Dave, here it is. I was way off in my assumption, you know what happens when one assumes. It is a fixed pitch designation, considered a changing pitch prop. It starts as a 10 pitch toward the center and tapers to a 6 pitch as it goes out toward the tip. The reason behind it is that it will flex less under load. Meaning that, static, an engine with a constant pitch prop, at full throttle, the tips of the prop will pull forward arcing the blades. On the other hand, mathematically a 15/6-10 prop averages out to a 15/8 which is considered too much pitch for this model. This info is from a 30 year vet, but I cannot say that it covers all the variables in prop selection and performance. Joe

Missed one. Low pitched props supply less speed and more thrust with a quicker spool up and higher RPMs. It will also slow the plane down faster resulting in greater speed control. With this prop it is now like a tractor, slower but more powerfull, or as Coomarlin put it, its like a stump puller, which is what you want for this type of flying.