Gyroscopic Instruments Questions and Answers

Answer: C

A flux valve in a wingtip or fin senses the earth's field away from cabin disturbances and a slaving torque motor holds the gyro to it. The result combines the compass's north-seeking property with the gyro's steadiness in turns.

Answer: D

Correct answer: Horizontal and lateral, with a single gimbal restrained by a spring

The rate gyro is deliberately constrained. Its spin axis lies horizontally across the aircraft, and the single gimbal is restrained by a calibrated spring so that precession is opposed by a restoring torque.

The gimbal therefore settles at a deflection proportional to the rate of turn rather than continuing to precess, which is exactly what a rate instrument needs. A gyro free in all axes would give a fixed reference instead - useful for attitude and heading, useless for measuring a rate.

Answer: A

It gives a full turn in two minutes and a half turn in one, which is why instrument procedures are built around it. A half standard rate turn is used at higher speeds where the bank angle for the full rate would be excessive.

Answer: B

The ball responds to the resultant of gravity and centrifugal force, so a centred ball means the turn is coordinated. It is an entirely mechanical device with no gyro in it, despite sitting inside the same case as one.

Answer: C

Canting the axis by about 30 degrees makes the instrument respond initially to roll, giving an earlier indication as a turn is entered. In a steady turn it settles to indicate rate of turn just as the older instrument does.

Answer: D

A vacuum pump draws air through a filter and across the rotor buckets. The arrangement fails silently as the filter clogs or the pump wears, and the resulting slow spin-down produces an increasingly untrustworthy indication rather than an obvious failure.

Answer: A

Vacuum systems lose effectiveness as air density falls, which limits them at altitude. Splitting the instruments between air and electrical drive is also a deliberate redundancy measure so that one failure does not remove every attitude reference.

Answer: B

Older instruments had limited gimbal freedom, and exceeding it in a steep manoeuvre caused the gyro to tumble and lose all reference. Modern designs are fully aerobatic, having gimbal freedom through the full range of attitudes.

Answer: C

Rotation makes the two paths differ in effective length, producing a beat frequency proportional to the rate. With no moving parts it has no bearing friction, no spin-up time and none of the drift mechanisms of a mechanical gyro.

Answer: D

At low rates the two beams couple and their frequencies lock together, so small rotations go undetected. Mechanically dithering the block keeps the instantaneous rate away from that dead band while averaging to zero over time.