Rocket Fin

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Rocket Fin.svg Rocket Fin

Menu location
Rocket → Fin
Workbenches
Rocket Workbench
Default shortcut
None
Introduced in version
0.19
See also
None

Description

Fins are used to aerodynamically control the direction of flight.

Nike Fin TTW 2.png

A Tapered fin with TTW tab

Usage

  1. There are several ways to invoke the command:
    • Press the Rocket Fin.svg Fin button.
    • Select the Rocket → Rocket Fin.svg Fin option from the menu.
    • Double click on a Fin object in the model view.
  2. Set options and press OK.

Options

Fin Type

At the moment, only trapezoid shape fins are supported. This will change as the workbench continues to be developed.

Cross Section

The cross sectional shape of a fin can greatly affect its performance at different speeds, as well as the looks of the rocket. A variety of fin cross sections have been implemented. Fins are created by lofting the root cross section to the tip cross section, so not all combinations of Root Cross Section and Tip Cross Section will produce useful fins.

  • Square. Both the leading and trailing edges are squared.

CS Square.png

Square Cross Section

  • Round. The leading and trailing edges are rounded.

CS Round.png

Round cross section

  • Airfoil. Uses the NACA symmetrical airfoil shape NACA airfoil with maximum thickness at 30% of the chord.

CS Airfoil.png

Airfoil cross section

  • Wedge. The trailing edge of the fin is square, converging to a point at the leading edge.

CS Wedge.png

Wedge cross section

  • Diamond. The diamond shape starts from a point at the leading edge, straight out to the maximum thickness at a point determined by Length 1, and back to a point at the trailing edge.

CS Diamond.png

Diamond cross section

  • Leading Edge (LE) Taper. The leading edge is tapered to a point as determined by Length 1

LE Taper.png

Leading edge taper cross section

  • Trailing Edge (TE) Taper. The trailing edge is tapered to a point as determined by Length 1

TE Taper.png

Trailing edge taper cross section

  • Taper. The leading edge is tapered to a point as determined by Length 1, and the trailing edge is tapered to a point as determined by Length 2

CS Taper.png

Taper cross section

Through the Wall (TTW) Tabs

Through the Wall fins add structural strength by extending though the outer body tube to an inner body tube such as a motor mount. Instead of attaching just to the outside of the outer body tube, it can be attached at multiple points. As such, tthe height of the tab would be the distance from the outer diameter of the inner body tube to the outer diameter of the outer body tube. Other parameters would vary depending on requirements.

TTWx4.png

4 TTW fins attached to a central motor mount inside the outer body tube

Properties

Rocket Component

These parameters are provided for information and have no effect on the design of the component.

  • DataManufacturer: Manufacturer when known
  • DataPart Number: Manufacturer part number
  • DataDescription: Description of the component
  • DataMaterial: Material when known

Nose Cone

  • DataFin Type: Defines the shape of the fin. At the moment, only Trapezoidal fins are supported.
  • DataHeight: The fin height.
  • DataSweep Length: The distance from the front of the fin root to the front of the fin tip along the x axis. This may be negative. Setting this value will cause the Sweep Angle to be adjusted.
  • DataSweep Angle: The angle of the front of the fin, with a vertical front being 0 degrees. This may be negative. Setting this value will cause the Sweep Length to be adjusted.
  • DataFin Root Cross Section: The cross section shape of the fin at the root, see Options
  • DataFin Root Chord: The distance between the fin leading and trailing edges at the root
  • DataFin Root Thickness: Maximum thickness at the root of the fin
  • DataFin Root Use Percentage: Expresses the Fin Root Length 1 and Fin Root Length 2 properties as a percentage of the Fin Root Chord
  • DataFin Root Length 1: Usage depends on the Fin Root Cross Section and will apply to a taper length or similar, see Options
  • DataFin Root Length 2: Usage depends on the Fin Root Cross Section and will apply to a taper length or similar when multiple values are required, see Options
  • DataFin Tip Cross Section: The cross section shape of the fin at the tip, see Options
  • DataFin Tip Chord: The distance between the fin leading and trailing edges at the tip
  • DataFin Tip Thickness: Maximum thickness at the tip of the fin
  • DataFin Tip Use Percentage: Expresses the Fin Tip Length 1 and Fin Tip Length 2 properties as a percentage of the Fin Tip Chord
  • DataFin Tip Length 1: Usage depends on the Fin Tip Cross Section and will apply to a taper length or similar, see Options
  • DataFin Tip Length 2: Usage depends on the Fin Tip Cross Section and will apply to a taper length or similar when multiple values are required, see Options
  • DataTTW Tab: True when a tab for Through the Wall fins is required, see Options
  • DataTTW Offset: Distance from the front of the fin to the front of the TTW tab
  • DataTTW Length: Length of the TTW tab
  • DataTTW Height: Height of the TTW tab
  • DataTTW Thickness: Thickness of the TTW tab

Scripting

See also: Category:API and FreeCAD Scripting Basics.

TBD

Tutorials and Learning

Rocket Workbench Fins Tutorial on YouTube


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