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01-20-2014, 07:24 PM
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Join Date: Jan 2014
Location: Evansville, In.
Posts: 30
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Fuel burn
I flew for 1 hr today, in my newly purchased 9A which is awesome, at 15 to 2500 feet MSL, 2200 rpm, with a 5 gal total fuel usage.
It has a 320-160hp, FP prop combo.
Is this pretty standard for this plane. Temp was 45 degrees F, Density Alt was minus 1000 feet.
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01-20-2014, 10:03 PM
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Join Date: Oct 2007
Location: Canada
Posts: 100
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Fuel burn
At that RPM and a low MP, I am closer to 6gph. If you did a number of circuits your total fuel consumption would be reasonable.
__________________
C-GVMK
RV9a Slow(ly) built
Flying as of July 2012
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01-21-2014, 09:11 AM
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Join Date: Oct 2008
Location: Utah
Posts: 8,151
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Enjoy your 9
That is a very good gph number. I rarely get that good fuel burn. Down the road there will be time when you won't care about gph anymore. You will be thinking of tpd (tankful per day). You may never go over 3 tpd 
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01-21-2014, 10:01 AM
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Join Date: Jan 2005
Location: Richmond, VA
Posts: 696
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I'd expect just a bit higher burn than 6 gph. Probably closer to 5.5 gph?but, I did a 1.2 hr flight with a tail wind, doing 150kts or a bit more, and I took 5.9 gallons of fuel when I arrived (4.9 gph). I have not duplicated those numbers and I tend to fly faster now. My memory is my IAS was just over 130.
Unequivocally, V-man has an iron arse. Three tankfuls of gas in one day? A 9A holds 36 gallons of fuel. If he keeps an hour reserve @ 6 gph, then a tank full = 30 gallons (if he cuts it to a 30 minute reserve add 1.5 hours to my calculation). 3 tankfuls = 90 gallons. 90 gallons at 6 gph = 15 hours of flying. I'm stunned - The most I've flown is literally half that long and felt like it was a long day. 15 hours! Wow. I'm not completely sure I could extract myself from the cockpit after 15 hours.
__________________
Don Alexander
Virginia
RV-9A 257SW Purchase Flying - O-320, Dynon D100
RV-9A 702DA (reserved) Finish Kit IOX-340
www.propjock.com
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01-21-2014, 10:38 AM
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Join Date: May 2005
Location: Tuttle, Oklahoma
Posts: 2,563
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Quote:
Originally Posted by Don
I'd expect just a bit higher burn than 6 gph. Probably closer to 5.5 gph?but, I did a 1.2 hr flight with a tail wind, doing 150kts or a bit more, and I took 5.9 gallons of fuel when I arrived (4.9 gph). I have not duplicated those numbers and I tend to fly faster now. My memory is my IAS was just over 130.
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Don, are you sure you are not talking MPH instead of KNOTS? 150kts is 172-173MPH. If this is true then I am stunned at the difference in fuel burn compared to my 9a. In my 9A it will easily cruise at 172MPH but I am burning 8-8.5gph in doing so. No way I can get down to 5.9/1.2 = 4.92gph at that speed.
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01-21-2014, 11:00 AM
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Join Date: Jan 2005
Location: Richmond, VA
Posts: 696
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Quote:
Originally Posted by RVbySDI
Don, are you sure you are not talking MPH instead of KNOTS? 150kts is 172-173MPH. If this is true then I am stunned at the difference in fuel burn compared to my 9a. In my 9A it will easily cruise at 172MPH but I am burning 8-8.5gph in doing so. No way I can get down to 5.9/1.2 = 4.92gph at that speed.
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I am positive its knots. Everything I have is calibrated in knots. The 150 kt figure is GS, not IAS, and I noted a tailwind in my post. I'm not positive but my memory is I had about a 20 knot tailwind, which sure helped. At 150 IAS I'd be burning around 8 gph?if I could get there.
FWIW, I regularly see fuel burns of less than 5.5 gph @ when I'm cruising around 130 knots IAS (2200-2250 RPM).
__________________
Don Alexander
Virginia
RV-9A 257SW Purchase Flying - O-320, Dynon D100
RV-9A 702DA (reserved) Finish Kit IOX-340
www.propjock.com
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01-21-2014, 11:05 AM
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Join Date: Mar 2005
Location: Ramona, Ca
Posts: 259
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Another data point: I normally/consistently cruise @ 145 KTAS, 4500ft / 5500ft MSL with throttle set to about 2400 RPM fuel burn is 6.8 to 7.2 gph. This is with O-320, fixed pitch Sensenich carbon fiber ground adj prop with #4 pin which is very close to the numbers I would get with the Van's standard recommended metal Sensenich prop.
YMMV
Bill
__________________
Bill RV-9A Flying
FFI- Flight Lead
N99WC
Ramona, CA (KRNM)
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01-21-2014, 11:19 AM
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Join Date: Dec 2005
Location: Mahomet, Illinois
Posts: 2,195
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I agree the 5gph seems w-a-y low for the performance numbers. I would see a burn very similar what others said. Somewhere likely between 6 and 7. Is that fuel burn corroborated by both tank gauges and fuel flo totalizer?
__________________
Terry Ruprecht
RV-9A Tip-up; IO-320 D2A
S. James cowl/plenum
(Dues paid thru Nov '18)
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01-21-2014, 11:36 AM
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Join Date: May 2005
Location: Tuttle, Oklahoma
Posts: 2,563
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Quote:
Originally Posted by Don
I am positive its knots. Everything I have is calibrated in knots. The 150 kt figure is GS, not IAS, and I noted a tailwind in my post. I'm not positive but my memory is I had about a 20 knot tailwind, which sure helped. At 150 IAS I'd be burning around 8 gph?if I could get there.
FWIW, I regularly see fuel burns of less than 5.5 gph @ when I'm cruising around 130 knots IAS (2200-2250 RPM).
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Aw, Don, now that makes much more sense!
Because of the great variability of wind conditions ( head, tail, cross winds) I never think of discussions associating speed readings as they relate to fuel burn in terms of ground speed.
Yes 5.5gph @ 130kts IAS does indeed sound very reasonable for the 9A.
Indicated Airspeed ( IAS), True Airspeed ( TAS), Calibrated Indicated Airspeed ( CIAS), Ground Speed ( GS) all have their place when discussing the performance of an aircraft. However, each has their purpose and usually is more meaningful in some discussions, less meaningful in others. I think it wise to define the TYPE of speed being discussed before hand anytime we are making comparisons.
In my case I typically use TAS when discussing cruise performance and fuel burn. In my opinion it is a much more accurate depiction of the true performance of the aircraft. Granted I have a nice GRT EFIS that constantly displays that information and am aware that many may not have instrumentation that will give them that information readily. In the absence of TAS information I think it would be better to discuss speed in terms of IAS when dealing with fuel burn. There are too many variables associated with wind and altitude for GS to be a good tool for that purpose.
As for my 9A, I typically cruise at 165mph TAS ( 143kts). Depending on the altitude I cruise I can typically see anywhere from 6.9 to 8.5 gph at that speed. Down lower equates to higher fuel burns ( 2000 to 6000 Mean Sea Level (MSL)). Up Higher I can see much lower burns ( 8000+ MSL).
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01-21-2014, 12:10 PM
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Join Date: Jan 2005
Location: MN
Posts: 2,269
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go lean......up high
It can be done........
130KTAS 4.9-5.1GPH down low
150KTAS 6.0-6.1 GPH up high
The Van's plane did even better at the CAFE Foundation!!!
http://www.vansairforce.com/communit...7&postcount=20
__________________
Cheers,
Pete
Amateur Plane - RV-9A N789PH - 2350+ Hrs
Amateur Radio - KD0CVN
Doggies Delivered - 25+
St. Paul, MN
Last edited by petehowell : 01-21-2014 at 12:15 PM.
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