1,669
edits
Aircraft speed: Difference between revisions
Jump to navigation
Jump to search
m
→Mach number
m (→Mach number) |
|||
| Line 51: | Line 51: | ||
=== Mach number === | === Mach number === | ||
*The '''Mach number''' (M) is the | *The [http://en.wikipedia.org/wiki/Mach_number|'''Mach number''' (M)] is the speed of the aircraft divided by the speed of sound (at that altitude). It is a calculated number without a unit. | ||
A Mach number below 1 means that the plane moves subsonic | The aircraft's behaviour at Mach 1 at sea level is about the same as the behaviour of the aircraft at an altitude of 60000 feet. | ||
A Mach number below 1 means that the plane moves subsonic. A Mach number above 1 indicates supersonic flight. The Mach number is critical because a number of phenomena take place just around Mach 1 (transonic speed), for example a sudden increase in drag induced by shock-wave generation (sonic-boom). The speed of sound changes with the compressibility (and hence temperature) of air, the Mach number is dependent on [[altitude]] (as the air temperature drops at higher altitudes). This implies that Mach 2 at sea level corresponds to a faster TAS than Mach 2 at 30.000 ft. The precise relation between TAS, Mach number and altitude is a complicated formulae and depends in essence on the local weather pattern determining the pressure and temperature gradients in the atmosphere. | |||
==V speeds== | ==V speeds== | ||