Download The magnetic compass

By: Paola Gabriel
October 21st, 2010
Think Tank, Factory B-3
Introduction
Well to me the magnetic compass is a very useful tool
for pilots. Now you might be asking yourself “what is
it for?” Well my friend in this next slides you will
know more about it. And you’ll learn it… you’ll know
it. Because when you go on a long trip, you might
show your intelligence to the pilots and maybe
become a pilot one day (if you want to) .  Well I
hope you get this info..
Main points
• The magnetic compass is a very useful tool for
the pilots.
• What is the magnetic compass exactly?
• How do pilots use it? What are its errors?
• The history has interesting history.
What is the compass?
 The magnetic compass is the only direction
indicating instrument. It does not need any
external power. It is extremely useful as a
standby or emergency instrument. But first a
pilot must know, and not only know but follow
the principles.
The next slide will tell you about the
principles..
What is it for?
• The compass works because Earth is like a huge magnet.
• In a two-minute or standard-rate turn, the aircraft turns
through 360° in two minutes, or 3°/sec. By dividing by three
the number of degrees in the planned turn, the pilot may
determine the number of seconds required in a standard-rate
turn to accomplish the desired heading change. After rolling
the aircraft out on the new heading, the pilot must wait a few
seconds for the compass to settle down. Then he or she can
check the new heading.
ERRORS!
o Deviation error: The compass needle is affected when
aircraft electrical equipment is operated and by the ferrous
metallic components within the aircraft. These internal
magnetic fields tend to deflect the compass from alignment
with magnetic north.
o . Dip error: As previously mentioned, the compass card
tends to align itself with the earth's magnetic field. At or near
the Equator this causes little or no problem, but as the aircraft
nears either of the magnetic poles, the dip error becomes
significant
More errors….
• Acceleration error occurs during airspeed changes and is
most apparent on headings of east and west. It is caused by
a combination of inertia and magnetic dip. As the aircraft
accelerates, the compass card, acting like a pendulum, tilts
slightly during the acceleration because of the card's
inertia.
• This momentary tilting displaces the compass card from its
normal alignment with magnetic north; therefore, when
the aircraft accelerates in either an easterly or westerly
direction, the compass card momentarily indicates a turn
toward the north. The reverse is true when the aircraft
decelerates. If the aircraft decelerates on a heading of
approximately east or west, the pilots should remember
the acronym ANDS: accelerate north, decelerate sout
Principles
 So the pilot must first understand this difference between
magnetic north and true north (variation) because some of
the directional values used in aviation are stated in terms of
magnetic north, while others are stated in terms of true
north.
 If you don’t get it here’s a hint. The direction of finding
instruments in the aircraft, including the magnetic compass,
present heading information in terms of the magnetic north.
 There are a lot more than you expect to see so let’s just go on
to the next slide…. 
Its history
The magnetic compass has a really interesting history, would you like to know
about it? Well it was first invented by the Chinese. It was made during the
Qin dynasty, (221-206 B.C.)Some fortune tellers used lodestones to build their
fortune boards, but then someone noticed they were better for pointing
out directions. So they started to
make the compass, using the lodestones.
It is the oldest instrument for navigation it has been a vital tool for navigators
at sea for many centuries.
Some were made from wooden brass fittings. I can’t tell you where exactly it
was first used. It really has improved from wood to metal.
More history!!! 
• Hans Christian Oersted was a professor of science at Copenhagen
University. In 1820 he arranged in his home a science
demonstration to friends and students. He planned to demonstrate
the heating of a wire by an electric current, and also to carry out
demonstrations of magnetism, for which he provided a compass
needle mounted on a wooden stand.
• Hans Christian Oersted..
Conclusion slide
• The magnetic compass is been used for
hundreds or maybe thousands of years.
• It is very useful………
• PILOTS NEED IT!! My friend you need to know
more than what I just told you! The magnetic
compass has a really interesting history, and
you need to know it! 
Sources
• They are………
• http://www.allstar.fiu.edu/aero/MagComp.htm
• http://www.solarnavigator.net/compass.htm
• http://www.navis.gr/navaids/compass.htm