Effects of Aerobatic Maneuvers on Gyros

Some manufactures have concluded that aerobatics or the g-loads associated with aerobatic maneuvers will not appreciably harm or shorten the life of operating gyros' so long as they are free or un-caged during these maneuvers. Locking the gyros in a caged position during these maneuvers may damage the spin bearings and/or gimbal bearings because of the large angular momentum of the spinning mass and the resulting quadrature forces. The best possible approach is to have the gyro free during aerobatic maneuvers and use caging to reset the gyros during straight and level flight when necessary.

Directional Gyros: Directional Gyros have a caging feature that is used to quickly erect the rotor in a horizontal plane and align the heading card with the magnetic compass. During aerobatic maneuvers the heading card may start to spin, if this happens the pilot should pull the caging knob to stop the spinning. Once he returns to straight and level flight, he should pull the caging knob and align the heading card with his magnetic compass.

SONIC BOOM EFFECT

Horizon Gyros without Caging: Standard Horizon Gyros without a caging feature have 360- degrees of freedom in roll and approximately +/or - 85 degrees of freedom in pitch. Controlled precession is used to maintain erection and the correct pitch and roll information during full loops. During most aerobatic maneuvers the Horizon Gyro will maintain its erection (spin axis aligned to the dynamic vertical) and provide correct pitch and roll references. However, it is certainly possible for some maneuvers to cause the Horizon Gyro to lose its vertical reference and even to "spin out." The only problem with this condition is that it may take several minutes (10 to 20) of straight and level flight before the Horizon Gyro is fully erected and providing useful pitch and roll information.

Horizon Gyros with Caging: With caging added to Horizon Gyro, if the gyro tumbles during an aerobatic maneuver the pilot can return to straight and level flight (*using the earth horizon as a reference) and pull the caging knob to immediately align the gyro rotor with a vertical reference. The gyro indication may be off a few degrees, depending on how well the pilot aligns his aircraft with level flight during the caging procedure, however the pilot will have useful pitch and roll information and the internal erection system will correct a small error within 2 or 3 minutes.

*Aerobatic maneuvers should only be made during VFR flight with a well-defined earth horizon for reference.

Effects of Aerobatic Maneuvers on Gyros