gyroscope types and principle operation and analysis

main functionality of gyroscope

1. UNIT III Attitude instruments

2. Primary Flight Instruments and EFIS Gyroscopic Principles and its properties The gyro system Limitations of a free gyro Apparent Drift and Transport Wander Directional Gyro indicator Artificial Horizon Turn and bank indicator

3. Gyroscope System containing a Heavy Metal Wheel or Rotor mounted in gimbal. So it Have 3 degrees of freedom Spinning Freedom Tilting freedom Veering freedom

4. Spinning freedom About axis Perpendicular to centre Axis of spinning is XX’ Gyroscope 3DOF

5. Tilting freedom About an Horizontal axis at right angle to spin axis Axis of tilt is YY’ Gyroscope 3DOF

6. Veering freedom About an Vertical axis at right angle to spin and tilt axis Axis of Veering is ZZ’ Gyroscope 3DOF

7. The 3DOF are obtained by mounting rotor in two rings Inner ring Outer ring The whole assembly is known as Gimbals System Normal operating condition all the axes are Mutually Perpendicular to each other Axis should be intersect the CG of Rotor Gyroscope

8. Gyroscope

9. The system exhibit the gyroscopic property When the rotor is spinning. The two properties are Gyroscopic inertia or rigidity Precession The properties are depend up on angular momentum. Angular momentum of body remain constant unless some force is applied to change. RIGIDITY: Property which resist any force tending to change the plane of rotation. Property depends up on Mass of the rotor Speed of the rotor Distance at which mass acting from the centre Gyroscope

10. Precession : The angular change in direction of the plane of rotor under the influence of an applied force. Change in direction is not in line with applied force. 90 degree away from the direction of rotation. The Rate of precession is depend up on the factors Strength and direction of applied force. Moment of inertia of the rotor. Angular velocity of the rotor.

11. Precession

12. Gyroscope in aircrafts -

13. Limitation of free gyro : Gyros spinning axis is aligned with earth reference or some point in space Gyro limitations are Apparent Drift Transport wander Deviation of horizontal alignment with spinning axis with reference is called gyro drift. There are two types of drift Apparent drift Real drift . Transport Wander is the drift created due to the fling of aircraft in lower regions

14. Apparent Drift : Assume Horizontal axis Gyros spinning axis is aligned with Greenwich meridian 0 degree longitude Gyro XX’ axis is parallel to earth surface. Earth having rotation Rate of 15 degree/Hr After 1 hr the gyro is not Aliened with earth surface. They produce some drift with Respective to earth Real Drift Due to friction and gimbal Unbalance It can be reduced by proper design and construction

15. Transport Wander : Assume Horizontal axis Gyros spinning axis is aligned with equator 0 degree lateral. Gyro XX’ axis is parallel to earth surface. Take the gyro to North or South Pole. The gyro makes 90 degree In North. They produce some drift by Traveling the gyro from Equator to north pole N S

16. N S

17. control of Drift : Before fixing the gyro to the aircraft controlling the drift and maintain relativity to the earth. The drift controlled gyro is called as earth gyroscope Control method for gyro Calculate the correction using earth rate formula and apply Apply fixed torque , it should unbalance the gyroscope and its rate equal and opposite to earth rate Apply fixed torque ,Varying the torque According to Latitude

18. Displacement gyro Limitations: There are two limitation Gimbal lock: The spinning axis is coincidence with one or other axis of freedom. Gimbal error : The gimbals are not mutually perpendicular to each others.

19. Gyro Horizon : It is also called Pitch and Bank Indicators Vertical axis gyro It is maintained vertical by gravity sensing device

20. Inner ring from rotor casing, pivot arranged parallel to the lateral axis YY’ Outer ring pivot Parallel to the Longitudinal axis ZZ’, it is fixed with outer casing. The indicating symbols are fixed. Level flight 3 axes are mutually right to each other. Pitch Bank Freedom of gimbal system Roll 360 degree Pitch 85 degree

21. Operating Gyroscope in Flight instruments : There are two Principles to drive the rotor Pneumatic Electrical The Pneumatic driven system have two methods Engine driven vacuum pump Venturi Located externally The pump or venturi system create an vacuum of 3.5 &4.5 Hg Rotor derived by the electrical motor

22. Venturi located externally

23. Venturi located externally

24. Electrical Driven Vacuum pump Vacuum Pump

25. Vacuum Driven Gyro Horizon The rotor is pivoted in ball bearing within case The case is an inner ring The outer ring is rectangular shape. The rotor is kept in case. The vacuum drive rotates the rotor approximately 15000 rev/min.

26. Electrical Driven Gyro Horizon : The rotor is pivoted in inner ring and outer ring Vertical gyro is an 3 phase squirrel cage induction motor In Induction motor - rotor inside the motor. But gyro the rotor is outside the motor. The power is given to the stator throw slip ring or brush. 3 Phase, 115V, 400 Hz, The electrical drive rotates the rotor approximately 20,000 - 23,000 rev/min.

27. Turn and bank indicators : It is using gyro as an detecting element. It have two Mechanism Gyroscope control pointer mechanism to determine and display the turning rate of aircraft. Mechanism for indicate the slip and/or bank.

28. Rate gyro: The rate of turning of the aircraft is measured by rate gyros It is differ from normal directional gyro and gyro horizon It has only one gimbal ring & spring connected between gimbal and casing. When the instrument is in its normal operating position, due to the spring restraint the rotor spin axis will always be horizontal and the turn pointer will be at the zero datum mark. we control the angular deflection of the girnbal ring by connecting it to the instrument case through the medium of a spring. precession of this type of gyroscope is equal to the product of angular momentum of the gyroscope and the rate of turn, then the spring force is a measure of the rate of turn.

29. Banking indicator : In addition to the primary indication of turn rate, it is also necessary to have an indication that the aircraft is correctly banked for the particular turn. It is operated on the gravity and centrifugal force . It have two types Gravity weight and pointer A ball in Curve liquid filled glass tube

30. Gravity weight and pointer : turning to the left at a certain airspeed and bank angle correct bank angle bank angle for a particular turn rate is not correct skid out of the turn turn is overbanked

31. Curve liquid filled glass tube :

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