|GM 17x8 Folding Propeller Blade Specifications|
|Prop diameter||43 cm||17 in|
|Prop pitch||20.5 cm||8 in|
|Weight of two blades||12.5 g||0.44 oz|
|Width of blade root||7.95 mm|
|Size of hinge hole||3 mm|
Review by: Roger SandersGM 17 x 8 Folding prop blades
These are beautifully designed and built prop blades that do exactly what is claimed -- they really do lay much flatter and closer to a fuselage than other prop blades. This reduces prop drag considerably.
However, there are two items that you should keep in mind when using these blades. First, because they have a higher aspect ratio (are narrower) than other blades, they do not produce quite as much thrust as conventional blades. This is not a problem, just be aware that you can use a slightly longer GM blade to produce the same thrust as a conventional blade.
Secondly, the spinner yoke that you use will have a significant effect on how flat and low-drag the blade lies against the fuselage. These blades are designed for straight yokes rather than the more common twisted yoke. While twisted yokes can be used with the GM blades, the blade will not be in as good alignment with the fuselage as it will be with a straight yoke.
An additional issue is the length of the yoke. In order for the blade to lay really flat against the side of the fuselage, the yoke must be short. If it sticks out from the spinner significantly, the prop will too, which defeats the intent of getting the prop to lay flat against the fuselage.
I know that I am being very picky here, but the main purpose of this prop design is to reduce drag and its effectiveness can be seriously degraded by a less-than-ideal spinner/yoke assembly. So if you want the lowest drag, pay attention to getting an ideal spinner/yoke.