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  #11  
Old 12-17-2020, 11:10 AM
Carl Froehlich's Avatar
Carl Froehlich Carl Froehlich is offline
 
Join Date: Dec 2007
Location: Dogwood Airpark (VA42)
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Not an issue for as I have a parallel valve (180hp) engine. Also I’m rarely above 24” in cruise as I’m typically WOT at altitude - or when above 24” I’m at 2700 RPM (for take off) and 2600 RPM for climb.

Carl

Last edited by Carl Froehlich : 12-17-2020 at 11:13 AM.
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  #12  
Old 12-17-2020, 06:01 PM
Karetaker's Avatar
Karetaker Karetaker is offline
 
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Location: USA
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Howdy Carl. I get what you are saying. I am seriously looking at the Hartzell BA aluminum props now. For those curious, here is the restriction from Hartzell:

For undamped 200 HP IO-360: Continuous
operation is prohibited above 24 Inches
manifold pressure between 2350 and 2550
RPM.
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  #13  
Old 12-17-2020, 06:14 PM
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Karetaker Karetaker is offline
 
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One more thing...for those wondering...I received an email from Aero Sport Power today stating that switching from a non-weighted to a weighted crank is a simple swap. Consumables such as bearings, nuts, bolts, etc. need to be replaced as well, of course. This is a task I would consider doing however, the new crank is expensive! Plus, having done the swap, I would be looking at all types of 3 blade composite fancy props further driving up my costs! I believe I will work with what I have;for now.
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  #14  
Old 12-17-2020, 07:50 PM
David Z David Z is offline
 
Join Date: Aug 2010
Location: Thunder Bay Ontario
Posts: 481
Default Weight

Did they say how much more the counterweighted crank weighs? I ask to compare the whole "power plant" package.

Non-CW IO-375 and Hartzell vs a CW IO-375 and WW prop. One having a lighter engine and heavier prop while the other has a heavier engine and lighter prop. If it turns out to be very similar in weight and quite a bit more expensive, that's an easy decision. Well unless you really want 3 blades, composite prop and the smoothness of operation that has to offer.

These operating restrictions seem pretty easy to live with:
Quote:
For undamped 200 HP IO-360: Continuous
operation is prohibited above 24 Inches
manifold pressure between 2350 and 2550
RPM.
Take-off at normal 2700rpm full throttle. Climb at 2550-2600. Cruise at 2100-2300rpm
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  #15  
Old 12-17-2020, 08:41 PM
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Karetaker Karetaker is offline
 
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I have no information on weight differences between engine/prop. combos, David. I do agree the restrictions are livable and will look further into the Hartzell blended airfoil propeller. I am hoping I may be able to pick the prop up from Hartzell as I live in the area...ish.
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  #16  
Old 12-18-2020, 07:44 AM
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Champ Champ is offline
 
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+1 with Carl. Prop/MP restriction has not been an issue.
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Bellanca Champ 7ACA since 1986, restored 1990.
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  #17  
Old 12-18-2020, 09:43 AM
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DanH DanH is online now
 
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Mike, don't discount operating restrictions, in particular from Hartzell. They have a huge body of experience actually measuring vibratory propeller strain. Flip side is high confidence; if they say you can run in some particular range, you really can. Unfortunately, that's not always been true with all.
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  #18  
Old 12-18-2020, 10:17 AM
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Karetaker Karetaker is offline
 
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Howdy everyone. Here is what I just received from Hartzell, if interested:

"The vibrational testing that Hartzell performed with the 375 undamped engine resulted in higher stress loading on the propeller than was seen with comparable engines. As a result, Hartzell would not recommend installing an aluminum or composite bladed propeller application with this engine configuration. If the engine was equipped with a damped crankshaft, aluminum and composite blade combinations could be recommended with no placards. Dual P-mags have not been tested at this time."


Answer from my follow up question was this:


"Unfortunately that engine (without dampers) is very hard on our propellers so much so that we cannot recommend our installations.

Unless you change the crankshaft, or go with a different engine, wood is probably the only option."
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  #19  
Old 12-18-2020, 12:09 PM
Northernliving Northernliving is offline
 
Join Date: May 2005
Location: Boston, MA
Posts: 496
Default Hartzell G2YR/N7605W-2X carbon fiber prop

Quote:
Originally Posted by Karetaker View Post
Howdy Everyone. I need some assistance in regard to propeller choice from people more experienced than I am on the subject. (Mostly everyone.)

I am building a -7 and just acquired an Aero Sport Power IO375-M1S engine. 8.5-1 compression, non-counterbalance crank, 200 HP @ 2700 RPM. Mounted on the rear case is a PCU5000X prop governor.

I want a CS propeller with focus on long cruise performance. I am building the plane as light as I can build it and understand CG can be an issue with this airframe and composite propellers. Still, I would consider a composite if the advantage was worthy.

What say you?
I went with the Hartzell G2YR/N7605W-2X carbon fiber prop. It was around 16lbs lighter than the the BA prop, has no operating restrictions, amazing climb performance, but may cost 1-2kts on the top end.

https://hartzellprop.com/owner-of-co...res-his-story/
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  #20  
Old 12-18-2020, 07:10 PM
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RV7Guy RV7Guy is offline
 
Join Date: Jan 2005
Location: Chandler, AZ
Posts: 2,932
Default Composite is fine

On my first 7 I had a parallel valve 360 with Whirlwind RV200 composite prop. It was no problem at all. You will still be well within CG range. The back side of the CG range makes the elevator sensitive but not at all dangerous.

Another data point. Another guy on our airport had a RV 7 with the exact engine as mine built by the same guy. He went with the Hartzell BA prop because of discussed GG concerns. We flew side by side at 6000 feet and set the power to 24/24. I flew away from him. Probably a 5 knot difference. I should point out, his plane was 50lbs lighter and the pilot weight difference was probably another 40.
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