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General control line discussion => Open Forum => Topic started by: Motorman on October 23, 2013, 11:08:56 AM

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Post by: Motorman on October 23, 2013, 11:08:56 AM
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Title: Re: 2 Blade to 3 Blade Conversion
Post by: Dave_Trible on October 23, 2013, 02:28:45 PM
I don't think there is any way to directly convert as you are wishing.  There are quite a few aspects of a prop that affect its performance;  blade shape and width, thickness, helical pitch, flat or under cambered, tips square or round,  what engine...... Given what little you really have to start with I guess I would start with 10" diameter since I'm adding a blade then use about the same design and pitch you have now.  It will still be a completely different prop but in carbon you will heat and re-pitch the blades anyway if its not on the money.  Make a number of them so you can modify the tips, etc., to experiment.

Dave
Title: Re: 2 Blade to 3 Blade Conversion
Post by: Howard Rush on October 23, 2013, 05:42:16 PM
You can get a clue from Javafoil,  http://www.mh-aerotools.de/airfoils/javaprop.htm , or from this paper: http://arc.aiaa.org/doi/abs/10.2514/6.1983-190 .  What powerplant do you have that works at less than 9570 RPM?
Title: Re: 2 Blade to 3 Blade Conversion
Post by: Howard Rush on October 23, 2013, 10:23:26 PM
Merely plugging numbers into a program that somebody else already wrote "drags down" an iterative process of making molds for three-bladed unpitchable propellers for a unique RPM range?
Title: Re: 2 Blade to 3 Blade Conversion
Post by: Randy Cuberly on October 23, 2013, 11:28:32 PM
Power is E flight power 15, thanks for the links but all that heady engineering stuff just drags down my process. I wanted to get pretty close on pitch because you can't re-pitch the props I make after they cure for some reason, not going to copy APC anyway. Did Tornado make a 10x6 and a 10x4?

Oh Holy Cow!  Why not just use and old fox 35 and a 10-6 Top Flite prop and forget about all this "heady engineering stuff"...if you want 1958 technology why not just use it!  LL~ LL~
 LL~ LL~

Randy Cubery
Title: Re: 2 Blade to 3 Blade Conversion
Post by: Trostle on October 24, 2013, 02:14:51 AM
Did Tornado make a 10x6 and a 10x4?

Yes, and they produced a 9-6, all three blade props.  I have seen some carbon copies of the 10-6, but do not know who did them.

Keith
Title: Re: 2 Blade to 3 Blade Conversion
Post by: wwwarbird on October 24, 2013, 05:10:59 PM
I have seen some carbon copies of the 10-6, but do not know who did them.

Keith

 That would be Steve Wilk, Eliminator Props, here in the Vendor section.