ekir

My Feedback: (1)

What is the difference between a 18x8 or 18x10 prop and a prop that is listed 18x6-10? What flight performance difference can I expect. Is the 18x6-10 prop a six pitch near the hub and 10 pitch at tip?

Thanks,

Ed

Tired Old Man

My Feedback: (1)

The 18-8 and 18-10 are in theory constant pitch props, and have the same curve or pitch in the blade from start to finish. The 18-8 will provide more rpm than the 18-10, but the 18-10 should provide more pull at slightly lower rpm. It should also provide a little more speed in level flight. The 18-6/10, in theory but not always in practice, will provide more rpm in level flight while providing more vertical pull.

Think of driving your car on flat ground in "drive". You come to a steep hill and the transmission will "downshift" to a lower gear to better pull the grade. That is, in effect, the design theory behind the split pitch props. Some prop manufacturers do the job much better than others, mostly because some props have a much higher efficiency built into their design.

Since you are talking about props in the 18" sizes, you would do well to first experiment a little with some quality wood prop manufacturers instead of the average props available to see what works well for your engine/airframe combination. Rarely have I seen rpm to be a fair indicator of how well a prop performs for a given airframe/engine combination. The best method for determining the planes' performance is to try a few different props and see what works best for the type of flying you want to do.

Some of the props that I consider to be usuable, but of low to barely average performance are Zinger (any type), Master Airscrew (any type, lots of flex), and Top Flight (lots of flex). In certain applications APC works well. For excellent to best performance look into MSC, Menz, BME, NX, and other high end wood prop manufactures. I have deliberately left out carbon fiber props due to their cost, but they generally fall into the excellent to best catagory.

Red B.

About 18x6-10: This is a progressive pitch propeller with more pitch at the root and less at the tip.

/Red B.

beepee

Red,

You have that backwards. A 6-10 pitch prop has 6" pitch at the root and 10" pitch at the tip.

Bedford

Geistware

My Feedback: (16)

I think the purpose of this was to get more thrust from teh same size propeller by increasing RPM. THe load on the engine would be less and the increase speed at the tips would give your thrust.

Red B.

Beepee wrote Oops!
Sorry about that.

/Red B.