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02 Nov 15
Originally posted by twhiteheadYes [ish], however if you are modelling the Earth as a perfect sphere, then a change in altitude will
Google Earth is displayed as a perfect sphere. Display of latitude / longitude, measurements etc all use the WSG84 datum which approximates the Earth as an oblate spheroid. It is the same datum used by GPS. From what I can tell, if altitude is not specified, it assumes an altitude of 80m (don't ask me why). It is however capable of calculating distances w ...[text shortened]... aft travelling at 40,000 feet must travel a longer distance than a ship travelling at sea level.
produce a linear and proportional change in distance.
So there will be no change proportionally between two routes if they are at the same altitude.
Both great circles will change by dC=2*Pi*[change in altitude] and the routes will change by
dC*[fraction of great circle occupied by route]
A route that occupies 20% of a great circle [~50,000km] that is @ 40,000ft [~12,200m] will be
longer than the same route @ sea level by only ~15.3km [~0.03% difference].
As the difference due to the Earth being an oblate spheroid instead of a perfect sphere are ~0.5%
those effects would dominate. [this is not true however of a surface route that follows terrain as that
could add a significant deviation that would vary significantly between different routes]
02 Nov 15
1 edit
Originally posted by googlefudgeYou must have quite a lot wrong there.
A route that occupies 20% of a great circle [~50,000km] that is @ 40,000ft [~12,200m] will be
longer than the same route @ sea level by only ~15.3km [~0.03% difference].
As the difference due to the Earth being an oblate spheroid instead of a perfect sphere are ~0.5%
those effects would dominate. [this is not true however of a surface route that fol ...[text shortened]... that
could add a significant deviation that would vary significantly between different routes]
1. The perimeter of the earth is closer to 40,000km.
2. The difference between a perfect sphere and an oblate spheroid depends on whether or not you are measuring along the equator or in the North-South direction and what diameter you are using for the sphere.
3. In my own tests of a great circle arc 8000km I get:
a) a difference of less than 1km approximately for an east west arc between the Haversine formula (sphere) and Vincenty (oblate spheroid). However a difference of 12,000 in altitude according to Google Earth adds 15km to the length.
b) for a north south arc the two formulas give a difference of about 17.6km only slightly more than the altitude difference makes.
In sum, you have the wrong perimeter for the earth and the wrong estimate for errors. This page says 'up to 22km or 0.3%':
http://gis.stackexchange.com/questions/25494/how-accurate-is-approximating-the-earth-as-a-sphere#25580
but it turns out I think that the 3% is not of the distance being measured.
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02 Nov 15
Originally posted by twhiteheadActually only one thing wrong... I was half asleep and used the Earth's circumference as it's radius. 😕
You must have quite a lot wrong there.
1. The perimeter of the earth is closer to 40,000km.
2. The difference between a perfect sphere and an oblate spheroid depends on whether or not you are measuring along the equator or in the North-South direction and what diameter you are using for the sphere.
3. In my own tests of a great circle arc 8000km I ge ...[text shortened]... h-as-a-sphere#25580
but it turns out I think that the 3% is not of the distance being measured.
My bad.
Nevertheless, my point that the altitude makes only a proportional and linear difference is still valid.
And by your own argument, the differences are of the same order as the difference between a sphere and
an oblate spheroid.
02 Nov 15
Originally posted by googlefudgeYes, it doesn't affect which direction one would travel, but then the sphere/oblate spheroid difference doesn't make much different to that either.
Nevertheless, my point that the altitude makes only a proportional and linear difference is still valid.
And by your own argument, the differences are of the same order as the difference between a sphere and an oblate spheroid.
Yes, whereas you had an order of magnitude difference. So my point still stands - altitude is as important as the sphere vs oblate spheroid difference (and more important for east-west paths.)
05 Nov 15
Originally posted by googlefudgeYou're simply doubling down on nonsense now, and you know it.2. Explain how the examples given (TPE to LAX and BOS to SEA) do not conform to this claim.
Well for starters they are not two points at the same latitude.
Also they are are not an equal distance apart nor are they an equal angle apart.
Also, as Twhitehead says, they do conform. The great circle linking TPE and LAX meets the equator ...[text shortened]... ted to exploring via the methods we have already proposed.
Ie, just look at a frickin' globe.
Your earlier claim of greater trajectory for distances further from the equator has been obliterated, but you are now attempting to claim the longitude differences are at play.
The differences in longitude in this case are approximately 2.4 times, i.e., one is 2.4 times greater than the other.
You offer no formulas because you have no formulas.
Those points where travel over the North Pole offer a shorter path?
Surprise!
They're a exacting straight line!
Not only is your explanation here an abysmal failure, you equally have no answer for those flights south of the equator, especially those flights which should be a straight shot but are always routed completely out of the way north and then to the destination.
One wonders why we never see flight across the South Pole as we do across the North.
Try again.
05 Nov 15
Originally posted by FreakyKBH
You're simply doubling down on nonsense now, and you know it.
Your earlier claim of greater trajectory for distances further from the equator has been obliterated, but you are now attempting to claim the longitude differences are at play.
The differences in longitude in this case are approximately 2.4 times, i.e., one is 2.4 times greater than the ot ...[text shortened]... e wonders why we never see flight across the South Pole as we do across the North.
Try again.
One wonders why we never see flight across the South Pole as we do across the North.Look at a map and look at where the land mass is.
Originally posted by FreakyKBHhttp://www.aircalculator.com/flightplan.php?from=BWU&to=PUQ
Great argument.
This is the closest I found to South Pole. (Australia to Chile)
Take a look at the map.
The route looks curved on the map.
The text explains why.
The site must be party to the same conspiracy as twhitehead and myself!!!!!
05 Nov 15
Originally posted by wolfgang59This is your "proof?"
http://www.aircalculator.com/flightplan.php?from=BWU&to=PUQ
This is the closest I found to South Pole. (Australia to Chile)
Take a look at the map.
The route looks curved on the map.
The text explains why.
The site must be party to the same conspiracy as twhitehead and myself!!!!!
Oy, vey.
05 Nov 15
Originally posted by FreakyKBHDid I present anything as proof?
This is your "proof?"
Oy, vey.
I'm merely showing a near trans-south-pole route.
And demonstrating that there are others (like most of the educated on the planet)
who believe great circles are the shortest route between two points on the Earth.
Perhaps you can explain why so many websites (and airlines) are wrong?
05 Nov 15
Originally posted by FreakyKBHLets see ...
You're simply doubling down on nonsense now, and you know it.
All of us except you, have the backing of hundreds of years of science and unimaginable volumes of evidence where as you have ... wait for it ..... nothing.
I think it is kind of obvious who is doubling down on nonsense and knows it.
The real question is why? What do you gain for making a monumental fool of yourself? I can't seem to figure it out.
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05 Nov 15
Originally posted by FreakyKBH
You're simply doubling down on nonsense now, and you know it.
Your earlier claim of greater trajectory for distances further from the equator has been obliterated, but you are now attempting to claim the longitude differences are at play.
The differences in longitude in this case are approximately 2.4 times, i.e., one is 2.4 times greater than the ot ...[text shortened]... e wonders why we never see flight across the South Pole as we do across the North.
Try again.
Your earlier claim of greater trajectory for distances further from the equator has been obliterated, but you are now attempting to claim the longitude differences are at play.
What language are you typing in? It isn't english.
You offer no formulas because you have no formulas.
'Formulas' as you put it have already been presented. They were as helpful as I anticipated.
Thus proving my point.
Those points where travel over the North Pole offer a shorter path?
Surprise!
They're a exacting straight line!
As viewed from what angle?
View the Earth from a position over the equator [lets say geostationary orbit] placed over the prime meridian.
Watch a 1000mile journey across the North Pole that is at 90 degrees to you [from 90E to 90W lets say].
Does this journey look 'strait' to you?
No, of course not, it looks curved as they go up over the pole and then back down again.
It only looks like a strait line if you look directly down at the route [from over the pole say] and thus can't
see the Earth bulging towards you.
The same applies for any other great circle, when viewed from directly above, it looks strait.
When viewed from any other angle, it will look curved.
This is what happens when you plot shortest distances on a spheroid.
Not only is your explanation here an abysmal failure, you equally have no answer for those flights south of the equator, especially those flights which should be a straight shot but are always routed completely out of the way north and then to the destination.
One wonders why we never see flight across the South Pole as we do across the North.
If we are talking about flights, as opposed to shortest distances, then I will again point out that flights get
routed to minimise distances away from emergency landing sites [particularly minimising long sea crossings
if at all possible], they get routed into defined flight corridors that simplify air traffic control, they get routed
around bad weather, they take routes that avoid or take advantage of the jet stream, they take routes that
avoid war zones or hostile/restricted airspace, They take routes that avoid flying through expensive airspace
that you are charged for... etc etc. They do not fly anything like the mathematically shortest route, and with
good reason.
Which is one reason for not flying over the most inhospitable continent on the planet. Often surrounded by giant
storms that are horrible to fly through.
The other, most of the worlds land masses and populations are situated north of the equator and by some margin.
[this has unsurprisingly already been pointed out, and is obvious to anyone looking at a map, just look where
the equator is. It's south of India, most of Africa is above it, it bisects Brazil and Indonesia, leaving ALL of Asia
Europe and North America WELL above the Equator. And the the farthest south the [inhabited] land masses
goes is ~55S and that point is well below the next nearest. 55N on the other hand goes through the North of England
and is below all of Scandinavia, and most of Russia and Canada. The worlds inhabitable areas are heavily biased
towards the north] Which means that there are very few routes in the southern hemisphere that you would
want to take that would be shorter going over the south pole.
Whereas there are lots of northern routes where you would want to go over the north pole.
Again this is obvious to anyone looking at a globe. [or Google Earth]
Try again
I'm mainly pointing out how stupid you and your arguments are for anyone reading who might mistake you for a
person who has any good reasons for thinking... well anything really.
Originally posted by wolfgang59Did I present anything as proof?
Did I present anything as proof?
I'm merely showing a near trans-south-pole route.
And demonstrating that there are others (like most of the educated on the planet)
who believe great circles are the shortest route between two points on the Earth.
Perhaps [b]you can explain why so many websites (and airlines) are wrong?[/b]
Yes, you did.
When you offered this as evidence of your point, that is the same as offering proof.
That escaped you?
I'm merely showing a near trans-south-pole route.
Perhaps a mere amount of research will help clarify exactly how many flights actually take the southern route in comparison to that taken over the northern center.
That's totally up to you if you want to find them, of course.
Perhaps you can explain why so many websites (and airlines) are wrong?
I don't think airlines are wrong.
I contend that they do, in fact, follow the shortest path.
I contend that the paths--- as shown--- do not represent the actual path, as it is shown from the viewpoint of a globe.
Take the same paths and superimpose them on a flat earth and see how "straight" the path becomes.
06 Nov 15
Originally posted by twhiteheadAll that science and you refuse to get in the water.
Lets see ...
All of us except you, have the backing of hundreds of years of science and unimaginable volumes of evidence where as you have ... wait for it ..... nothing.
I think it is kind of obvious who is doubling down on nonsense and knows it.
The real question is why? What do you gain for making a monumental fool of yourself? I can't seem to figure it out.
You've offered nothing to answer the questions and yet you take a position as though you've won the entire war.
Questions put to you or anyone else in the group ask very specific questions, and you've all failed to address them--- or, as is the case with googlefudge, claim one thing and then contradict it with the following posts.
The fact remains, planes do take the shortest path possible, but that path only makes sense when seen on a flat earth model.