Balsa wood has been used for many years as a model making material. However, light weight modern, alternatives are also available. One such material is depron foam. It is a form of polystyrene sheet. It is lightweight and does not absorb moisture making ideal for model aircraft. It is available in two colours - grey and white. It is also available in three thickness 2, 3 and 6mm. Depron is a polystyrene foam, popular as a material for the manufacture of fast food trays and packaging.
It is much lighter than balsa wood and can be cut with a sharp blade, sawn with a fine toothed mod- elling saw or fretsaw with a very fine blade. It can be sanded and smoothed using the usual files and abrasive papers (eg. wet and dry paper). Heat can be used to shape it although great care should be taken. Glue guns can be used to join depron or zepron although solvent free glues can also be used effectively. Using Figure 1.9 in the text-book, develop a system of equations and solution for free deflection of a morphing wing in the d33 operating mode.