Design Concept 1:

General Component Layout, Nomenclature and Definitions

Initial Sizing Approach

Assumptions

1. Load distributed uniformly along span
2. Bending moment carried by spar caps
3. Shear loading carried by shear web
4. Upper and lower spar caps are identical thin laminates
5. Wing carries weight of entire aircraft - including weight of wings
6. Spar cap cross sections are of rectangular shape, width being constant throughout span - only height varies

Loads

The load is uniformly distributed along the span of the wing. Thus, the loading, shear and moment equations are:

$$ \begin{equation}\omega= \frac{N(m_0)g}{b} \end{equation} $$

$$ \begin{equation} V(y)=\omega y-\frac{1}{2}\omega b \end{equation} $$

$$ \begin{equation} M(y)=\frac{1}{2}\omega y^2-\frac{1}{2}\omega by+\frac{1}{8} \omega b^2 \end{equation} $$

Spar Cap Sizing

The stress in the spar cap can be approximated as: