Welcome Guest. Sign in or Signup

2 Answers

Factors of VMC – Bank

Asked by: 7627 views , , , , , , , , , , , ,
General Aviation

Can sompine please explain why if you have greater than 0 degree side slip with an engine inoperative you will have a lower VMC speed and more control. Also why if you have less than zero degree sideslip your VMC speed will increase.  The way I am thinking of this in my head means that I have it reversed.

Thanks

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.

2 Answers



  1. Nathan Parker on May 10, 2012

    A sideslip towards the dead engine reduces the effective AoA on the vertical stabilizer, reducing the pilot’s ability to maintain directional control.  A sideslip towards the good engine increases the effective AoA on the vertical stabilizer, increasing the pilot’s ability to maintain directional control.  With enough bank towards the good engine, you can maintain control with no rudder input at all.
     
    You can visualize it this way.  On a piece of paper draw the following:
     
    1) ME aircraft with left engine out.
    2) Rudder deflected to the right.
    3) Virtual chordline from the trailing edge of the rudder to the leading edge of the vertical stabilizer.
    4) Measure the AoA between a straight ahead relative wind and the virtual chordline
    5) Now measure the AoA between the relative wind coming from the left in a left sideslip and the virtual chordline.
     
    You will see that the AoA in the left sideslip is reduced compared with the relative wind coming from straight ahead of the airplane.  I think you can extrapolate to the right sideslip.

    0 Votes Thumb up 0 Votes Thumb down 0 Votes



  2. Bob Watson on May 14, 2012

    Another way to think of it is that Vmc is the speed at which your rudder can’t keep the plane flying straight. If you don’t have any bank, the rudder will be doing all the work of keeping the plane straight, so it will need a certain amount of airflow to make that happen. If you bank into the operating engine, that takes some of the work off the rudder allowing it to keep the plane straight with less airflow (i.e. at a lower speed).
    This is basically what Nathan said, but without thinking about it in terms of AoA (directly).

    +2 Votes Thumb up 2 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.