Pneumatic, Vacuum, and Electrically Driven Gyroscopes
Gyroscopes are instruments used in aircraft systems for the purposes of coordinating the turning, direction, and attitude of the aircraft. The instrument comprises of a wheel and a rotor, which serve to give the aircraft toe very important aspects of flight namely rigidity and precession. The instrument is comprised of a gyro which is rigidly placed inside concentric rings known as gimbals, whose role is to give the gyroscope system specific movements of freedom. The gyroscope is driven through electrical systems or through the pneumatic systems or vacuum systems. The vacuum and pneumatic gyroscope systems require the engine of the aircraft to contain a specific pump to which generates the required high RPM for the gyroscope system to function accordingly (Richardson, 2014).
The vacuum drive gyroscope systems specifically entail a vacuum pump which powers the instrument, and this vacuum pump is attached to the engine, and thus derives all of its power from the engine. The vacuum driven system contains suction connectors which connect the pump to the gyroscope. The connectors suck air from the atmosphere through the openings of the instrument. As the sucked air enters the gyroscope, it is pushed and accelerated towards the small pockets inside the gyro wheel. The gyro is fixedly attached to two gimbals that serve the purpose of maintaining index bank and controlling height. The system also contains a small regulator which manages the pressure of suction into the gyroscope. It also contains regulators that aid to keep the speed of the gyro constant and thus the instrument can have reliable readings (Myung, et al., 2010). The pump also contains an outlet where the air from the gyroscope is taken back to the atmosphere. The speed of rotation of the gyro is an important property in gyroscopes as low speeds result in a lad on the indications due to the gyroscope responding slowly, while high speeds may lead to an overreaction of the gyroscope to yield fast wearing and thus a reduced life cycle. The limitation of the vacuum system is that it is not applicable for high altitude aircrafts as the air in high altitudes could significantly reduce the efficiency of the vacuum pump. This affects its ability to suck air through the instrument and out of the system, due to thermodynamic properties of high altitude air (Myung, et al., 2010).
The pneumatically driven gyroscope is similar to the vacuum driven in that they both use vacuum pumps that are incorporated to the engine, although the role of the pump in pneumatic systems is to reduce the pressure of the air passing through the gimbals. The pump draws filtered air from the cabin into the gyroscope and accelerates it towards the gimbals of the instrument causing them to turn. The limitation of this system is that it is susceptible to errors from any pressure drops within the system caused by the reduction of the rotor speed of the instrument. This risks erroneous readings. The system is also not applicable for high altitude flying due to the quality of air being both cold and thin, which may reduce the efficiency of the pump (Tazartes, 2010).
Operation of Gyroscopes in Modern Aircrafts
The electrically driven gyroscope, on the other hand functions like an electric motor, since the spin of the gyro behaves in the same manner as the amature of the motor. The electric system provides a.c current to drive the gyros from the inverters in the system which converts d.c current to a.c. These electrically driven gyroscopes have a fixed speed of 8000 rpm and are mainly used in high altitude aircrafts where pumps are not suitable. The limitation of this system is that it is susceptible to electrical failure and the accuracy of the system is affected by presence of dust and moisture (Tazartes, 2010).
In modern flight instrumentation, gyroscopes are mainly used to offer the planes precession and rigidity. Rigidity is achieved through the gyros ability to resist any forces that try to move it from its spinning axis. Precession, on the other hand is achieved through the ability of the gyroscope instrument to transfer any forces applied perpendicular to the instrument’s rotation axis such that the force is manifested along the axis but at 90? further. Precession and rigidity in modern flights as is seen in Boeing and modern flights is achieved through vacuum gyroscopes for attitude indication, and the electrically driven gyroscope system is incorporated as the turn indicator (Tazartes, 2010). The attitude Indicator is driven by either vacuum or pneumatic systems for when the engine is running and the suction from the pump spins the instrument to give the pilot a reference of the horizon. In both Boing and Airbus aircrafts, the vacuum system gyroscopes continue to function even after the electrically driven gyro has stopped functioning because of its role in providing reference for the pilot. The attitude indicator achieves this through remaining at a level altitude with the horizon and thus exploiting the aspect of rigidity. Modern aircrafts achieve this through having the gyroscope which is fixedly attached to two gimbals that serve the purpose of maintaining the index banking and controlling height (Tazartes, 2010).
On the other hand, the electrically driven system in modern aircrafts like the Boeing and Airbus plays the role of giving the aircraft information about its rate of turn as well as its banking information. As the plane begins to turn, the aircraft gyros indicate that banking is on and after the turn is established the standard rate of turn is signaled. This instrument can also be used to ensure that the flight is both level and straight. This gyroscope system works through exploiting the concept of precession. This because, with the turning of the aircraft, a perpendicular force is experienced by the gyro and is in turn translated to a perpendicular force on the gimbal through precession (Richardson, 2014). This causes the banking of the icon. Information about banking is provided through canting the plane slightly and thus stopping the rotation of the instrument with regard to its rotational axis.
Magnetism in Aircraft Navigation
The main and standby compass system in an aircraft is a simple way of giving direction to aviators in all types of aircrafts. These compasses utilize the earth’s magnetic field. The earth’s magnetic field has a flux, which refers to lines of magnetic force that influence the north and south orientation of the compasses in planes (Stewart, et al., 2016). Variation occurs as a result of the fact that the magnetic north pole and the True north pole are not located at the same spot. This phenomenon occurs because of the impact of the magnetic flux and alignment of the earth’s iron deposits. The concept of magnetism in aircraft navigation is very complicated not only because of the variation between the true north and the magnetic north, but also because of the concept of the angle of dip. The angle of dip refers to the angle the flux lines between the magnetic north and the south towards the poles since they tend to be parallel at the equator. The angle of dip could also result in errors when trying to establish the navigation of the aircraft especially in the high latitude areas near the poles. In addition, the magnetic north and south are also not fixed points as they tend to shift towards the north-west on annual basis (Stewart, et al., 2016). The compass in an aircraft thus ought to be adjusted to find the true north while factoring in the angle of dip and the variation in these points. This is achieved through adding the variation for the specific location the aircraft is in to the compass reading in the plan, to obtain the true direction and orientation of the plane (Lawrence, 2012).
Errors in navigation could occur when the navigator does not know the specific variation for the locale the aircraft is in (Pallett, 2008). A direct reading compass in a plane therefore is helpful as a standby compass because it enables the pilot to read the direct location of the plane in relation to the magnetic assembly of the planes main compass system. The impact of terrestrial magnetism on the readind of direction in the planes is therefore a great one, although it can be controlled by depending on the direct reading standby compasses. The compasses in airplanes are behave in this manner because their construction is comprised of a float that is attached to a fixed magnet. This assemblage is placed on a compass card, which is graduated to the 360 degrees of compass points. As the compass assemblage notices any movement, it adjusts itself to point towards the earth’s magnetic north and thus the computations have to be conducted to establish the accurate direction of the plane. The compass is an important instrument in the aircraft as the magnetic compass is the fundamental tool for navigation in planes. The location considerations ought to factor in the angle of dip, variation, acceleration and turning errors ought to be considered before the exact location of the plane can be deciphered. There are a number of errors that could be factored in during these location considerations as the terrestrial magnetism greatly impact the accurateness of the compass systems in the plane.
As the airplane makes any turns, the compass system plays a great role, the dynamic behavior of the magnetic compass system in the plane must be aperiodic. An aperiodic dynamic behavior of the compass system means that the airplane continues to operate even when the electrical, pitotic, and vacuum static systems are not running. Any deviation caused by terrestrial magnetism can be used to determine the location of the plane by analyzing the location considerations. This process of identifying the deviation and assessing the impact of the terrestrial magnetism on the direction of the plane is what is referred to as an analysis of deviation. Compensation refers to the correction of any magnetism related errors on the direction of an aircraft (Caruso, 2010).
Operation of the Magnetic Heading Reference System
The Magnetic Heading Reference System (MHRS) is a system that outputs the heading, attitude and flight dynamics of the plane by utilizing magnetic signals. The technology utilizes magnetic flux valve that is combined with a magnetometer, so as to identify the horizontal components of the magnetic field of the earth, and thus detecting the heading of the aircraft. The differences in the flux of the magnetic signals of the earth’s magnetic field is computed to incorporate voltage differences in the system so as to yield the heading and directional information displayed on the flight for the aviators including the direction, altitude and heading of the instrument (Tomczyck, 2002). The magnetic signals in the system are sent as one long block of data to ensure that the plane always has information about the heading and altitude that it is flying at, which is a better option than the slowly fading horizontal and vertical gyros that require to be driven. This phenomenon is known as synchronous data transmission. The integrated instruments in aircraft technologies also incorporates other types of data and information that work hand in hand with the magnetic sensors and other signals, to ensure that aviators can retrieve the required information as they fly the aircrafts, enabling them to operate the different modes of the plane in safety (Tomczyck, 2002). This is what is referred to as synchro types.
The MHRS element of detecting the magnetic signals mainly entails a directional gyroscope unit and a joining an indicator of the heading of the aircraft, an amplifier, and a compensator for the deviation of the results. The deviation refers to the error in the obtained heading of the plane as a result of the hard iron errors in the magnetic relations within different components of the aircraft (Caruso, 2010). The compensation of this error on the other hand refers to utilizing different elements so as to correct this error. The operation modes of the magnetic heading reference systems include altitude referencing and directional referencing. These MHRS systems are incorporated in the modern aircraft types as Attitude Heading Referencing systems (AHRS) which uses inertial sensors which output the heading, attitude, and other flight controls using the rate gyroscopes that have been made to suit the principle axes of the modern aircraft. Appropriate solutions to magnetic heading reference systems can be achieved through the installation of remote heading indicators which have an impact of limiting errors through reducing impacts of terrestrial magnetism in the plane.
This paper discussed the gyroscope systems in planes by explain the limitations and the properties of these gyroscope systems. In so doing, the discussion was able to explain the principles and technology utilized in gyroscopes and how they have been adopted to fit in modern planes like the Boeing planes and the Airbus planes. The effects of terrestrial magnetism on the efficiency of the plane to express direction and also explains the strategies that can be implemented to reduce the erroneous effect of terrestrial magnetism on the planes compass systems.
References
Caruso, M., 2010. Applications of Magnetic Sensors for Low Cost Compass Systems. Position Location and Navigation Journal, 2000(41), pp. 177-184.
Lawrence, A., 2012. Modern Inertial Technology: Navigation Guidance and Control. 1st ed. New York: Springer Science & Business Media.
Myung, H., Lee, H. K., Choi, K. & Bang, S., 2010. Mobile Robot Localization with Gyroscope. International Journal of Control Automation Systems, 8(3), pp. 667-676.
Pallett, E., 2008. Aircraft Instruments and Intergrated Systems. 10th ed. London: Longman Publishing Group.
Richardson, K., 2014. The Gyroscope Applied. 11th ed. London: Philosophical Library.
Stewart, H., Nichols, A., Wailing, S. A. & Hill, J. C., 2016. Aircraft Navigation. Methods and Systems of Navigation Control, 14(8), pp. 263-266.
Tazartes, D., 2010. Modern Inertial NAvigation Technology and Its Application. Electronics and CommunicationEngineering Journal, 12(2), pp. 49-64.
Tomczyck, A., 2002. Testing the Attitude and Heading Reference System. Aircraft Engineering and Aerospace Technology, 74(2), pp. 154-160.
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