Van's Air Force
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usable fuel
- Thread starter Ron B.
- Start date
czechsix
Well Known Member
Were you measuring this using a flowmeter (running a tank until all useable fuel is gone), or looking at the meter at a fuel pump when filling the tank? Flowmeters need to be calibrated, so if that's what you're using it's probably off by a couple gallons. If it's a faulty meter at your local fuel pump I'd recommend using it often, since it's likely giving you ~25 gallons and you're only paying for 23
.Obviously there's going to be a small amount of unusable fuel below the pickup, but I'd be surprised if it's more than half a gallon or so. Scott or one of the guys with a flying -14 should be able to confirm...
I filled the tanks checking for leaks then removed the line from the flow meter (before) and used the boost pump to return the fuel to my tank (portable). Went the boost pump started to sputter I turned it off. I then used a 2 US gallon fuel can and filed it to the 2 gallon mark and poured the fuel back in calibrating the Skyview at each fill.
BillL
Well Known Member
Unusable or tank capacity?
Kudos for running the test, Ron. I think you really want unusable, and fuel tank capacity. Right? Unusable should be done at cruise, nose down, and stall(or go-around) nose up attitude. It sounds like you are running the test properly, you could restrict the boost pump output to the max/min fuel pressure and measure flow at the same time to validate it's performance also.
If it is like the 10, there is very little unusable fuel, but it is sensitive to wing level. That test will have to be run in a flight test to ensure you will not run out of fuel in uncoordinated flight on landing.
Kudos for running the test, Ron. I think you really want unusable, and fuel tank capacity. Right? Unusable should be done at cruise, nose down, and stall(or go-around) nose up attitude. It sounds like you are running the test properly, you could restrict the boost pump output to the max/min fuel pressure and measure flow at the same time to validate it's performance also.
If it is like the 10, there is very little unusable fuel, but it is sensitive to wing level. That test will have to be run in a flight test to ensure you will not run out of fuel in uncoordinated flight on landing.
Ron,
I just did mine and my first engine start tonight. I was able to squeeze in about 25.5 gallons into each tank in level flight attitude. I am guessing you just missed recording one 3 gallon measure. Also, the unuseable fuel in the wing is just like the RV-10 was....basically about 1 cup. I filled and drained the tanks both. The floats stop reading around 22 gallons, very similar to the approx 23 that I got in the RV-10.
The engine fired right up within a couple of prop blades, so I was pretty happy with that.
I just did mine and my first engine start tonight. I was able to squeeze in about 25.5 gallons into each tank in level flight attitude. I am guessing you just missed recording one 3 gallon measure. Also, the unuseable fuel in the wing is just like the RV-10 was....basically about 1 cup. I filled and drained the tanks both. The floats stop reading around 22 gallons, very similar to the approx 23 that I got in the RV-10.
The engine fired right up within a couple of prop blades, so I was pretty happy with that.
Unuseable fuel (Visual)
Here is a photo I took just a minute ago. I took my fuel tank, ran it dry using the engine fuel pump, and then pulled the sump plug.
That should give you a good reference to how much fuel is left when running dry. And for size reference in the pic, my hands are normal size, not like Marco Rubio. But not really enormous like Donald Trump hands. (What a year, eh?)
Here is a photo I took just a minute ago. I took my fuel tank, ran it dry using the engine fuel pump, and then pulled the sump plug.
That should give you a good reference to how much fuel is left when running dry. And for size reference in the pic, my hands are normal size, not like Marco Rubio. But not really enormous like Donald Trump hands. (What a year, eh?)
