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  #11  
Old 12-02-2011, 10:04 PM
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DanBaier DanBaier is offline
 
Join Date: Mar 2009
Location: Rochester NY
Posts: 669
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Specific fuel consumption should have it that you would be in the range of 7 - 8 gallons if you're turning 65% power leaned to peak.

For estimating, multiply whatever horsepower you're turning by .0725 to get fuel flow in gallons. (For example 65% for a O-320 at altitude would be 104 hp = 7.5 gph.) Conversely, divide your observed fuel flow by the same factor and it should yield the horsepower.

That could all be out the window if you lean by another method.

YMMV

Dan
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  #12  
Old 12-03-2011, 05:48 AM
Steve Steve is offline
 
Join Date: Jan 2005
Location: Roy, Utah
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Default Actual numbers

I flew my fixed pitch, carb'd and mag'd o-320 -9A from Ogden UT to Oshkosh WI then on to Vero Beach FL back in 2010.
Most legs were flown at 11,500 msl, 2 legs at 9,500, 1 leg at 7,500.
Total GPS distance was 2098.2 nm
Avg ground speed was 148.4 kts
Total fuel used was 122.32 gals
Total flight time was 14.1 hours
Fuel burn computes to 7.83 gph
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  #13  
Old 12-03-2011, 07:36 AM
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tc1234c tc1234c is offline
 
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Location: Port Orange, FL
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My experience is closer to Vlad, Reiley, and a few others. Mine is a little slower. Pete's is much more efficient than mine (we did a comparison a few years back and I had much lower mpg). I have FP O320-D2A with one mag and one lightspeed. Prop is pitched between climb and cruise. I usually see 12.5 gph WOT at sea level takeoff. At 65% cruise I burn around 7 gph, at 60% it is 6.2 gph (specific fuel burn at .39 - this is what on GRT engine display, I forgot the unit). During descend it could burn between 4.5 to 7 depending on the airspeed (not only VS). I flight plan 7 gph since climb and descend kind of cancel out each other. Of course how much you burn depends on how aggressive you are on the mixture knob. How much true airspeed you get is another story (I have to admit that I am slow ).
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Last edited by tc1234c : 12-03-2011 at 02:33 PM.
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  #14  
Old 12-03-2011, 08:31 AM
49clipper 49clipper is offline
 
Join Date: Dec 2006
Location: Belleville
Posts: 306
Default 49clipper

Over the last 215 hrs on my O-320-D1A powered RV-6 (FP), I have used 7.0gph overall. Now I admit, I lean to just a few degrees rich of peak and use economy power settings (60-70%). I typically cruise at 140-145kts IAS at 5000-9000', and burn about 6.5-7.5gph. Sure, I could cruise at 155kts, but why burn the fuel. Incredibly more efficient from anything I owned previously.

Jim
N189EM RV-6
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  #15  
Old 12-03-2011, 11:48 AM
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Leland Leland is offline
 
Join Date: Jan 2005
Location: Livermore, California
Posts: 146
Default RV-9A Fuel flows

My fuel-burn rate for a 2.9 hour flight from Livermore, California to Wells, Nevada averaged 6.2 gallons/hour (GPH), including a full-throttle climb to 13,500?, cruise and decent. The burn rate at 13,500?, with the mixture leaned to the "edge of roughness", was 6.0 GPH while cruising at 146 knots TAS. (The density altitude was 14,900?.) The cruise burn-rate was measured over a 20 minute period since the instantaneous EIS reading fluctuates. The full-rich, full-throttle TAS at this altitude was 150 knots (2460 RPM and 18.4" M.P.).

The second leg of the flight from Wells to Kemmerer Wyoming at 11,400? showed a TAS of 156 knots at 2540 RPM and 20.1" M.P, for full-throttle and full-rich conditions (burn rate was estimated at 6.9 GPH). The maximum TAS of this plane near sea level is 162 knots. Its airspeed indicator has been calibrated to 1-2 knots. Subsequent testing shows that leaning to the "edge of roughness" for this plane is zero-to-twenty degrees lean of peak, depending on the cylinder.

This aircraft has one P-Mag and one magneto on an O320D1A (600 hour since new from Van's) with a carburetor. On most trips, I only fly an hour and the average fuel burn is about 6.6 gallons/hour. When I have gone on longer trips in-trail with other RV's, my plane burns a little less than the others.

Leland
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  #16  
Old 12-05-2011, 10:30 AM
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flyboy1963 flyboy1963 is offline
 
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Location: Lake Country, B.C. Canada
Posts: 2,416
Default great data pool! ...now to use it....

thanks everyone! I have a much better idea now....wouldn't have guessed the fuel flow WOT climb as high as you folks show.
I have no instrumentation other than a single CHT & EGT, so don't lean too agressively, no do I like the noise at 2400, so typically throttle back a little to a happy drone.
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  #17  
Old 12-15-2011, 10:20 PM
ksouthar ksouthar is offline
 
Join Date: Apr 2005
Posts: 111
Default Fuel Flows

150 HP fixed pitch 3-blade Catto.

Flight plan 8 gph at 152 Knots. Never miss it by more than a couple gallons chock to chock on cross countries of 3 hours......

Keith
N355RV
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