Due to the superior strength and construction of Bolly Props, many of the (prop) sizes we produce are a little different from the norm'. For example, our 10.5 x 6.5 is equivalent to (in terms of RPM) a nylon 10 x 6, but performs much better due to the extra diameter and pitch. For practical reasons some of our quoted sizes differ slightly to the end result, ie the Bolly 12 x 12N is actually a 12.2 x 12.2 and our 10 x 6 is a 10.2 x 6.2. Most Bolly props are quoted to within .2" of true size and are subject to a similar variation of size in manufacture (especially in pitch).

As a guide to the load a propeller will place on an engine, the maximum chord is noted in the prop listing. For example, the chord of our 10.5 x 6.5 is by design, about 2mm less than most nylon propellers. The narrower high aspect ratio propeller is however more efficient.

There are applications which require a larger chord. For example the 12.5 x 11W (chord 29mm) has far more load than our 12 x 12 (12.2 x 12.2 with 23mm chord). This prop was developed to absorb the power of Long Stroke Pattern engines without increasing diameter (higher tip noise).

A similar situation applies to C/L Aerobatics, where high diameters create unwanted gyroscopic forces.

Carbon Fibre propellers are black. Bolly Glass Fibre propellers are also usually black in colour, and occasionally may be grey/silver, orange or copper/brown. Different colours may be ordered. To tell black carbon and glass props apart from each other, hold the prop to the light. Glass props are semi transparent (with a blue hue), carbon props are a solid black.

Many of the Bolly propeller range were developed for a specific purpose, ie, the 12.2 x 4.2 was developed for .60 C/L stunt but has a big following for Old Timer contest work. The range of models, motors and ways of using propellers is so vast it is impossible to publish all the variables of prop use.

Specials and modifications of existing props. We can often increase the diameter or repitch an existing prop to suit your needs. Please enquire by mail or phone before ordering specials.

Props which are noted NYA are new sizes planned for production, but are ‘not yet available’. As this edition of the book is being printed for a 6+ month supply, all sizes planned for the next 6 months are listed. There may or may not be an update sheet with this book.