Who is the best to help me with a propeller

aeroplumber

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Mar 31, 2017
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2213 3rd st east Wenatchee wa. 98802
I have a sport copter with a 618 engine with a three to one gear ratio. It has a powerfin with a 66 inch prop now. I called Darrell @ warp drive and he told me that the three to one gear ratio with a 66 inch prop is wrong. He said it will work OK on a 582 and of course a 618. But with the 10 extra HP your losing torque and thrust. Jim @ Sportcoter said he could never see much difference between the 618 and and 582. Darrell says that reason is in the just assuming whats good for a 582 is OK for a 618. He says a 618 is real beastly when set up write. He says the higher the gear ratio the larger the prop needed and the lower the diameter of the prop the smaller ratio needed like 2.62 would work best. I only have room for a 66 inch prop. I installed a 68 inch prop with the 3 to 1 ratio which gives me just 1" clearance. Darrel also explained by using the three to one gear ration with a 66 inch prop turns it into a cruise prop like 120 mph and not good for a gyro. So what do you guys think. Mick
 
I've dealt with Darell at Warp Drive since the 90's.
He is a very personable and knowledgeable man.
I would listen to his recommendations on props before anyone else.
Why would you even question a reputable Propeller Manufacture on how props work.
There is actually a lot that goes into the performance of a prop.
Do ya want to climb like a bat outta hell, do ya wanna moderate RPM at cruise, or do you want the best all-around performance for your bird?
These are the questions you ask your self before you buy a prop and gearbox gear ratio.
 
Hi gyrojake, thanks for the repley. It isn't that I question Darrell. The follks @ Sportcopter are pretty adamant that because it works, it is the right combo. So I'm just trying to see what others did. I only have one inch clearance but I'm going to do a thrust test. What the 66 inch powerfin does and what the 68 warp does. Mike
 
Darrell at WarpDrive really knows his stuff,I would listen to him over any one else.
 
A 66 inch prop is to short for a 3 to 1 gear box, 70 or 72 would be much better, you are not getting the best that you can from that engine, that type engine and others in its family, 583, 500 , 670, 800 and 1000 really needs a variable pitch prop to have the best performance in all conditions due to not a lot of torque at the low rpm compaired to the power at wide open throttle and full rpm.
norm
 
No Title

A 3-blade propeller with a diameter of 1700 mm will work quite well.
Especially at high speed. At low speeds, he will lose. In this case, a 4-blade propeller with a diameter of, for example, 1620 mm is possible.
 

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