Structural carbon fiber sheets and technical considerations.
We are proud to introduce a new innovative type of product to the market.
These are aero grade structural carbon fiber and basalt fiber sheets.
I designed these sheets specifically for jet modelers.
The very specific thing about this product is that it is designed for both structural reinforcement and to improve the look of the internal structure. As such it features one face with a nice satin look and one face with a ready to remove peel ply fabric.
The peeled side will ensure the absolute best bounding characteristics onto any type of material used in a jet and is totally free from any release agent. So it is just a matter of cutting your plate, removing the peel ply and gluing it with any type of epoxy in your plane.
Up to now, carbon fiber plates were having two shiny faces produced in a hydraulic press with release agents. This type of product would require careful prepping to ensure maximum bounding with in a three stage sequence.
.The first stage implied the removal of the release agent with a chemical. This in itself could be a problem as very few manufacturers publish the type of release agents used. There are different types on the market that need to be removed either with warm soapy water, white vinegar, or acetone .In the case where the release agent was not known, all three methods had to be used. .The second stage was about scuffing the face to be glued to ensure a proper bounding surface. This would be done with a coarse grit carbide rotating tool at fairly low speed to avoid heat soaking and could have taken a long time if the surface was large. .The first stage required to remove any dust from the gluing area via a careful vacuuming then washing. drying was required after washing and would also increase the prepping time.
All these step were taking a very long time and keeping the sequence was necessary . Skipping the first step for example exposed you to the risk of embedding the release agent into the carbon structure while sanding it down, reducing the future bounding effect. Similarly skipping the third stage would make you glue your plate on a layer of carbon dust.
For all these reasons I found out that laying up the plates with a peel ply on one side would be extremely valuable for the user. The added benefit of leaving the peel ply in place is: protection of the carbon fiber surface, and ease of cutting. We recommend cutting the plate from the peel ply side with a hack saw fitted with a ceramic cutting blade ( the ones that have a diamond coating ). This will ensure that the satin face is not scratched. The peel ply being still in position during the cutting process will help the hack saw socket to glide on the plate. Additionally, the plates feature a very unique construction. The outer plies on both satin and peel side are laid up from high quality waving fabric with a perfect visual aspect, without any air bubbles. The core of the plate is layed up from a very specific fabric called quadriaxial. This fabric is waved at 90 degrees and 45 degrees at the same time, ensuring optimal rigidity in 4 directions, hence its name. This ensures a very high structural characteristics in 4 directions and gives an almost uniform stiffness to the plate.
The other very specific feature of these plates is the type of impregnation. I tried different type of techniques for my plates for several years: wet layup, pre-preg and infusion.
.Wet layup tends to get the fabric over-sutured by the resin and not optimally resistant. Good visual aspect without any air bubble requires to use a hydraulic press at extremely high pressure. In practice, air bubbles are always present. .Prepreg is better but also requires a very strong hydraulic press to chase all the entrapped air out of the satin surface. .The best process I found was to infuse the plates with specific resins. The fabrics are layed up dry on the marble and the resin is sucked by vaccum, chasing absolutely all the air bubbles. The fabric is also optimally impregnated with this method with no resin excess.
Finally, the plates are post cured at 60 c/ 140 F and have a plastic point of 80 c/ 175 F, and will keep their strength even in the hottest summer conditions.
We use similar structural plates on all our professional multi copters and for UAV applications with 100% success. The plates will be available in 1,5 mm/ 0,06" and 2 mm/ 0.08" thickness for the time being. Sizes will be 10" by 20" and 20" by 20" initially.