Hi, when using these balsa propellers I’m having an issue where the entire flight itself is shaking while torqued with rubber, when we let it go it shake a lot in the front and doesn’t fly. May you advise us on how to fix this? The propellers are made well and pitched correctly but it seems that it won’t fly cuz of this shaking.
There are two kinds of balance, static and dynamic. When a propeller can stop rotating at any position, static balance is achieved. Sounds like the dynamic balance on your propeller is off. Since pitch is true/same on the two blades, my guess is that flexibility of the two blades are not the same. Balsa wood density and grain distribution vary a lot. Extra care is needed when picking the wood for the two blades. We always cut the two blades out of the same sheet of wood, sometimes along the grain, sometimes side by side, depends on the grain distribution. Hold the wood sheet against light to see the density and grain, to plan your cut. See the first few slides in the video to see how I paired up the wood. With enough extra care, both static and dynamic balance could sometimes be achieved at the same time. 😎 Good luck! 👍
Here is the direct link to my latest OpenSCAD program for creating balsa-blade propeller molds. www.thingiverse.com/thing:6720495 (August 2024) To run the program, you also need to install OpenSCAD, openscad.org/, on your machine. My program has many adjustable parameters, e.g. propeller diameter, P/D, blade width, washout, stem location (flaring), blade profile, etc. See screenshot on the Thingiverse page for more. Depends on which indoor free flight class you are competing in, you may fine tune these parameters before printing out your mold. (In OpenSCAD, open my prop mold program, adjust parameters you like, hit F5 to preview, F6 to render, and F7 to export the .STL file.) Feel free to contact me at aero.martin at yahoo dot com if you have any questions on how these parameters should be adjusted. Good luck! :-)
