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Is there a specific ratio between lift and wing size? Answered

I am working on an rc plane and wondered if there is a ratio between propeller size to wing size, wing size to lift, or weight to wing size. Thanks!

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bolognaonawallBest Answer (author)2009-02-16

I don't know about a specific ratio, but that's just because there are so many different factors that effect the lift created by a wing. The longer it takes air to move over the air-foil from the leading edge to the trailing edge, the more lift you're going to have. Look up the cross sections of the wings on old heavy bombers and fighters from WWII. What you'll see is a really beefy airfoil that creates a lot of lift at relatively low speeds. These are great for getting heavy loads (like WWII aircraft) off the ground. The downside to beefy air-foils like that is that they also create a lot of drag, meaning that you have to have a more powerful engine pulling it through the air, and you also won't be able to achieve the same speeds that you would with a more trim cross section. As a former RC builder, here's what I would suggest; find a model that is similar in size, style, and desired performance characteristics and copy its airfoil. Also take into consideration the size of the engine you'll be putting in compared to the engine in your copied model. I was involved with a youth club and we'd spend entire saturdays hacking together planes with different wings and all sorts of different parts from other planes. The great thing about RC planes is that the physics are a lot more forgiving on these small planes than they are on big ones. Odds are good that it'll work no matter what you do. Definitely get hooked up with your local AMA chapter, there'll be people there that can help you too.

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captmike (author)2009-06-23

You can get an answer at nasa web site. check out this link.
http://www.grc.nasa.gov/WWW/K-12/airplane/size.html

Capt Pierce

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The Jamalam (author)2009-02-16

all of what kiteman said, plus the addition of the factor of the wing tip vortex created by the high pressure air from underneath the wing being forced around the wing tip and creating a high pressure vortex above the wing. This will create a downwards force. Adding an angled part to the end of the wing (the name of which escapes me) will eliminate this. So there may be anomolous results if you do not take the wing tip vortex into account.

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Kiteman (author)2009-02-15
Simply, bigger wings give more lift, but there are lots of other factors involved -

  • the wing profile
  • the ratio of length to width
  • rake angle
  • speed (gliders have long, thin wings, for instance)

I would suggest taking one of three routes:

  • make a kit or work from a commercial fuselage
  • follow an existing plan (there are lots online)
  • go with gut feelings - you'll be surprised what will fly, especially in small aircraft, and you can always adjust it later.

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