RCU Forums - View Single Post - Does the increase thrust of a 3 bladed make up for the decrease in rpm?
Old 07-07-2015 | 03:31 PM
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Originally Posted by gregoryshock
When I decided that I needed to ask my question, I didn't know that this is a debated subject. I wanted to use a 3 bladed propeller because it looks right for the Corsair. I was hoping that it would work good enough for the application. I am not concerned about getting max. speed (I'm not sure what people mean by speed. RPM or How fast will the aircraft will fly?) I'm concerned that the Engine will turn enough RPMs to get the airplane off the ground and fly well. If I must, I'll switch to a 2 bladed propeller. I feel a bit mislead. When I bought the engine I looked at the propeller recommendation and followed the conversion directions to choose the right size 3 bladed propeller. Where the issue came in, is that that Tower Hobbies says that my engine can turn 15x7 2 bladed propeller. But the OS manual recommends the max size of 14x6-8. I've contacted tower hobbies and Hobbico about this conflicting information. What I'm trying to determine is if the propeller I already have will work.

* I already contacted top flite about weight specs. And they say that power ratio I'm using is fine. So the only thing in question here is the propeller size and the number of blades.

Go into OS support and ask Bill Baxter directly with your question. I have spoken to him on the phone a couple times when I called service and Bax is a bundle of information about OS engines.
Due to the selection or lack of I have limited time playing with the 3 blades and never did any real testing. The only thing I really noticed was when I shut down the throttle it was like putting on the breaks, the plane slowed really fast. I was using a Kaos at the time and it really slowed down the landings. I just went down an inch and up one on the pitch, didn't notice any power or speed change. I only tried two brands and both the same size and pitch Groupner and MAS. I also didn't have a spinner if that means anything to you?