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  #1  
Old 01-10-2021, 08:54 PM
Maxrate Maxrate is offline
 
Join Date: Dec 2008
Location: League city, TX
Posts: 590
Default Best prop for aerobatics

After reading the “propeller selection” thread with great interest I’m looking for feedback from those that have flown IAC beginners, sportsman and even advanced sequences in their RV and what prop performed the best during Acro. My main concern is prop reliability and longevity.

The Hartzell BA looks like it’s limited to the stock 180HP. The Hartzell G2YR/N7605W-2X carbon fiber looks like the most robust one on the market but comes in at a whopping 14,500$. The WW 200RV is also limited to the stock 180 horse unless going with the additional cost of a counterweighted crank, then there’s the issue of performing aerobatics with a CW crank? Wood is out of the question as I definitely want the flexibility of CS for cross country ops.

Thanks
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  #2  
Old 01-10-2021, 09:34 PM
David Z David Z is offline
 
Join Date: Aug 2010
Location: Thunder Bay Ontario
Posts: 486
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MT makes some aerobatic props. The prop is counterweighted, so works in reverse fashion to normal props. Oil pressure pushes the blades fine, so in a small/short oil pressure interruption to the governor results in the blade angle going coarse. This prevents overspeeds.

Whirlwind also makes some aerobatic props, but they're 77" diameter and probably too long for most 2 seat RVs. Unless I missed something.

I'm not well versed at all regarding the aerobatic competition levels. Maybe there isn't enough negative or 0 "g" operation to make this worth while.
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  #3  
Old 01-10-2021, 10:09 PM
Maxrate Maxrate is offline
 
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I guess I should restate that I’m actually trying to determine the best engine/prop combo for my -7. Aerobatics will be in its future, but xcountry flying will too. The “prop selection” thread raises some serious concerns about the higher HP engines with the wrong prop combos.
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  #4  
Old 01-11-2021, 05:06 PM
smithflys23 smithflys23 is online now
 
Join Date: Feb 2017
Location: Jupiter
Posts: 171
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Quote:
Originally Posted by Maxrate View Post
After reading the “propeller selection” thread with great interest I’m looking for feedback from those that have flown IAC beginners, sportsman and even advanced sequences in their RV and what prop performed the best during Acro. My main concern is prop reliability and longevity.

The Hartzell BA looks like it’s limited to the stock 180HP. The Hartzell G2YR/N7605W-2X carbon fiber looks like the most robust one on the market but comes in at a whopping 14,500$. The WW 200RV is also limited to the stock 180 horse unless going with the additional cost of a counterweighted crank, then there’s the issue of performing aerobatics with a CW crank? Wood is out of the question as I definitely want the flexibility of CS for cross country ops.

Thanks
I have not done any competitions, but I fly aerobatics several times per week. I recently switched from a ground adjustable Sensenich, to a WW 74HRT. The 74 HRT was recommended by WW after explaining that I do a lot of aero, and telling them my engine is rated at 190hp. The prop is a beast, and I’ve had noticeable improvement in the vertical. This data is difficult to quantify. All I can tell you is that the switch to the WW was a big improvement. Lastly, the prop is beautiful. I have the clear coated carbon fiber finish. I hope this is helpful.
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  #5  
Old 01-11-2021, 06:28 PM
Maxrate Maxrate is offline
 
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Location: League city, TX
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Matt, on your 190HP engine can you tell me if you have a counterweighted crank? I assume it’s a parallel valve engine. Thanks
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  #6  
Old 01-11-2021, 07:42 PM
spatsch spatsch is offline
 
Join Date: Nov 2014
Location: Plano, TX
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I have a fixed pitch Cato 3 blade prop on an IO-360 on my RV-8 and am VERY happy.

Would I get longer vertical lines with a constant speed prop. Sure. Do I need longer vertical lines to compete in Sportsman. No.

I do like the extremely low weight of the Cato prop. The gyroscopic force on your crankshaft from a heavy prop is substantial during acro so you not only pay a lot more for the prop but you also put more load on the engine with a heavier prop.

Also tried the new Sportsman known last weekend and I fly the entire routine with full power without going over redline on RPM. Only time I generally have to touch power is in spins despite having fixed pitch.

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  #7  
Old 01-11-2021, 08:31 PM
Taltruda Taltruda is offline
 
Join Date: Oct 2017
Location: Las Vegas, NV
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Quote:
Originally Posted by Maxrate View Post
After reading the “propeller selection” thread with great interest. My main concern is prop reliability and longevity.

Wood is out of the question as I definitely want the flexibility of CS for cross country ops.

Thanks
I cut down your post to address some of your concerns.. if you want CS for cross country flying, I think you will find the fixed pitch props to be identical or nearly so in cruise. I too want a CS prop, but just wanted you to know where they shine. They climb faster, they land shorter, but in cruise (like 99% of your cross country travels) they are identical. Perhaps you can pull down some RPM and get better fuel burn.. the lightness of a fixed pitch prop is really nice. Maybe your -7 could use the nose weight to prevent an aft CG for the planned baggage...
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  #8  
Old 01-12-2021, 07:47 AM
smithflys23 smithflys23 is online now
 
Join Date: Feb 2017
Location: Jupiter
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Quote:
Originally Posted by Maxrate View Post
Matt, on your 190HP engine can you tell me if you have a counterweighted crank? I assume it’s a parallel valve engine. Thanks
The crank is not counter weighted. It’s a parallel valve engine with 9:1 pistons.
One more point, for my airplane, the extra weight of the CS prop helped even out the CG. That being said, the WW is one of the lighter CS props you can buy.
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  #9  
Old 01-12-2021, 07:52 AM
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uk_figs uk_figs is offline
 
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Location: Tulsa, OK
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Quote:
Originally Posted by Taltruda View Post
I cut down your post to address some of your concerns.. if you want CS for cross country flying, I think you will find the fixed pitch props to be identical or nearly so in cruise. I too want a CS prop, but just wanted you to know where they shine. They climb faster, they land shorter, but in cruise (like 99% of your cross country travels) they are identical. Perhaps you can pull down some RPM and get better fuel burn.. the lightness of a fixed pitch prop is really nice. Maybe your -7 could use the nose weight to prevent an aft CG for the planned baggage...
I have a -7 with the 0-360/Catto 3 blade combination and it is a very good all around performer, with respect to the light weight on the nose CG issue rather than add weight (which I have done) there have been some threads on here about using a 0-320 mount which moves the motor forward a couple of inches and helps with the CG issue. If you are not at the finishing kit stage that might be an option to explore.
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  #10  
Old 01-12-2021, 04:07 PM
Maxrate Maxrate is offline
 
Join Date: Dec 2008
Location: League city, TX
Posts: 590
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Thanks for the great replies.
Quote:
The crank is not counter weighted. It’s a parallel valve engine with 9:1 pistons.
Matt, that really helps narrow down the selection of prop and engine combo. WW website lists 9.6:1 as the max comp ratio for use with the HRT 2 blade. It seems like a great combo for acro and cross country flying to keep the CG in a reasonable all around range. The other option is the Hartzell BA that Vans sells. Price wise you can’t beat it. And the TBO is an astounding 72 months or 2400 hours.

I’ve flown with a friend in his 6A with the Cato 3 blade and it’s a great performer in cruise. I think the CG issues that others have described in different threads is not territory I want to venture into.
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