what are the 5 basic navigation systems? - ANSWERS1. pilotage - flying by landmarks
2. dead reckoning - knowing your heading and speed, work out where you're going
3. celestial navigation - using time and angle bwtn known celestial object (moon, sun, etc)
4. radio navigation - GPS, ILS, VOR, AD...
AMEM10019 - AVIONICS TEST 4
Questions & Answers
what are the 5 basic navigation systems? - ANSWERS1. pilotage - flying by landmarks
2. dead reckoning - knowing your heading and speed, work out where you're going
3. celestial navigation - using time and angle bwtn known celestial object (moon, sun,
etc)
4. radio navigation - GPS, ILS, VOR, ADF, etc
5. inertial navigation - INS and ADIRU
what is INS? what does it stand for? - ANSWERS- inertial navigation system
- advanced navigation concept designed as an integral part of the avionics system
- provide steering commands to autopilot to steer the airplane through predetermine
waypoints
- accurately determine an AC position using internal sensing devices
what are some features of INS? - ANSWERS1. auto self-alignment and calibration are
accomplished each time the INS is turned on
2. does not require any input from navigation aids external to the AC
3. continuously monitors its on performance and warns when signals are unreliable
4. present position, waypoint and destination data are easily entered by using a
keyboard
5. performance can be improved during flight by making a position fix when accurate
present position reference is available
what are the 3 laws of motion? - ANSWERS1. body continues in a state of rest, or
uniform motion in a straight straight line, unless acted on by an external force
2. the acceleration of a body is directly proportional to the sum of the forces acting on
that body
3. for every action, there is an equal and opposite reaction
an aircraft moves in 3 dimensions over the earth's surface, how many degrees of
freedom? - ANSWERS6 degrees of freedom
- 3 translation (N/S, E/W, UP/DWN)
- 3 rotational (roll, pitch, and azimuth)
what is a gimbal platform - ANSWERS- plat that effectively decouples the inertial
reference system from the airframe and provides all-attitude freedom and rotation
- AC are seldom perfectly lvl in flight, all airborne accelerometers must be mounted on
gimbal plat
- consist of 3 gyros, which stabilize the unit
, the combo of gimbals and gyroscopes creates a platform that.... - ANSWERS- remains
level in any AC attitude
- does not sense changes in AC attitude, the output signal accurately measures
changes in accel
- signal is amplified and sent to INS comp
INS is capable of continuously updating what? - ANSWERS-position
-ground speed
-heading and distance
-time to destination
what is used to detect acceleration? - ANSWERS- accelerometer
- sense change in velocity
- consists of a small weight suspended between two spring
- acceleration sensed in the horizontal direction causes the mass to compress one of
the supporting springs, and to stretch the other
- must be kept perfectly level as to not misinterpret gravity as acceleration
what is a strap down inertial navigation sys? - ANSWERS- uses solid state parts,
including the laser gyro
- eliminates the limitations of gimbals, bearings, torque motors and other moving parts
- ring laser gyro uses two laser light beams to measure angular rotation
- sys uses a helium neon gas combo, and the two laser beams are circulated in a
contrarotating triangular path
- mirrors are used to reflect each beam in triangular area
- resonant freq of each laser is a function of its optical path length and when at rest,
both beams travel equal distance and have identical freq
what change is measured by photosensors and converted to a digital signal? -
ANSWERSthe two resonant freq of the individual beams in ring laser gyros
what is laser lock? - ANSWERS- during low gyro rotation rates, the 2 lasers can
become coupled together.
- to prevent loss of information during low rotation rates, a dither motor is installed which
vibrates the gyro assembly
what are the components in an INS system? - ANSWERS1. Mode selector unit - allows
selection (align and nav). READY NAV light luminate to indicate INS high accuracy
alignment has been attained
2. Control Display Unit - used to insert present position for INS alignment. this MUST be
done with the AC NOT moving. can be done through the MCDU
3. inertial reference unit - sense and compute linear accelerations and angular turning
rates (6 thingy). AC power fails, switches to AC battery
what is initialization or alignment? - ANSWERS- a process that is initiated manually
when the AC is on the ground in a parked condition
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