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Thread: 180hp propeller options...2,3,4,5 blades

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    180hp propeller options...2,3,4,5 blades

    Working on getting the particulars together on the cub build and I’m looking at different options for props. Constant speed vs fixed and number of blades of course. I realize the 2 blade is the staple and clearly has proved to be a great option. I am looking for any experience or ideas on plus and minus of something different. I know warp has a 5 blade fixed pitch.

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    I put a new 3 blade Catto on my 180 hp lightweight O-340 that I bought from Cubcrafters.

    The pilot said, “it goes like a scalded ape!”

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    cubdriver2's Avatar
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    Most efficient is a single blade

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

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    PerryB's Avatar
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    A friend has our old Breezy and put a Warp Drive 4-blade on it. It sounds like s lawnmower now. I don't know if it would be different in a tractor configuration, but as it is, the sound is terrible.
    Last edited by PerryB; 12-08-2019 at 11:28 AM.

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    Quote Originally Posted by cubdriver2 View Post
    Most efficient is a single blade

    Glenn
    I just do not understand how a single blade prop can be a good thing. Maybe there's more to it that I don't understand, but even if the blade's weight is counterbalanced, the thrust is not. Therefore the engine will be constantly yawing around the center line as it makes a revolution. Not good for the engine mounts and it seems like the vibration would be terrible.
    Wikipedia does not have much to say, but it's not very flattering.
    https://en.wikipedia.org/wiki/Single-blade_propeller

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    CamTom12's Avatar
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    Quote Originally Posted by Tennessee View Post
    I just do not understand how a single blade prop can be a good thing. Maybe there's more to it that I don't understand, but even if the blade's weight is counterbalanced, the thrust is not. Therefore the engine will be constantly yawing around the center line as it makes a revolution. Not good for the engine mounts and it seems like the vibration would be terrible.
    Wikipedia does not have much to say, but it's not very flattering.
    https://en.wikipedia.org/wiki/Single-blade_propeller
    Lots of citation needed in that article.
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    mvivion's Avatar
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    Frankly I don’t think a 180 HP engine has the power or torque to benefit from more than two blades. About The only reason I might consider a three bladed prop on a 180 HP engine would be a case where prop to ground clearance was an issue.

    MTV

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    When I changed a 2 blade to 3 blade on the Skywagon the smoothness was remarkable. Three blades on 6 cylinders made sense for that. A 3 blade on a 4 cylinder makes less sense, but Whirlwind makes a ground adjustable 3 blade that seems to work well with an IO-390. With respect to length? I found it interesting that Whirl Wind’s highest performance CS STOL prop is a 2 blade 80”. What you don’t see in the ads is how thick and deep the blades are, the amount of twist near the hub, and the leading edge curve. Props are evolving in the composites age. It isn’t all about length and number of blades.

    If I wanted a simple prop on 180hp I'd have a ground adjustable 2 blade Whirlwind. The empirical evidence has been in on that prop for a couple of years. If a CS? I'd have a conversation with Whirl Wind. The question is whether the CS advantage is worth 25# plus on the nose.
    Last edited by stewartb; 12-08-2019 at 01:31 PM.

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    Dave Calkins's Avatar
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    Quote Originally Posted by PerryB View Post
    A friend has our old Breezy and put a Warp Drive 4-blade on it. It sounds like s lawnmower now. I don't know if it would be different in a tractor configuration, but as it is, the sound is terrible.
    Every pusher prop I ever heard sounds funny. even model airplanes that are pushers
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    Dave Calkins's Avatar
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    Quote Originally Posted by Tennessee View Post
    I just do not understand how a single blade prop can be a good thing. Maybe there's more to it that I don't understand, but even if the blade's weight is counterbalanced, the thrust is not. Therefore the engine will be constantly yawing around the center line as it makes a revolution. Not good for the engine mounts and it seems like the vibration would be terrible.
    Wikipedia does not have much to say, but it's not very flattering.
    https://en.wikipedia.org/wiki/Single-blade_propeller
    The single bladed props on model airplane Line-control speed racers have a counterweight that is aft of the thrust-face of the prop. That balances the force on the crankshaft from the single blade

    Obviously this isnt for full scale REAL airplanes

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    PerryB's Avatar
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    Back when my Dad and I were flying it we had a ground adjustable Hartzell made from a CS and it produced very little discernible noise. This Warp Drive sounds God-awful.

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    skywagon8a's Avatar
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    Quote Originally Posted by Tennessee View Post
    I just do not understand how a single blade prop can be a good thing. Maybe there's more to it that I don't understand, but even if the blade's weight is counterbalanced, the thrust is not. Therefore the engine will be constantly yawing around the center line as it makes a revolution. Not good for the engine mounts and it seems like the vibration would be terrible.
    Wikipedia does not have much to say, but it's not very flattering.
    https://en.wikipedia.org/wiki/Single-blade_propeller
    http://rexresearch.com/unibladeprop/onebladeprop.htm
    N1PA

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    I have a hard time buying into the single blade propeller being any improvement over a conventional design. From what I can discern it had some sort of pivoting/articulated hub that allowed pitch to increase as power was pulled back. This would give it an "unfair" advantage (for purposes of comparison) over a standard fixed prop. Also I think you'll find all the empirical testing was done static, and the one-blade will shine in that environment. Add a little forward speed and the advantage disappears, like a helicopter going through translation. I think the advantages of the one-blade were mostly wishful thinking on the part of its maker. I know the story has hung on for a long time, but so has Bigfoot. My Dad used to talk of the efficiency of the one-blade prop, but I've yet to see any data to support it. Much like the "step". Finally there is the issue of the constantly spinning asymmetric thrust line. I just can't see how you get around that. The hinge/flapping mechanism might actually reduce P-factor (if I'm understanding it correctly) because it allows the blade to run at a more constant angle of attack throughout its arc, but the one sided thrust line is inescapable.
    Last edited by PerryB; 12-09-2019 at 08:40 AM.
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    Yea I’m completely out on the one blade wonder. No need to debate that item. I’m more to debate the 2 blade or more and constant speed versus fix pitch. Anybody know the weight difference of the constant speed?

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    Assuming Whirl Wind constant speed you'd likely use the 284. Prop and governor total 44#. https://m.whirlwindaviation.com/props/284series.asp

    Compare to the Whirlwind ground adjustable GA-200L at 18#. https://whirlwindpropellers.com/airc...t/ga200l-stol/

  16. #16

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    My thought on the single blade prop for aircraft use. I bet very little effort has been needed to protect the patents on that prop over the past 80 years.
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