Welcome Guest. Sign in or Signup

3 Answers

Momentum of thrust

Asked by: 878 views , ,
General Aviation

Dear Aviators, 

In a symmetric rotating multi engine aircraft, Though there is a difference in momentum of thrust produced by each engine, why there is no effect of it while both engines are operative?

Thanks in advance

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. Best Answer


    Skyfox on Mar 16, 2016

    I’m not entirely sure what you mean by symmetric rotating multi engine aircraft. If you mean counter-rotating where the left engine is rotating clockwise and the right engine is rotating counterclockwise, if they’re set to the exact same power settings (throttle & prop RPM) then they should be producing the same thrust output and therefore have symmetric/equal thrust. If you mean a multi engine aircraft where both engines are rotating the same direction (usually clockwise), the right engine will have a slightly higher amount of thrust because of asymmetric thrust on the props causing the greater thrust on the descending blades of the right prop having a greater arm from the center of gravity as compared the more inboard descending blades on the left engine which are closer to the center of gravity. In that case, at cruising speed and power settings the effect of asymmetric thrust is greatly minimized as compared to slow flight at high power settings.

    +1 Votes Thumb up 1 Votes Thumb down 0 Votes



  2. srishan on Mar 16, 2016

    Thank you for your answer .
    I mean to say both propeller rotating on same direction say clockwise..
    Is there any special mechanism build in to minimise the assymetric thrust ?
    while flying not able feel the assymetric thrust, so I just want to make sure whether the assymetric thrust is minimal or its been reduced with mechanism.
    Theoritcally I understood that there should be a assymetric thrust as the right down going propeller is further away from cg as compare to left side..

    0 Votes Thumb up 0 Votes Thumb down 0 Votes



  3. Skyfox on Apr 11, 2016

    There could be any number of corrections engineered into the aircraft such as a very slight upward angle on the left side engine to give it slightly higher asymmetric thrust on its inboard descending blade to counteract the thrust produced by the right engine’s outboard descending blade. Or the rudder could be positioned with a very shallow angle to the left to cause more yaw to the right to counteract asymmetric thrust (which would be unnecessary if the airplane is designed with rudder trim). It really varies from one manufacturer to the next, so check the POH of the particular airplane to see if it describes any built-in correction factors.

    0 Votes Thumb up 0 Votes Thumb down 0 Votes


The following terms have been auto-detected the question above and any answers or discussion provided. Click on a term to see its definition from the Dauntless Aviation JargonBuster Glossary.

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.