As covered in minor detail in the Symmetry with Propellers tutorial, there are multiple ways that you can modify propeller symmetry. These applications are not limited to only traditional propellers but for any geometric shape that you wish to have both axial and planar symmetry about different points. In this example, we show how to create a reflected, counter-rotating propeller across the XZ plane and also how symmetry can be ineffective at producing left/right same-direction propellers. To accomplish such a feature, a copy of the primary propeller should be made and placed on the opposite side manually. For the purposes of actuator disk modeling, this left/right anti-symmetry isn’t an issue and the direction of propeller rotation may be simply altered with the RPM setting.
Due to the unique way that the Prop component operates, there are some specifics to cross-section control that need to be addressed. For many cross-section types such as airfoils, the Chord, Thick, and CLi curves are going to control the overall shape of the section. However, for traditionally body-type sections such as ellipses, rectangles, and General Fuse, the height and width are controlled by the Chord and Thick curves while CLi has no effect as there is no analogous parameter. Custom airfoil files are affected differently. The thickness of the custom airfoil (or other custom section file) will be automatically set by the Thick curve but the camber of the section will remain unaffected. If you wish to have a custom airfoil file retain the proper thickness, you may either input the proper value to the Thick curve at the given blade station or if you are unsure of the value, the Base T/C is calculated for each AF_File under the XSec tab.
The location along the blade (Radius) of cross-section 0 (root) defines the innermost station for the propeller, not the r_0 parameter under the Design tab which is actually the lower limit of activity factor integration. The radius of XSec_0 may be set anywhere between 0.0 and the location of the following section. Similarly, the radius of any Prop cross-section may be set between the radial location of the prior and following cross-sections. The final cross-section radius is always set to 1.0.
This tutorial covers the propeller blade CLi curve. This curve defines the cross-section ideal lift coefficient along the blade for airfoil section types. For airfoils, this value is relatively straightforward since CLi is a common defining characteristic of these shapes or may be solved for using other parameters like camber. Other section types, such as ellipses or rectangles, do not have camber or similar features and so the CLi values at these stations will have no effect. Custom airfoil file (AF_File) types will NOT have their camber or CLi changed by the curve! For more information about how to manipulate these curves, please refer to the Propeller Blade Control Curve Interface page.
Note that the XSec values for camber or CLi are deactivated for propeller components as these values are controlled by the CLi curve! To apply a specific CLi at a given blade station, you must have a curve control point at that station and set the desired CLi.
This tutorial covers the propeller blade Thickness curve. This curve defines the cross-section thickness-to-chord ratio along the blade for whatever type of section is set. For airfoils, this value is relatively straightforward since T/C is a common defining characteristic of these shapes. Other section types, such as ellipses or rectangles, have their width set by the chord (C/R) and the height set by T/C automatically. For more information about how to manipulate these curves, please refer to the Propeller Blade Control Curve Interface page.
Note that the XSec values for height and width or chord and T/C are deactivated for propeller components as these values are controlled by the Chord and Thick curves! AF_File (custom airfoil) types will have their base T/C overridden by the T/C curve. To apply a specific T/C at a given blade station, you must have a curve control point at that station and set the desired T/C.
This tutorial covers the propeller Tangential parameter. This parameter translates the blade section normal to the blade construction axis within the propeller plane of rotation either with or against the direction of rotation. Tangential differs from Sweep in that Sweep is a rotation of the blade section about the propeller thrust axis while Tangential is a translation in a straight direction normal to the blade construction axis. For example, a propeller thrusting in the -X direction exhibits Tangential shifts in the +/- Z direction. For more information about how to manipulate these curves, please refer to the Propeller Blade Control Curve Interface page.
