Fluid transfer question?

[Buckaroo]

I understand the gas follows the ball concept. My question is if you fly wings lever, on a course and ball let’s say left of center will fuel still transfer left.  Basically you’re just yawed right so to me no transfer but maybe I’m wrong. 

[Ed Cesnalis]

15 minutes ago, Buckaroo said:

I understand the gas follows the ball concept. My question is if you fly wings lever, on a course and ball let’s say left of center will fuel still transfer left.  Basically you’re just yawed right so to me no transfer but maybe I’m wrong. 

The force that moves your ball from center is the force that transfers the fuel.  You can't yaw without yaw forces. If your not turning it seems to be a steady state with no forces but your left wing will be higher than the right and gravity still works.

[Buckaroo]

Yes but wings level just yawed. 

[Ed Cesnalis]

7 minutes ago, Buckaroo said:

Yes but wings level just yawed. 

no such thing.

as soon as you transition into the yaw you need bank to counter to prevent the turn

[Buckaroo]

37 minutes ago, Ed Cesnalis said:

no such thing.

as soon as you transition into the yaw you need bank to counter to prevent the turn

This is getting fun! 

This is getting fun! I disagree. The key is wings level. One can fly a bearing sideways but if the wings are level there will be no gravity flow unless some relative wind force through the vents caused some action.

[Tom Baker]

2 hours ago, Buckaroo said:

This is getting fun! 

This is getting fun! I disagree. The key is wings level. One can fly a bearing sideways but if the wings are level there will be no gravity flow unless some relative wind force through the vents caused some action.

I think you are confusing crabbing for a crosswind with yawing. Yawing is in relationship with the relative wind, crabbing is in relation to a ground track. Your wings can be level when crabbing. To maintain a ground track while yawing your wings will be banked.

[Buckaroo]

11 minutes ago, Tom Baker said:

I think you are confusing crabbing for a crosswind with yawing. Yawing is in relationship with the relative wind, crabbing is in relation to a ground track. Your wings can be level when crabbing. To maintain a ground track while yawing your wings will be banked.

Yes but can’t one yaw with wings level to the earth while maintaining a straight line?

[Mike Koerner]

If your wings are level and the ball is off center, you are turning. It's a flat turn. g forces are pushing the ball, and the fuel, toward the outside of the turn.

Mike Koerner

[Buckaroo]

4 hours ago, Mike Koerner said:

If your wings are level and the ball is off center, you are turning. It's a flat turn. g forces are pushing the ball, and the fuel, toward the outside of the turn.

Mike Koerner

So if I’m traveling cross country with my AP engaged yawed to the right with my wings level one ball left I’m turning?

[Tom Baker]

10 hours ago, Buckaroo said:

Yes but can’t one yaw with wings level to the earth while maintaining a straight line?

When you yaw the airplane the keel effect will try to change the direction of the flight path. This is due to the relative wind hitting the side of the airplane. To overcome the effect of the turning tendency of the yaw, the wing must be banked to produce some horizontal component of lift in the opposite direction. Depending on the amount of yaw the amount of bank may be very small, but it has to be there to maintain that straight track.

[FlyingMonkey]

2 hours ago, Buckaroo said:

So if I’m traveling cross country with my AP engaged yawed to the right with my wings level one ball left I’m turning?

Either that or there is an opposite crosswind countering the yaw turn, causing you to fly a straight line.  The AP will happily fly you with the ball way out as long as it maintains the line specified in its programming.

[Mike Koerner]

No Monkey! This has nothing to do with wind... you know that.

The ball is acted on by two forces: gravity and inertia (g-loads).

Gravity pulls the ball toward the center of the Earth... the lowest spot in the tube. If the instrument is level, that will be in the middle. If the instrument is mounted crooked, or the plane is banked, gravity pulls the ball to the new low point on one side or the other of the middle.

Inertial forces try to keep the ball going the same direction it was going, just as a cat tries to go straight as you swing it around and around by its tail. While you are turning the ball is trying to go straight. That pushes it to toward the outside of the turn. (Highly-technical content warning: Centrifugal force is not really a force at all. It's just evidence of conservation of momentum). 

So, a turn toward the right pushes the ball toward the left while a bank to the right makes it fall to the right. You can adjust the turn rate, with the rudder, to keep those two forces equal; in which case the ball stays in the center, your fuel stays where it is, your butt stays in the seat, and the cat goes home happy.

If the ball is not in the center either the instrument is not level or you are turning.

As Tom points out, the bank may be subtle. The ball is much more sensitive than your butt and even your eye, unless your over level terrain and compare the wing tip heights carefully.

Mike Koerner

[ZZ Top]

Thank you Mike! Takes courage . Need the ball, my butt has no feelings.

[Buckaroo]

57 minutes ago, Mike Koerner said:

No Monkey! This has nothing to do with wind... you know that.

The ball is acted on by two forces: gravity and inertia (g-loads).

Gravity pulls the ball toward the center of the Earth... the lowest spot in the tube. If the instrument is level, that will be in the middle. If the instrument is mounted crooked, or the plane is banked, gravity pulls the ball to the new low point on one side or the other of the middle.

Inertial forces try to keep the ball going the same direction it was going, just as a cat tries to go straight as you swing it around and around by its tail. While you are turning the ball is trying to go straight. That pushes it to toward the outside of the turn. (Highly-technical content warning: Centrifugal force is not really a force at all. It's just evidence of conservation of momentum). 

So, a turn toward the right pushes the ball toward the left while a bank to the right makes it fall to the right. You can adjust the turn rate, with the rudder, to keep those two forces equal; in which case the ball stays in the center, your fuel stays where it is, your butt stays in the seat, and the cat goes home happy.

If the ball is not in the center either the instrument is not level or you are turning.

As Tom points out, the bank may be subtle. The ball is much more sensitive than your butt and even your eye, unless your over level terrain and compare the wing tip heights carefully.

Mike Koerner

Wow Mike do you carry a slide ruler in a pocket protector!Lol

[WmInce]

3 hours ago, Mike Koerner said:

 . . . Inertial forces try to keep the ball going the same direction it was going, just as a cat tries to go straight as you swing it around and around by its tail . . . 

Still trying to wrap my head around that . . . it detracted from the whole point.

Now . . where were we?

[Ed Cesnalis]

34 minutes ago, WmInce said:

Now . . where were we?

Coordination in a CT does not come naturally. Its far from intuitive.  My reliance on that blackball showing me which way the net of gravity + yaw forces are pointing is high and never goes away.

That black ball shows me both kinds of forces

1. big ones I can easily feel and understand
2. subtle ones that I would otherwise miss

[Buckaroo]

11 hours ago, Ed Cesnalis said:

Coordination in a CT does not come naturally. Its far from intuitive.  My reliance on that blackball showing me which way the net of gravity + yaw forces are pointing is high and never goes away.

That black ball shows me both kinds of forces

1. big ones I can easily feel and understand
2. subtle ones that I would otherwise miss

Can’t the plane have wings horizontal to the earth or gravity in a yaw and fly a direct course?? 

[Tom Baker]

1 hour ago, Buckaroo said:

Can’t the plane have wings horizontal to the earth or gravity in a yaw and fly a direct course?? 

You are confusing flight in relationship to the ground with flight in the airmass. Yaw is in relationship to the relative wind. If you yaw the airplane the longitudinal axis is no longer aligned with the relative wind, and will try and change direction. The only way to stop that change of direction is by introducing a horizontal component of lift. This is done by banking the wing the opposite direction. If you don't bank the wings the airplane will continue to turn as long as it is yawed.

You are thinking about the airplane being crabbed into the wind to correct for crosswind drift. In this case the airplane is flying a heading that is different than the ground track to compensate for the wind. In this case the wings are level, but the airplane is not in yawed flight.

If you go way back to when you learned ground reference maneuvers. There are 2 ways to maintain your position flying over a road. One is to crab into the wind, and the other is fly in a slip. As a pilot you use both. In a crab the airplane is coordinated and flies wings level at a different heading than your ground track. In a slip the airplane is banked into the wind, and then yawed to keep the horizontal component of lift from turning the airplane.

The autopilot doesn't know how to crab the airplane to maintain a course. The wind blows you off course and the autopilot turns to bring you back. The turn is what gives you the low wing. You can trim the rudder towards the low wing, but the airplane is still turning to come back to your course line. The only difference is that it has becomes a slight skidding turn to bring the airplane back on course when it is blown off. The wings will stay near level because of the rudder yawing the airplane to make the turn.

[Buckaroo]

53 minutes ago, Tom Baker said:

You are confusing flight in relationship to the ground with flight in the airmass. Yaw is in relationship to the relative wind. If you yaw the airplane the longitudinal axis is no longer aligned with the relative wind, and will try and change direction. The only way to stop that change of direction is by introducing a horizontal component of lift. This is done by banking the wing the opposite direction. If you don't bank the wings the airplane will continue to turn as long as it is yawed.

You are thinking about the airplane being crabbed into the wind to correct for crosswind drift. In this case the airplane is flying a heading that is different than the ground track to compensate for the wind. In this case the wings are level, but the airplane is not in yawed flight.

If you go way back to when you learned ground reference maneuvers. There are 2 ways to maintain your position flying over a road. One is to crab into the wind, and the other is fly in a slip. As a pilot you use both. In a crab the airplane is coordinated and flies wings level at a different heading than your ground track. In a slip the airplane is banked into the wind, and then yawed to keep the horizontal component of lift from turning the airplane.

The autopilot doesn't know how to crab the airplane to maintain a course. The wind blows you off course and the autopilot turns to bring you back. The turn is what gives you the low wing. You can trim the rudder towards the low wing, but the airplane is still turning to come back to your course line. The only difference is that it has becomes a slight skidding turn to bring the airplane back on course when it is blown off. The wings will stay near level because of the rudder yawing the airplane to make the turn.

Great understandable explanation Tom Thank You! There’s a lot to this stuff. 

[Ed Cesnalis]

4 hours ago, Buckaroo said:

Can’t the plane have wings horizontal to the earth or gravity in a yaw and fly a direct course?? 

no

[WmInce]

3 hours ago, Tom Baker said:

. . . . If you yaw the airplane the longitudinal axis is no longer aligned with the relative wind, . . . . 

Tom, I think that is wrong.

Don’t you mean “vertical” axis?

Roll is about the longitudinal axis . . . yaw is about the vertical axis.

[Mike Koerner]

Bill,

Yes, rotation around the longitudinal axis is roll. But Tom is not talking about rotation about that axis, he is talking about the axis itself - a line which runs from the tip of the spinner to the taillight.

If you yaw the aircraft that line is no longer aligned with the relative wind.

Mike Koerner

[Tom Baker]

1 hour ago, WmInce said:

Tom, I think that is wrong.

Don’t you mean “vertical” axis?

Roll is about the longitudinal axis . . . yaw is about the vertical axis.

Mike beat me to the answer.

[Buckaroo]

If someone could put this in mathematical formula it would be easier to understand! Lol

[Tom Baker]

It is not that hard to understand. I'm not a rocket surgeon and I understand it, well kind of.