Props

Now a word about props. It would be nice if we had available an assortment of very light props perfect for pager motor gearboxes. But, we don't. Both the Didel and Falcon gearboxes use 1mm shafts for weight reasons. The U80 prop will press fit on this size shaft. And recently Falcon has added a special version of the folding KP00 96mm folding prop that is also a press fit on a 1mm shaft. But, other than the GWS 2.5x1.0 and 2.5x0.8 props none of the GWS props are a press fit on a 1mm shaft. Bob Selman Designs has just introduced a set of six molded prop adapters that will convert the 4mm bore GWS props to a press fit on a 1mm shaft. These adapters are a micro necessity as they allow a wide range of GWS props to now easily be used. The 3mm bore GWS props can be used with these adapters if the hole in the prop is carefully reamed or drilled out to 4mm. The famous blue 10cm and 12cm rubber props have about a 1.5mm bore and won't work with a 1mm shaft. However, I've found that by cutting a short length of aluminum tube that is a snug fit (use CA) over a 1mm shaft, I can sleeve the shaft up to a larger size and then I ream out the blue props to fit over this sleeved shaft. All the Didel gearboxes come with a similar sleeve to adapt the shaft to 2mm bore props such as the Westechnik CF props.

These are some of the props that can be used with pager motors.	The new Bob Selman Designs prop adapters allow the popular GWS 4mm bore props to be used with a 1mm shaft.

Weight in any pager powered plane is always a concern. Weights for these props (without adapters) is given in the table. If you truly want to save weight, molding a CF copy of the GWS 5x3 prop will result in a prop that weighs between 0.55 and 0.65g. That's nearly a gram of weight savings, which is quite substantial on a plane weighing between 13 and 18 grams. See the June 2003 Inside Story for more information on how to mold your own CF props. And, of course there are other light weight props that can be made. There are the popular yogurt container thin plastic props. Didel also sells a variety of hubs that press on the 12t gear on the front of their spur gears. These allow balsa or plastic prop blades to be glued to CF rod which is then inserted into the hub from each side. These allow easy adjustment of the pitch of the blades.

Didel prop hubs allow constructing your own props with adjustable pitch blades in any size or pitch desired. They are available in configurations to press on the front of Didel spur gears or for use with a 2mm shaft.