Advanced Assembly Solutions for the Airbus RACER Joined-Wing Configuration

Compound helicopters, featuring lateral rotors as well as a primary rotor, are increasingly seen as the future of rotorcraft design. Capable of supporting a range of service applications, compound rotorcraft have the potential to deliver increased efficiencies and higher speeds relative to traditional rotorcraft. The Rapid And Cost Effective Rotorcraft (RACER) demonstrator is being developed by Airbus Helicopters (AH) to further validate the compound rotorcraft configuration. AH have chosen to employ a joined-wing design, which increases the stiffness relative to a traditional wing design. The RACER de sign also includes two lateral rotors, mounted aft of the Nacelles at the outboard extent of the wings, as depicted in Figure 1.

Two assembly methodologies were considered for the RACER wing structures - determinate assembly or traditional assembly set by jigs. Determinate assembly, also known as ‘part-to-part’ or ‘jig-less’ assembly relies on the precision manufacturing of a few critical features, within the definition of each child part, that allow interfacing items to be accurately positioned. This approach significantly reduces the importance of an assembly jig, which may only be required to support the mass of the wing structure. Resultant jig structures may be more cost-effective given requirements on their ability to set part positions are much less stringent. This approach can also reduce the need for assembly processing, deliver a shorter build duration, and reduce the lead-time for assembly tooling. Conversely, the requirement to include precision location features within component definitions can transfer cost into the manufacturing processes. Equally, significant analysis of 3D tolerance stack-ups must be completed to confirm the assembly can meet geometrical requirements.