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  #1  
Old 07-27-2017, 12:54 AM
Sylvainsting's Avatar
Sylvainsting Sylvainsting is offline
 
Join Date: Nov 2014
Location: In the center of France
Posts: 76
Default Best cruise settings

Hi,

I now have about 130Hrs on my RV-7 with a WW 200RV /Aerosport Power IO-375, 195 HP.
What a great combination!

There are now a few Vans airplanes flying with your 200RV propeller in France, and we are trying to find the best prop/engine setting to fly behind your 200RV.
Not much info out there...

According to you what is the best RPM setting for best cruise efficiency?

Do you have some tables or graphs that we could use ?
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RV7 QB (F-PSED), Tip Up, Aerosport IO-375, James Cowl, WW 200RV, Dynon Skyview, VP-X sport, Day VFR,

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  #2  
Old 07-27-2017, 02:01 AM
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swisseagle swisseagle is offline
 
Join Date: Feb 2005
Location: 20km outside of Zurich, Switzerland
Posts: 369
Default Look also at the RPM Recommendations from WW

Hello Sylvain

Also keep an eye on here: Operation Manual WW Propeller on chapter 5-4, RPM-Recommendations.

Hopefully others with this propeller join in.
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RV-7A, TMX-IO-320, FM-150, Sensenich FP
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  #3  
Old 07-27-2017, 02:39 AM
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mike newall mike newall is offline
 
Join Date: Jan 2005
Location: Yorkshire, England
Posts: 1,314
Default

What a strange graph....

It advises you avoid 2000 - 2300rpm, yet the stress at 2200 is the same as 2400, it is virtually identical to 2500, 2300 seems a no, no which suggests you are doomed wherever you set the rpm

Our MT 3 blade doesn't have avoid rpm's and is super smooth at 23/23 which is our combination of choice for cruise on an IO-360 with dual P-Mags. At that we see around 140kts indicated and leaned it burns around $63 of gas per hour

We think that is great btw
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  #4  
Old 07-27-2017, 04:02 AM
SuperCubDriver SuperCubDriver is offline
 
Join Date: Feb 2011
Location: Germany
Posts: 277
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Sylvainsting,
I have the same engine-prop combination with two Pmags. I usually cruise at 60% power LOP with 2350 RPM, this gives me around 140 KIAS which is around 160 KTAS at 10000ft with FF 7.9 GPH.
If you are interested I could send you my cruise speed grapgh.
Where are you flying in France?
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  #5  
Old 07-27-2017, 07:13 AM
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erich weaver erich weaver is offline
 
Join Date: Aug 2006
Location: santa barbara, CA
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I agree that the graph provided does not logically support the whirlwind recommendations in the text.

Cruise for me is 2300-2400 square and LOP operation at around 7.2 gph at 6-8,000 ft gives me about 185 mph TAS.

IO360B1B with WW200RV



Erich
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  #6  
Old 07-27-2017, 10:44 AM
rv7charlie rv7charlie is offline
 
Join Date: May 2006
Location: Pocahontas MS
Posts: 2,038
Default

The doc reads like nonsense to me.

Advice to conform to rpm restrictions based on a completely different prop-engine combination vibration characteristics?? Advice to avoid '2600-2700 rpm' with an engine that is designed to operate at 2700 rpm to make 75% power at ~8k feet??? Research by prop manufacturerS (note plural of mfgr) shows ops above 2600 rpm have 'excessive' (but unquantifed) vibration????

This reads like WW doesn't even know their prop's actual characteristics, so they boilerplated various other mfgrs' recommendations. Why not say, "Here are the characteristics of *our* prop. Here are the rpms to avoid, and these are the specific reasons why, and here are the limits that will be exceeded."
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  #7  
Old 07-28-2017, 12:36 AM
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Sylvainsting Sylvainsting is offline
 
Join Date: Nov 2014
Location: In the center of France
Posts: 76
Default Best settings

Hi,

Thanks for your replies.
Here is a cruise conditions screenshot.
I noticed no significal change when I move from 2350 RPM to 2500. I imagined the speed will increase but not. Why ?

I have a little private runway in the center of France, near Moulins (LFHY).

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Location: France
RV7 QB (F-PSED), Tip Up, Aerosport IO-375, James Cowl, WW 200RV, Dynon Skyview, VP-X sport, Day VFR,

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  #8  
Old 07-28-2017, 02:00 AM
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High_Flyer High_Flyer is offline
 
Join Date: Sep 2010
Location: Saint-Jorioz, France.
Posts: 175
Default

Quote:
Originally Posted by rv7charlie View Post
The doc reads like nonsense to me.

Advice to conform to rpm restrictions based on a completely different prop-engine combination vibration characteristics?? Advice to avoid '2600-2700 rpm' with an engine that is designed to operate at 2700 rpm to make 75% power at ~8k feet??? Research by prop manufacturerS (note plural of mfgr) shows ops above 2600 rpm have 'excessive' (but unquantifed) vibration????

This reads like WW doesn't even know their prop's actual characteristics, so they boilerplated various other mfgrs' recommendations. Why not say, "Here are the characteristics of *our* prop. Here are the rpms to avoid, and these are the specific reasons why, and here are the limits that will be exceeded."
The ranges to avoid are "contiunuous" RPM and does not include takeoff, climb or descent.
It is for continuous operations only.

There is no data available for the WW200RV regarding best cruise setting, or "best efficiency" setting.
Other prop manufacturers do provide some data, such as graphs or tables to extract that data.
Having said that the WW200RV is a great propeller...
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  #9  
Old 07-28-2017, 09:33 AM
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swisseagle swisseagle is offline
 
Join Date: Feb 2005
Location: 20km outside of Zurich, Switzerland
Posts: 369
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Sylvain

Do you have a MPG value that can be displayed on your Dynon?
I think then you should be able to collect some data for best economic flight.
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RV-7A, TMX-IO-320, FM-150, Sensenich FP
Flying since 28. April 2016
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  #10  
Old 07-28-2017, 09:46 AM
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DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
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Default

Quote:
Originally Posted by High_Flyer View Post
The ranges to avoid are "contiunuous" RPM and does not include takeoff, climb or descent.
Is there a reference or manual which specifically excludes takeoff, climb, and descent from the restrictions?
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