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Right ANSWER is (B) Airborne magnetometer

Explanation: Aircraft have magnetic fields that add to the Earth’s FIELD and are sensed by the airborne magnetometers. The induced error, called deviation, can be 10° or more.

The correct option is (a) Magnetic pole MIGRATION

Easy EXPLANATION: Magvar has a DIURNAL change, a long term change due to the migration of magnetic poles, and random changes because of magnetic STORMS. The magnitude of the magnetic field changes about 0.5% PER year.

Right answer is (c) 11°

The explanation is: The EARTH’s MAGNETIC field is produced by a bar magnet oriented 11°away from the spin AXIS and passing WITHIN a hundred kilometers of its CENTER.

The correct answer is (a) USE higher ORDER leveling LOOP

The explanation: The stand off error DEPENDS upon the gravity sensors SWITCH’s dead and gives poor acceleration errors. Significant improvement can be obtained in the averaging vertical reference by using a high order leveling loop.

Right answer is (d) Standoff constant ERROR

The BEST I can EXPLAIN: A stand off constant error exists since the direction of the local vertical CHANGES as a result of both the ROTATION of the Earth and the aircraft’s own motion around the Earth.

Right ANSWER is (a) True

Easy explanation: When erection cutoff is used, there is a need for a special MODE of OPERATION that provides initial leveling, because no precession rate would exist in the PRESENCE of large initial TILT.

Correct option is (b) Earth’s GRAVITATIONAL FIELD

For explanation I would say: The basic vertical REFERENCE in all forms of heading and attitude reference devices is the Earth’s gravitational field. The direction of Earth’s gravitational field can be SENSED with great ACCURACY in stationary systems. However, when the platform moves, all the instruments indicate the vector sum vehicle acceleration and local gravity.

Right answer is (a) Deviation is large

Explanation: The ERROR caused in the vertical REFERENCING can be rectified by introducing nonlinearities. One such method is the erection cutoff where the precession of the GYROSCOPE is interrupted when a large deflection is SENSED.

Correct choice is (b) Time AVERAGE of apparent vertical

To elaborate: The simplest approach to the DETERMINATION of the true vertical is to time-average the direction of the apparent vertical(vector SUM of gravity and VEHICLE acceleration).

Right option is (a) Flush air data system

To elaborate: Hypersonic vehicles used the CONCEPT of locating multiple pressure ports around an aircraft forebody to EXTRACT total pressure and flow DIRECTION. This type of configuration is REFERRED to as the flush air data system and has been used at NASA Dryden research flights.

Right OPTION is (b) False

Explanation: Air data measurements in hypersonic flight do not PROVIDE any primary flight control parameters. They usually SUPPORT aerodynamic research to confirm structural loading and aero THERMAL models.

Right CHOICE is (a) 1 knot and below

The best explanation: Test results SHOW an accuracy of 1 knot or better at altitudes where the particle density is adequate. AEROSOL densities and particle densities vary with altitude, TIME and volcanic eruptions.

Right option is (c) Laser velocimeter

Explanation: In a laser velocitimeter, optical SENSORS are LOCATED within the aircraft and look out through the flow into the free stream. They measure the Doppler shift from backscatter of NATURALLY occurring aerosol PARTICLES in the free stream.

The correct option is (d) Radio altimeter

Explanation: The PRINCIPLE of the probe is that the horizontal component of the INDUCED flow velocity is a repeatable function of horizontal AIRSPEED but varies with ground proximity. Hence, a RADAR altimeter is required to accommodate the ground effect.

The CORRECT option is (a) Swiveling pitot tube below rotor

To EXPLAIN: In the swiveling pitot tube below rotor system, a gimballed pitot tube containing vane arrangement that causes the tube to align with the airflow within the DOWNWASH FIELD emanating from the rotor blades is used. CHANGES in the airflow field vector are correlated with changes in true airspeed.

Correct choice is (b) FREQUENCY

Explanation: A vortex sensor measures vortices shed by FLUID flow over a deliberately-inserted OBSTRUCTION. The frequency of vortices is PROPORTIONAL to the airspeed. This METHOD has been used in helicopters and in ground vehicle fire control systems.

Right choice is (c) AIRSPEED is measured in forward direction

Easiest explanation: Rotating anemometer is like a pitot TUBE for HELICOPTERS to measure low velocities below 40 knots. In addition to OBTAINING improved sensitivity at low speeds, the rotating probe measures omnidirectional airspeed, including backward velocities.

Correct answer is (d) Rotating ANEMOMETER

The best I can explain: Rotating anemometer increases the magnitude of pressure CHANGE caused by the change in airspeed when the aircraft airspeed is near zero. They are used in LOW OMNI range airspeed systems for helicopters.

The CORRECT answer is (b) 40 knots

The explanation: The conventional pitot tube and the PRESSURE transducer become ineffective as airspeed drops below 40 knots. At the lower SPEEDS, IMPACT pressure is equal to dynamic pressure q, and the sensitivity of this pressure to a change in velocity is minimal.

Correct option is (d) PRIMARY radar

For EXPLANATION: Velocity from Doppler, inertial and GPS can be used as an approximation for velocity. It is possible for the radio controller on the GROUND to OBTAIN the velocity of the ROTORCRAFT but it is not possible for the pilot to get velocity data from primary radar.

The correct CHOICE is (a) True

Explanation: Unlike fixed WING aircraft, where KNOWLEDGE of airspeed is essential for safe flight, a helicopter’s airspeed is not an essential pilotage quality, EXCEPT for certain ENGINE failure conditions where hover capability is lost.

Right option is (d) Software is flexible

Explanation: In centralized ARCHITECTURE, the software is not flexible. A minor change or UPDATE in one of the parts of the software requires the whole software to be written and CHECKED again. Updating the software to the rapidly changing hardware is not POSSIBLE.

Correct OPTION is (a) True

The explanation is: CADC uses long tubing from the probes to the CADC for the transfer of pressure data whereas distributed AIR data system transmits the data via electric wires. Electric wiring weighs less than tubing and the ELECTRICAL transmission of pressure INFORMATION eliminate lags.

Correct OPTION is (d) Better accuracy

To elaborate: Accuracy is independent of the ARCHITECTURE used. The accuracy of a CADC is same as that of a distributed air data SYSTEM but might suffer from lags OCCURRING from long lengths of tubing.

The correct choice is (a) True

Explanation: A distributed AIR data system provides corrected pressure, temperature, and ANGLE of attack data to a CENTRALIZED flight control computer that computes altitude, mach, calibrated and true AIRSPEED.

The correct choice is (b) DISTRIBUTED air DATA system

The best explanation: With the advent of smaller and CHEAPER microprocessors, it became possible to pack them with probes and transducers. The result is a distributed air data system that REPLACES the CADC. A key feature is the packing of signal processing units with or adjacent to the probes.

The correct answer is (a) INPUT processing

The explanation is: Input processing usually involves A/D conversion and packing of discrete signals into LOGIC WORDS, PLUS implementation of special serial data interfaces.

Right choice is (d) Non ERASABLE ROM

Explanation: The AIR data equations are solved in the processor assembly, which CONTAINS the CPU, memory for the OPERATIONAL flight program which can be electrically erased or EEPROM, data storage memory( usually a volatile RAM), and non volatile RAM.

The correct choice is (a) True

Explanation: The CADC INCLUDES program PIN status which is designated CONNECTOR PINS that allow a standard CADC to serve in more than one aircraft. Thus, pin i could recognize that the installation is in the aircraft I, thereby activating its own pitot correction algorithm.

The correct option is (a) PRESSURE ports

Explanation: A typical CENTRAL AIR data computer is a box containing: the pressure transducers, ASSOCIATED excitation circuitry, and signal conditioning circuitry, the computer, and the output drivers that are compatible with interfacing SUBSYSTEMS.

Correct CHOICE is (C) Ground speed

Explanation: When you stand on the ground with a RADAR speed gun pointing at the aircraft, the speed measured is called the ground speed and is measured relative to the ground. True AIRSPEED is measured relative to the wind.

The correct answer is (a) Mach NUMBER

Easy explanation: Mach number is used for programming STABILIZER position for speed STABILITY, defining high speed performance boundaries such as flutter ONSET, and for defining optimal CRUISE paths.

Right choice is (b) False

The BEST I can EXPLAIN: Pressure altitude is the standard PARAMETER used for vertical navigation in controlled navigation. However, density altitude is needed to assess an aircraft’s performance margin.

Correct answer is (b) False

The explanation: CALIBRATED speed is the speed under sea level conditions which WOULD GIVE the same impact pressure. TRUE airspeed is the velocity of the AIRCRAFT relative to the local wind.

Right answer is (a) ICE FORMATION

To explain I would say: Pitot-static tubes are generally placed with heating elements to stop the formation of ice in the orifice of the probe. Formation of ice on the probes causes erroneous readings and has LEAD to FATAL air crashes.

The correct option is (b) Stealth configuration

For explanation I WOULD say: Stealth planes, such as the B2 SPIRIT stealth BOMBER, USE retractable pitot tubes to maintain their stealth. When not in stealth mode they extend the probes for air data measurements.

The correct answer is (d) Thrust produced by the aircraft

Easy EXPLANATION: The mach number is computed from the corrected VALUES of static and stagnation pressures. Mach number is COMPARATIVELY easier to calculate than AIRSPEED in supersonic speeds due to the compression shocks that form in the pitot tube.

Right answer is (d) Not the true altitude

For explanation I would say: Pressure altitude is always referenced from the sea LEVEL. When flying over hilly areas, the ACTUAL altitude of the aircraft from the ground is DEFINITELY lesser than the pressure altitude, thus showing erroneous altitude READINGS.

Correct ANSWER is (c) PRESSURE ALTITUDE

The best explanation: The altitude at which the standard temperatures are used is called the pressure altitude. Pressure altitude is the altitude of the aircraft above sea level. It always takes it’s REFERENCE as sea level.

Correct answer is (c) PRESSURE altitude

To elaborate: Pressure altitude, as the name suggests, is the altitude derived from pressure MEASUREMENTS. It is measured from the static port of the pitot-static probe. The static pressure of AIR varies with altitude with APPROXIMATELY 101Kpa at SEA level.

The correct ANSWER is (a) STALL warning system

Easiest explanation: When angle of ATTACK sensors are installed on an aircraft they are USUALLY apart of an independent stall warning or stall control system. Since such systems are FLIGHT critical, redundant sensors are usually installed.