The spar box is a continuous box beam with 0.1-inch/2.5-mm thick walls. Both its A and B (inner and outer) sides are critical dimensions. The outside locates the fore and aft gussets â€” they add stiffness and supplementary paths for landing gear loads while the wing spars must fit inside the spar box ends. A 3-D fabric, woven from T700 carbon fiber supplied by Toray Industries, was chosen to handle the structure’s high interlaminar shear loads. Supplied in the form of a sock-like preform by Highland Industries, a subsidiary of technical textile source Takata (Tokyo, Japan), it enables quick lay up of 10 plies over an expandable mandrel.
Notably, VX Aero has replaced the sandwich construction of the original craft, which featured extensive use of foam and honeycomb core, with monolithic skins reinforced by post-bonded hat stiffeners to reduce weight and enhance manufacturability. The canopy cutout is now bolstered by a CFRP rail that Skillen integrated into the glare shield as a one-piece structure. Thus, a reliably consistent fuselage/canopy interface is achieved with minimal parts and assembly. “The canopies will fit easily into the fuselage opening every time and be interchangeable with each other in the field,” Skillen explains.
Once the wingbox assembly is complete, fixed inner cockpit panels will be attached to the forward and aft seat beams and then the rail/glare shield will be affixed, followed by the cabin floor and firewall, which separates the engine from the cabin. Finally, the fuselage halves will be bonded using a fixture designed to account even for the glue thickness tolerances.
After the firewall and fuselage are bonded, the aircraft’s engine, still connected to its wheeled stand, is bolted to the firewall. Because the Falcon fuselage will only weigh 70 lb/154 kg, the assembly can be wheeled around the production floor easily, eliminating the need for a crane.
The wingbox assembly is all CFRP: 3-D woven material in the spar box and 3K plain weave in the other components. Like the original, the new Falcon will use glass fiber prepreg in the fuselage. Glass reinforcement is sufficient because the fuselage loads are smaller than those in the wing, and glass reinforcement will enable the radio transmissivity of internal antennae.
Prepreg layup, rather than what would be a complex infusion setup, was chosen for the fuselage, based on manufacturability and consistency/repeatability. Pre-pregged C-PLY will be used in the wing spars, wing skins and horizontal tail. Most of the other small parts will be infused, but some will be made using wet layup. Each material and process has been chosen with the balance between part performance and manufacturing efficiency in mind.