• Welcome aboard HomebuiltAirplanes.com, your destination for connecting with a thriving community of more than 10,000 active members, all passionate about home-built aviation. Dive into our comprehensive repository of knowledge, exchange technical insights, arrange get-togethers, and trade aircrafts/parts with like-minded enthusiasts. Unearth a wide-ranging collection of general and kit plane aviation subjects, enriched with engaging imagery, in-depth technical manuals, and rare archives.

    For a nominal fee of $99.99/year or $12.99/month, you can immerse yourself in this dynamic community and unparalleled treasure-trove of aviation knowledge.

    Embark on your journey now!

    Click Here to Become a Premium Member and Experience Homebuilt Airplanes to the Fullest!

Ground Effect - Flying Planks and Control Deflection

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Topaz

Super Moderator
Staff member
Joined
Jul 29, 2005
Messages
15,986
Location
Orange County, California
Okay, I can't find any direct reference on this one, so I'm hoping that more-knowledgeable people can confirm or deny my guesswork.

The case I'm looking at is for an arbitrary unswept tailless aircraft (flying plank) as shown in schematic below. The dark gray area is the elevator, and controls pitch primarily by changing the pitching moment of the wing.

What happens in ground effect? If I'm reading my sources correctly, the lift-curve slope of the wing (dCL/dalpha) increases in ground effect, but what change might this have on the pitching moment? My guesswork is that, overall, for a 3D wing, there will be an increase in pitching moment, just as there is an increase in CL, both due to the reduction in 3D span effects. In short, I'll have to pull more elevator to maintain a given angle of attack, just like in 'conventional' airplanes.

Am I right with that guess, or have I missed something?

Thanks in advance for any help.
 

Attachments

  • plank_wing_sample.jpg
    plank_wing_sample.jpg
    2.6 KB · Views: 444
Last edited:
Back
Top