Metal wing structure

About the project

A team project: a metal wing with a semi-monocoque structure. I was responsible for the 3D model of the whole assembly in Siemens NX and for manufacturing, meaning every part had to be either bent from sheet or bought from a supplier. The model couldn’t contain shapes that look fine in CAD but can’t be made in a workshop.

Structure

The wing’s nose carries the loads, working as a torsion box. It is made up of the skin from the leading edge back to the spar, and the spar itself.

The spar sits at about 35% chord. It has a 0.8 mm sheet web and two 30×30 mm angle caps, upper and lower, which take the bending. Four nose ribs run from the leading edge to the spar, holding the aerofoil shape and supporting the skin, spaced 1250, 1875 and 1250 mm apart. Four stringers, two on top and two underneath, stiffen the nose skin along the full span.

Everything is riveted. The model has 1196 rivets: 1012 join the spar web to its caps, and the rest hold the stringers and ribs.

The wing spans 5000 mm with a 1000 mm chord. The aerofoil is at most 154 mm thick, about 15% of the chord.

Manufacturing

For every part in the assembly I checked how it would actually be made. I designed the sheet parts as bent parts in the Sheet Metal module of Siemens NX. Such a model stores its bend radii and bend lines, and NX derives the flat pattern from it, the outline cut from the sheet before bending. I chose the remaining parts so they could be bought from suppliers as finished products.

In the 3D view above the skin is translucent, so you can see the spar, ribs, stringers and rivet layout. Zoom in to see individual rivets.