DUBAI | Burj Khalifah (Burj Dubai) | 828 M / 2,716.5 FT - Pinnacle | 162 FLOORS

[graham]

Originally Posted by Mocholate

surely somewhere on the net you will find info regarding the distance that is viewable from the tower

Hi Mocholate - the question in hand was how much would the curvature of the earth cutoff from the bottom of Burj Dubai when it's viewed from 150kms.
A flat topography is assumed. Haze notwithstanding and binoculars or telescope allowed. Also atmospheric lensing notwithstanding. And with one's eyeball at 5 to 6 feet above the ground.
We've had a wide range of answers from 50 feet to more than 2,650 feet.
We are sort of stumbling along to a good approximation. Stay tuned.

In the meantime, here's another great Von Studach shot. Simliar to the previous one by him, but different....

[graham]

Originally Posted by Imre

I put some new Burj Dubai, Lake Hotel pics here because the internet connection is wrong here, thanks for the du ( will post later The Index, Emirates Towers and some Business Bay pics as well)

http://www.flickr.com/photos/imresolt/

They promised , maybe after 2-3 days will be good again

flickr , yahoo and some websites good but most of them I can not open.

Thanks Imre - your contribution is the greatest.

[jason111]

lol u guys still going at that stupid math crap......what does it matter?

[graham]

Originally Posted by jason111

lol u guys still going at that stupid math crap......what does it matter?

It's just interesting to know how such a massive structure interplays with the earth's curvature. And what limits viewing distance of the entire structure from a great distance - haze or curvature cutoff?
We're almost done - keep your pants on - lol.

[MolsonExport]

A few more middling miles and it could become the space elevator!

Truly amazing stuff going on in Dubai.

[koops65]

Here's my 2 cents worth... while 'math' may not have anything to do with the actual construction of Burj Dubai, the discussion is still about the Burj Dubai, and how far away it can be viewed from, or how far you could see from the top if it... just because some people might not be 'into' discussing that particular subject, or feel that it wastes their time, doesn't mean its off-topic... when I log in and check out threads with new posts, I dont get all 'pissed-off' when people post things like 'nice building' or things of that nature, which don't contribute anything at all to the thread... everyone needs to learn to RELAX and CALM DOWN

[graham]

OK Jasonhouse..........

Can you get your autocad proggy solving for x please? Thanks.



We'll be done with it soon.
Thanks for your patience folks.

And thanks for your several dollars worth, koops65.
Here's another PAN-O-RAMA fantastico by Von Staudach......

[Rilestone75]

^ At first go, my calculation is that X = 855.36 ft. +/- a couple feet.

[graham]

Originally Posted by Rilestone75

^ At first go, my calculation is that X = 855.36 ft. +/- a couple feet.

thats real close to my 800' guess.
let's see what others peeps get.

In the meantime, looks like Imre has been inspired (no pun intended) lately.
Check these pics of his out......

[towerguy3]

One degree of arc distance (distance measured along the curve of the Earth)is 24,903 miles / 360 = 69.2 miles. This is equivalent to 60 Nautical miles. The angular separation between the eye and BurjDubai, in this scenario, is 1.3 degrees. 1.3 degrees is the angular separation between the two points.

1.3 degrees * 69.2 miles/degree = 90 miles of arc distance, but the diagram shows that distance as the chord distance (the straight line distance through the Earth between BurjDubai and the eye).

The chord distance and arc distance will not be the same.

[towerguy3]

quote: the question in hand was how much would the curvature of the earth cutoff from the bottom of Burj Dubai when it's viewed from 150kms

Yes but when you say "viewed from 150 km", that means 150 km distance as measured along the curve of the earth. For example, when people say the distance between Seattle and Vancouver is 120 miles, that's measured along the surface of the earth, not through the Earth (chord distance).

What you drew in the diagram as 150 km is the chord distance between the tower and the eye. That is a different value of d than used in my equations. The d in these equations is arc distance:

d = SQRT (2Rh + h^2) and h = R - SQRT {(R^2)-(d^2)} where R = 6391 km

[towerguy3]

your x is my h

[Rilestone75]

Originally Posted by towerguy3

quote: the question in hand was how much would the curvature of the earth cutoff from the bottom of Burj Dubai when it's viewed from 150kms

Yes but when you say "viewed from 150 km", that means 150 km distance as measured along the curve of the earth. For example, when people say the distance between Seattle and Vancouver is 120 miles, that's measured along the surface of the earth, not through the Earth (chord distance).

What you drew in the diagram as 150 km is the chord distance between the tower and the eye. That is a different value of d than used in my equations. The d in these equations is arc distance:

d = SQRT (2Rh + h^2) and h = R - SQRT {(R^2)-(d^2)} where R = 6391 km

I agree with you on the Chord Distance vs. Arc, but in this scenario, with A = 428 ft, the difference between Arc and Chord is so miniscule that it changes the amount of Burj that is viewable from that point, by a foot or two.

I still think that from 90 miles away, you would lose sight of the first 855 ft or so.

[towerguy3]

h = 6391 - SQRT {(6391^2 - 150^2)} = 1.76 km or 1,760 meters

from 150 km away, 1,760 meters of BurjDubai would be cutoff, and it'll never be that high so no part of BurjDubai would be visible from 150 km

[Rilestone75]

Originally Posted by towerguy3

h = 6391 - SQRT {(6391^2 - 150^2)} = 1.76 km or 1,760 meters

from 150 km away, 1,760 meters of BurjDubai would be cutoff, and it'll never be that high so no part of BurjDubai would be visible from 150 km

Okay, I'm going to disagree with you based on "real life".... I live in Chicago. I travel to the south suburbs frequently. If you've been here, you know it is a VERY flat city. I can see almost 80% of the Sears Tower (on a clear day) from more than 40 miles away. The Sears Tower isn't nearly as tall as BD, so at 90 miles, I would think you would be able to see a portion of the building.

[towerguy3]

The atmosphere acts as a lens and bends the light that reaches your eyes, increasing your visual distance. My formulas assume no air lens effect.

The variation between r and d is not linear; r varies as the square of the d. Double the distance d and r (the part cutoff) quadruples. From 40 km out the bottom 125 meters is cut off, from 80 km out the bottom 500 meters is cut off.

[towerguy3]

These formulas assume eye near ground level. The two situations, viewing the distant horizon from a height and conversely, being at that same point on the horizon and looking back at the tower, use the same formulas.

Assume you are 500 meters up Burj Dubai and I am standing on the horizon 80 km away. We are both using telescopes to sight each other.

From my viewpoint, I could see you 500 meters up the BurjDubai tower (you would be barely visible on the horizon), and the part of the tower above you would appear above the horizon.

The part of the tower below you would be below the horizon and not visible to me.

Again, neglecting the effects of the atmosphere acting as a lens....

[graham]

yeah - don't forget the diagram is schematic.
The difference between the length of the straight and curved lines is miniscule.

wow - you guys got vastly different calcs.

Rilestone says 855 feet.
towerguy says 5,720 feet.
I think were gonna need Jasonhouse with his autocad proggy to sort it out.

My very latest numbers has it at 1,128 feet of cuttoff.
Probably autocad will prove that wrong.
We'll have to wait for Jasonhouse to fire it up again.

[towerguy3]

also, a second project is to derive an equation that will calculate amount of BurjDubai cutoff (h) seen from a distance d away from that tower and at a specific eye elevation (h').

Instead of eye elevation (h') at a man's height, make it 100 meters. One person is 100 meters up one tower, the other 600 meters up BurjDubai, both 60 km apart; how much of each other's tower can the other person sight neglecting air lens effect?

[photoLith]

This building is amazing! and that pano photo of Dubai is so sexy, I love it! Dubai is going to be incredible in just a few years, heck I might even go there and see it myself one of these days. Anyways, this may have already been stated but how tall is it now?