Welcome Guest. Sign in or Signup

1 Answers

Why is there a nose-up change in moment after leaving ground effect?

Asked by: 833 views General Aviation

The Airplane Flight Handbook states:
The aircraft leaving ground effect will
1) Require an increase in AOA to maintain the same CL
2) Experience an increase in induced drag and thrust required
3) Experience a decrease in stability and a nose-up change in moment
4) Experience a reduction in static source pressure and increase in indicated airspeed

I'm having a hard time understanding the number 3 here. What's the aerodynamical reasons you experience a nose-up change in moment right after leaving the ground effect?

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.

1 Answers

  1. JDJ on Apr 18, 2017

    The opposite reason that you get a nose down pitching moment when you enter ground effect (assuming conventional horizontal stabilizer, not T-Tail). In ground effect, the downwash from air flowing over the wing is reduced because of the disruption of airflow close to the ground. When you enter ground effect, you lose some of the downwash flow over the horizontal stabilizer (downward force on tail plane), resulting in nose down pitching moment. Vice versa, as you depart ground effect, the downwash then takes place acting with greater force over the tail plane. You then experience a nose up pitching moment as a result.

    +3 Votes Thumb up 3 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.