Great circles route?
ECON cruise, LR cruise...
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Shortest distance between two points on a flat 2D surface = straight line
Shortest distance between two points on a spheric 2D surface = curve
If in doubt about the latter, get an apple & a rubber band. If you wrap the rubber band around the apple, you will see it describing an a curve on the surface.
Thus: rhumb line = constant true track - great circle = changing true track.
These are the very basics - but hope it helps
Cheers,
Empty
Shortest distance between two points on a spheric 2D surface = curve
If in doubt about the latter, get an apple & a rubber band. If you wrap the rubber band around the apple, you will see it describing an a curve on the surface.
Thus: rhumb line = constant true track - great circle = changing true track.
These are the very basics - but hope it helps
Cheers,
Empty
Join Date: Jul 2002
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I had some better graphics to help get my kids' heads around this, but can't seem to find them (the graphics, not the kids' heads). This'll have to do... ( I didn't have an apple or a rubber band, so I had to opt for this approach.)
Imagine Cathay Pacific is enroute from Los Angeles to Hong Kong. On a Mercator projection (flat map) the route might look curved, like this:
However, if you were to look at that same route plotted on a globe, it might look more like a straight line, like this:
Same route, different view.
I, for one, think it is magic.
Dave
Imagine Cathay Pacific is enroute from Los Angeles to Hong Kong. On a Mercator projection (flat map) the route might look curved, like this:
However, if you were to look at that same route plotted on a globe, it might look more like a straight line, like this:
Same route, different view.
I, for one, think it is magic.
Dave
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great graphics and explanation Av8boy
This is an excellent thingy to play with...
Great Circle Mapper
This is an excellent thingy to play with...
Great Circle Mapper
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Originally Posted by av8boy
I had some better graphics to help get my kids' heads around this, but can't seem to find them (the graphics, not the kids' heads). This'll have to do... ( I didn't have an apple or a rubber band, so I had to opt for this approach.)
Imagine Cathay Pacific is enroute from Los Angeles to Hong Kong. On a Mercator projection (flat map) the route might look curved, like this:
However, if you were to look at that same route plotted on a globe, it might look more like a straight line, like this:
Same route, different view.
I, for one, think it is magic.
Dave
Imagine Cathay Pacific is enroute from Los Angeles to Hong Kong. On a Mercator projection (flat map) the route might look curved, like this:
However, if you were to look at that same route plotted on a globe, it might look more like a straight line, like this:
Same route, different view.
I, for one, think it is magic.
Dave
Hes a witch!!!!!!
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But in practice, to avoid the need to constantly change heading, the actual route flown is more likely to be a composite great circle route, which is a tad longer but makes navigation easier by flying series of small GC's between lines of longitude which closely follow the true GC arc, usually at around 10degree increments. The heading between the waypoints being averaged out to a single course.
