Instrumentation: Air Data and Gyros
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Flashcards
Gyro: What are possible reasonsto switchteh remote compass system to mode DG?
Possible reasons to switch to DG mode are for example a defective flux valve or a flight at latitudes at where the intensity of the earth's horizontal component is not sufficient
Gyro: Which sensor(s) of a remote compass system is/are in use in mode slaved?
In slaved mode the directional gyro (DG) and flux valve are in use
Gyro: For which mose is it necessary to use teh Set HDG knob and why not for the other mode?
The use of the SET HDG knob is necessary in DG to compensate the gyro's drift. In SLAVED the usage of the SET HDG knob is not useful or necessary, because the flux valve guarantees the long time accuracy
Gyro: Which instruments are able to be supplied with HDG information of teh remote compass system?
HSI, VOR RMI, ADF RMI
Gyro: The flux valve produces an error when teh aircraft accelerates or decelerates because it is mounted as a pendelum. How is it possible to reduce this error to a negligible value?
It is possible to reduce this error by the low pass filter inside the remote compass coupler
Gyro: The inlcination of the magnetic field is very high so that a magnetic compass as well as a flux is unusable. What you make?
A polar path compass had been designed operating without any sensing of the earth's magnetic field => operates near the poles and with a special method of correction the navigation in this region was possible
Gyro: Is the polar path compass still in use?
No, the polar path compass is a old system and replaced in modern aircraft by an Inertial Navigation System (INS)
Gyro: Stable platform?
are expected to produce more precise pitch than a vertical gyro without any gimbal lock
Gyro: A platform equipped with gyros and accelerometers is used in
Intertial Navigation System (INS) => In principle a so calles Intertial Reference System (IRS) performs much the same as an INS
Gyro: INS vs. IRS?
Inertial Navigation system is an independent system => When it is part of a complex navigation system (FMS, FMGS) it is typically called Inertial Reference System (IRS)
==> INS consist of mechanical gyros mounted in moveable gyros => IRS consists of Laser Gyros without any moveable gyros ==> Less maintenance ==> operating principles of both system are teh same
Gyro: AHRS ?
Altitude and Heading Reference System: able to measure and calculate pitch, bank and yaw attitude, but not position on earth => To assimilate these values gyros and liquid level sensors or accelerometers are used !
Gyro: For AHRS and INS/IRS the gyros have to
to measure the movement of the aircraft about all three axis but not position on earth. To assimilate these values gyros and liquid level sensors or accelerometers are used !
Gyro: Which type of gimbaled platform is able to avoid the gimbal error?
A four gimbal is able to operate without gimbal error
Gyro: A gimbaled platform which can be used for inertial navigations system is equipped with?
1. three accelerometers and either three single degreee of freedom gyros (SDF)
or
2.two gyros with two degrees of freedom (TDF)
=> These degrees of freedom represent around how many axes one gyro can measure movements
Gyro: What makes a torquer motor?
teh torquer motors operate as a servo system to keep the platform parallel to the earth with the highest possible precession
Gyro: Four gimbal Platform?
With the addition of a fourth gimbal where all gimbals are servomotor controlled and maintain the angle the angle between the described second and third gimbal at 90 degrees ==> Total aerobatic maneuverability
Gyro: ESG
Electro statically supported gyro (ESG): The angular momentum is imparted to the gyro by the spin coils, which generate a rotating magenta field => 150'000 RPM => gradually slowed down by the residual gas molecules in the gyro cavity => to run for naby moonth on its own
Gyro: ESG => the problem of measuring of the housing with respect to the rotor is solved as follows:
marker lines are etched on the surface as well as on top of the sphere => These marker lines are detected by the optical pickoffs and from their corresponding variations => The ESG precession i sensitive to temperature variations
Gyro: TDF?
Tuned Rotor Gyro (TDF) => flex gyro =>is a narrow angle gyro which means it can measure only small angles up to max 2. degrees
Gyro: Whiche very important measurement sensors are in use in an Inertial Navigation System ?
Three accelerometers and three SDF gyros, or two TDF gyros
Gyro: What is the main difference between a gimbaled platform and a strap down system?
A gimbaled platform is a device with four gimbals, a strap down system is constructed without any gimbal
Gyro: Which sensors are in use inside an AHRS ?
Two liquid sensors (x.y) or three accelerometers (x,y,z) together with three SDF gyros or two TDF gyros
Gyro: What are the differences between an INS compared with an IRS?
INS/IRS: significant higher if compared with the accuracy of an AHRS
AHRS: supplies teh pilot with angles in pitch, bank and yaw => together with a flux valve calculates and indicates magnetic HDG
INS(IRS: supplies the pilot with angles in pitch, bank and yaw, pitch rate, bank rate abs yaw rate => calculates magnetic HDG by use of the measured angular rtes and accelerations combined withe the values of a Vibration Memory
INS/IRS: is able to calculate teh aircrafts position on earth during the whole flight, but not the AHRS
Gyro: Hos is the currently flown GS of an aircraft calculated?
The currently flown GS is calculated by one time integration of the measured accelerations
Gyro: How is the travelled GS of an aircraft calculated?
The travelled ground distance i calculated by two times integration of the measured accelerations
Gyro: Rotations around hoy many axes can be measured by one ESG = Electrostatic Gyro ?
One Electrostatic Gyro is able to measure angular rates around two axes (TDF gyro)
Gyro: How is the ball inside an Electrostatic Gyro (ESG) mounted?
The inside an ESG is mounted in computer controlled electrostatic fields
Gyro: Rotations around how many axes can be measured by one Tuned Rotor Gyro?
One Tuned Rotor Gyro is able to measure angular rates around two axes (TDF gyro)
Gyro: What is the task of the torsion bars of a Tuned Rotor (TDF) Gyro which are mounted between the inertia ring and the rotating shaft?
Th torsion bars have to allow that the spinning mass keeps position if the housing is rotated against the spinning ass to approximately 2 degrees
Gyro: Single Degree of Freedom Gyro => Rotations around how many axes can be measured by one SDF gyro?
AN SDF gyro allows the measurement in one axis ==> The most important component of a rate gyro is its spring
Gyro: Rotations around how many axes can be measured by one TDF gyro?
A TDF gyro allows the measurement in two axes
Gyro: What is the most important component of a mechanical gyro with rate behaviour ?
The most important component of a mechanical gyro with a rate behavior is its spring
Gyro: WHat is teh most important component of a mechanical gyro with rate integrating behaviour?
The most important component of a mechanical gyro with rate integrating behavior is ists damping device
Gyro: Float Suspended Gyro => What is that ?
This gyro is suspended in gas bearings (Helium), that means the spinning rotor of this gyro does not touch the float mechanism ==> low friction = reduced maintenance
Gyro: Rotations around how many axis can be measured by one float suspended gyro?
The float suspended gyro is able to measure angular rates in one axis
Gyro: How is the rotor of the float suspended gyro mounted?
The rotor of the float suspended gyro is mounted in gas bearings (Helium)
Gyro: HRG What's that?
Hemispherical Resonator Gyro is SDF: principle is that Coriolis forces produced by rotation cause a transfer of energy between two of the gyro's mode of vibration
Gyro: Which type of gyro (SDF/TDF; rate/rate integrating) is the Hemispherical Reasonator Hyro (HRG)?
The Hemispheric Resonator Gyro (HG) is an SDF gyro with rate integrating behavior
Gyro: Which type of gyro (SDF/TDF; rate/rate integrating) is the Fiber Optic Gyro?
The fibre Optic gyro (FOG) is an SDF gyro with rate behavior.
Gyro: What does the Fiber Opric Gyro measure?
The fibre Optic Gyro measures phase differences of two opposed rotating light beams
