601
edits
Avionics and instruments: Difference between revisions
Jump to navigation
Jump to search
→Compass
Legoboyvdlp (talk | contribs) (→Directional Gyro: Complete merge) |
|||
| Line 1: | Line 1: | ||
=== Compass === | === Compass === | ||
The compass aligns itself along the magnetic field that surrounds the earth. | The compass aligns itself along the magnetic field that surrounds the earth. As such, it is subject to various influences that affects the direction in which it points. | ||
==== Magnetic variation ==== | |||
Note that The magnetic north pole and the geographic north pole are not located at the same spot. The difference between the magnetic field and true north is called "magnetic variation" or "magnetic declination". The magnetic variation is expressed as an angle east or west of true north. Not only does the magnetic variation vary with position on the planet, it also slowly varies over time since the magnetic poles are not stationary. | Note that The magnetic north pole and the geographic north pole are not located at the same spot. The difference between the magnetic field and true north is called "magnetic variation" or "magnetic declination". The magnetic variation is expressed as an angle east or west of true north. Not only does the magnetic variation vary with position on the planet, it also slowly varies over time since the magnetic poles are not stationary. | ||
| Line 23: | Line 24: | ||
You ''can'' cheat and get the magnetic variation from the current coordinate when flying in FlightGear, from the property tree (/environment/magnetic-variation-deg). But being a good student you of course want to know the magnetic variation ''before'' rolling out from the hangar, already during the flight planning. You do plan your flights, right? | You ''can'' cheat and get the magnetic variation from the current coordinate when flying in FlightGear, from the property tree (/environment/magnetic-variation-deg). But being a good student you of course want to know the magnetic variation ''before'' rolling out from the hangar, already during the flight planning. You do plan your flights, right? | ||
==== Magnetic deviation ==== | |||
A compass measures a magnetic field which is influenced by metal parts nearby. The electrical equipment in a plane and its metal parts deflect the compass in non-linear ways which is called "magnetic deviation". This is usually calibrated and noted on a "Compass Deviation Card" which is commonly located near the compass. It shows the deviation in 30° steps ("FOR <x> STEER <y>"). | |||
==== Acceleration forces ==== | |||
When changing speed of the aircraft, the compass is subject to acceleration forces. This makes the compass to show more westwards when accelerating and eastwards when decelerating. | |||
To get exact measurements, make sure that the aircraft does not change its speed. | |||
=== Altimeter === | === Altimeter === | ||