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  #1  
Old 01-25-2014, 12:34 AM
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ScottSchmidt ScottSchmidt is offline
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Default RV-12 RPM, Speed and Efficiency

Today I did some flying and wanted to see how the -12 was in efficiency at different power settings. I need to try this again at a higher altitude where I would typically cruise. I know this is not perfect data and there are more accurate ways of accomplishing this.

I was flying at 5200 ft with an OAT of 32F, only one person and 6 gallons of fuel.

Prop pitch setting would change these numbers between -12's. I would be interested in seeing what others are seeing.
I only measured TAS from the Dynon. WOT (wide open throttle) had a max RPM of 5770.

I will try lower RPM settings to see how efficient the -12 can be.





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Last edited by ScottSchmidt : 01-25-2014 at 12:38 AM.
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  #2  
Old 01-25-2014, 08:25 AM
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Thanks for sharing that, very interesting and I too wish others would do the same.
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  #3  
Old 01-25-2014, 08:44 AM
AZLeeJay AZLeeJay is offline
 
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Nice, thanks for the data points.
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Old 01-25-2014, 09:42 AM
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N941WR N941WR is offline
 
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Default Playing with numbers

Let's say you were going to take a 200 nautical mile trip. The time difference between running at 4800 vs 5770 RPM is 25 minutes ( 1.9 vs. 1.5 hours) and the fuel burn difference is .4 gallons (8.7 vs. 10.3 gallons).

Interestingly, if I take that same 200 nautical mile trip in my -9, it will take me 1.3 hours at 150 KTS and only 9.5 gallons burning 7.1 GPH, slightly better than the -12 running full out.
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  #5  
Old 01-25-2014, 10:45 AM
RFSchaller RFSchaller is offline
 
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The fuel burn seems high. Have you checked your K-factor?
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  #6  
Old 01-25-2014, 11:41 AM
rvbuilder2002 rvbuilder2002 is offline
 
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For the altitude Scott was flying at, if you run the engine at right near the max continuous of 5500 RPM, they will typically burn just shy of 6 GPH, so his chart looks pretty close.
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  #7  
Old 01-25-2014, 11:45 AM
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az_gila az_gila is offline
 
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Pretty amazing.

To put it in automotive terms, even at the worse point on your chart you are getting 22 mpg at 150 mph...
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  #8  
Old 01-25-2014, 11:59 AM
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gblwy gblwy is offline
 
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Thumbs up A couple more points

As it happens, I noted a couple of parameters last week. Slightly lower temperature, one-up, but with full fuel, at 4000 feet, with spats. I've had to translate into your funny fuel units ;-)

rpm fuel speed
4700 4.2 100kt 115mph
5000 4.8 109kt 125mph
5500 5.6 120kt 138mph

Cheers...Keith

Last edited by gblwy : 01-25-2014 at 12:01 PM.
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  #9  
Old 01-25-2014, 12:03 PM
NASA515 NASA515 is offline
 
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Keith, what's 5000 rpm in metric???

Bob Bogash
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  #10  
Old 01-25-2014, 12:08 PM
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gblwy gblwy is offline
 
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Well, for an ex-Lycoming driver it's much too fast in any currency ;-)

Having said that I wouldn't swap my engine - starts in a heartbeat, sounds fine in the cockpit, and people on the ground have commented how quiet the plane is in the air.

Cheers...Keith
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