wing loading???
 

can anyone please explain what the numbers means as pertains to wing loading of a certain RC model. Is it the bigger numbers means better to do 3D with? I'm currently shopping for my 2nd plane and interested on a .60 size 3D plane.

RE: wing loading???
 

With wing loading, less is usually better. The numbers are expressed in ounces per square foot. Less loading means less weight each sqare inch of the wing must carry. This usually results in a lower stall speed, lower takeoff speed, easier and tighter maneuvering, BUt less wind penetration. On other words, it might get blown around more than a comparable plane with a higher loading.

Performance sailplanes might carry 5-15 loading, while sport models will have 15-20 or 25. Above 25 gets heavy, especially in the smaller models, but many warbirds carry 25-35. These weights are not due to the type of plane, but to the design and amount of wood and equipment carried. It's certianly possible to build a sport model with under 15 and a warbird with under 20. A larger plane can carry a higher loading without as much penalty as a smaller plane.

All in all, lighter is ALWAYS better.

Dr.1

RE: wing loading???
 

How do you calculate wing loading?

RE: wing loading???
 

Simple, divide the aircraft's weight by the wing area ;)

RE: wing loading???
 

Actually, lower numbers mean better performance. To understand why, you have to know what wing loading is.
Wing loading is how much weight is supported by each square foot of wing area. Here's a simple way to simulate it :
1) Take 2 bathroom scales and set them a few feet apart
2) Place a board on them so that it is laying across them evenly. I'll use a 6' 1X12 for simplicity
3) Put some weight on top of the board, right in the center. How about a few bricks, again for simplicity
Now, read the scales and add up the total. If this was an airplane, that would be your total load. At this point, you need to compute your wing area(6' X 1'=6 square feet). Lets say your 1X12 and bricks total weight is 18 pounds. By dividing the weight by the square footage (18/6), you would get your wing loading figure, in this case 3 pounds per square foot.
Now that you know what wing loading is, how does it affect an airplane? The higher the wing load, the harder it is for the wing to lift it. By adding bricks to the example above, the load gets heavier, till eventually the board breaks. A wing will do the same thing. By pulling too tight of loop, the wing won't be able to handle the stress, resulting in a wing failure. There fore, a lighter plane will be able to handle more stress on the wings due to lower loading. Hope this helps

RE: wing loading???
 

Brilliant! though not my post many thanks, I always wondered why they were wasting ink printing such value:D Now I know it's not a waste and should be considered

RE: wing loading???
 

Higher wing loadings normally make a difference during the low speed phases of flight, for example a lightly loaded trainer is very forgiving to slow down and land, perhaps to the extent that it permits bad habits to be learned.

A scale warbird on the other hand is always deemed to be totally unsuitable for beginners. The reason for this is that the high wing loading means a higher stall speed. Warbirds don't like flying slow thus landings take much more judgement and skill than a trainer needs.

Flying slowly, a high wing loading will mean you're aircraft is easy to stall, either by plain flying too slow, or by pulling a tight turn at lowish speeds. Conversely, as said above, if your speed is high enough that you don't stall first, your wings will clap hands [:@]

The Wing loadings is basically an expression to judge how hard the wing must work to fly any given aircraft. Clearly, the warbird wing in the example above must work much harder than the typical trainer. You may also find (but this is not without exception) that higher wing loadings correlate to worse manners, eg there is less warning of an approaching stall etc.

RE: wing loading???
 

Thanks a lot guys, very enlightening information. Now I can use the wing loading info to help me decide for my 2nd plane. I learned on a GP Big Stik and found out it has a 19-21 oz/sq ft wing loading that's probably why it's very stable in high winds and practically lands itself, very forgiving. But kinda sluggish for my taste now.

RE: wing loading???
 

As stated above, a plane with a higher wing loading doesn't necessairily mean that the plane is harder to land or that the plane needs to land faster than other planes. [8D]

RE: wing loading???
 

It also has a relatively thick wing with a blunt leading edge. The nose also creates a lot of drag. All of this helps to slow the plane down in a hurry for landing. The thick wing also lands well though.

RE: wing loading???
 

So, does the airfoil type/shape has any relation with the wing loading and if so what is the relationship (good/bad, etc)

RE: wing loading???
 

No.

RE: wing loading???
 

A high wing loading means that the aricraft must always fly faster than a lighlty loaded plane for the wing to support the weight of the airframe. It also means that the heavily loaded aircraft can more easily stall AT ANY SPEED. A tight turn, or hard pull-up in a highly loaded aircraft can produce a stall at very high speeds -- with impressive results -- usually a violent snap-roll & spin. Lots of warbirds are lost in high speed stalls.

High wing loading does have at least one benefit -- it makes the plane more resistant to wind gusts -- as long as it doesn't stall.

RE: wing loading???
 

Only when you're considering VOLUME loading. For the most part, we ignore that in R/C.

Dr.

RE: wing loading???
 

Hello All,

Thanks for all of the great information on wing loading.

One question that I have is does wing loading basically determine the amount of payload that a plane can safely fly. For example can I use wing loading numbers to determine how much weight a plane can lift? And if so does that mean that if I want to lift more I just have to make a bigger wing??

Hope this makes sense and thanks to anyone that has any advice on this.

-Greg-

RE: wing loading???
 

It can have an effect on stalling speed, gross weight, take off speed and distance, landing speed, general handling and structural integrity (depending upon how well it is built).

RE: wing loading???
 

Keep in mind that a real Learjet has a wing loading of about 55 pounds per square foot.

So, a large model might have a wing loading of 40 or 45 ounces per square foot and still have a relatively light wing loading.

You use this value to compare apples to apples and oranges to oranges.

RE: wing loading???
 

Thanks for the quick replies!!!

I am thinking about adding an extra 1 pound of weight to a .20 sized model such as this one.

Wingspan: 99" Wing area: 916 sq in
Flying weight: 50 oz Wing loading: 7.5 oz/sq ft
Length: 48.5"
Center of Gravity: 3-3/16" Back From Wings Leading Edge.


But I am unsure if something like this could carry that much extra weight and I would to have that decided before I spend the time and money building the model.

Thanks,
-Greg-

RE: wing loading???
 

A friend and I took a Bobcat glidder wing and used it to build a C-130. The Herk came in at 7 and 1/2 lbs. Flew fine.

RE: wing loading???
 

So I shouldn't have a problem then. Like I say I just want make sure it will carry all that before I build it. I guess if it doesn't I could just make a bigger wing.

Thanks
-Greg-

RE: wing loading???
 

Todays 3D planes laugh at, gravity / vertical / and wing loadings, for any sport use.
All the ones at the club field fit the above.

Some good advice by experienced 3D fliers is called for at this point to answer his original question.

Which planes and motors make up a good first 3D plane ?

RE: wing loading???
 

Generally speaking, horsepower to weight ratio should be about 1 Hp for every 3 pounds of airplane. A 60 size engine will produce almost 2 Hp. So look for an airplane that weighs under 6 pounds. Currently Aeroworks sells a 40/60 class Edge that claims a flying weight of 5 1/2 pounds.
The company also claims the plane is capable of limited 3D with a .46 .

People have acheived 3D with more than 3lbs/hp by using extremely flat pitch and oversized propellers. Ex: 12 X 3.5 on a .46.