Propeller forming question

From: torqueburner <beammeup42_at_ptd.net>
Date: Sat, 16 Jan 2010 14:04:15 -0000

Although there is no Wright Stuff event in Science Olympiad this year (alas!), my students are building a wind turbine for the Physics Lab event, and have been experimenting with balsa blades formed around a bottle or other cylindrical object, as described in Don Ross's book and elsewhere.

Is there a rule of thumb that relates the diameter of the "bottle" to the diameter of the blade? It seems to me that changing this parameter would change the distribution of pitches along the blade, is that correct? Also, Ross and others instruct you to slant the blade at a 15 degree angle relative to the axis of the bottle - it seems that changing this angle would also change the shape of the blade.

To start with, we are assuming that what works for indoor props would work for a turbine, maybe a good assumption, but maybe not. We'll appreciate any comments from the group. Thanks.

Dave Drummer
Kutztown Sr. High School
Kutztown, PA
Received on Sat Jan 16 2010 - 06:07:19 CET