I'd like to know a little more about an airplane spec figure that is listed when describing airframes/planes: "Wing Loading" (ex: Wing Loading: 22oz/sq ft (67g/sq dm) for a Sig Four-Star 120). What does the "Wing Loading" really mean and how does it play a part in wing design? Is a high or low wingloading better than the other? (let me guess the answer on this: It depends on HOW you plan to fly the plane) How does a high or low loading really work out with the way the plane flies? Is it a measure of how much pressure the wing can take before shearing? (like putting it into a high speed dive and then snapping back on the elevator or attempting a high speed turn?)

I can imagine that a "trainer" has a MUCH different "wing loading" than say, a sport or aerobatic, but how can I put the numbers into "perspective" so that I can understand what I'm reading about?

I know this is a TOTALLY DUMB question that redefines "basic", but my wife asked me earlier and I found out that I really didn't have a good answer (and if you can't explain it, you probably don't know it as well as you should !)

Wing loading is simply how much wing area you have divided by the weight of the airplane.
Simply put the higher the wing loading the faster the airplane need to fly to stay in the air.
Trainers have low wing loading so are able to fly slower and land slower. Warbirds have high wing loading so they have to fly faster and land hotter.

Newly big aerobatic gasers have a very low wing loading and that allows them to float a lot. In my point of view is not a way to fly the plane but a characteristic of it in self, this characteristic allows you to fly the plane more slowly than a High wing loading plane just like missileman said.
A high wing loading plane usually keeps you busy on the sticks and needs to be flown in landings.

Can you give an example? ie. wing area is widthxlength 12inchesx70inches=840sq.in. divided by weight (with fuel or without?) ie. 4lbs. or 840/4=210 - is this correct for the example given?
What units are typically used to do the calcs - square inches and lbs or ounces or grams??

Not all big aerobatic gassers have low wing loadings. I have a nice big 50cc aerobatic bipe with a pretty high wing loading. It stalls easily (which I actually like) and needs to be flown in with power. I'm not just talking a few clicks of throttle here, I'm talking like quarter throttle. It's actually pretty cool because I can spot land the airplane much easier than the "floaters". I've never deadsticked it and hope I never need to - it doesn't glide.

Wing loading is typically given in oz./sq. ft. The formula is (weight x 2304) / wing area - where weight is in pounds and area is in square inches. Beware, 12 square inches is NOT equal to 1 square foot!!!!

(and yes, I've actually seen somebody do that!!) In case you're still scratching your head, there are 144 square inches in a square foot.

Example:

You have an airplane that weighs 19 pounds and has a wing area of 1024 square inches. (19 x 2304) / 1024 = 42.75 ounces/ft^2

You have an airplane that weighs 8 pounds and has a wing area of 3.6 square feet. First, convert 3.6 square feet to square inches. (3.6 x 144) = 518.4 square inches. Now use the formula: (8 x 2304) / 518.4 = 35.5 oz/ft^2

There are a number of wing loading calculators online, google them, that you can just plug in the numbers.
Here is one:
http://www.csd.net/~cgadd/eflight/calcs_wingload.htm

Bah! Use your brain and keep yourself sharp. There are enough drooling idiots walking around the earth, don't inadvertantly become one.

This isn't even basic algebra.

And before I'm attacked let me clarify. I'm not calling anybody that asks a question or doesn't know how do calculate wing loading an idiot. I'm focusing that on people that habitually refuse to use their God given intellect to the point where they need the cash register to tell them how much change to give out. [X(]

I think sometimes God forgets to give intellect to some individuals.

If only common sense were common.

It is far too late for me [:-]

Nah, I've seen you're posts. They don't sound like the incoherent ramblings of such people I was referring to.

Back on topic, as stated above, wing loading is measuring how much weight each part of the wing is supporting, and therefore how much lift each bit of wing has to create to maintain level flight. Increase the weight (wingloading), and you have to get more lift from the same wing, which means flying faster or at a higher AOA. (since you increase wing lift by increasing airspeed or AOA or both. Increasing AOA also increases drag and at some point you increase AOA past the critical angle, and the wing stalls, and lift drops off).

One thing to keep in mind, wingloading is often misleading. It's really only useful for comparison between two simular size and type of airplane. What is a "high" wingloading number in a .40 size plane is "feather light" in a 50cc gaser, for example. And if you lookup or calculate the wingloading on a full scale Cessna, you'd think it wouldn't get off the ground (compared to model numbers).

As a way around this, some people calculate the "cubic loading", which is roughly a way of calculating the weight of the plane divided by the volume of the wing rather than the area. Of course, figuring out the volume of an airfoil shaped wing is a pain, so there are a couple of short-hand versions that usually involve squaring the wingspan. You get the idea. Anyway, cubic loading does seem to track performance better across airplane sizes, but has never caught on.

Generally, lighter wingloading is going to result in a better flying plane. Yes, a heavier plane will often seem to "track" better on final, but when it comes to pretty much anything else you'll do with a model, lighter wingloading is better. Just take your favorate model and start adding weight to the CG to see for yourself

common sense isn't...the old saying use it or lose it applies to the human brain as well.....did I mention common sense isn't...oh yea the old saying use it or lose it applies to the human brain as well....lol

Very good point. And thanks for steering us (me especially) back onto the runway, so to speak.

Lighter wing load= more lift / lower stall speed.

In other words , you have to maintain a higher airspeed in order to prevent stall.

Not necessary that top speed will increase.

A heavier model won't fall to the ground any faster.
The next time you attend an amuzment park , flick a coin out on one of those drop rides, such as the super man.
You'll see the coin float. I forget the name of the guy the dropped a couple of marbles off a tower a couple of centery ago.
Bascailly you're falling at the same speed, that's why you'll see the coin float.

less drag = more speed
more power= more thrust

thank you all for such well thought out and concise answers. This makes sense to me. "Wingloading" is the amount of force put on wing, and therefore how much lift you have to have to keep flying. And lighter wingloading is going to be a little easier to fly because it wants to "float" a little more and doesn't require lift generated by forward thrust and therefore SPEED (this would explain alot of why I find flying planes like the F22 IMPOSSIBLE on simulators! i'm guessing it's got a GIANT wingloading characteristic)

This is the kind of information that goes into my "little red book" for future reference ! ( a 6"x8" pocket sized "journal" I always carry around to make notes about flying in > I've also got a separate notebook I carry for"daily nonsense"; I'm also starting a third "green" journal as a "flight notebook" to help me log my hours, crashes, achievments, and embarassments

Exactly..that's why i clipped the wings to my 4*...it feels like a floater to me or it wants to keep on flying at a very slow air speed.

If I add total weight to the mdel..my model won't travel as fast in a vertical using the same engine.
That's why it's recommended to shift the radio equipment around to achive desire CG instead of adding weight.

My suggestion to you is go to library and see what you can find on aerodynamics. Now much of this likely will be way over you head (and mine) but some may be understandable, and you may even find info on models. There are many things that affect and pertain to an aircrafts performance. Such as center of lift. thrust line, airfoil, lateral area, C.G.,incidence, dihedral, aspect ratio, decaledge, power to weight ratio, etc.These are all common terms used in aircraft. Research can be rewarding and fun

I just recalled that no need for you to go to library. Go to the RCU glossary, got it all there, enjoy.

Library? Library? You are sitting in front of a web connected computer. One of the most powerful devices ever created. Use the search engine and find out everything about anything.

Yeah, but your computer can't do everything a library can. Sometimes I wonder if my future children will ever have the pleasure of reading a book. []

"A heavier model won't fall to the ground any faster." - Actually it will due to wind resistance, i.e. a heavier model has more force acting on it via gravity compared to the same model that weighs less. This allows it to overcome more wind resistance, hence a faster free fall.

Intersting note about cubic loading. This sort-of fudges in the scale factor/reynolds.

Ditto on you must compare similar planes to make much sense of the numbers. Giant scale aerobatic planes, i.e. 35%-50%, often have what seems to be a high wing loading, but they feel light in the air due to the higher renyolds number they operate at, i.e. the wing got bigger but the air denisty stayed the same, so the wing is more efficient.

-cheers

You can't get compair a biger model to a smaller model just on wingload alone.. there's too many variable.
Such as the size of air molecules.

A bigger model should fall to the groud slower due to drag, but mostly boeincy.
That's why a big metal ship won't sink.

You can do a simple experiment...Just drop a quater and penny. They'll both hit the ground at the same time.
But the quarter is bigger and heavier. Or drop a 1lb object and the quarter or a penny. They all hit the ground
at the sametime.

I just looked over on my desk and saw my copy of the "Flight Training Handbook" for pilots )

what do you want to bet there's something in there about this useful?