Just last night, I figured out hou to draw ship propellers better than I was doing horribly last year. I got the inpiration by warching a tutorial of a twisted vase and flower with petal and bulb. I should have mentally arrived at this in 2009, not last night in 2012. Worse, last year i wasted inordinate amounts of time drawing wires when i should have thought of deformations of prismoids and thickeneded surfaces. Cheers!
Consider initialy experimenting with a crude figure -8-like blade. Also, consider whether tou will use one propeller or two. Also, consider whether they turn inboard or outbord as this will determine which way you prefer to draw, and whick way you mirror, as well as which side you manipulate the parent blade.
You will primarily use these key tools : the Extrude tool, Twist tool, Bend tool, Radial Copy with Associative copies setting on.
Change the view to looking down the long axis
Draw a line for the extrude path
Draw along that path a tube representing the diameter of the propeller
Remember that you will draw one blade but do so at the approximate intended position, NOT AT ORIGIN IN MODEL SPACE? Why not? Later, whenyou make radial copies and translate move the blades, they will for some reason expand or radially reposition away from their parent. (I am still troubleshooting why)
Explode the edge at the hub area to obtain a circle representing blade tip distance from the hub
If your new circle is segments, create a new one using the Circle, 3-point tool
Draw a smaller, concentric circle to represent the shaft diameter and attachment to the hub bossing
Hide the barrel/oversized tube
Activate a plane for keeping the first blade in line with the hub and bossing
From the hub outer curve, create one or two splines in the shape or profile of a raked, skewed blade (use the Internet to find relevant cross section examples), out to the maximum diameter or tip distance
At the hub, use another curved spline which is not joined operationally, but merely is snapped to the blade profile (do not join as joining introduces accurate but excessive amounts of control points)
Shape the blade such that a sharpish tip is a slight bit lower than the hub origination point
Shape the blade such that the leading edge or advancing piece has a surface are similar to your Internet findings.
Shape the trailing edge accordingly.
Add more control points in advance to later on avert vanishing solids if the model curvature is too tight for the manipulated cover surface tou will create shortly
Add a cover surface
Thicken the blade to some representative amount but one that allows you to see see what is going on
Hide the cover surface
RADIAL COPY TOOL
Radialy copy the blade to 5 copies, associatively, around a 360 deg path
USING THE TWIST TOOL
Test making finer adjustments without solid matter vanishing
Set the twist angles to somemthing such as 22 deg start and 65 deg finish
Notice that the associatively-created blades adjust. For cooler effect, place the solids on layers separate from the surface and radially copy the untwisted parent surface, noticing the geometry shift as the blades change orientation. More change can be observed if later on you create rotation or blade pitch rotation points to simulate putting the propeller blades in forward and astern positions.
Select a twist path experimentally, sampling from hub to mid point, hub to leading edge centroid, and hub to tip
Inspect it, and if necesary, use Ctrl Z or the Inspector to change values.
USING THE BEND TOOL
Use the Bend tool to add realistic bending of the blade to achieve raking and skewing wnd other effects
Use the Blend/Blending tool to round out or sharpen the blade leading and trailing edges, and to more realistically match the transition from blade root to shaft bossing.
ENJOY!
