Please explain wing loading to me!!

[BigGee]

Right guys I understand how wing loading is calculated. What I want to know is what are the effects of light and heavy wing loading. And how it effects the planes performance. What are the pro and cons for light and the pros and cons for heavy?

Please help

Thanks.

[willhaney]

Wing Loading???? (http://www.rcgroups.com/forums/showthread.php?t=14756)
Wing loading is really just a guide to how fast the plane will fly and it also determines it's stall speed. The higher the wing loading, the faster it flies and the higher it's stall speed.

A friend of mine used to say, "you can make a brick fly with enough thrust." Take a look at the EDF planes in the jet forum if you want to see some ridiculous wing loadings and outrageous watt per pound drive systems. My experience is that under 6 ounces per sq/ft on conventional airframes is a "floater" and up to 10 - 12 oz/sqft on sailplanes are floaters. Up to 17oz/sqft is still a good trainer. Past that is intermediate pilot and so on. As long as your plane has a proven drive system that correctly matches prop pitch speed and static/inflight thrust to weight ratios to your airframe, you are just fine.

Jim


Wing loading - Please explain (http://www.rcgroups.com/forums/showthread.php?t=582484)
Generally, a higher wingloading makes an airplane harder to fly. The plane needs to fly faster to generate the lift required to keep the plane in the air. However, a high wingloading does have the effect to making the plane more stable in windy coditions due to the greater model weight.

A lighter wingloading makes the plane easier to fly, however it normally means the model is lighter, which means it is more easily affected by wind. I know for the foamies I fly (3D hehe :D ) a good wingloading is around 5oz/ft^2.

What is wing loading? (http://www.rcgroups.com/forums/showthread.php?t=803294)
Yeah, lower wing loading = slower stalling speed. Stall speed is proportional to the square root of wingloading. If you increase wingloading 4x, the stall speed rises about 2x, assuming the airfoil behavior doesn't drastically change with speed.

[Brandano]

Actually, lower wing loading = higher speed too, while induced drag is dominating. More thrust goes into accelerating the plane and less in fighting induced drag, keeping the plane up. When surface drag takes over (at higher speeds) then a higher wing loading has a speed advantage, not because of the wing loading per-se, but because of the smaller wet surface of the wing.

[JetPlaneFlyer]

Lighter is almost always better; that's why we build model airplanes out of lightweight balsa wood and foam rather than materials you may make houshold furnature from ;)
The only time you may want to deliberatly increase wing loading is in a glider in high wind where you may want faster glide speed. For a power model though, as noted earlier, heavier wing loading (assuming same wing area and power) will produce a plane with slower climb and slower speed in level flight. In all cases the heavier wing loading will have higher stall speed which makes it harder to land and take off. Heavier wing loading also makes the plane less manouvrable, meaning turns and all other manouvres have to be wider and pull less 'g'.

Bottom line; build the model as light as practical.

Steve

[BigGee]

Thannks for response guys - thats a great help. :)

[vintage1]

Slight disagreement with JetPlane. To get ultimate top speed you HAVE to reduce wing area. Yes, it makes a harder to fly model, but if speed is the aim..

[JetPlaneFlyer]

Slight disagreement with JetPlane. To get ultimate top speed you HAVE to reduce wing area. Yes, it makes a harder to fly model, but if speed is the aim..

No disagreement Vintage.. i said "heavier wing loading (assuming same wing area and power) will produce a plane with slower climb and slower speed in level flight."
The point I was making is that a heavier plane, all other things being equal, will be slower.

If you increase your wing loading by making the wings smaller then, maybe (and it is only maybe) your top speed will increase... But the question was "What are the pro and cons for light and the pros and cons for heavy"... not big wings vs small ;)

[dk944s2]

BigGee, I strive for lighter wing loadings in general, but more heavily loaded models tend to be more stable in windy conditions. And the fact that it's windy means that your more wing-loaded plane's ground speed at touchdown is still manageable (assuming you're landing into the wind!).

--Doug

[macboffin]

I wonder how a DeBolt "Speedwagon" would go on RC?

[MCarlton]

In the case of something like the Speedwagon, I would imagine (if one ignores the absence of a vertical fin) that the firstly, torque reaction from the motor would introduce a roll which couldn't be countered by aileron.
Next, to keep it in sight, introducing enough elevator to turn would probably stall the wing, that high wing loading and low lift would scrub off speed very quickly as soon as the AOA of the wing was increased.
Any attempt to slow the model down would result in it stalling also, as the stall speed would be high, requiring probably a 45 degree dive to keep flying in deadstick. At the end of which, pulling up elevator to flair would stall the wing and flick the model into the ground.
As I see it, the only way it would work would be to make the model really light, and mount a much smaller motor up front, together with a more cambered wing section.

I don't know if I am right here, but I'll chance my arm;

Wing loading is related on model size, in that a larger model can cope with a higher wing loading without detriment to flying abilities. So, for example, a wing loading of 24oz/ft2 might not be out of place on a large scale aerobatic model, and might even be light for a scale turbine model, but it would be a nightmare on a 36" span sport model.