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Engine failure today and forced landing.


Buckaroo

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1 hour ago, Tom Baker said:

The same process that you use to transfer fuel from one tank to the other, is the same action that moves fuel outboard in the tank you are transferring to. By moving the ball you are moving the fuel. If you are trying to transfer from the left to the right all the fuel must move to the right. This includes the fuel in the right fuel tank. That is why the sight tube for the right tank showed that you had less fuel, because you move the fuel in the right tank to the right which is outboard and away from the sight tube.

This makes sense as to why you move the fuel slowly with one or 1/2 ball width. 

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1 hour ago, Ed Cesnalis said:

This is normal.  Turbulence disturbs the level and the level is only correct when your calibrated ball is centered.

To find the correct level as well as where your nose is in the relative wind, focus on one wing at a time.  Position the rudder so that the fuel in the sight tube will go up if given rudder travel in one direction and the fuel will go down if you move the rudder the other way.  Its best to find this middle with trim and then just look for left rudder = level up and right rudder = level down.  Now check the other wing and it should do the opposite.  When you have found this position your sight tubes are correct and your nose is in the wind.  Note your ball, is it in the center?  Until your binacle moves again this is your  new 'middle'.

 

I'll try this Ed thanks! This is starting to make sense!  

Ive come a long way from last week flying around in la la land!

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Buckaroo, I believe that you are probably spooking yourself due to your engine out event and are over thinking this sight tube fuel situation.  Although I have not run out of fuel, I understand this situation would leave a lasting impression on me too.  Even so, with one tube @ 3/4 and the other showing even more fuel, If it were me, I'd just continue on with my flight while keeping the ball 1/2 towards the side with 3/4 showing.  I would not be eagle eyeing the tubes but would occasionally fly with ball centered and glance at my sight tubes.  In a while, after flying with the ball @ 1/2 towards the low side, you should see that you are slightly better for fuel balance when you fly level.  An example of a maximum worst condition is where one wing may be totally dry and the other has a few gallons remaining.  As others have said here, as long as you can see fuel on at least one sight tube, and you continue to fly in a manner which keeps this fuel showing, the engine will continue running. Obviously, this situation would be one where it is HIGHLY recommended that a suitable landing spot, preferably with fuel available, is quickly found and utilized!

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4 hours ago, Buckaroo said:

This makes sense as to why you move the fuel slowly with one or 1/2 ball width. 

My guess is that rate of transfer has to do with fuel line diameter and not bank angle.

You could simulate this with clear tubing and a glass of water.  Start a siphon with the glass 1' above the drain and note the flow rate.  Now raise the glass to 3' above the drain and notice the flow rate appears the same.  If you have a pressure differential you have a flow rate mostly constricted by the diameter. If you increase bank angle and therefore pressure differential there is little/no change because the increase in differential is negligible. 

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Ed, sorry, but physics says otherwise.  The higher the column of fluid (i.e., the difference in the level of fuel in the tanks - or in your terminology - the bank angle [without any yaw, also known as a slip]), the faster the flow rate.  

Of course, flow rate is also a function of the diameter of the orifice (tube diameter), but both operate independently of each other.  

flow rate = pressure / resistance

So, both the difference in the height of the tanks as well as the resistance to flow affect flow rate. And, each affects flow rate regardless of the effect that the other is also having.  

Fred

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5 minutes ago, FredG said:

Ed, sorry, but physics says otherwise.  The higher the column of fluid (i.e., the difference in the level of fuel in the tanks - or in your terminology - the bank angle [without any yaw, also known as a slip]), the faster the flow rate.  

Of course, flow rate is also a function of the diameter of the orifice (tube diameter), but both operate independently of each other.  

flow rate = pressure / resistance

So, both the difference in the height of the tanks as well as the resistance to flow have the ability to affect flow rate. 

 

Fred

Fred I said the relative height of the source (or bank angle) makes a negligible difference. Say I'm at 10,000', the diameter is a fixed component of our equation but the pressure differential (and gravitational differential) are negligible because the distance from the surface to 10,000' ( or from the center of the earth ) compared to the the differential in the fuel tank levels is negligible. It will be something like a rounding error that won't change your result.

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12 minutes ago, FredG said:

Ed, sorry, but physics says otherwise.  The higher the column of fluid (i.e., the difference in the level of fuel in the tanks - or in your terminology - the bank angle [without any yaw, also known as a slip]), the faster the flow rate.  

Of course, flow rate is also a function of the diameter of the orifice (tube diameter), but both operate independently of each other.  

flow rate = pressure / resistance

So, both the difference in the height of the tanks as well as the resistance to flow affect flow rate. And, each affects flow rate regardless of the effect that the other is also having.  

Fred

?

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3 hours ago, Runtoeat said:

Buckaroo, I believe that you are probably spooking yourself due to your engine out event and are over thinking this sight tube fuel situation.  Although I have not run out of fuel, I understand this situation would leave a lasting impression on me too.  Even so, with one tube @ 3/4 and the other showing even more fuel, If it were me, I'd just continue on with my flight while keeping the ball 1/2 towards the side with 3/4 showing.  I would not be eagle eyeing the tubes but would occasionally fly with ball centered and glance at my sight tubes.  In a while, after flying with the ball @ 1/2 towards the low side, you should see that you are slightly better for fuel balance when you fly level.  An example of a maximum worst condition is where one wing may be totally dry and the other has a few gallons remaining.  As others have said here, as long as you can see fuel on at least one sight tube, and you continue to fly in a manner which keeps this fuel showing, the engine will continue running. Obviously, this situation would be one where it is HIGHLY recommended that a suitable landing spot, preferably with fuel available, is quickly found and utilized!

Runtoeat thank you for your clear and pragmatic post! You hit on many of my concerns in a easy to understand approach! It almost sounds like you might of been faced with the same questions I have when starting new in the CT series. 

I hope my questions have helped new CT pilots understand the unique idiocycrocys  of the aircraft and be that much more safe! 

I really am starting to enjoy this fine airplane! 

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Buckaroo,

Think of each tank like a baby bottle. If you don't get the milk to the nipple baby does not eat!  Tip up the bottle. Very same thing with your tanks. If you can see fuel in the sight tube the nipple is full and the engine eats. Even if the other side has nothing in the sight tube keep the opposite side showing fuel in that sight tube and the engine eats. I never worry about transferring fuel to another tank, only transferring it to the engine by keeping at least one nipple loaded with fuel at all times, that is what counts.

There have been lots of comments about banking..a proper coordinated turn has no effect on the fuel differently than coordinated level wings flight. Only skids or slips have an effect on the location of the existing fuel. And like others have said, you probably have to fly a little uncoordinated when you are really getting down on fuel in order to keep that nipple full on the tank that has fuel in it. And at all costs don't skid a turn or slip in the wrong direction with one tank empty. Always keep that fuel showing in the sight tube but especially when low on fuel.

Larry

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20 minutes ago, Flying Bozo said:

Buckaroo,

Think of each tank like a baby bottle. If you don't get the milk to the nipple baby does not eat!  Tip up the bottle. Very same thing with your tanks. If you can see fuel in the sight tube the nipple is full and the engine eats. Even if the other side has nothing in the sight tube keep the opposite side showing fuel in that sight tube and the engine eats. I never worry about transferring fuel to another tank, only transferring it to the engine by keeping at least one nipple loaded with fuel at all times, that is what counts.

There have been lots of comments about banking..a proper coordinated turn has no effect on the fuel differently than coordinated level wings flight. Only skids or slips have an effect on the location of the existing fuel. And like others have said, you probably have to fly a little uncoordinated when you are really getting down on fuel in order to keep that nipple full on the tank that has fuel in it. And at all costs don't skid a turn or slip in the wrong direction with one tank empty. Always keep that fuel showing in the sight tube but especially when low on fuel.

Larry

Thanks Larry! My natural instinct to bank left when I saw my left empty site tube ironically turned out to be my mistake because evidently I was uncoordinated. 

For safety it's too bad the fuel can't be somehow encapsulated against the feed tubes thus making a "sling out" unlikely! 

In level flight things should sort themselves out! I wonder if just wiggling the rudders back and forth while level would even things out?

Great post thanks!

Dave

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Dave, I would not wiggle the rudders. That will alternately un-port the "nipples" on and off giving baby GAS!! and in the plane that is not gasoline. You will be sending air pockets down the fuel line and at some point might actually kill the engine. Just a little steady rudder in the proper direction to keep the fuel against the sight tube.

I hesitate to tell you how little fuel I had left one day after a flight when my stickers were in the wrong place when I bought the plane. The plane did just fine since I already knew about keeping the fuel in sight on whichever tank had any in it from other fuel management airplanes.

Somebody posted, "If you can see fuel you can use the fuel" and thanks whoever did that post. Saved my BUTT!.

Larry

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2 hours ago, Flying Bozo said:

Dave, I would not wiggle the rudders. That will alternately un-port the "nipples" on and off giving baby GAS!! and in the plane that is not gasoline. You will be sending air pockets down the fuel line and at some point might actually kill the engine. Just a little steady rudder in the proper direction to keep the fuel against the sight tube.

I hesitate to tell you how little fuel I had left one day after a flight when my stickers were in the wrong place when I bought the plane. The plane did just fine since I already knew about keeping the fuel in sight on whichever tank had any in it from other fuel management airplanes.

Somebody posted, "If you can see fuel you can use the fuel" and thanks whoever did that post. Saved my BUTT!.

Larry

Thanks Larry I'm posing as many scenarios as I can to sort out the does and don'ts. 

Curious what other fuel management small planes require the same or close to same procedures? 

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There seems to be 2 scenarios:  Selectable fuel valve (left/right/both/off) or a simpler ON/OFF.  With the selectable valve, the routine is generally a time interval thing, where you change the valve every X minutes.  Many aviation timers have been invented to facilitate these reminders.  The other scenario, like the CT, requires the pilot to be familiar with the potential for uneven tank use and to monitor and compensate for it.  The problem with the selectable fuel valve is that history has proven that it's easy to forget, or turn the valve the wrong way, or to a bad position, and you end up with a problem.  A large number of incidents are directly attributed to fuel valve screw-ups.

Both methods have their proponents.  The new CTs, and perhaps other aircraft, have a header tank that collects from both wings.  It's not there solely for the feed problem, but it helps mitigate the issue.  But, then, it creates another problem of having another tank somewhere in the plane, that you have to worry about.

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14 hours ago, sandpiper said:
33 minutes ago, CT4ME said:

There seems to be 2 scenarios:  Selectable fuel valve (left/right/both/off) or a simpler ON/OFF.  With the selectable valve, the routine is generally a time interval thing, where you change the valve every X minutes.  Many aviation timers have been invented to facilitate these reminders.  The other scenario, like the CT, requires the pilot to be familiar with the potential for uneven tank use and to monitor and compensate for it.  The problem with the selectable fuel valve is that history has proven that it's easy to forget, or turn the valve the wrong way, or to a bad position, and you end up with a problem.  A large number of incidents are directly attributed to fuel valve screw-ups.

Both methods have their proponents.  The new CTs, and perhaps other aircraft, have a header tank that collects from both wings.  It's not there solely for the feed problem, but it helps mitigate the issue.  But, then, it creates another problem of having another tank somewhere in the plane, that you have to worry about.

Even in an an airplane with a tank selector, uncoordinated flight can unport the (now only) feeding tank can cause a starvation stoppage.  That's why most airplanes with selectors have a header tank.  I think a 1-2 gallon header tank in the CTSW would end 90% of concerns over this issue, giving some margin of time to fly with both pickups dry until the fuel sloshed back over them.

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Sorry Ed.  You can have your own opinions, but you can't have your own physics.

The difference in fluid column height is not with respect to the distance to the center of the earth (in which case you would be correct).  It is the difference in the height of the two columns of fluid with respect to each other.  

You would be correct if we were discussing the effect of gravity, but we are not.  We are discussing the effect of column weight on the pressure (sometime called head pressure) generated at the tube connecting the two tanks.  That can change quite a bit when one wing is lifted.  

Here is an example.  Suppose two tanks are connected by a tube (just like the fuel tanks on our airplanes).  Also suppose that the level of fuel in the transfer "from" tank is three inches higher than the level of fuel in the transfer "to" tank.  Absent forces other than gravity, after some period of time the fuel levels will equalize. Suppose now that the plane is banked further and the the level of fuel in the transfer "from" tank is now 12 inches higher than the level of fuel in the transfer "to" tank.  The fuel levels will equalize in half the time it took for them to equalize at three inches.  Each doubling of the column height results in a reduction of time needed to transfer a given amount of fluid by the square root of 1/2 (a value of approximately 0.71).

fg

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3 hours ago, FredG said:

Sorry Ed.  You can have your own opinions, but you can't have your own physics.

The difference in fluid column height is not with respect to the distance to the center of the earth (in which case you would be correct).  It is the difference in the height of the two columns of fluid with respect to each other.  

You would be correct if we were discussing the effect of gravity, but we are not.  We are discussing the effect of column weight on the pressure (sometime called head pressure) generated at the tube connecting the two tanks.  That can change quite a bit when one wing is lifted.  

Here is an example.  Suppose two tanks are connected by a tube (just like the fuel tanks on our airplanes).  Also suppose that the level of fuel in the transfer "from" tank is three inches higher than the level of fuel in the transfer "to" tank.  Absent forces other than gravity, after some period of time the fuel levels will equalize. Suppose now that the plane is banked further and the the level of fuel in the transfer "from" tank is now 12 inches higher than the level of fuel in the transfer "to" tank.  The fuel levels will equalize in half the time it took for them to equalize at three inches.  Each doubling of the column height results in a reduction of time needed to transfer a given amount of fluid by the square root of 1/2 (a value of approximately 0.71).

fg

Thanks Fred I just learned something.

 

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1 minute ago, FredG said:

Ed, you have changed the topic.  Of course we can transfer fuel when the fuel levels are equal, all we have to do is create a force acting on the fuel which can be done with wings level by performing a skidding turn.  Back to the original question.  

Your statement (and the reasoning you offered) above, "If you increase bank angle and therefore pressure differential there is little/no change because the increase in differential is negligible." is just plain incorrect.  In my previous post, I provided you with an example that shows the actual amount by which you were incorrect.  The transfer time is cut in half when the difference in fuel heights increases from 3" to 12".    

This isn't a matter of opinion and it doesn't need to be tested empirically.  All you need to do is look up Torricelli's Law on the internet.  

Yes Fred I deleted that post.  I have learned something.  I guess your saying your formula is true regardless of diameter?

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In light of what I just learned I suppose the distance the ball is moved from the center in order to transfer fuel speaks to the rate just like bank angle will.

If more head pressure from gravity increases rate more head pressure from slipping would as well and I'm now guessing that the ball speaks to direction and rate.  Is that right Fred?

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First question:  Yes, both diameter of the tube and height of the column (pressure head) are independent determinants of flow rate.  So, both are important and neither can negate the effect of the other.

Second question:  Yes, the greater the deviation of the ball from the center of the "cage" the greater the rate of fuel transfer (assuming a correctly rigged ball).  In fact, the ball deviation is the most accurate indicator because it indicates all forces acting on the airplane.  As you know, it is possible to bank the airplane without moving the ball from the center.

 

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1 hour ago, FredG said:

First question:  Yes, both diameter of the tube and height of the column (pressure head) are independent determinants of flow rate.  So, both are important and neither can negate the effect of the other.

Second question:  Yes, the greater the deviation of the ball from the center of the "cage" the greater the rate of fuel transfer (assuming a correctly rigged ball).  In fact, the ball deviation is the most accurate indicator because it indicates all forces acting on the airplane.  As you know, it is possible to bank the airplane without moving the ball from the center.

 

Interesting debate! So if we use a lot of slip or ball to quickly gather fuel in a needed tank what happens in a tank that has six holes that gathers fuel in a trapped fuel tip chamber? 

The other day I banked left to feed the left tank but skidded therefore throwing 8 gallons of fuel across a barrier that restricted flow back to the engine in a timely manner. I wonder why the tank design includes the fuel tank chamber therefore slowing critical fuel return to the engine! I think I have the answer! If there was no fuel tank tip chamber in a skid or in turbulence fuel would slash out of the vents. 

I think maybe the long horizontal fuel tanks holding 34 gallons of fuel may be the problem! A shorter tank containing less fuel but more flow say 25 gallons may of best suited the design! 

Yes or no??

 

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It's always going to be an issue... between slosh, angles, and forces associated with flying, there will be some "unavailable" fuel sometime.  I'd rather start out with 34, and end up with 28, than start out with 25 and end up with 20.  I've flown around 700 hours in CTs and only had one "close call".  That particular time was a 4.5 hr flight, and I landed with 8 gallons in the tank I thought was low.  I suspect you'd hear similar experiences from the high-hours-in-CT folks here on the forum.

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3 hours ago, FredG said:

First question:  Yes, both diameter of the tube and height of the column (pressure head) are independent determinants of flow rate.  So, both are important and neither can negate the effect of the other.

Second question:  Yes, the greater the deviation of the ball from the center of the "cage" the greater the rate of fuel transfer (assuming a correctly rigged ball).  In fact, the ball deviation is the most accurate indicator because it indicates all forces acting on the airplane.  As you know, it is possible to bank the airplane without moving the ball from the center.

That explains a lot.

Thanks Fred!

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