

2. 2D Color

• Allows users to assign a custom color to the fin set for easy identification in the design view.
• Example: The fin set is assigned a Custom Blue color.

Material and Structural Properties:

3. Material

• Specifies the material of the fins, such as balsa, plastic, or fiberglass.
• Change Button: Opens the material selection dialog, where users can choose the material based on the structural needs and weight constraints of the rocket.
• Example: Balsa is a lightweight and common material for low-power rockets.

4. Fix Weight and Fixed CG

• Fix Weight at: Users can manually set a fixed weight for the fin set, overriding the calculated weight.
• Fixed CG Position at: Allows users to set a fixed center of gravity (CG) for the fin set, affecting the rocket’s overall balance.

Fin Count and Thickness:

5. Fin Count

• Specifies the number of fins in the set.
• Example: A typical design may use 3 or 4 fins, depending on stability requirements.

6. Material Thickness

• Defines the thickness of the fin material, which affects both the strength and aerodynamic properties of the fins.
• Example: A 3.2 mm thickness is common for balsa fins.

7. Start Angle (°)

• Specifies the angle at which the fins are attached to the rocket body, typically aligned at 0° for standard configurations. This can be adjusted for specialized designs.
• Example: A 0-degree start angle aligns the fins along the rocket’s vertical axis.

Fin Form Configuration:

8. Fin Form

• Free Fin Form: Users can define a custom fin shape using a point list that shows key coordinates. This list is provided for reference, but the primary method for adjusting the shape is through the visual editor in the main window, where users can move the fin points with their mouse for ease and precision.
• Basic Fin Forms: SpaceCAD provides several pre-configured basic fin shapes, such as rectangular, trapezoidal, or swept fins. Users can select from these if they do not need a custom shape.
• Point List: Shows the x and y coordinates of the key points defining the fin’s shape. Though visible in the dialog, most adjustments to these points should be done through the visual editor.
• Hint Image: Updates as users modify the fin’s shape, providing a visual reference for the current design.

Fin Tab Configuration:

9. Fin Tab

• Users can configure a fin tab if the fin needs to be securely attached to the rocket’s motor mount or body tube. A fin tab provides a more rigid connection and ensures the fin remains stable during flight.
• Fin has Tab: Enables or disables the fin tab option.
• Offset from Fin Tip: Defines the distance between the fin’s tip and the start of the fin tab.
• Length of Tab: Specifies the length of the fin tab that extends into the rocket body.
• Tab Height: Defines the height of the fin tab, impacting how far the tab extends into the body tube.

Internal Element Positioning:

Fins, like other external elements, can be positioned relative to the rocket’s body in four ways:

• Absolute Position: Fixes the fin’s position at a set distance from the reference point.
• Relative to Top of Owner: Adjusts the fin’s position relative to the top of the body tube or other owner element.
• Relative to Middle of Owner: Positions the fin relative to the middle of the owning element.
• Relative to Back of Owner: Keeps the fin aligned with the back of the owning element, ensuring correct positioning even when the design is resized.

10. Distance from Owner’s Top

• Specifies the distance between the top of the owning element (such as the body tube) and the fin set, ensuring precise placement.
• Example: The fin set is positioned 139.7 mm from the top of the body tube.

Additional Controls:

11. Preview Button

• Provides a real-time preview of the fin set and its placement on the rocket. This feature allows users to confirm the fin’s position and shape before finalizing the design.

12. OK and Cancel Buttons

• OK: Saves the fin set configuration and applies it to the rocket design.
• Cancel: Closes the dialog without saving changes.

Example Workflow:

1. Configuring a Basic Fin Set:

   • Open the Edit Fin Set Dialog and set the name to “Main Fins.”
   • Select Balsa as the material and set the fin count to 3.
   • Choose a basic fin form and set the material thickness to 3.2 mm for stability.
   • Position the fins 139.7 mm from the top of the body tube and ensure they are aligned at a 0-degree start angle.
   • Click Preview to check the fin shape and placement, and click OK to apply the fin set.

2. Designing a Custom Fin Shape with Tabs:

   • Open the Edit Fin Set Dialog and select Free Fin Form to create a custom fin shape using the visual editor in the main window.
   • Adjust the fin points by dragging them with your mouse in the visual editor.
   • Enable the Fin has Tab option and set the length of tab and tab height for secure attachment to the motor mount.
   • Click Preview to visualize the custom fin and tab, and click OK to apply.