Welcome Guest. Sign in or Signup

3 Answers

Precession

Asked by: 5268 views General Aviation

What is a Precession?

Ace Any FAA Written Test!
Actual FAA Questions / Free Lifetime Updates
The best explanations in the business
Fast, efficient study.
Pass Your Checkride With Confidence!
FAA Practical Test prep that reflects actual checkrides.
Any checkride: Airplane, Helicopter, Glider, etc.
Written and maintained by actual pilot examiners and master CFIs.
The World's Most Trusted eLogbook
Be Organized, Current, Professional, and Safe.
Highly customizable - for student pilots through pros.
Free Transition Service for users of other eLogs.
Our sincere thanks to pilots such as yourself who support AskACFI while helping themselves by using the awesome PC, Mac, iPhone/iPad, and Android aviation apps of our sponsors.

3 Answers



  1. Kris Kortokrax on Jun 14, 2015

    There is a detailed explanation of gyroscopic precession on page 4-27 of the Pilot’s Handbook of Aeronautical Knowledge.

    0 Votes Thumb up 0 Votes Thumb down 0 Votes



  2. Robert Andreas on Jun 19, 2015

    Precession is when the spin axis of the gyroscope moves. Recall a gyro should display “rigidity” in space. The axis is not supposed to move. When it does, it is called precession. Hope that helps.

    0 Votes Thumb up 0 Votes Thumb down 0 Votes



  3. Kris Kortokrax on Jun 29, 2015

    The definition of precession you quote looks like a definition of astronomical precession one might find in Wikipedia. It has nothing to do with aviation.

    Precession with respect to aviation dictates that when a force is applied to a spinning disc such as a propeller or helicopter rotor, the resultant force shows up 90 degrees after the force was applied in the direction of rotation.

    It explains why pitch change links on a rotor system apply changes to the rotor 90 degrees prior to the point that the designer wants the force to take effect.

    It also explains why you need to apply more right rudder when you raise the tail on a tailwheel airplane or why you need more left rudder when you let the tail down during a wheel landing.

    We also speak of precession when describing the drifting of a Heading Indicator due to bearing friction.

    +1 Votes Thumb up 1 Votes Thumb down 0 Votes


Answer Question

Our sincere thanks to all who contribute constructively to this forum in answering flight training questions. If you are a flight instructor or represent a flight school / FBO offering flight instruction, you are welcome to include links to your site and related contact information as it pertains to offering local flight instruction in a specific geographic area. Additionally, direct links to FAA and related official government sources of information are welcome. However we thank you for your understanding that links to other sites or text that may be construed as explicit or implicit advertising of other business, sites, or goods/services are not permitted even if such links nominally are relevant to the question asked.