Hawthorn Composites “Delivers high value, complex composites”.

Today we’ll be demonstrating the fabrication of a carbon fiber,  Sub-section Trailing Edge control surface with acute internal cavity geometry.

Hawthorn Composites will be utilizing Smart Tools to make the two cavities and the shear web of the sub-section control surface and incorporate a floating lid mold to ensure consolidation of the solid trailing edge.

First 2×2 twill carbon fiber pre-preg  is cut to the required ply shapes using an Autometrix automated table cutter.

The upper and lower half of the aluminum cure mold were previously prepped for layup. 10 layers of carbon fiber pre-preg is hand applied to the lower mold, per the laminate schedule.

The lay-up is then de-bulked to consolidate the prepreg, reducing the bulk in the material and ensuring proper fitment/assembly of all tooling.

Next, the pre-preg plies are laid up onto both of the smart tools. The smaller of the two Smart Tools has an acute angle that results in a cavity thickness at the edge of 1/16^th of an inch.

The laid up Smart Tools are now placed sequentially onto the debulked laminate on the lower mold.

In-between placing the two Smart Tools, unidirectional carbon fiber pre-preg is used to create noodles that are used to fill in the cavity created by where the two smart tools intersect at the top and bottom of the shear web.

Now the upper half of the aluminum mold is laid up with 19 plies of pre-preg. Once the upper laminate is complete, build-up plies are added to the area of the hinge pockets. The upper laminate is then de-bulked in the same fashion as the lower laminate that was previously shown.

Next, the upper mold half is flipped and carefully placed over the lower mold half that includes the laid-up Smart Tools. The mold was designed with a floating lid that will remain proud due to the trailing edge solid laminate. Once the cure progresses in an autoclave, the heat and pressure will consolidate the solid laminate trailing edge via the lid being forced all the way down onto the cure mold base.

Breather is added to the topside of the mold and then vacuum bags are run down the cavities of both Smart Tools and tied into a vacuum bag that seals the upper mold half to the lower mold half.   A vacuum leak check is preformed to ensure there are no bag leaks.

After passing the leak check, the sub-section control surface assembly is placed into an auto clave to complete the pre-preg manufacturers recommended cure schedule.

Once the cure is complete, the sub-section control surface is removed and the cured control surface, that still has the two Smart Tools inside, is demolded.

The sub-section control surface is then put into a heated oven and once the Smart Tools are heated above their activation temperatures, the now highly flexible Smart Tools are easily removed from the cured sub-section control surface.

The sub-section control surface is then trimmed, finished, cleaned and inspected.

Applying the Hawthorn Advantage, including the use of novel manufacturing methods that include Smart Tools and a floating lid mold design, allowed the fabrication of a sub-section control surface with acute angles without foam. The end result is a composite control surface with reduced weight, reduced scrap and cost, and improved through-put. In other words, a composite part made better, cheaper, and faster.