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  • Originally posted by Highkeas View Post
    The aircraft flying East to West due to the Coriolis effect.
    Nope. There are two reasons why Coriolis forces are not a factor here.
    One is that Coriolis forces happen when something moves in the "normal" direction (perpendicular to the axis of rotation), and a movement due East or due West is 100% tangential (circumferential, has no "normal" component).
    The other one... I withheld it by now.

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
    --- Defend what you say with arguments, not by imposing your credentials ---

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    • Is there by any chance a mispelt word in your problem ?
      If it 'ain't broken........ Don't try to mend it !

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      • Originally posted by brianw999 View Post
        Is there by any chance a mispelt word in your problem ?
        If there is, it was not intentional.
        What do you have in mind?

        --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
        --- Defend what you say with arguments, not by imposing your credentials ---

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        • I was wondering if you were being a bit devious with your wording...

          At the same time another Malaysian Boeing 777 is flying West over Malaysia at 37000 ft and M 0.8 too. There is no wind.
          ...Intimating M 0.82 ! 2 = too !!
          If it 'ain't broken........ Don't try to mend it !

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          • unless it is totally hypothetical, there is always wind...

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            • Originally posted by brianw999 View Post
              I was wondering if you were being a bit devious with your wording...

              ...Intimating M 0.82 ! 2 = too !!
              No, not playing with words here. I could have said "also M 0.8".

              --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
              --- Defend what you say with arguments, not by imposing your credentials ---

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              • Originally posted by TeeVee View Post
                unless it is totally hypothetical, there is always wind...
                It's hypothetical. Say that there was no wind.

                --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                --- Defend what you say with arguments, not by imposing your credentials ---

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                • Let's try this theory....

                  Both aircraft are travelling through the air at M 0.8 with identical loadings, settings etc. Mach speed is speed through the air and changes with altitude/air density.

                  Both aircraft are travelling through the air at the same Mach speed.

                  The earth rotates counterclockwise on its axis (from west to east).

                  Therefore the aircraft flying to the west has a faster groundspeed than the easterly heading aircraft.

                  Therefore the westerly heading aircraft will cover more ground in a given amount of time than the easterly heading aircraft in the same amount of time.

                  Fuel burn is measured against time vs distance travelled therefore the westerly heading aircraft will burn less fuel to cover the same distance as the easterly heading aircraft.

                  (Takes a deep breath......how did I do ?)
                  If it 'ain't broken........ Don't try to mend it !

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                  • Originally posted by brianw999 View Post
                    (Takes a deep breath......how did I do ?)
                    You are in the good path by taking the rotation of the Earth into account.

                    But since there is no wind, and the wind is by definition the movement of the air mass relative surface of the Earth, "no wind" means "the air doesn't move relative to the surface of the Earth", and hence equal airspeed means equal groundspeed too.

                    For the sake of the puzzle, I could have said that they are both traveling at the same Mach number, the same airspeed, or the same groundspeed.

                    And, maybe more important, one of them is burning a little less of fuel, be it per mile or per hour. And the reason for that is that one of them is making a little less of drag. But the reason doesn't lie in the plane itself. Swap headings and fuel burns will be swapped too.

                    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                    --- Defend what you say with arguments, not by imposing your credentials ---

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                    • If the moon and or sun was not directly overhead then there would be a extremely small gravitational gradient between the two aircraft. The moon is in its first quarter today so the Eastbound aircraft would need slightly higher thrust [Except thrust would be different, not drag.]

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                      • Originally posted by Highkeas View Post
                        If the moon and or sun was not directly overhead then there would be a extremely small gravitational gradient between the two aircraft. The moon is in its first quarter today so the Eastbound aircraft would need slightly higher thrust [Except thrust would be different, not drag.]
                        Well thought. I had not taken this into account.
                        Let's say that it's local midday and there is a solar eclipse.

                        We already had the rotation of the Earth and now we have gravity too. We are in the good path. Come on team, last effort!

                        --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                        --- Defend what you say with arguments, not by imposing your credentials ---

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                        • Well... I could say that whichever plane has been flying longer would have given the fuel more time to cold-soak, thus its fuel temp would be lower. Assuming the autothrottle is maintaining a constant thrust, the fuel flow *by volume* on that plane would therefore be less since its fuel is denser and thus less (again by volume, not mass) fuel is required to produce the same thrust level.

                          But I'm guessing that's not what you're looking for.
                          Be alert! America needs more lerts.

                          Eric Law

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                          • Originally posted by elaw View Post
                            Well... I could say that whichever plane has been flying longer would have given the fuel more time to cold-soak, thus its fuel temp would be lower. Assuming the autothrottle is maintaining a constant thrust, the fuel flow *by volume* on that plane would therefore be less since its fuel is denser and thus less (again by volume, not mass) fuel is required to produce the same thrust level.

                            But I'm guessing that's not what you're looking for.
                            Nope, but keep trying!

                            The slight difference in fuel burn is measured in mass, not volume. Anyway, for the sake of this puzzle it's safe to assume that the fuel in both airplanes have identical properties.

                            We had people that was playing with the right variables to solve this problem:
                            - Gravity
                            - Rotation of the Earth
                            - Direction of flight (one West, one East)

                            Aaaaaaand...

                            Both airplanes are flying along the ecuator (okay, to prevent that they collide let's have one of them 1 mile North and the other one one mile South of the ecuator, to which they are flying parallel). This was the second reason why Coriolis forces are not a factor. There is no Coriolis forces on the ecuator.

                            Come on, it's served in a golden tray!!!

                            --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                            --- Defend what you say with arguments, not by imposing your credentials ---

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                            • We all flunked the test - answer please

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                              • plane going west to east will be in the jet stream.
                                Live, from a grassy knoll somewhere near you.

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