Posted by: Miguel E. Mármol G. | Apr 20, 2012

600 words on attaching the horizontal stabilizer to the fuselage

Some of you remember the post about when the horizontal stabilizer was closed. After that we spent a lot of time working on the finishing touches and on making the elevators. The culmination of all those efforts are the attaching of the now fully complete horizontal stabilizer to the fuselage! A major step in the right direction!

Horizontal stabilizer attached to the fuselage. The first securing plies have just been laid.

After we closed the horizontal stabilizer the next series of plies were reinforcing plies to the leading edge and the rear spar. At the conclusion of these reinforcements the stabilizer had a nice smooth and sturdy-looking leading edge as seen in the picture below.

Detail of leading edge reinforcement. Things will be further smoothed at the end of the construction process.

We then began work on the elevators. This was interesting because it required to do the same process twice and we struggled with whether we should go through the entire process with one elevators and work out all of the kinks and nuances of the process and then repeat with the second elevator or if we should do both simultaneously. We ended up doing things simultaneously. The first step in the elevator process was to attach the front spar of the elevators to one of the skins. The spars are where the hinges attach the elevator to the stabilizer. This required some lining up to make the hinge mounts. The spars were a little short in length so we spent some time devising and implementing a repair that turned out to work very well. Then the ribs were attached to the elevator.

Elevator skins with attached spars and ribs before the top skins were attached.

The elevators were then closed. One would think that this was the end of the process but after that it was necessary to attach the hinges and spend a lot of time contouring the tips.

Closed elevators showing detail of hinges.

A big part of the process was also to add the elevator counterweights. This involved casting some lead into the shape of the cavity where they were supposed to fit. It also had to very precise as the weight distribution has a strong effect on the flutter characteristics of the airplane.

Molten lead being poured into the mold of the cavities in each elevator

Final laminate to close up the cavity containing the lead counterweight in the elevator.

Now comes the time where the stabilizer is attached to the fuselage. This involves laying plies on the inside and outside of the fuselage where it meets the stabilizer to attach them together. The outside plies are not that difficult but the inside plies involve a two-person team with one crawling inside the fuselage and another helping from the back of the fuselage where the rudder will attach.

Judy inside the fuselage laying the reinforcement plies for the horizontal stabilizer.

After these plies are laid we will add some reinforcement bulkheads to the whole assembly. It should be a blast to crawl around the fuselage for these.

One last note; after writing this post I am amazed at how short it was considering how much work our team went through to get these done. The post is just over 600 words long and it covers a year of work (hence inspiring me to change the title of the post). I just want to give the reader an appreciation of just how long this stuff actually takes. The last positing where we closed the stabilizer was in April of 2011. We actually closed the elevators somewhere in September 2011. The casting of the lead for the counterweights took place in January of 2012. We finally attached everything about 3 weeks ago. Almost a whole year of work confined to ~600 words!!! I am looking forward to what the next year and 600 words will bring!


  1. […] to read about wiring the wing, making the ribs, closing the wing and the horizontal stabilizer, attaching the horizontal stab to the airplane, making the engine mount and nose gear and header tank, […]

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