Due to the rotation of the earth the apparent drift of a horizontal free gyroscope at a latitude of 30°N is ?
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Source: Telepilote theorique examen 47
A free gyro has the axis of the spinning rotor horizontal and aligned with the geographic meridian If this free gyro is situated at latitude 60°N the apparent drift rate according to the earthbound ?
For a directional gyro the system which detects the local vertical supplies ?
A directional gyro corrected an apparent drift due to earth's rotation at latitude 30°s during a flight at latitude 60°n a drift rate of 15 5°/h to right observed the apparent wander due to change of aircraft position A levelling erection torque motor. earth rate 15°/h if gyro had been corrected at 30°south latitude nut would have been adjusted 15 x sin 30 = 7 5°/h at 60°north earth rate should be 15 sin 60° = 13° 13° + ( 7 5) = 20 5° the gyro drifting at a rate of 15 5° to right apparent wander due to change of aircraft position is 20 5 + 15 5 = 5° to left. 
A control system consisting of four pendulous vanes used in An air driven artificial horizon. air driven artificial horizon the rotor mounted in a sealed housing spins in a horizontal plane about vertical axis the housing pivots about lateral axis on a gimbal which in turn free to pivot about longitudinal axis the instrument case the third gimbal necessary universal mounting the horizon bar linked to gyro a lever attached to a pivot on rear of gimbal frame connected to gyro housing a guide pin when attitude indicator in operation gyroscopic rigidity maintains horizon bar parallel to natural horizon when pitch or bank attitude of aircraft changes miniature aircraft being fixed to case moves with it these movements of instrument case with respect to gyro are shown on face of instrument as pitch bank attitude changes of miniature aircraft with respect to horizon bar air sucked through filter then through passages in rear pivot inner gimbal ring then into housing where it directed against rotor vanes through two openings on opposite sides of rotor the air then passes through four equally spaced ports in lower part of rotor housing is sucked out into vacuum pump or venturi tube the chamber containing ports the erecting device that returns spin axis to its vertical alignment whenever a precessing force such as friction displaces rotor from its horizontal plane the four exhaust ports are each half covered a pendulous vane which allows discharge of equal volumes of air through each port when rotor properly erected any tilting of rotor disturbs total balance of pendulous vanes tending to close one vane of an opposite pair while opposite vane opens a corresponding amount the increase in air volume through opening port exerts a precessing force on rotor housing to erect gyro the pendulous vanes return to a balanced condition acceleration deceleration induce precession errors depending upon amount extent of force applied during acceleration horizon bar moves down indicating a climb control applied to correct this indication will result in a pitch attitude lower than instrument shows the opposite error results from deceleration other errors such as 'transport precession' 'apparent precession' relate to rotation of earth are of importance to pilots navigators concerned with high speed long range flight. 
Considering an air driven artificial horizon when an airplane accelerates during take off r the result A false nose up indication. errors in the artificial horizon (suction) acceleration errors (linear acceleration) these errors are also known as 'takeoff' errors as they are most noticeable during takeoff two elements cause errors pendulous unit vanes error from the pendulous unit the pendulous unit makes rotor bottom heavy as aircraft accelerates a force from inertia of unit felt at bottom the unit tends to lag behind it tends to swing bottom of gyro towards pilot air driven rotors spin anti clockwise (when viewed from above) so this inertial force will precess through 90° in an anti clockwise direction lifting up right hand side of outer gimbal the skyplate attached to outer gimbal rotates in an anti clockwise direction lifting up right hand side of outer gimbal the skyplate attached to outer gimbal rotates anti clockwise and bank indicates a false right bank error from exhaust vanes during acceleration vanes on right left sides are thrown rearward the result that right hand port more than half open the left side port more than half closed this upsets balanced exhaust of air more air being discharged from right side than from left side the reaction occurs on left side precesses through 90° and lifts up inner gimbal from point nearest pilot to indicate a false climb thus with gyro running anti clockwise a slight indication of right bank climb are obtained during an acceleration. 
Considering an air driven artificial horizon when an airplane decelerates on ground during landing result A false nose down indication. errors in the artificial horizon (suction) acceleration errors (linear acceleration) these errors are also known as 'takeoff' errors as they are most noticeable during takeoff two elements cause errors pendulous unit vanes error from the pendulous unit the pendulous unit makes rotor bottom heavy as aircraft accelerates a force from inertia of unit felt at bottom the unit tends to lag behind it tends to swing bottom of gyro towards pilot air driven rotors spin anti clockwise (when viewed from above) so this inertial force will precess through 90° in an anti clockwise direction lifting up right hand side of outer gimbal the skyplate attached to outer gimbal rotates in an anti clockwise direction lifting up right hand side of outer gimbal the skyplate attached to outer gimbal rotates anti clockwise and bank indicates a false right bank error from exhaust vanes during acceleration vanes on right left sides are thrown rearward the result that right hand port more than half open the left side port more than half closed this upsets balanced exhaust of air more air being discharged from right side than from left side the reaction occurs on left side precesses through 90° and lifts up inner gimbal from point nearest pilot to indicate a false climb thus with gyro running anti clockwise a slight indication of right bank climb are obtained during an acceleration. Question 47-8
Concerning directional gyro apparent drift rate due to earth's rotation a function of A false nose down indication. errors in the artificial horizon (suction) acceleration errors (linear acceleration) these errors are also known as 'takeoff' errors as they are most noticeable during takeoff two elements cause errors pendulous unit vanes error from the pendulous unit the pendulous unit makes rotor bottom heavy as aircraft accelerates a force from inertia of unit felt at bottom the unit tends to lag behind it tends to swing bottom of gyro towards pilot air driven rotors spin anti clockwise (when viewed from above) so this inertial force will precess through 90° in an anti clockwise direction lifting up right hand side of outer gimbal the skyplate attached to outer gimbal rotates in an anti clockwise direction lifting up right hand side of outer gimbal the skyplate attached to outer gimbal rotates anti clockwise and bank indicates a false right bank error from exhaust vanes during acceleration vanes on right left sides are thrown rearward the result that right hand port more than half open the left side port more than half closed this upsets balanced exhaust of air more air being discharged from right side than from left side the reaction occurs on left side precesses through 90° and lifts up inner gimbal from point nearest pilot to indicate a false climb thus with gyro running anti clockwise a slight indication of right bank climb are obtained during an acceleration. Question 47-9
The spin axis of turn indicator gyroscope parallel to A false nose down indication. errors in the artificial horizon (suction) acceleration errors (linear acceleration) these errors are also known as 'takeoff' errors as they are most noticeable during takeoff two elements cause errors pendulous unit vanes error from the pendulous unit the pendulous unit makes rotor bottom heavy as aircraft accelerates a force from inertia of unit felt at bottom the unit tends to lag behind it tends to swing bottom of gyro towards pilot air driven rotors spin anti clockwise (when viewed from above) so this inertial force will precess through 90° in an anti clockwise direction lifting up right hand side of outer gimbal the skyplate attached to outer gimbal rotates in an anti clockwise direction lifting up right hand side of outer gimbal the skyplate attached to outer gimbal rotates anti clockwise and bank indicates a false right bank error from exhaust vanes during acceleration vanes on right left sides are thrown rearward the result that right hand port more than half open the left side port more than half closed this upsets balanced exhaust of air more air being discharged from right side than from left side the reaction occurs on left side precesses through 90° and lifts up inner gimbal from point nearest pilot to indicate a false climb thus with gyro running anti clockwise a slight indication of right bank climb are obtained during an acceleration. Question 47-10
Parallax error due to A reading under an oblique angle. the ball centered parallax error due to a reading under an oblique angle. Question 47-11
What angle of bank should you adopt on attitude indicator a standard rate 'rate 1' turn while flying at an ias of 120 kt A reading under an oblique angle. the rate of turn the number of degrees your heading changes in a period of time usually one second or one minute a standard rate turn ('rate 1' typically spoken of in terms of instrument flight) performed at 180 degrees of heading change in a one minute period (3° per second) this gives a complete 360° turn in two minutes a convenient approximation the bank angle in degrees taking 15% of ias 15% of 120 kt = 18. Question 47-12
The term drift refers to wander of axis of a gyro in A reading under an oblique angle. for information drift the wander in horizontal plane topple the wander in vertical plane. Question 47-13
What causes a freely suspended space gyroscope to precess The gyro will precess when a force applied to spinning rim of gyroscope in same direction as axis of rotation. for information drift the wander in horizontal plane topple the wander in vertical plane. Question 47-14
While inertial platform system operating on board an aircraft it necessary to use a device with following characteristics in order to keep vertical line with a pendulous system With damping a period of about 84 minutes. Schuler oscillations have a period of 84 4 minutes are damped out when a gyro stabilised platform moved over surface of earth gyro control system moves it to local horizontal but it ends up oscillating about new horizontal schuler figured that it would act as if it was swinging about at end of a pendulum the period of oscillation of a pendulum depends on square root of its length schuler suggested that it would swing about as if length of pendulum was radius of earth that gives us a period of oscillation of 84 4 minutes. Question 47-15
In order to align an irs it required to insert local geographical coordinates this enables irs to 1 compare computed latitude with one entered the pilot 2 compare computed longitude with one entered the pilot 3 know longitude the combination that regoups all of correct statements With damping a period of about 84 minutes. Schuler oscillations have a period of 84 4 minutes are damped out when a gyro stabilised platform moved over surface of earth gyro control system moves it to local horizontal but it ends up oscillating about new horizontal schuler figured that it would act as if it was swinging about at end of a pendulum the period of oscillation of a pendulum depends on square root of its length schuler suggested that it would swing about as if length of pendulum was radius of earth that gives us a period of oscillation of 84 4 minutes. Question 47-16
Compared with a conventional gyro a laser gyro Has a longer life cycle. Laser gyros are used in inertial reference systems use a partially silvered mirror 2 contra rotating laser beams that go opposite direction to each other compared with a conventional gyro a laser gyro more accurate has a longer life cycle because there are no moving parts therefore no friction. Question 47-17
The mode selector of an inertial unit comprises off stby align nav att positions 1 on 'stby' unit aligns on local geographic trihedron2 'att' position used in automatic landing mode land 3 on 'nav' coordinates of start position can be entered4 platform levelled before azimuth alignment5 in cruise unit can only be used in 'nav' mode the combination regrouping all correct statements Has a longer life cycle. Laser gyros are used in inertial reference systems use a partially silvered mirror 2 contra rotating laser beams that go opposite direction to each other compared with a conventional gyro a laser gyro more accurate has a longer life cycle because there are no moving parts therefore no friction. Question 47-18
The principle of a laser gyro based on Frequency difference between two laser beams rotating in opposite direction. Two light beams travelling a different distance in same time because of rotation of device rate of rotation proportional to phase difference. Question 47-19
As a result of failure of adc inertial navigation system ins will no longer provide information about Wind direction speed. ins itself does not know wind direction velocity it only knows ground speed using true airspeed (tas) from an air data source they can easily calculate wind the ins get data (tas altitude) from an air data computer from position ins can provide information about drift can compute time at next waypoint. Question 47-20
In order to align an inertial reference system irs it required to insert local geographical coordinates this enables irs to Compare latitude it finds with that entered the operator. ins itself does not know wind direction velocity it only knows ground speed using true airspeed (tas) from an air data source they can easily calculate wind the ins get data (tas altitude) from an air data computer from position ins can provide information about drift can compute time at next waypoint. Question 47-21
Compared with a conventional gyro a laser gyro Is much more cumbersome. ins itself does not know wind direction velocity it only knows ground speed using true airspeed (tas) from an air data source they can easily calculate wind the ins get data (tas altitude) from an air data computer from position ins can provide information about drift can compute time at next waypoint. Question 47-22
The operating principle of an inertial system consists in Measuring acceleration of aircraft performing integrations to elaborate ground speed the position. the ins measures accelerations north/south accelerations east/west which go through two integrations to give distance travelled north/south east/west from initial position distances travelled north/south east/west it computes present position from change of position it computes track ground speed. Question 47-23
Compared with a stabilised platform inertial system a strapdown inertial system 1 can aligne while aircraft moving2 has a quicker alignment phase3 more reliable in time the combination that regroups all correct statements Measuring acceleration of aircraft performing integrations to elaborate ground speed the position. the ins measures accelerations north/south accelerations east/west which go through two integrations to give distance travelled north/south east/west from initial position distances travelled north/south east/west it computes present position from change of position it computes track ground speed. Question 47-24
In an inertial navigation system to know distance travelled Integrating once speed in time sufficient. distance travelled = speed x time and in 'integrating once speed in time sufficient' just formula. Question 47-25
To obtain instantaneous speed from accelerations It necessary to integrate acceleration once in time to know initial speed only. distance travelled = speed x time and in 'integrating once speed in time sufficient' just formula. Question 47-26
To obtain instantaneous position from accelerations It necessary to integrate twice acceleration in time to know initial position the initial speed. distance travelled = speed x time and in 'integrating once speed in time sufficient' just formula. Question 47-27
In a inertial navigation system integration process makes a It necessary to integrate twice acceleration in time to know initial position the initial speed. acceleration x time = change of speed speed x time = distance travelled. Question 47-28
If acceleration of an aircraft zero its velocity It necessary to integrate twice acceleration in time to know initial position the initial speed. acceleration x time = change of speed speed x time = distance travelled. Question 47-29
The time a normal alignment not a quick alignment of a strapdown inertial system It necessary to integrate twice acceleration in time to know initial position the initial speed. a rapid self alignment of a strapdown inertial system (irs) can be performed in less than 10 minutes inertial reference systems with laser gyro has caused a technological revolution in design of inertial reference navigation systems this solid state high precision angular rate sensor ideally suited highly reliable strap down system configuration it eliminates need gimbals bearings torque motors other moving parts consequently changes system operation considerably from conventional inertial navigation systems (ins). Question 47-30
The position error of a stand alone inertial system approximately 5 to 2 nm per hour. a rapid self alignment of a strapdown inertial system (irs) can be performed in less than 10 minutes inertial reference systems with laser gyro has caused a technological revolution in design of inertial reference navigation systems this solid state high precision angular rate sensor ideally suited highly reliable strap down system configuration it eliminates need gimbals bearings torque motors other moving parts consequently changes system operation considerably from conventional inertial navigation systems (ins). Question 47-31
The output data of an irs include 1 attitude2 altitude3 present position lat long 4 static air temperaturethe combination regrouping all correct statements 5 to 2 nm per hour. in their normal navigation mode irss provide attitude true magnetic heading acceleration vertical speed ground speed track present position wind data to appropriate airplane systems irs outputs are independent of external navigation aids. Question 47-32
The alignment sequence of an irs consists of 1 searching the local vertical2 searching the true north3 comparison between computed longitude and one entered the pilot4 comparison between computed latitude and one entered the pilotthe combination that regroups all of correct statements 5 to 2 nm per hour. in their normal navigation mode irss provide attitude true magnetic heading acceleration vertical speed ground speed track present position wind data to appropriate airplane systems irs outputs are independent of external navigation aids. Question 47-33
The output data of an irs include 1 present position lat long 2 total pressure3 static air temperature4 true headingthe combination regrouping all correct statements 5 to 2 nm per hour. in their normal navigation mode irss provide attitude true magnetic heading acceleration vertical speed ground speed track present position wind data to appropriate airplane systems irs outputs are independent of external navigation aids. Question 47-34
The output data of an irs include 1 satellites status2 altitude3 drift angle4 present position lat long the combination regrouping all correct statements 5 to 2 nm per hour. in their normal navigation mode irss provide attitude true magnetic heading acceleration vertical speed ground speed track present position wind data to appropriate airplane systems irs outputs are independent of external navigation aids. Question 47-35
The output data of an irs include 1 angle of attack2 altitude3 ground speedthe combination regrouping all correct statements 5 to 2 nm per hour. in their normal navigation mode irss provide attitude true magnetic heading acceleration vertical speed ground speed track present position wind data to appropriate airplane systems irs outputs are independent of external navigation aids. Question 47-36
The output data of an irs include 1 number of satellites tracked2 mach number3 ground speed4 true trackthe combination regrouping all correct statements 5 to 2 nm per hour. in their normal navigation mode irss provide attitude true magnetic heading acceleration vertical speed ground speed track present position wind data to appropriate airplane systems irs outputs are independent of external navigation aids (such as satellite) the adc (air data computer) will compute mach number. Question 47-37
To obtain instantaneous position from accelerations it necessary to 1 integrate twice acceleration in time2 know initial position 3 know initial speedthe combination that regroups all of correct statements 5 to 2 nm per hour. in their normal navigation mode irss provide attitude true magnetic heading acceleration vertical speed ground speed track present position wind data to appropriate airplane systems irs outputs are independent of external navigation aids (such as satellite) the adc (air data computer) will compute mach number. Question 47-38
To obtain instantaneous speed from accelerations it necessary to 1 integrate once acceleration in time2 know initial position 3 know initial speedthe combination that regroups all of correct statements 5 to 2 nm per hour. the first integration of acceleration with respect to time gives change of speed apply this to initial speed you have instantaneous speed. Question 47-39
In an inertial navigation system principle used to obtain position 1 single integration of acceleration according to time2 double integration of acceleration according to time3 single integration of speed according to time4 double integration of speed according to timethe combination that regroups all of correct statements 5 to 2 nm per hour. the first integration of acceleration with respect to time gives change of speed apply this to initial speed you have instantaneous speed. Question 47-40
Considering a strapdown inertial system operating principle requires use of at least 3 laser gyros 3 accelerometers. the first integration of acceleration with respect to time gives change of speed apply this to initial speed you have instantaneous speed.
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