[wollins]

I need a 7X10 folding prop that can handle 20,000 rpm. Is this commercially available? If not who can custom build it for me?

Colin

[Nev]

7 x 10 or 10 x 7 ?
Any of these....http://www.icare-rc.com/propellers_folding.htm

[wollins]

There's no 7x10 on that site.

Colin

[Guest]

Looks like you might need to find like a 10x10 folding prop and cut the blades down. Don't know how good of an idea that would be, but doesn't seem to be much in the way of over square props in that diameter.

[wollins]

Originally Posted by LGM Graphix

Looks like you might need to find like a 10x10 folding prop and cut the blades down. Don't know how good of an idea that would be, but doesn't seem to be much in the way of over square props in that diameter.

I've had that suggestion before but if you know anything about these folders you'' know that they seem to have a certain airfoil and I don't know if I can replicate that when I cut it down ... also if I cut it down in that shape I don't know if that will compromise the integrity of the prop. Besides none of the folder props I've researched seem to handle more than 18.000rpm anyway. I need one that can handle at least 20,000.

Colin

[OLD PRAIRIE RED NECK]

My understanding of props is that for every inch you cut off of the diameter, you gain aproximately one inch in pitch. Prop pitch is the average pitch calculated between root pitch & tip pitch Therefore if you cut the tips off you increase the average pitch.
So, cut down a 9/8 prop & you should have close to a 7/10.
Can't see how shortening a prop could effect it's "integrity" (strength).Again you are taking away the weakest part of the prop & the overall average cross section will be greater.(stronger)
Now Efficiency & ballance is a completely different matter. You will be changing both of those!

One can only speculate as to what application this prop is going on!

Hope that helps.

[wollins]

Originally Posted by OLD PRAIRIE RED NECK

My understanding of props is that for every inch you cut off of the diameter, you gain aproximately one inch in pitch. Prop pitch is the average pitch calculated between root pitch & tip pitch Therefore if you cut the tips off you increase the average pitch.
So, cut down a 9/8 prop & you should have close to a 7/10.
Can't see how shortening a prop could effect it's "integrity" (strength).Again you are taking away the weakest part of the prop & the overall average cross section will be greater.(stronger)
Now Efficiency & ballance is a completely different matter. You will be changing both of those!

One can only speculate as to what application this prop is going on!

Hope that helps.

Thanks "OPRN"! To address your speculation:

It needs to be a "folder" because my intention is to do some "hybrid" sport flying with a new F5D plane that I'm getting this year. "Hybrid" in the sense of a mixture of "hotliner" style flying (climb to height then dive) and all out "speed" flying. (Pylon racer style)

The problem with regular pylon racer style speed props is that you tend to break them every few flights of so on landing ... that can get quite expensive. Another reason for a folder.

Colin