In Turn and slip indicator, which of the following is true and why?
a. No erection devices are used
b. Speed of the rotor should be kept constant
c. Both a and b are correct
The turn & slip (or turn & bank) works completely different from the other gyro instruments.
It's gyro is mount rigid and gimbaled at 37 degrees. The speed to to achieve a calibrated gyro force. Any attempt to displace the gyro drives the turn rate needle. The bank angle angle and corrodinated turn condition is seen on the inclinameter ball. Unlike the caged or erected position that remains as long as it is displaced. The turn indicator returns to center after an airplane is held in a yaw yaw position because it is in affect an a accelerator devise that responds to a rate change not a displacement. The 37 degrees is required to combine the rate change with respect to the tilt angle of the gyro. Vision this! a lateral accellerometer in the aiplane. The plane is yawed and the instrument records the rate of speed the displacement makes but returns to zero if the plane is held in a yaw. Now do this in a bank and you will see the accellerometer sensitivity diminishes as the bank is increased. So the gyro gimbal is ofset to compensate for the lost. The math to determine this angle escapes me at this time. It's been decages since I calibrated a T&B. Hope this answer your question. BTW The speed of the rotor was kept at the disired speed by the use of a regulator in the vacumm systems whether using venturi tubes or engine driven pumps.