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United States, PA, Telford
Joined Mar 2010
67 Posts
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Help!
three bladed prop
So can any one out there tell me if there if there is a conversion chart or something out there that can tell me what size of three bladed prop to use on various gas engines?I can't find any info on line.
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Rough info would be drop two inches of diameter for the same pitch as a two blade as a starting point/estimate. For example, 28x10 two blade to a 26x10 three blade. That’s my opinion, I’m sure there will be others.
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On a DLE55 use the Mejzlik 20x10 3 blade. It has almost identical performance to the 22x10 2 blade on the same engine.
To answer your original question though... it's not as simple as just a conversion. I'm a 3 blade nut and use them on most of my aircraft. I have found over the tears it has more to do with each particular setup than it does dropping a set amount of diameter and adding pitch. Things that come in to play are blade shape, torque curve of engine, blade material, and the performance expectation. I have found a 3 blade for just about any engine size that is directly comparable to a 2 blade counterpart. You do have to expect a higher top speed, lower rpm band, different thrust feel, and a slower pullout from a hover. You can still get the same amount of thrust just in a lower rpm band. That's a good and a bad for 3 blades. This lowers the exhaust note but also tricks the ear into thinking the aircraft has less power. If you were to watch just the performance side by side of a correctly sized 2 and 3 blade without sound it would show very similar performance. |
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You cannot go wrong w 20x10 3-blade prop for DLE 55 motor.
One other thing to consider: 3 blade prop looks cool but 20” size may look small for that airframe/warbird? Better off wait until you can put 60cc motor in to swing bigger 22x10 3-blade prop. Now your warbird has nicer balance of good look, proper size, and power to swing that big 3-bladed propeller. |
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United States, PA, Telford
Joined Mar 2010
67 Posts
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Thanks for all of the reply's. I am just trying to gather some info because I am thinking about putting a three bladed prop on my GP Pitts. It will probably be strictly for looks but I do like the idea of a lower exhaust note.
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