VARIABLE PITCH PROPS ARE GENERALLY USED ON COWLED AIRCRAFT. A 16X6-10 SOUNDS LIKE A ZENOAH G-23 OR COMPARABLE SIZE ENGINE. THIS SIZE PROP WOULD WORK JUST FINE ON A 1/5 SCALE WACO. WITH A BIG RADIAL COWL, THE 6 PITCH PASSES BY THE COWL OUTWARD AND GRADUALLY INCREASES TO 10 PITCH AT THE TIP. THIS IS A VERY EFFICIENT PROP FOR THIS CONFIGURATION. HENSE THE 16X6-10 PROP. THIS EFFECT IS MINIMAL ON 60 SIZE AIRCRAFT. YOU GENERALLY WONT FIND MULTIPITCH PROPS IN 14 INCH AND SMALLER.