Wing loading

[RMaia]

After some analysis, it seems that the gasser planes (in the 27 - 31% range) have wing loadings neighboring 30 oz/sq ft.

From common 40 size glow designing experience, that wingloading is supposed to give crap 3D flying.
Most profile planes sport wingloadings of 12-15 oz, and they completely 3D'able.

However, these larger gasser planes also are very 3D capable, and feature wingloadings which would render common glow planes useless.

So, it seems that the larger the plane, the higher the wingloading it's able to withstand while still maintaning good 3D ability. Is this observation correct?

[AirMcNair]

	Quote: Originally Posted by RMaia
	After some analysis, it seems that the gasser planes (in the 27 - 31% range) have wing loadings neighboring 30 oz/sq ft. From common 40 size glow designing experience, that wingloading is supposed to give crap 3D flying. Most profile planes sport wingloadings of 12-15 oz, and they completely 3D'able. However, these larger gasser planes also are very 3D capable, and feature wingloadings which would render common glow planes useless. So, it seems that the larger the plane, the higher the wingloading it's able to withstand while still maintaning good 3D ability. Is this observation correct?

Kinda, Wing loading has not too much do do with 3D as much as how the airplane will fly and how slow. You can have a brick 3D with the correct amount of power, but to get it to fly is a completly diffrent problem......

[GremlinX]

The weight ratio should not care what scale size it is....

[Pro1Foam]

Where did I read that? It had something to do with you can make the plane smaller but not the air molecules.

[Ion01]

Maybe I am completely wrong, but, shouldn't a plane that is half the size have half the wingloading. Anotherwords, a if you had a 50% with wingloading of 40 oz/sq.ft. then a 25% plane should have a wing loading of 20oz. Just like the weight of the plane will be half the weight to the 50%. Unfortunately, because of the materials and things the numbers don't work out that way. Therefore it is next to impossible to get the plane to wiegh half of the 50% plane and, because of things like the properties of air and the way it acts when things like a wing gets smaller, and other factors I am probably not aware of, a 50% plane will fly better. However, I could be completely wrong about all that so hopefully someone else knows for sure.

[AirMcNair]

	Quote: Originally Posted by thaflyer
	Where did I read that? It had something to do with you can make the plane smaller but not the air molecules.

Yes kinda the same theory as a small spider being able to walk on watter as opposed to a big spider doing it. at some point the Mass of the object has to be the variable to wing loading since as stated the air molecules are not the changing variable..... One other thing. Wing loading only applys to a airplane that is in flight. It determines the stall speed. 90% of 3D flight occours at stall speed or slower....

Check this website out. all you need to know on wing loading http://www.performancedesigns.com/docs/wingload.pdf

[Ion01]

So, I was wrong....If a plane is half the wieght but still half the size then the wing loading should be the same?

[bodywerks]

As the size of a plane goes up, so does the wingloading. To give you an idea, a full scale aerobatic plane has something like a 60 POUND/Sq.ft winloading! The thing is, we all fly in the same density of air - that never changes for a given altitude/humidity/temperature. Although a 35% plane might have a 30 ounce wingloading and fly what is perceived to be like a foamie, It is actually flying faster in a high-alpha maneuver than most foamies do in straight and level flight, it just doesn't look like it is.

[bodywerks]

	Quote: Originally Posted by Ion01
	So, I was wrong....If a plane is half the wieght but still half the size then the wing loading should be the same?

More precisely, if a plane has half the wing area of another plane and also half the weight, then the wingloading is the same. But this has nothing to do with the real world, because weight increases exponentially with size. Otherwise, based on the weight of a 25% scale aerobatic plane at 12.5 pounds, it's full scale counterpart would only weigh 50 pounds. Yet, in reality, a full scale aerobatic plane, like the 300L, weighs 1500 pounds, empty! Also, a 25% scale aerobatic plane cruises at about 60 mph, but a full scale aerobatic plane's stall speed is at around 60 mph. It also has a maximum speed of over 200 mph, and that would rip the wings off a 25% scale counterpart!

[spun]

Wing loading is nothing more than a ratio of how much an aircraft weighs compared to the total wing area. It has nothing to do with scale at all. simply weight and square feet of wing surface.

"Maybe I am completely wrong, but, shouldn't a plane that is half the size have half the wingloading. Anotherwords, a if you had a 50% with wingloading of 40 oz/sq.ft. then a 25% plane should have a wing loading of 20oz"

This is not necessarily true. For a plane to have a wing loading of 40 oz/sq ft it simply has to have for example:

Typical 33% aerobatic plane 1700 sqin wing = 11.80 sqft of wing area, so if it weighed 472 oz it would have a 40 oz/sqft loading (29.5 lbs)


27% Extra 260 1140 sqin wing = 7.92 sqft, so if it weighed 317 oz (19.8lbs) it would als have a 40 oz/sqft loading. Now if it weighed 472 oz it would have and 80 oz/sq ft loading.

The number of air molecules is constant, however given that a smaller wing has less surface for the molecules to act on it will produce an amount of lift thats not directly proportional to the same airfoil/ planform of a larger size. So this is why you see that bigger planes even with higher wing loadings tend to "fly better"

You want to strive to keep the wing loading as low as possible to get a good flying plane, a stall resistent airfoil can only go so far, and must move fatser through the air the more weight it carries. In 3D post stall manuevers this is not too critical, until you have to make the plane fly again and have to gian more speed to achieve this, so yes you can always get a bigger motor but then you just have a plane that has to go really fast to take off and land.

As for the speed thing, A plane appears to go slower, like when you see a 747 or C-17 fly by, because its bigger, it takes longer for it to pass a given reference point. So you brain percieves a slower speed. Its still going 280 knots.

[why_fly_high]

Do some research on reynold's numbers. It will make more sense as to why bigger planes fly better at higher wingloadings than smaller ones at the same wing loading.

By the way, an Edge 540 has a wing loading of about 16 lbs per square foot in an aerobatic configuration.

Dan

[Ryguy]

Also check into cubic loading. If you check that out, then the 35oz./sq. foot loading of a 35%-er is often less than that of a foamy.

Search the 3D electric forum on RCGroups (hope I dont get shot for saying that). There was an excellent thread a while back about wing loading and cubic loading.

http://www.rcgroups.com/forums/showt...=cubic+loading