Rocket Fin

Description
Fins are used to aerodynamically control the direction of flight.



Usage

 * 1) There are several ways to invoke the command:
 * 2) * Press the button.
 * 3) * Select the option from the menu.
 * 4) * Double click on a Fin object in the Tree view.
 * 5) Set options and press.

Fin Type
The general shape of the fin.


 * Trapezoid.

This fin type is used for almost all 4 sided fins. The root remains fixed, but the leading and trailing edges can have variable amounts of sweep. The chord length of the root and tip are set independently.




 * Elliptical.

A generalized rounded shape. Circular fins are a special case where the height is 1/2 of the root chord.




 * Custom.

Most fins will fit into one of the standard shapes. In cases where they don't it's possible to create a custom shape using a sketch.

The sketch must be created first. The fin root is drawn along the positive X axis. With the sketch selected in the model tree, selecting the Fin icon will create the custom fin. The fin profile can be changed at this time.

There is no way to associate a custom fin with a sketch within the dialog after it's been created, so it is important to create the sketch first. It can be selected from the Properties view. Updating the sketch will update the fin.





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.




 * Round. The leading and trailing edges are rounded.




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




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




 * 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.




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




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




 * 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.



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, the 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.



Properties

 * : Defines the shape of the fin. At the moment, only Trapezoidal fins are supported.
 * : The fin height.
 * : The sketch associated with the custom fin type.
 * : The distance between the fin leading and trailing edges at the root
 * : The cross section shape of the fin at the root, see Options
 * : Usage depends on the Fin Root Cross Section and will apply to a taper length or similar, see Options
 * : Usage depends on the Fin Root Cross Section and will apply to a taper length or similar when multiple values are required, see Options
 * : Expresses the Fin Root Length 1 and Fin Root Length 2 properties as a percentage of the Fin Root Chord
 * : Maximum thickness at the root of the fin
 * : 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.
 * : 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.
 * : The distance between the fin leading and trailing edges at the tip
 * : The cross section shape of the fin at the tip, see Options
 * : Usage depends on the Fin Tip Cross Section and will apply to a taper length or similar, see Options
 * : Usage depends on the Fin Tip Cross Section and will apply to a taper length or similar when multiple values are required, see Options
 * : Expresses the Fin Tip Length 1 and Fin Tip Length 2 properties as a percentage of the Fin Tip Chord
 * : Maximum thickness at the tip of the fin
 * : True when a tab for Through the Wall fins is required, see Options
 * : Height of the TTW tab
 * : Length of the TTW tab
 * : Distance from the front of the fin to the front of the TTW tab
 * : Thickness of the TTW tab

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


 * : Description of the component
 * : Manufacturer when known
 * : Material when known
 * : Manufacturer part number

Tutorials and Learning
Rocket Workbench Fins Tutorial on YouTube