Im in the design stage of one of my projects and cant figure out howto find the wing loading. From what I came up with the plane has 70.21 sq inches of total wing area(canards and main wing). If I figured right that is .49 sq/ft. I tried several times to get the last step but cant get it right. Right now I am not sure what it will weigh but I was trying to figure it at 15 ounces and 25 ounces to see where it came out at.
Thanks
Nick

15 oz at .49 sqft is about 30 oz/sqft

You're right that 70.21 sq. in = .49sq ft. (144 sq. in. = 1 sq. foot) So if you said your model weighed 15 oz, double that (actually: 15 oz. x .49 sq ft.) to get your wing loading in oz./sq.foot, or about 30 oz./sq.foot, a little on the high side unless it's a warbird. Must be an electric to weigh so little.

Formula is : planes weight (in oz.) divided by wing area (in sq. feet)

But - the question is - did our man calulate the wing area correctly? [sm=devious.gif]

You need to determine the planform of the wing to account for the wing area correctly. Same for the canard. Extend the leading and trailing edge lines in to the center line of the airplane. That constitutes your true wing planform. Calculate the area of that shape, and you have your wing area. --- just making sure we are all playing with apples, not oranges.

also - the FULL projected area allows one to look at span loading.
If the panels only are used as a point of referrence - you really have no worthwhile comparative info.

Thanks for the input guys. The model is a 19 inch span X-29. I started with 3-views and transfered it over to graph paper. I also increased the wing span, canard area, and rear strake flap width by 10% to get me some more wing area without messing up to overall look. I already know the challenge ahead in getting it to fly stable and am kinda looking forward to it. Right now I am still working on details as I start to make the plans. I have tried four times now to upload a top view of the enlarged design but it wont let me upload right now. I will try again in an hour or so. When I figured the wing area I only figured what was outside of the fuselage(canards main wing lex and the strakes along the sides). The original X-29 had a fairly small wing and even after enlarging it is still quite narrow. I figured at 27 inches long and 19 inches wide I should be able to get it under 12-15 oz but I need to watch what I put in it for gear. I know it wont be a floater but it would be nice to have the wing loading somewhat reasonable.
Nick

here is a link to a web page where you can download a utility program to calculate wing loading and thrust by just plugging in some data.
[link=http://www.bmaps.net/software/goodies.html]Thrust and loading download site[/link]

quint

Well it still wont let me up load the top view. So when I figure the wing area am I supposed to figure in the area of the fuselage between the wings and the canards? What about the rear of the fuselage? The strake flaps run from the rear of the main wing all the way to the back of the plane. Thanks for all your inputs.
Nick

With many modern high-performance aircraft, the fuselage adds tremendously to the wings' job of developing the lift to fly. There's a story going about how an Israeli F-15 had an air-to-air collision and lost much of one wing panel. The aircraft was controllable at high speeds because the remaining roll controls were effective, and the fuselage developed enough lift at speed to allow the aircraft to stay in the air. Don't know if it's true, or if the plane landed. I'd suspect that the pilots would fly to a safe area and then eject. Good story, though.

The point is, though, that the design of the aircraft may just warrant including the projected area of the fuselage into the total lifting area of the airplane concerned. For most aircraft, though, this isn't a consideration. If the plane has large strakes, then they may be a consideration. Canards or horizontal tail surfaces are usually not considered when calculating wing loading.

It's not an easy call when you get farther away from "conventional" designs.

The story is true. I was in the F-15 group at McDonnell Douglas when we received word of it. The amount of wing loss was most of the panel outboard of the strake fillet area.

The pilot after his first initial shock discovered that if he rearranged his thinking and made pitch motions on the stick at somewhere around 30 to 40 degrees to the normal that the airplane could be flown. It allowed him to coordinate the highly assymmetrical airplane that he had. Normally a pilot would eject but the Israelies are men with lots of hair on their chest. He was able to land the airplane (at a very high speed) successfully.

We were all elated of course, it's nice bragging material that our airplane was so good that you could lose one wing panel and still fly. Of course we didn't mention that we were totally surprised at what the airplane was able to do.

See the story here.

http://www.angelfire.com/va/laserlight/nowing.htm

It's all about the pressure field around the wing. Think about the low pressure volume of air above the wing. What happens to this pressure when you get to the wing root at the fuselage, does it drop to zero? NO! It can't, it's PRESSURE. High pressure will at least flow to low pressure.

That's a simplification, but that's a visualization how the fuselage "contributes" to lift and why the planform area is a true representation of the wing. The low pressure area continues over the fuselage between the wing, and the pressure does indeed apply lift to the fuselage skin. In general, the value of pressure at the root of the wing remains constant along the span of the fuselage creating that much lift. So, the difference in lift between an airplane(wing + fuse) and a plain wing of the same planform and span is minimal, on the order of 1%. If you (like some hobbyists) think you know better and only consider wing area to be the "exposed" part you can touch, you will be introducing 5-10% error into whatever calculation you use this incorrect wing area for.

THis can easily be shown in a wind tunnel by swapping the two examples I've used and measuring performance.

As for the speciallized shapes of unusual fuselages - strakes, etc; they contribute vastly more to stability considerations than the lifting ability of the plane. On an F-18, the strakes in front of the CG will bias the CG about 10% forward of where it would be on the same plane without strakes. On the X-29, the opposite may be true.

Do it the easy way as suggested by other in this thread, use the wing area including the part of the wing inside the fuselage, to calculate the wing loading.
Wether or not to add or subtract other horizontal areas is IMHO of academic interest only. The reason is that the number you end up with is of little use when it comes to comparing your specific aircraft with other aircraft. For example, a 30 oz/sq.ft. wing loading is considered rather high for a small aircraft like yours but for a quarter scale model it is rather low.
The usefulness of the wing loading for modelling purposes is mostly to get a rough estimate of the stalling speed. Also, it can be used for comparing performance changes for one specific aircraft if some parameter is changed, e.g. what effect will a 20% increase in weight have on the stalling speed.

/Red B.

Cautrell05,
Here is another link where you can calculate wing loading by just typing in some data.
http://adamone.rchomepage.com/design.htm#calculate