Rhumb Lines and Great Circles

East to west are circles on FE, therefore just travel in straight line and there's your rhumb line.

East to west are circles on FE, therefore just travel in straight line and there's your rhumb line.

Yup.. But these rhumb lines are also geodesics.

I never thought about this before, but going from East to West on FE would require changing your bearing! East-to-West motion is a circle, and rhumb lines are straight lines... This is a rather strange idea, and I haven't yet thought of the implications.

I'll tell you the implications:

The earth is flat.

I'll tell you the implications:

The earth is flat.

Please explain why.

Also, please explain why, on a flat Earth, you would have to change direction in order to travel directly East.

You only have to change directions to maintain an easterly course.

However, you can save time by navigating in a straight line. So if one were to travel from NY to London, they could save miles by starting out on an east by north-east course, and end the journey on a east by south-east course.

You only have to change directions to maintain an easterly course.

However, you can save time by navigating in a straight line. So if one were to travel from NY to London, they could save miles by starting out on an east by north-east course, and end the journey on a east by south-east course.

That proves the earth is round. 

No it doesn't.

No it doesn't.

Read it again. 

Quote from: Roundy the Bright on August 01, 2007, 05:13:06 PM

No it doesn't.

Read it again. 

You read it again.

Quote from: sokarul on August 01, 2007, 05:41:10 PM

Quote from: Roundy the Bright on August 01, 2007, 05:13:06 PM

No it doesn't.

Read it again. 

You read it again.

Ok, two  non continuous lines make a shorter path then one continuous line.  That calls for a round earth. 

Quote from: Roundy the Bright on August 01, 2007, 05:46:16 PM

Quote from: sokarul on August 01, 2007, 05:41:10 PM

Quote from: Roundy the Bright on August 01, 2007, 05:13:06 PM

No it doesn't.

Read it again. 

You read it again.

Ok, two  non continuous lines make a shorter path then one continuous line.  That calls for a round earth. 

That's not what Narcberry said.  He said a single straight line is shorter than a east/west ring.

You only have to change directions to maintain an easterly course.

However, you can save time by navigating in a straight line. So if one were to travel from NY to London, they could save miles by starting out on an east by north-east course, and end the journey on a east by south-east course.

Yeah I guess I read this wrong.  One a flat earth map, one line could do this. 

AND IT GETS THROUGH! 

I'm asking again:

1) Why, on a flat Earth, do you have to constantly change your "bearing" in order to keep a constant Eastwards "bearing"

2) Why, on a flat Earth, do rhumb lines turn out to be geodesics, when in real life, they are not geodesics?

I'm asking again:

1) Why, on a flat Earth, do you have to constantly change your "bearing" in order to keep a constant Eastwards "bearing"

You don't.  An Eastwards bearing is an Eastwards bearing...nice try at a trick question though.

Quote from: andrews on August 02, 2007, 01:18:25 AM

I'm asking again:

1) Why, on a flat Earth, do you have to constantly change your "bearing" in order to keep a constant Eastwards "bearing"

You don't.  An Eastwards bearing is an Eastwards bearing...nice try at a trick question though.

East-to-West on flat Earth is a circle. Do you agree?

If you agree, then you must change bearings to go East-to-West...

Re-read what you said and it'll all make sense.

I do not understand what you are trying to say. RE and FE both have to change direction to maintain a heading.

I do not understand what you are trying to say. RE and FE both have to change direction to maintain a heading.

Yeah, but he said change a 'bearing' to maintain a 'bearing'.  It's such an attempt at a trick question it's not even funny.  It would be different if he said, for instance, "Why do you have to constantly turn left to travel East along the equator?"  Too bad that's been asked before and you can't prove you're not turning left.

If you agree, then you must change bearings to go East-to-West...

On a Round Earth we are also curving as we travel East or West.

Consider: Lets say that we are at the North Pole on a Round Earth and have a compass. We are positioned twenty feet from the point of magnetic north and we want to travel East. In order to continue East we must constantly curve around the point of magnetic north.

On a round Earth, you must change direction in order to stay on a Rhumb line.  On a Flat Earth you do not.  On a Round earth, you make no corrections in order to go east to west.  On a Flat Earth you do.  See?

You guys are missing what he is gettign at.  Look up "bearing". 

On a round Earth, you must change direction in order to stay on a Rhumb line.  On a Flat Earth you do not.  On a Round earth, you make no corrections in order to go east to west.  On a Flat Earth you do.  See?

That only holds true at the Equator.

On a round Earth, you must change direction in order to stay on a Rhumb line.  On a Flat Earth you do not.  On a Round earth, you make no corrections in order to go east to west.  On a Flat Earth you do.  See?

2 yards south of the north pole, how long will a straight line allow you to travel directly east?

In the Southern Equator, you make opposite adjustments.  How do you explain that?

Quote from: andrews on August 02, 2007, 01:18:25 AM

I'm asking again:

1) Why, on a flat Earth, do you have to constantly change your "bearing" in order to keep a constant Eastwards "bearing"

You don't.  An Eastwards bearing is an Eastwards bearing...nice try at a trick question though.

Yeah yeah... Okay:
1) Why, on a flat Earth, do you have to constantly change your direction in order to keep a constant Eastwards bearing?

I'm no expert, but I'm gonna guess it's because east and west go in circles on a flat earth. 

I'm no expert, but I'm gonna guess it's because east and west go in circles on a flat earth. 

That's the point. I'm asking for an explanation.

Anyhow, this point isn't the main point of the thread. The question still remains:

In FE, rhumb lines are always geodesics. In real life, rhumb lines are not always geodesics. Hence, the Earth is not flat.

Can anyone refute this?

Quote from: CommonCents on August 02, 2007, 06:22:41 AM

Quote from: andrews on August 02, 2007, 01:18:25 AM

I'm asking again:

1) Why, on a flat Earth, do you have to constantly change your "bearing" in order to keep a constant Eastwards "bearing"

You don't.  An Eastwards bearing is an Eastwards bearing...nice try at a trick question though.

Yeah yeah... Okay:
1) Why, on a flat Earth, do you have to constantly change your direction in order to keep a constant Eastwards bearing?

It's the same for RE...

Quote from: andrews on August 02, 2007, 11:46:15 AM

Quote from: CommonCents on August 02, 2007, 06:22:41 AM

Quote from: andrews on August 02, 2007, 01:18:25 AM

I'm asking again:

1) Why, on a flat Earth, do you have to constantly change your "bearing" in order to keep a constant Eastwards "bearing"

You don't.  An Eastwards bearing is an Eastwards bearing...nice try at a trick question though.

Yeah yeah... Okay:
1) Why, on a flat Earth, do you have to constantly change your direction in order to keep a constant Eastwards bearing?

It's the same for RE...

No, it's not. (At least if you think of the Earth's surface as a manifold...)