HOME MADE PROP HANGER
by Bob Kopski
The following method has been successfully applied for motor sticks from 3/32″ X 3/16″ to 1/2″ square. Pictured is a prop hanger for a 1/4″ square fuselage stick. A similar one is shown completed on a Cloud Tramp.
Begin with the subject motor stick and place two pieces of cardstock paper strip as shown. These effectively increase the dimensions of the stick slightly otherwise the resulting hanger will become overly tight on the stick.
Slip on a length of heat shrink tubing as pictured and shrink tight.
Allow it to cool, remove the paper spacers, and verify the tubing will slide off / on the motor stick. Neat, huh?!
Next cut a balsa spacer block as required, taper for down thrust as desired, and spot CA to the heat shrink tubing. Medium CA works well for this but be sure not to get any CA between the hanger and fuselage stick. Move on to making the shaft bearing.
This example uses a 3/32″ OD aluminum tubing 3/4″ long intended for a 0.055″ prop shaft.
The shaft would be a sloppy fit in the tubing so in this case each end of the tubing is necked down a bit using a keyed 3 jaw chuck and tightening it until the sample shaft is just beginning to drag inside the tubing. Note that this technique works just as well with brass tubing and results in a good working shaft and bearing assembly.
Position this tubing bearing on the balsa spacer block setting any desired side thrust in place and apply a spot of thin CA to fix the position.
Carve and sand the spacer block as shown, bind with thread and apply thin CA – keeping it out of the bearing tube of course! Finally trim and clean up your new prop hanger and effect a proud smile!
Some notes. Some small balsa “stop blocks” can be glued to the motor stick behind the hanger to prevent the hanger from being pulled back by a wound motor. Next – a really neat trick: A fully thrust adjustable version of this hanger can be made by assembling it on a stick larger than the motor stick. Clearly this will allow the hanger to fit loosely so now just wedge in some tapered wood shims between the hanger and the fuselage stick to tilt the bearing and tighten the pair. In this example one might use a 5/16″ square forming stick to make a hanger for a 1/4″ sq. fuselage stick. This whole process is harder to describe than to do.