Picture source is from here.
Here are wing areas of several airplanes. As we can see the Spitfire, B747-400, and Mirage 2000, their wing area are not rectangular. The line drawn from left side to the right side of the fuselage are not parallel to their fuselage's cross-section, or they are not perpendicular to the fuselage. The connecting line in the drawing of the Spitfire is curving (bulge) on the trailing edge side, while the B747-400 and the Mirage 2000 have pointing shape on the leading edge side. As we know that the wing area (hence also affects the aspect ratio) is very critical to an airplane to make it fly as wing area is included in the lift formula, so, what I want to ask here are:
- Is that depiction correct? If it is correct, then my further question is, why does not all the airplane body (except the horizontal stabilizer) considered as wing area?
- If it is not true, then how should I determine the wing area?
So far, what I found in many explanations is that the wing is the area from root to the wing tip times two, both sides calculated then times two as there area two wings, left and right. With the information in that link then all calculation will be changed: both wing area and the aspect ratio will be changed, calculation will be affected.
Edit/Added: There is a good article here explains about wing area. Based on that article, neither the first nor the second question is true as there is no solid method about how to calculate that wing area. There are three definition about wing area: Trapezoidal, Wimpress (which is used by Boeing), and Airbus. But what is confirmed from that article is that the fuselage between the wing root in included as wing area regardless of whether it defined according to Trapezoidal, Wimpress, or Airbus' definition.