Common Power Sources for Gyroscopic Instruments

Gyroscopic instruments are an essential part of any aircraft, allowing for pilots to safely operate under Instrument Flight Rules and to generally be aware of various important flight conditions. Depending on the aircraft and its design, the power source that drives such instruments can vary. Regardless, it is crucial that any power source is capable of rotating the gyroscope at high speeds as that is how they are capable of operating efficiently. While there are numerous systems that can be used for gyroscopic instruments, common configurations include those that utilize vacuum systems, venturi tube systems, and engine-driven vacuum pumps.

Vacuum systems were the original driving force behind gyroscopic instruments, and they are still commonly used today. With such systems, an air stream is directed at the gyro rotor vanes, causing them to rotate with high speed. The air that is utilized for the gyro is supplied at atmospheric pressure and forced through a filter. Then, the air is directed into the instrument in which it is forced against the gyro rotor. After air spins the rotor, it is directed into a suction line so that it can be vented out of the vacuum system. The pressure needed for the system’s functionality often sits between 3.5 Hg and 4.5 Hg, and this value is maintained through the use of a vacuum relief valve that is implemented within the supply line.

Venturi tubes are also useful for a number of aircraft due to the fact that the velocity of rushing air within venturi tubes is sufficient to achieve the suction needed to drive gyroscopic instruments. Placed on the airframe, low pressure within the tube causes air to be forced through the assembly, passing through a line and into the gyroscopic instruments to spin them. Once the air is used, it is then expelled from the system through the venturi. Such assemblies were common to many early aircraft, and they still benefit numerous single-engine models. With a small 2-inch venturi, instruments such as turn and bank indicators can be supplied with sufficient air for their operation. For instruments such as the attitude and heading indicator on the other hand, larger 8-inch venturi tubes may be required. As compared to other gyroscopic power sources, venturi tubes are advantageous due to their low cost and simplicity. Nevertheless, there are various disadvantages that they have, including their risk of being blocked by ice and their inability to reach normal operating speeds until after takeoff.

For light and general aviation aircraft that utilize vacuum power for driving gyros, the engine-driven vacuum pump is the most common. Depending on the type of engine-driven vacuum pump one implements, the system may either be geared to the engine and lubrication system or utilize a dry vacuum pump. Due to their configuration and connections, engine-driven vacuum pumps do not require any external lubrication as well as do not need to be attached to the engine oil supply. During the standard operation of the system, the vacuum pump develops a vacuum alongside positive pressure located at the pump’s outlet. As compared to other types, the vacuum pump excels in providing consistent performance both on the ground and in flight. Additionally, they also operate well at low engine RPM.

Apart from the aforementioned gyroscopic instrument power sources, other methods may be used such as relying on pressure, electricity, and more. When it comes time to begin sourcing the gyroscope parts and components that you need for your aviation endeavors, let the experts at Complete Sourcing Solution help you procure everything that you need with competitive pricing and rapid lead-times. As you peruse our various part lists and manufacturer catalogs, we invite you to take advantage of our offered RFQ services in order to receive personalized quotes for your comparisons. See why customers steadily choose Complete Sourcing Solutions for their operational requirements when you fill out and submit an Instant RFQ form through our website.


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