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3 Blade props

Stuka Stunt Main Forum · 4 of 4 known posts recovered

Colnago · Feb 12, 2007 12:22 AM

#0 source
Have been thinking of using a 3 blade prop, I have never used one before and was wondering how you choose what size you need. Say if you were using a 10x6 what would you want to use in a 3 blade?

stringjobs · Feb 12, 2007 04:04 AM

#1 source
A 9X6 3b = a 10X6 2b
Greg Howie

Clint Ormosen · Feb 12, 2007 05:44 AM

#2 source
Just take an inch off the diameter of the two blade and *PRESTO*, ya' got your three blade size.
Clint
Master of the Figure Nine

captcurt · Feb 13, 2007 10:57 AM

#3 source
The "One Inch Rule" works for props around 10-11 inches. Its more like a percentage tho..if the 2 bl is a 15" then a 14 three bl is going to be too big. But for the props we seem to use, an inch plus or minus is a good start.

BUT.. saying an 10-4 3 bl = a 11-4 two bl is a stretch. They must be similar in blade shape, tip config, thickness etc.

And a particular motor might respond better to a three than a two even in the same family.

A good example of this is the Tornado 10-4 three bl v. an APC 11-4 2 Bl.

Both load the engine approximately the same but the run will be different because the APC is heavy. It is also alot different shape blade.

Best thing is to get a good reference from someone with a same engine/plane /prop combo as a starting point.

FWIW

Curt