Posted by: Miguel E. Mármol G. | Apr 4, 2011

A Full Rack of Ribs

As tasty as that sounds this full rack of ribs is a little different; it’s a wingful of ribs. We have been working hard on all of the ribs for the wing for the past month. Last week we reached a major milestone, we installed all of the rib foam cores into the wing.

Maria, Guillermo, and Ahmed working on the fully installed ribs.

The process to get all of the ribs installed was quite involved. We first rough-cut the foam from templates. We then sanded all of the ribs to be flush with the top and bottom skin.  While it only takes two sentences to write it involved placing the rough cuts on the wing skin. Using a flashlight you find the gaps between the rib and the skin. Then you sand down the high parts to make them lie evenly.

Using flashlight to find low spots in the foam.

While sanding the ribs we realized we did not provide enough margin from the templates so we had to re-cut and re-sand some of the ribs.  After all nineteen ribs were finally sanded to the appropriate shape the time came to seal the surfaces with a layer of q-cell to keep the foam from absorbing the epoxy when we laid down the fiberglass. We then bonded the ribs to the lower wing skin using q-cell.  A nice wide radius was used so that the fiberglass would bond properly without any bubbles.

Using q-cell to attach the ribs

Several of the ribs required inserts of stronger foam for things like aileron bell cranks, flap mounts,  landing gear, etc. so we put those in there right before we sealed them with q-cell. Those ribs also required that we lay up the fiberglass on them before we bonded them to the wing skin so that we could reinforce them later.

Laying up the glass on the reinforced ribs. Notice the darker portions which are the stronger foam inserts

We were finally ready for laying some fiberglass on those ribs.

Laying some plies down on the ribs

Current state of the build is that we are in the process of laying fiberglass on all the ribs that are installed on the lower wing panel. On the fuselage we have also been doing some rib building. One rib to be exact. That one rib though has ten layers of fiberglass on a very complex shape. It took two weeks to lay up this one single rib but it is finally complete. The rib is on the front of the fuselage.

Close up of one half of the rib

Location of rib on fuselage


  1. […] spar. The top skin comes separately and is cut in half at the aircraft centerline. The builder then adds the ribs, rigs the control system, adds all the system components, and in our case the flap attachment […]

  2. […] of – many of the key milestones. For example, you may wish to read about wiring the wing, making the ribs, closing the wing and the horizontal stabilizer, attaching the horizontal stab to the airplane, […]

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