Timeline for Is gravity less on an airliner at cruise altitude?
Current License: CC BY-SA 3.0
27 events
| when toggle format | what | by | license | comment | |
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| Oct 21, 2016 at 1:40 | comment | added | Steve Kuo | @Antzi a ton is a unit of mass. Mass is constant regardless of gravity. 1 ton at sea level = 1 ton at 35,000 feet = 1 ton on the moon | |
| Oct 20, 2016 at 19:33 | comment | added | Jan Hudec | The $\frac{g_h}{g}$ ratio is wrong. While $g$ is called "gravitational acceleration", it is actually defined as the total weight acceleration in the Earth frame of reference, i.e. including the centrifugal force due to own rotation of Earth. And since the centrifugal force increases with altitude, $g$ decreases faster than by that equation. Further complicated by the fact that aircraft speeds are significant compared to Earth rotation, so flying east or west does make a difference. | |
| S Oct 20, 2016 at 14:23 | history | suggested | CommunityBot | CC BY-SA 3.0 |
shortened it a little just by putting together nessecary paragraphs
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| Oct 20, 2016 at 13:40 | review | Suggested edits | |||
| S Oct 20, 2016 at 14:23 | |||||
| May 13, 2016 at 18:15 | history | edited | user13197 | CC BY-SA 3.0 |
added 2 characters in body
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| Mar 23, 2016 at 17:52 | comment | added | JS. | @SteveJessop: Please take your bathroom scales on your next flight and perform the test in the lav. I look forward to seeing your results. | |
| S Mar 23, 2016 at 16:29 | history | suggested | ArtOfCode | CC BY-SA 3.0 |
Edited for sense
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| Mar 23, 2016 at 16:14 | review | Suggested edits | |||
| S Mar 23, 2016 at 16:29 | |||||
| Mar 22, 2016 at 22:37 | comment | added | DarcyThomas | for a Lockheed SR-71 Blackbird it is about 1.53% (according to my calculations) | |
| S Mar 22, 2016 at 11:26 | history | suggested | user5604 | CC BY-SA 3.0 |
typography corrected
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| Mar 22, 2016 at 11:18 | review | Suggested edits | |||
| S Mar 22, 2016 at 11:26 | |||||
| Mar 22, 2016 at 10:23 | comment | added | Steve Jessop | My bathroom scales can tell me when my weight varies by 0.37%. I won't feel the difference, but when you say "sensitive instruments", it doesn't take special equipment to detect it. | |
| Mar 22, 2016 at 10:04 | comment | added | Aron | I'm afraid you are in fact wrong. You are trying to use a "fixed" Newtonian frame of reference, when in fact the correct frame of reference is to use the local frame of reference of the atmosphere, which we can approximate to a fluid that rotates around the earth once every 23.9 hours (a sidereal day). | |
| Mar 21, 2016 at 21:31 | comment | added | user14115 | @wedstrom Actually, I am sure you are wrong. If you are using Newtonian Physics (which we are), then the gravity equation is the same for a point mass for which spin has no meaning. The gravity equation you are using is just the solution to Poisson's equation is a spherical and rotationally symmetric system. Meaning that by definition, rotations of our system must leave the equations of motion invariant. | |
| Mar 21, 2016 at 21:20 | comment | added | user14115 | @wedstrom Ummm. I don't think you are right. My equations of motion in my accelerated frame (ie. the plane) are invariant of the rotation of the earth. They only depend on the absolute distance (ie 1/r) from the system's center of mass. In fact, for spherically symmetric uncharged bodies rotating in free space, it is impossible to tell what speed they rotate at. Spherical symmetry and free space assumptions will hold to high order for the earth plane system. | |
| S Mar 21, 2016 at 20:55 | history | edited | Ralph J♦ | CC BY-SA 3.0 |
Messed up formulas // R is distance between centers, not R^2.
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| S Mar 21, 2016 at 20:55 | history | suggested | CommunityBot | CC BY-SA 3.0 |
Messed up formulas
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| Mar 21, 2016 at 20:42 | review | Suggested edits | |||
| S Mar 21, 2016 at 20:55 | |||||
| Mar 21, 2016 at 20:29 | comment | added | wedstrom | That depends on the direction, IE East/West. It could add perceived weight just as easily as remove it (by actually reducing it's overall rotational speed, up to the speed of the Earth's rotation at which point it would become negative again). | |
| Mar 21, 2016 at 20:04 | comment | added | rbp | does this change the stall speed in an accellerated stall?! | |
| Mar 21, 2016 at 19:45 | comment | added | user14115 | If you count centrifugal forces, then you get another 0.11% decrease at 12km and 965km/hr!! By a = v^2/r | |
| Mar 21, 2016 at 16:50 | comment | added | Trebia Project. | The difference is big enough to be considered in A/C performance calculations, bigger than other effects that manufacturers spend significant amount of money (like parasitic drag of specific areas). However, is a data, a you can not do a lot to use it... bigger is the effect of air density. Relevant, but only for complex calculations. | |
| Mar 21, 2016 at 16:35 | comment | added | Michael Seifert | Most of those $R$'s should be $R^2$ instead. | |
| Mar 21, 2016 at 15:24 | vote | accept | Ralph | ||
| Mar 21, 2016 at 14:43 | comment | added | Jon Story | But a ton when you weigh 590 tons, is still pretty insignificant... | |
| Mar 21, 2016 at 14:33 | comment | added | Antzi | That's over a ton for a fully loaded A380 :) | |
| Mar 21, 2016 at 14:15 | history | answered | aeroalias | CC BY-SA 3.0 |