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Fueling a RV-6...

H

H-Ottawa

Member
Sorry if this has somewhere been answered in this wealth of information on this site.

On my newly acquired RV-6: Obviously, the tanks hold 19 gallons each.

The question I have is about what is considered a full tank on a RV-6, compared to a RV-6A with it being in a more "level" attitude ?

When I fill up my tanks and reset the Dynon 180 to "FULL" do I actually have 38 gallons in the tank with a tailwheel RV ?

Is there a difference with an "A" model ?
Rgds
Harold
 
gas

Would be very little difference. The best way would be to completely empty the tanks. Fill a few gallons at a time, till they are topped off. During this time you can make a "dip stick" and mark the amount of fuel, plus calibrate your gauges (they need to be at zero with no fuel). You can also make note of where the gas is in relation to various parts in the tank. Ex 5 gallons the fuel just touches the lower stiffener. this is a very helpful way to visually check fuel qty. One last thing, sometimes the last gallon or so takes a few minutes to settle in the tank, just depends on the holes in the ribs, and vent line location.
so before you are done topping it off wait 5 minutes to see if it settings down.
 
For what it's worth:

I calibrated a dipstick for my 1993 vintage RV-6. I ran the right tank completely dry in flight and then filled it, marking a dipstick as I went. When I got to the bottom of the filler "neck" it had taken 19.0 gallons of fuel. The aircraft was level left to right and in a normal 3 point attitude.
 
In my opinion, anytime someone buys an already-built experimental, one of the first things the new owner should do is confirm total fuel, fuel flow at the max climb angle, and useable fuel.

Having said all that, I can't really cant see a significant difference in tank capacity when the tail is low vs up on a sawhorse.
 
H-Ottawa said:
When I fill up my tanks and reset the Dynon 180 to "FULL" do I actually have 38 gallons in the tank with a tailwheel RV ?
Click to expand...

I would think the more important question would be how much useable fuel do I have...................
 
H-Ottawa said:
Hence the question...:)
Click to expand...
By "confirm" I meant test it yourself. Though RVs are relatively standard, each has its own unique characteristics. Depending on pickup tube placement, for example, useable fuel could vary greatly from one plane to the next, or even one tank to the next! Fuel flow is another very critical test that can't be answered without testing. Finally, and more directly related to your specific question, calibrating the D180 for fuel level is easy and re-doing it yourself will provide an answer about fuel tank quantity that you know is accurate. All these tests need to be done for each plane.
Hope this helps and Have fun with your new purchase!
 
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I am a fuel chicken. I set my fuel totalizer for a max of 36 gallons usable. My unusable fuel was less than a gallon, but I put it at one gallon total, then added a gallon margin to get my 18 gallons. I did the same in calibrating my gauges.
Some may find that silly but I flight plan for 36 gallons too. That's just me.
 
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JonJay said:
I am a fuel chicken.
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YEP. Me too.

JonJay said:
My unusable fuel was less than a gallon, but I put it at one gallon total, then added a gallon margin to get my 18 gallons.

Some may find that silly but I flight plan for 36 gallons too. That's just me.
Click to expand...

Same here, but the actual numbers in the 10 work out different, concept is the same though.
 
Fuel Chicken

JonJay said:
I am a fuel chicken. I set my fuel totalizer for a max of 36 gallons usable. My unusable fuel was less than a gallon, but I put it at one gallon total, then added a gallon margin to get my 18 gallons. I did the same in calibrating my gauges.
Some may find that silly but I flight plan for 36 gallons too. That's just me.
Click to expand...


That's my plan as well.
I rather be overly cautious than overly optimistic.
In the same tone : I like that the RV6 can structurally perform aerobatics, but I won't myself, I like that built in (extra) safety factor though.:D
 
19 gal/tank exactly

I have ran both of my tanks dry in flight (not on the same flight, please) to check usable and total fuel in my RV-6. I was amazed that all but a few teaspoons of fuel was unusable and that it took exactly 19 gal to fill. I am sure it depends on how the fuel pick up tubes are oriented in the tank, I know mine are right on the bottom. Also I know that when the fuel is at the top of the bottom stiffiner angle just below the fuel fill I have 8 gal left (11 used) and when at the bottom of the same angle I have 5 gal left (14 used). Even when the bottom of the tanks are showing and it looks like you are on empty you still can have an hour of fuel remaining (2x5=10 gal). I will not take off with less than 5 gal in each tank even for a short hop around the patch.
 
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JonJay said:
I am a fuel chicken. I set my fuel totalizer for a max of 36 gallons usable. My unusable fuel was less than a gallon, but I put it at one gallon total, then added a gallon margin to get my 18 gallons. I did the same in calibrating my gauges.
Some may find that silly but I flight plan for 36 gallons too. That's just me.
Click to expand...

Guess I'm even sillier.....not only is my totalizer set for 36 gal with tanks topped, my RV-6 tanks are placarded for 18 gal each.
 
I calibrated two milk jugs with a measuring cup and a Sharpie and used those to calibrate my tanks. With my -9, I found each tank holds slightly more than 19 gallons, even though Van's list the number at 18. This may be a result of mine being a taildragger.

What I'm saying is that you need to test your plane.
 
Instead of setting the wrong quantity in the totalizer why not just set it up correctly and use proper fuel planning and reserves. It seems like using a incorrect total could lead to mistakes when cross checking totalizer accuracy after fueling and in comparisons between the gauges and the tanks.
In the back of your mind you always know you changed the amounts much like someone who sets their watch forward in a effort to be on time. It rarely makes a difference because you know how far ahead you set it.
George
 
Is there a difference between a -6 and a -6A in fuel capacity? I don't know, but a -6 could be toped off, and then the tail raised to a -6A attitude and see if any fuel spills out (fuel caps removed), or if there is additional space available.
 
noelf said:
Is there a difference between a -6 and a -6A in fuel capacity? I don't know, but a -6 could be toped off, and then the tail raised to a -6A attitude and see if any fuel spills out (fuel caps removed), or if there is additional space available.
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That probably wouldn't work.

IIRC, the plans call (called?) for a minor relocation of the location for the fuel filler neck if you were going to build a -6 vs a -6A so the opening was at the highest point of the tank with the airplane parked on the ground.
 
sailvi767 said:
Instead of setting the wrong quantity in the totalizer why not just set it up correctly and use proper fuel planning and reserves. It seems like using a incorrect total could lead to mistakes when cross checking totalizer accuracy after fueling and in comparisons between the gauges and the tanks.
In the back of your mind you always know you changed the amounts much like someone who sets their watch forward in a effort to be on time. It rarely makes a difference because you know how far ahead you set it.
George
Click to expand...

Not to worry, the one gallon difference in tank capacity and how the gauges and totalizers are calibrated has caused no problems in 15 years of flying the RV-6. I never fill the tanks all the way to the brim so 18 gal is closer to how the tanks are actually topped.

Yep, proper flight planning is essential, but there is no way I will plan (or execute) a flight where that one gallon will be the difference between a safe conclusion and otherwise.
 
I recall locating the tank filler as far to the rear as they would go for my -6A. Skins came as a simple rectangle so you had to cut them where necessary. Front skins were rolled to the approximate shape. Ribs did not have the lighting or drain holes cut so I enlarged the drains slightly. I think you didn't cut out the lighting holes in the tank ribs.

Rather than the flop tube shown on the plans, I put a piece of 1/2" aluminum in the bottom corner of the tank tapped for a AN fitting with a screen like used in my -10.

Once complete I do not think the filler location made much difference. The outlet change works well. When I did a tank dry test there was less than 2 oz. remaining.
 
Fuel cap position

I remember there being two positions for cutting the filler hole on the 6 and 6A that are a slightly different position fore and aft. Either this was in the plans or I did it myself.

Steve
 
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