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Buckaroo

Another fuel tube question?

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If your flight isn't long enough fuel transfer will be slight at best. If you're just flipping around doing T&G's then it won't happen either. It needs to be in a cruise situation and the flight needs to be arouind 1 hr. or more.

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Everyone in this thread talks about transferring fuel either intentionally or not by slipping.

Fuel will follow the ball either way, from a slip or a skid.  A slip has a visual clue (bank) where a skid is likely a failure to hold heading with wings level and therefore can be the real culprit.

In the hangar with a level the the only force at play is gravity but in the air you can transfer from the low wing to the high wing that's why we look at a ball and not our bank.

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Buckaroo, I'm not sure how much fuel you are starting with, but you can't even start the balance process until you can see air in the sight tube on one side. I know it may not be an option for you with your landscape or airplane equipment, but here in the flat lands with my airplane I can figure out where things need to be to keep fuel balanced by flying on autopilot and trimming the rudder so the wings are level with the horizon. If I do this my fuel stays balanced, and the ball is 1/2 a ball out like Roger says.

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23 minutes ago, Tom Baker said:

Buckaroo, I'm not sure how much fuel you are starting with, but you can't even start the balance process until you can see air in the sight tube on one side. I know it may not be an option for you with your landscape or airplane equipment, but here in the flat lands with my airplane I can figure out where things need to be to keep fuel balanced by flying on autopilot and trimming the rudder so the wings are level with the horizon. If I do this my fuel stays balanced, and the ball is 1/2 a ball out like Roger says.

Tom, 

Trimming your rudder on AP (holding a heading) so wings are level works. 1) your eye checking level wings makes sure you are not slipping and your AP holding the course makes sure you are not skidding. :) 

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2 minutes ago, FlyingMonkey said:

I usually don't balance any fuel until the lowest tube is at the halfway mark.  There's not any real reason to worry about it before then. 

I pretend that my binnacle gets moved around all the time so as soon as the level(s) appear I see the trend for today and trim my rudder to counter that tendency but just a slight amount.  This often keeps me balanced all the way to low fuel and sometimes not.

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I'm thinking that now shimming my plane level in the hanger instead of starting off with a 4 inch lower right wing may moderate this huge fuel imbalance! 

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37 minutes ago, Tom Baker said:

Buckaroo, I'm not sure how much fuel you are starting with, but you can't even start the balance process until you can see air in the sight tube on one side. I know it may not be an option for you with your landscape or airplane equipment, but here in the flat lands with my airplane I can figure out where things need to be to keep fuel balanced by flying on autopilot and trimming the rudder so the wings are level with the horizon. If I do this my fuel stays balanced, and the ball is 1/2 a ball out like Roger says.

So if the wings are perfectly level and the ball is one ball out of center to the left say that will feed the left tank. With this in mind what forces are pushing fuel to the left tank with wings level??

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13 minutes ago, Buckaroo said:

So if the wings are perfectly level and the ball is one ball out of center to the left say that will feed the left tank. With this in mind what forces are pushing fuel to the left tank with wings level??

If the wings are level and the ball is calibrated (reading correctly) and it is out of center to the left it will feed the left tank. The same yaw forces (centripetal?) that allow you to fly by the seat of your pants move the ball and now have the fuel transferring from the leading wing to the trailing wing (via uneven usage not actual transfer).

The reason people fly with the ball off center is because they know their ball is wrong and they are trying to prevent unwanted transferring.

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13 minutes ago, Buckaroo said:

So if the wings are perfectly level and the ball is one ball out of center to the left say that will feed the left tank. With this in mind what forces are pushing fuel to the left tank with wings level??

There is an old saying that says, "If it ain't broke don't fix it". I start with both tanks equal, and this method keeps both tanks equal. By doing this you don't have to push any fuel from one tank to the other, because they both drain equally.

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18 minutes ago, Ed Cesnalis said:

If the wings are level and the ball is calibrated (reading correctly) and it is out of center to the left it will feed the left tank. The same yaw forces (centripetal?) that allow you to fly by the seat of your pants move the ball and now have the fuel transferring from the leading wing to the trailing wing (via uneven usage not actual transfer).

The reason people fly with the ball off center is because they know their ball is wrong and they are trying to prevent unwanted transferring.

Yes but pushing the ball to the left puts the left wing in front. ?

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9 minutes ago, Buckaroo said:

Yes but pushing the ball to the left puts the left wing in front. ?

I think you got me, skids transfer to the outside or leading.

The concepts that fuel follows the ball and both slips and skids transfer remain true.

thanks

 

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On 8/29/2017 at 10:54 AM, Tom Baker said:

You can help the flow get started by climbing on a ladder and placing you mouth on the vent tube and gently adding some air pressure to the tank, just be careful.

WARNING Never used compressed air to pressure the tank or blow out vent lines.

Tom I just tried this and damn it worked!? The tanks are totally equal. 

One of the local A&P's suggested I switch vents.?

 

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11 minutes ago, CT2K said:

Came across this video and wondered if the Header Tank solution can help with the tank imbalance issue. Any thoughts?

https://www.youtube.com/watch?v=i_sVFpfxOuc

 

A header might help (there is one in the CTLSi), BUT...

Where would you put it?  You need to run the lines from each tank to the header, and those lines currently run down the A pillars to T off ahead of the fuel valve.  There is nowhere that is a suitable or large enough location in that route to install a header.  If you were to install it in the baggage bay, you then have to reroute the entire aft-firewall fuel system to make it work.  The only way to do that would be to run fuel lines down through the central tunnel.  

Personally I see additional fuel lines running through the cockpit as a bigger hazard than the potential for fuel starvation due to fuel levels in the main tanks. 

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2 hours ago, Buckaroo said:

Tom I just tried this and damn it worked!? The tanks are totally equal. 

One of the local A&P's suggested I switch vents.?

 

You do have the bevel facing forward on both vents, don't you?

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Hi fellows,

there is much said about fuel transferring from one side to the other and I agree with all of you. There is only one thing unmentioned in the discussion:

The air vent tubes on top of the filler caps have a little hat, which is cut at an specific angle. This is to steal a little air pressure from the outside air and to pressurize the tank a little bit in flight. If the two vent tubes are not aligned, one pressurizes its tank a little bit more than the other which induces unintended fuel flow.

On one of our club CTSWs, which had always the tendency to move fuel from one side to the other, I found, that the cut angles of the vent tube hats were different. We then compared the filler caps of two CTSWs and found, that the cut angles are all different. After filing the hats to have all the same angle and to align them correct to the wind, the tendency to transfer fuel has gone away.

Maybe this helps you.

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1 hour ago, FlyRatz said:

Hi fellows,

there is much said about fuel transferring from one side to the other and I agree with all of you. There is only one thing unmentioned in the discussion:

The air vent tubes on top of the filler caps have a little hat, which is cut at an specific angle. This is to steal a little air pressure from the outside air and to pressurize the tank a little bit in flight. If the two vent tubes are not aligned, one pressurizes its tank a little bit more than the other which induces unintended fuel flow.

On one of our club CTSWs, which had always the tendency to move fuel from one side to the other, I found, that the cut angles of the vent tube hats were different. We then compared the filler caps of two CTSWs and found, that the cut angles are all different. After filing the hats to have all the same angle and to align them correct to the wind, the tendency to transfer fuel has gone away.

Maybe this helps you.

My left tanks little hat is slightly turned left of center maybe 10 degrees. 

Question: can I just loosen the nut and turn it straight or do I need titanium locktight and laser testing?

Also can that small degree of cant cause that tank to drain more?

IMG_5163.JPG

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I don't think that would matter much.  As long as it's generally forward withing 20° or so I think it's fine.  Mine have been slightly off a bit from time to time like your picture with no ill effects.

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Back in 2007 I did a research project and turned that to each 90 degree mark. It makes no difference. I even put on different vent tubes and some facing forward for a positive pressure setup.

It makes no difference.

 

Just fly with 1/2 ball out to keep fuel equal.  (Don't make me send this in a certified letter.) ;)

 

Yes you can loosen the nut and turn it so the dot faces forward.

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21 hours ago, Roger Lee said:

Back in 2007 I did a research project and turned that to each 90 degree mark. It makes no difference. I even put on different vent tubes and some facing forward for a positive pressure setup.

It makes no difference.

 

Just fly with 1/2 ball out to keep fuel equal.  (Don't make me send this in a certified letter.) ;)

 

Yes you can loosen the nut and turn it so the dot faces forward.

I'm special could you send it certified????

Seriously since I now hanger the plane level as opposed to 4 inches low on the right wing the frustrating effects of "one hung low"are vastly improved. By the time I taxi, warm up and run up the left tube is showing air so she's transferring some during that time. At least it's improved a bunch. 

Id still like to find out what fuel will flow to wings level in a slip say ball left of center??

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1 hour ago, Buckaroo said:

Id still like to find out what fuel will flow to wings level in a slip say ball left of center??

Wings level ball left is a skid not a slip fuel flow will favor burn from right tank and appear as though transferring from right to left. 

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