4 ms·

Also, large compasses about 1km in diameter: http://goo.gl/maps/6wTtb http://goo.gl/maps/6wTtb

by biot 14y ago

Raphael 14y ago
If it's a compass, then why is it 20 degrees off?
- jonburs 14y ago
  The magnetic north pole isn't in the same spot as the geographic north pole -- see http://en.wikipedia.org/wiki/Magnetic_declination http://en.wikipedia.org/wiki/Magnetic_declination.
  - taejo 14y ago
    Does ATC use magnetic bearings?
    - rory096 14y ago
      Yes. This is why runway numbers (which are the heading with the last digit removed) are known to change from time to time. Aviation charts also display the variation between magnetic and true north. (See the purple dashed lines with 14/15° W http://skyvector.com/?ll=40.55464932694554,-70.94216669067579&chart=15&zoom=4 http://skyvector.com/?ll=40.55464932694554,-70.9421666906757... )
_djo_ 14y ago
Those aren't for the same purpose, they're for test pilots to use when landing on the lakebed runways that you can see next to the compass. Both the X-1 and X-15, amongst many other experimental planes, landed on the lakebed rather than on conventional runways at Edwards AFB.
- sargun 14y ago
  Why did they land on the lake bed as opposed to runways?
  - lutusp 14y ago
    Because in experimental craft, one doesn't want to have to line up with a runway when the controls have stopped functioning or a wing has partly fallen off. Once, when a test pilot landed the X-15 on a lakebed, the fuselage broke in two: http://www.air-and-space.com/x-15%20forty%20years%20later%20200001.htm http://www.air-and-space.com/x-15%20forty%20years%20later%20... Quote: "The X-15-2 on Rosamond Dry Lake following mission 2-3-9*. The fuselage failed when the nose gear impacted the ground. The shock absorbing ability of the front landing gear strut was impaired by foaming of the oil in the strut when it was extended. The back of the X-15 broke at a structural join behind the cockpit."
  - _djo_ 14y ago
    What lutusp said plus the fact that the lakebed runways are much, much longer than the tarred runways. So the combination of much more width and much more length means its far safer to get an aircraft like the X-15 on the ground.

Also, large compasses about 1km in diameter: http://goo.gl/maps/6wTtb http://goo.gl/maps/6wTtb

by biot 14y ago

Also, large compasses about 1km in diameter: http://goo.gl/maps/6wTtb http://goo.gl/maps/6wTtb

Raphael 14y ago

If it's a compass, then why is it 20 degrees off?

jonburs 14y ago
The magnetic north pole isn't in the same spot as the geographic north pole -- see http://en.wikipedia.org/wiki/Magnetic_declination http://en.wikipedia.org/wiki/Magnetic_declination.
- taejo 14y ago
  Does ATC use magnetic bearings?
  - rory096 14y ago
    Yes. This is why runway numbers (which are the heading with the last digit removed) are known to change from time to time. Aviation charts also display the variation between magnetic and true north. (See the purple dashed lines with 14/15° W http://skyvector.com/?ll=40.55464932694554,-70.94216669067579&chart=15&zoom=4 http://skyvector.com/?ll=40.55464932694554,-70.9421666906757... )

_djo_ 14y ago

Those aren't for the same purpose, they're for test pilots to use when landing on the lakebed runways that you can see next to the compass. Both the X-1 and X-15, amongst many other experimental planes, landed on the lakebed rather than on conventional runways at Edwards AFB.

sargun 14y ago
Why did they land on the lake bed as opposed to runways?
- lutusp 14y ago
  Because in experimental craft, one doesn't want to have to line up with a runway when the controls have stopped functioning or a wing has partly fallen off. Once, when a test pilot landed the X-15 on a lakebed, the fuselage broke in two: http://www.air-and-space.com/x-15%20forty%20years%20later%20200001.htm http://www.air-and-space.com/x-15%20forty%20years%20later%20... Quote: "The X-15-2 on Rosamond Dry Lake following mission 2-3-9*. The fuselage failed when the nose gear impacted the ground. The shock absorbing ability of the front landing gear strut was impaired by foaming of the oil in the strut when it was extended. The back of the X-15 broke at a structural join behind the cockpit."
- _djo_ 14y ago
  What lutusp said plus the fact that the lakebed runways are much, much longer than the tarred runways. So the combination of much more width and much more length means its far safer to get an aircraft like the X-15 on the ground.