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  #1  
Old 05-18-2018, 08:13 PM
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rjarrell rjarrell is offline
 
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Default 3 Blade lower cowl Mods

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Struggling with pix for now

Read a lot of post about the extended opening required for a 3 blade prop but had to guess at measurements. Sharing pix of my modification after swapping a 2 blade Whirlwind for a 3 blade Hartzell composite. Should be at the Hartzell display at Osh...oops Air Adventures this year if you want a closer look.

Removal is not fun but doable with two people, protect the blades by covering the hinge on top of the bottom cowl (I used brake tubing and trying different sizes of PVC trim from McMaster Carr) I'll share when I get it right.

Tie down the tail to lift the front wheel off the ground (chock the mains first). Tried it without this step and it can be done but very difficult, you pick up over and inch of clearance.

Cowl installation seems easier if you slide in from the side, tape up anything you don't want scratched up. Remove the front gear leg cover, pants can stay on.
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Last edited by rjarrell : 05-19-2018 at 06:17 PM. Reason: trying to add pix
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  #2  
Old 06-12-2018, 09:37 AM
greghale greghale is offline
 
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Default 3 blade lower cowl mods

I installed Rod Bower's Ram system on my RV10. Not only did it give me 1-2" of manifold pressure increase in cruise, it also makes it easier getting the lower cowl off around my 3 blade prop. A side benefit is you can remove the ram air duct and examine the bottom of the engine without having to remove the lower cowl.
I've got pictures on my web site http://www.nwacaptain.com/eng_induction.html

Greg...
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  #3  
Old 06-12-2018, 09:55 AM
AviatorJ AviatorJ is offline
 
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I did what Greg did. Just make sure you get the correct Scoop from Rod if you go that route!
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  #4  
Old 06-12-2018, 10:19 AM
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This may be a silly question, but what are the benefits of going with a 3-bladed prop, besides the cool factor? Anybody want to lay out their version of the pros and cons of a 3-blade?
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  #5  
Old 06-12-2018, 10:27 AM
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One quick answer is that for a well balanced propeller, the three blades at 120` are out of phase with the power pulses at 90`of a four cylinder engine, and the result is less vibration. But you know you can read anything on the internet.
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  #6  
Old 06-12-2018, 01:32 PM
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Auburntsts Auburntsts is offline
 
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Quote:
Originally Posted by rv7boy View Post
One quick answer is that for a well balanced propeller, the three blades at 120` are out of phase with the power pulses at 90`of a four cylinder engine, and the result is less vibration. But you know you can read anything on the internet.
Maybe, but since we're in the RV-10 Forum it's a 6 cylinder engine not a 4 so the power pulses aren't 90 deg apart. I'd argue that the "perceived" smoothness comes more from the lower tip speed and vibration of the 3-bladed prop than anything else.

Anyway here's an old thread that sums up the 2 v 3 debate: http://www.vansairforce.com/communit...ead.php?t=1495
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  #7  
Old 06-12-2018, 12:47 PM
MConner MConner is offline
 
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Quote:
Originally Posted by ppilotmike View Post
This may be a silly question, but what are the benefits of going with a 3-bladed prop, besides the cool factor? Anybody want to lay out their version of the pros and cons of a 3-blade?
Three bladed props “generally” feel smoother and have more ground clearance at the cost a a little speed and some added weight. YMMV
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