Question 63-1 : Without any external action the axis of a free gyroscope is fixed with reference to ? [ Diploma registration ]

Question 63-2 : Due to the rotation of the earth the apparent drift of a horizontal free gyroscope at a latitude of 45°n is ?

11° per hour to the right.

Earth rate is 15°hat 45°north the earth rate is 15°h x sin 45° = 106°hin northern hemisphere the gyro is drifting at a rate of 15°h to the right the heading increases

Question 63-3 : Due to the rotation of the earth the apparent drift of a horizontal free gyroscope at a latitude of 30°s is ?

75° per hour to the left.

Earth rate is 15°hat 30°south the earth rate is 15°h x sin 30° = 75°hin southern hemisphere the gyro is drifting at a rate of 15°h to the left the heading decreases

Question 63-4 : Due to the rotation of the earth the apparent drift of a horizontal free gyroscope at a latitude of 30°n is ?

75° per hour to the right.

Earth rate is 15°hat 30°north the earth rate is 15°h x sin 30° = 75°hin northern hemisphere the gyro is drifting at a rate of 15°h to the right the heading increases

Question 63-5 : A free gyro has the axis of the spinning rotor horizontal and aligned with the geographic meridianif this free gyro is situated at latitude 60°n the apparent drift rate according to the earthbound observer is ?

13°h to the right.

Earth rate is 15°hat 60°north the earth rate is 15°h x sin 60° = 13°hin northern hemisphere the gyro is drifting at a rate of 15°h to the right the heading increases kn0027 in the northern hemisphere the earth rate causes the dgi indication to decrease not increase 15sin lat this would appear to show a turn to the leftin the northern hemisphere earth rotation which is our only consideration is negative which means the readings will decrease due to the apparent driftwhen viewed from the top the compass card will appear to have turned clockwise which is right where as anti clockwise is considered left

Question 63-6 : For a directional gyro the system which detects the local vertical supplies ?

A levelling erection torque motor.

The question refers to a gyro compass levelling system and a gyro compass is nothing more than a sophisticated direction indicator the aim of the game is to keep the gyro spin axis horizontal with reference to gravity acting on a pendulumif we take each answer in turn a torque motor on the sensitive axis the gyro has two degrees of freedom which gives two sensitive axes not one two torque motors arranged horizontally only one torque motor is required to keep the spin axis horizontal a nozzle integral with the outer gimbal ring in an air driven system twin air jets are used not a single nozzle a levelling erection torque motor a single torque motor inducing topple in the vertical plane to keep the gyro spin axis horizontal

Question 63-7 : A directional gyro is corrected for an apparent drift due to the earth's rotation at latitude 30°sduring a flight at latitude 60°n a drift rate of 155°h to the right is observedthe apparent wander due to change of aircraft position is ?

5°h to the left.

Earth rate is 15°hif the gyro had been corrected at 30°south the latitude nut would have been adjusted 15 x sin 30 = 75°hat 60°north the earth rate should be 15 sin 60° = 13° 13° + 75 = 205°the gyro is drifting at a rate of 155° to the right the apparent wander due to change of aircraft position is 205 + 155 = 5° to the left

Question 63-8 : A control system consisting of four pendulous vanes is used in ?

An air driven artificial horizon.

Air driven artificial horizon 1011the rotor mounted in a sealed housing spins in a horizontal plane about the vertical axis the housing pivots about the lateral axis on a gimbal which in turn is free to pivot about the longitudinal axis the instrument case is the third gimbal necessary for universal mounting the horizon bar is linked to the gyro by a lever attached to a pivot on the rear of the gimbal frame and connected to the gyro housing by a guide pinwhen the attitude indicator is in operation gyroscopic rigidity maintains the horizon bar parallel to the natural horizon when the pitch or bank attitude of the aircraft changes the miniature aircraft being fixed to the case moves with it these movements of the instrument case with respect to the gyro are shown on the face of the instrument as pitch and bank attitude changes of the miniature aircraft with respect to the horizon bar 1012air is sucked through the filter then through passages in the rear pivot and inner gimbal ring then into the housing where it is directed against the rotor vanes through two openings on opposite sides of the rotor the air then passes through four equally spaced ports in the lower part of the rotor housing and is sucked out into the vacuum pump or venturi tube 1013the chamber containing the ports is the erecting device that returns the spin axis to its vertical alignment whenever a precessing force such as friction displaces the rotor from its horizontal plane the four exhaust ports are each half covered by a pendulous vane which allows discharge of equal volumes of air through each port when the rotor is properly erected any tilting of the rotor disturbs the total balance of the pendulous vanes tending to close one vane of an opposite pair while the opposite vane opens a corresponding amount the increase in air volume through the opening port exerts a precessing force on the rotor housing to erect the gyro and the pendulous vanes return to a balanced conditionacceleration and deceleration induce precession errors depending upon the amount and extent of the force applied during acceleration the horizon bar moves down indicating a climb control applied to correct this indication will result in a pitch attitude lower than the instrument shows the opposite error results from deceleration other errors such as 'transport precession' and 'apparent precession' relate to rotation of the earth and are of importance to pilots and navigators concerned with high speed and long range flight

Question 63-9 : Considering an air driven artificial horizon when an airplane accelerates during the take off run the result is ?

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 takeofftwo elements cause the errors the pendulous unit the vaneserror from the pendulous unit the pendulous unit makes the rotor bottom heavyas the aircraft accelerates a force from inertia of the unit is felt at the bottom and the unit tendsto lag behind it tends to swing the bottom of the gyro towards the pilotair driven rotors spin anti clockwise when viewed from above so this inertial force will precessthrough 90° in an anti clockwise direction lifting up the right hand side of the outer gimbalthe skyplate attached to the outer gimbal rotates in an anti clockwise direction lifting up the righthand side of the outer gimbal the skyplate attached to the outer gimbal rotates anti clockwiseand the bank indicates a false right bankerror from exhaust vanes during acceleration the vanes on the right and left sides are thrown rearwardthe result is that the right hand port is more than half open and the left side port is more thanhalf closed this upsets the balanced exhaust of air more air being discharged from the rightside than from the left side the reaction occurs on the left side and precesses through 90° andlifts up the inner gimbal from the point nearest the pilot to indicate a false climbthus with the gyro running anti clockwise a slight indication of right bank and climb are obtainedduring an acceleration

Question 63-10 : Considering an air driven artificial horizon when an airplane decelerates on ground during the landing the result is ?

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 the errors the pendulous unit the vaneserror from the pendulous unit the pendulous unit makes the rotor bottom heavyas the aircraft accelerates a force from inertia of the unit is felt at the bottom and the unit tendsto lag behind it tends to swing the bottom of the gyro towards the pilotair driven rotors spin anti clockwise when viewed from above so this inertial force will precessthrough 90° in an anti clockwise direction lifting up the right hand side of the outer gimbalthe skyplate attached to the outer gimbal rotates in an anti clockwise direction lifting up the righthand side of the outer gimbal the skyplate attached to the outer gimbal rotates anti clockwiseand the bank indicates a false right bankerror from exhaust vanes during acceleration the vanes on the right and left sides are thrown rearwardthe result is that the right hand port is more than half open and the left side port is more thanhalf closed this upsets the balanced exhaust of air more air being discharged from the rightside than from the left side the reaction occurs on the left side and precesses through 90° andlifts up the inner gimbal from the point nearest the pilot to indicate a false climbthus with the gyro running anti clockwise a slight indication of right bank and climb are obtainedduring an acceleration

Question 63-11 : Concerning the directional gyro the apparent drift rate due to the earth's rotation is a function of ?

Latitude.

Question 63-12 : The spin axis of the turn indicator gyroscope is parallel to the ?

Pitch axis.

Question 63-13 : Parallax error is due to ?

A reading under an oblique angle.

1002the ball is centered parallax error is due to a reading under an oblique angle

Question 63-14 : What angle of bank should you adopt on the attitude indicator for a standard rate 'rate 1' turn while flying at an ias of 120 kt ?

18°.

The rate of turn is the number of degrees your heading changes in a period of time usually one second or one minutea standard rate turn 'rate 1' typically spoken of in terms of instrument flight is performed at 180 degrees of heading change in a one minute period 3° per second this gives a complete 360° turn in two minutesa convenient approximation for the bank angle in degrees is taking 15% of ias 15% of 120 kt = 18

Question 63-15 : The term drift refers to the wander of the axis of a gyro in ?

Horizontal plane.

For information drift is the wander in the horizontal planetopple is the wander in the vertical plane

Question 63-16 : What causes a freely suspended space gyroscope to precess ?

The gyro will precess when a force is applied to the spinning rim of the gyroscope in the same direction as the axis of rotation.

Question 63-17 : While inertial platform system is operating on board an aircraft it is necessary to use a device with the following characteristics in order to keep the vertical line with a pendulous system ?

With damping and a period of about 84 minutes.

Schuler oscillations have a period of 844 minutes and are damped outwhen a gyro stabilised platform is moved over the surface of the earth the gyro control system moves it to the local horizontal but it ends up oscillating about the new horizontal schuler figured that it would act as if it was swinging about at the end of a pendulum the period of oscillation of a pendulum depends on the square root of its length and schuler suggested that it would swing about as if the length of the pendulum was the radius of the earth and that gives us a period of oscillation of 844 minutes

Question 63-18 : In order to align an irs it is required to insert the local geographical coordinates this enables the irs to 1 compare the computed latitude with the one entered by the pilot 2 compare the computed longitude with the one entered by the pilot 3 know the longitude the combination that regoups all ?

1 3.

Question 63-19 : Compared with a conventional gyro a laser gyro ?

Has a longer life cycle.

Laser gyros are used in inertial reference systems and use a partially silvered mirror and 2 contra rotating laser beams that go the opposite direction to each othercompared with a conventional gyro a laser gyro is more accurate and has a longer life cycle because there are no moving parts and therefore no friction

Question 63-20 : The mode selector of an inertial unit comprises the off stby align nav att positions 1 on stby the unit aligns on the local geographic trihedron2 the att position is used in automatic landing mode land 3 on nav the coordinates of the start position can be entered4 the platform is levelled ?

4.

Question 63-21 : The principle of a laser gyro is based on ?

Question 63-22 : As a result of the failure of the adc the inertial navigation system ins will no longer provide information about the ?

Wind direction and speed.

Ins by itself does not know wind direction and velocity it only knows ground speed using true airspeed tas from an air data source they can easily calculate windthe ins get data tas and altitude from an air data computerfrom position ins can provide information about drift and can compute time at the next waypoint

Question 63-23 : In order to align an inertial reference system irs it is required to insert the local geographical coordinates this enables the irs to ?

Compare the latitude it finds with that entered by the operator.

Question 63-24 : Compared with a conventional gyro a laser gyro ?

Is much more cumbersome.

Question 63-25 : The operating principle of an inertial system consists in ?

Measuring the acceleration of the aircraft and performing integrations to elaborate the ground speed and the position.

The ins measures accelerations northsouth and accelerations eastwest which go through two integrations to give distance travelled northsouth and eastwest from initial position and distances travelled northsouth and eastwest it computes present position and from change of position it computes track and ground speed

Question 63-26 : Compared with a stabilised platform inertial system a strapdown inertial system 1 can aligne while the aircraft is moving2 has a quicker alignment phase3 is more reliable in timethe combination that regroups all the correct statements is ?

2 3.

Question 63-27 : In an inertial navigation system to know the distance travelled ?

Integrating once the speed in time is sufficient.

Distance travelled = speed x timeand in the integrating once the speed in time is sufficient is just the formula

Question 63-28 : To obtain the instantaneous speed from the accelerations ?

It is necessary to integrate the acceleration once in time and to know the initial speed only.

Question 63-29 : To obtain the instantaneous position from the accelerations ?

It is necessary to integrate twice the acceleration in time and to know the initial position and the initial speed.

Question 63-30 : In a inertial navigation system the integration process makes a ?

Time multiplication.

Acceleration x time = change of speedspeed x time = distance travelled

Question 63-31 : If the acceleration of an aircraft is zero its velocity ?

Is constant.

Question 63-32 : The time for a normal alignment not a quick alignment of a strapdown inertial system is ?

3 to 10 minutes.

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 the design of inertial reference and navigation systems this solid state high precisionangular rate sensor is ideally suited for highly reliable strap down system configurationit eliminates the need for gimbals bearings torque motors and other moving parts and consequently changes the system operation considerably from conventional inertial navigation systems ins

Question 63-33 : The position error of a stand alone inertial system is approximately ?

05 to 2 nm per hour.

Question 63-34 : The output data of an irs include 1 attitude2 altitude3 present position lat long 4 static air temperaturethe combination regrouping all the correct statements is ?

1 3.

In their normal navigation mode the irss provide attitude true and magnetic heading acceleration vertical speed ground speed track present position and wind data to appropriate airplane systems irs outputs are independent of external navigation aids

Question 63-35 : The alignment sequence of an irs consists of 1 searching for the local vertical2 searching for the true north3 comparison between the computed longitude and the one entered by the pilot4 comparison between the computed latitude and the one entered by the pilotthe combination that regroups all of ?

1 2 et 4.

Question 63-36 : The output data of an irs include 1 present position lat long 2 total pressure3 static air temperature4 true headingthe combination regrouping all the correct statements is ?

1 4.

In their normal navigation mode the irss provide attitude true and magnetic heading acceleration vertical speed ground speed track present position and wind data to appropriate airplane systems irs outputs are independent of external navigation aids

Question 63-37 : The output data of an irs include 1 satellites status2 altitude3 drift angle4 present position lat long the combination regrouping all the correct statements is ?

3 4.

In their normal navigation mode the irss provide attitude true and magnetic heading acceleration vertical speed ground speed track present position and wind data to appropriate airplane systems irs outputs are independent of external navigation aids

Question 63-38 : The output data of an irs include 1 angle of attack2 altitude3 ground speedthe combination regrouping all the correct statements is ?

3.

In their normal navigation mode the irss provide attitude true and magnetic heading acceleration vertical speed ground speed track present position and wind data to appropriate airplane systems irs outputs are independent of external navigation aids

Question 63-39 : The output data of an irs include 1 number of satellites tracked2 mach number3 ground speed4 true trackthe combination regrouping all the correct statements is ?

3 4.

In their normal navigation mode the irss provide attitude true and magnetic heading acceleration vertical speed ground speed track present position and wind data to appropriate airplane systems irs outputs are independent of external navigation aids such as satellite the adc air data computer will compute the mach number

Question 63-40 : To obtain the instantaneous position from the accelerations it is necessary to 1 integrate twice the acceleration in time2 know the initial position 3 know the initial speedthe combination that regroups all of the correct statements is ?

1 2 3.