Unmanned Systems Technology 009 | Ocean Aero Submaran S10 | Simulation and testing | Farnborough report | 3W-110xi b2 TS HFE FI | USVs | Data storage | Eurosatory/UGS 2016 report

29 generating aerodynamic surface can be called an aerofoil, and the chord is an imaginary line joining the leading and trailing edges. The cables terminate with swaged studs that allow precise adjustment of tension. This design brings versatility and scalability, says the company, because changes to parameters such as aerofoil thickness and wing/flap gap require only a change in cable length. Cable tensile strength increases with the square of the diameter, and multiple cables can be used in parallel, meaning that greater stresses from a larger wing can be handled easily. Furthermore, pulleys are inexpensive and easy to make in any size. The wing’s king spar, which is its main structural member, is mounted to the front face of the stub spar, while the wing’s smaller aft spar and a flap actuator bracket are attached to its rear face. Either welded from stainless steel or cast in aluminium, the flap actuator bracket has upper and lower arms with bearing sets that support the flap hinge shaft, plus a central arm that supports a pulley aligned with these bearings and a pair of cable termination bosses between the pulley and the stub spar. Pulley system In total, there are three pairs of pulleys connected by three crossed cable sets. The first pair takes the drive from the transmission to the first flap axis – defined by the flap hinge shaft – while the second and third pairs take the drive from the first flap axis to the second, which is supported between upper and lower flap hinge arms on a tube secured with a vertical bolt. In the first stage of the flap drive, a large flap pulley is fixed to the lower end of the flap hinge shaft and below the lower arm of the flap actuator bracket. The pulley is driven by a pair of cables from the idler pulley on the mast axis. Above the lower arm of the mounting bracket, a smaller pulley drives another of equal size on the second axis. This is fixed to the flap stub rib, to which the flap king rib is attached. Above the second pair of pulleys is the third, slightly smaller pair connected by a figure-of-eight cable set. Arranged in this way, the pulleys are equivalent to pairs of meshed gears in that they force equal rotation about the two flap rotation axes. The crossed-cable configuration allows the flap to feather in the same direction as the main wing when the AOI clutch disengages. Pulleys and hinges run in dry, self- lubricating bearings, the preferred bearing materials for which are sintered brass and PTFE. 3D printing Ocean Aero made extensive use of 3D printing during the r&d process, with services provided by Stratasys. The wing deployment and control mechanism was designed, printed in plastic, tested, redesigned and sent back to the printer several times in an iterative loop. “I think if we’d had to do that conventionally it would have taken a lot longer and would have been a lot more expensive,” Childress says. While many of the parts that were 3D printed in the prototypes will be more conventionally manufactured in the production version, about 30 components – both internal and external – will still be 3D printed, some being simple things such as servo mounts, others more complex. “There are going to be a few parts on our main control clutch that will remain 3D printed, although most of those are all machined now, but the hinge systems on the top and the bottom, we’ve pretty much got those perfected with 3D printing,” Childress says. Solar power Critical to the Submaran S10’s long endurance are solar panels, but it proved hard to find any that will tolerate being submerged. In the end, the company selected panels from Gochermann Solar Technology in Holm, Germany. They are very thin and flexible, so they conform to the curvature of the hull; they are somewhat delicate before installation, but become waterproof and robust when properly installed. “We have to be really careful when applying them to the boat, but once they are applied and fixed to the boat, and coated, they are pretty sturdy,” says Unmanned Systems Technology | August/September 2016 Ocean Aero Submaran S10 | Dossier The photovoltaic panels are laminated into the S10’s structure, encapsulated and coated to ensure they are tough enough for operations on and under the ocean