Types of Ribs

The Different Kinds of Wing Ribs and How They Differ

Here at Flight Club Aerospace, we are all about keeping things simple to save time and money, but sometimes it’s just not possible. We have five different types of wing ribs, each with its own unique purpose, and hopefully this article can shed some light on their differences to dispel any confusion. Note that despite their differences, all ribs share the Clark Y airfoil as their outer edge. Also, as we refine our wing design, the exact size of these ribs is likely to change. For the latest rib designs, and to see them in 3D, check out our public Onshape document. In order from root to tip, they are:

Bulkhead Rib

There is only one bulkhead rib, and it’s located at the root of the wing. Because of its inward placement, it lacks a hole for a drag strut.

False Rib

Ribs are used to transfer the load to the spars and to support the wing fabric to form the airfoil profile. Our ribs are constructed like a composite “sandwich” where e-glass and epoxy resin are the bread and house insulation foam is the filling. This makes them very strong so that only a few ribs are needed to carry the large wing load. However, using so few ribs would cause the fabric to sag inwards and deform the airfoil profile, decreasing efficiency and flight performance. To mitigate this, our main ribs are interspersed with false ribs which don’t bear any major loads but just support the upper wing fabric.

Standard Rib

The standard rib is identical to the bulkhead rib except for its oval-shaped hole for a drag strut. Standard ribs occupy the root and tip zones of the wing. The number of standard ribs and the placement of the drag strut hole depends on the value of independent variables RootRibMultiplier and TipRibMultiplier. Since the drag strut hole placement is unique for each rib, their order from root to tip matters.

Half Rib

The half rib is the standard rib with the back chopped off to make room for the aileron. It has a drag strut hole and is placed in the middle zone of the wing in front of the aileron. The exact number of half ribs is determined by the variable MidRibMultiplier.

Wingtip Rib

The wingtip rib is identical to the bulkhead rib except it lacks a hole for an aileron bushing. There is only one wingtip rib, and it’s located, as the name implies, at the tip of the wing before the Hoerner wingtip.

*Editors’ note: the thought processes and design choices presented in this article don’t necessarily represent those implemented into the final design and are subject to change. Flight Club Aerospace is a group of amateur students with no formal education in any fields of engineering. We present this information for educational purposes only, with the understanding that it is not to be re-created without adequate professional oversight and mentorship. For our latest designs and updates, please see our most recent blog posts.