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What do you flight plan for cruise speed and fuel burn?

Top Cat

Well Known Member
What do you folks use for cruise speed and fuel burn when planning a cross country in the RV-12?

I would really appreciate any and all experienced input, thanks!
 
Cruising at 3000'msl 5450 RPM 5.5 gals an hour.:) Lower RPM means lower gals per hour!
 
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Fuel burn

Can't give you much on cruise speed since I just made by first flight about a week ago but I have 1000 hours on the same engine in my other airplane and that burn sounds right.

I cruise @5000 rpm and get consistent 4.2-4.3 gal/hr. @5200 rpm, 4.6 - 4.8 gal/hr. @5500 rpm, 5.5-5.6 gal/hr.

The RV-12 is faster but WOT on both are about the same.

Bill
 
You will need to refine the numbers for your own airplane, and your cruising habits, because there are just two many variables to quote a "standard" number. For example:

Prop pitch, which affects RPM vs. MP ratio.
Desired cruise speed.
Cruising altitude.

The nice thing is, you can fly this engine/airplane combination at a wide range of power settings, depending on your mission that day. Going somewhere in a hurry? WOT at high altitude. Local sightseeing? Low power, low fuel burn, low speed.
 
Thanks for the info!

So…one guy told me 5140 rpm (about 21MAP) produces 4.5 gph. That sound right? (for planning).

Thanks again.

Look in the POH. Should be listed there after initial flight test determines the numbers for your aircraft.
 
Look in the POH. Should be listed there after initial flight test determines the numbers for your aircraft.

I haven't picked my airplane from Vans yet so I don't have access to POH.

I appreciate the actual working numbers from experienced owners as I start planning flying trips. Thanks guys!
 
Cheapskate

Given the cost of fuel in Europe and, being retired, there's no rush so I fly at 100 kts burning 15.5 litres an hour, that's under 4 gph.

Cheers...Keith
 
I plan for 100 kts over ground and 5 gallons per hour. If the wind is favorable and I make much more than 100 kts ground speed, I try to slow her down to conserve gas as coming back might require a bit higher fuel burn to compensate for the head wind.
 
On my. Way home from Aurora in my new SLSa and I have found that about 5100 rpm really does produce 4.5 GPS.

performing very well...out of Tucson at 2pm (I know...) at 105f with a hot engine she climbs well all the way to 7500 with lots of level offs for cooling and kept climbing! -awesome:)
 
Howard,

I get 4.5 GPH AT 5100 RPM as I posted earlier. What TAS did you get in cruise at 5100 RPM?

Rich

Rich,

Today was the last day of my journey back from Vans to my home in SC. I did 2 legs today and made a point of trying to see what I got?at 5140-80 I consistently got 114-116kts TAS.
Although the fuel flow indicator was usually showing 3.9 to 4.0 gph the gph based on the refueling amount was constantly 4.5gph.

I'm VERY happy with the plane!!:D
 
Howard,

Glad you like your 12. You can reset your K factor and get the computed fuel burned to within a few tenths of a gallon on a flight of two hours. I set mine by fuel flow indication as opposed to actual fuel burned based on my typical cruise. The result was right on the money for computed fuel burn.

Rich
 
Rich,

I had a conversation with Vans about that and figured it was something I'd deal with (and figure out!) later.
Vans also said the same thing about the K factor and the fuel quantity mis-match (I think). They said by fine tuning it, you can, in conjunction with tuning the fuel burn, get the fuel computer and tank senders to agree much more closely.
I guess this is the same thing really. Vans said they arrive at a K-factor which is their best idea of the right number.

I found on my flight home from Vans I've found that the fuel remaining seems to be about 2 gals under what the tank gauge says. When I land my number of the tank indication plus 2 is accurate but I'd like it to read that on the gauge, if that's possible.
It'll be a work in progress I'm sure.
 
You can recalibrate the float by emptying the tank and adding 2 gallons at a time in the "calibrate" mode. It's a bit of a pain in the posterior, but if done right you will be happy. Mine reaches the float stop at 16 gallons, but once the actual level drops below 16 gallons my indicated fuel level is within 1/2 gallon of actual.
 
I learned from a guy with more experience than I have that the tank's mechanical Moeller (?sp) gage shows full when the float hits the top and that is about 16 gallons. Then another 3.8 can be added without filling the fueling trunk between the cap and the tank for the full 19.8 gallons available.

Filling the tank more than that.....up into the fueling trunk.....will cause fuel to overflow from the drain under the tank and, especially so, if it's hot outside. It may also give you a face full of gas:)

My Skyview shows "15+" gallons as remaining until the total goes below that. Then it seems the Skyview is accurate as to the gallons remaining because using the 19.8 gallon procedure above.....adding 3.8 gallons after the Moeller gage reads full.....works.

EBB
 
Moeller location

A bit off topic. Since the Moeller gauge is used primarily for fueling, we mounted our gauge further back toward the rear of the tank. When it reads full the tank is full! It is fairly accurate down to about half tank but not as accurate after that. Works well for pre-flight inspection. A look in the window pretty much says it all.

Richard
 
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