Unmanned Systems Technology 024 | Wingcopter 178 l 5G focus l UUVs insight l CES report l Stromkind KAT l Intelligent Energy fuel cell l Earthsense TerraSentia l Connectors focus l Advanced Engineering report

96 to give an overall unladen airframe weight of 1.5 kg across the 1.3 m wingspan. The UAV’s structural parts, which include the internal chassis and spars, are made from carbon fibre. A lightweight material called Zylon is used as the fuselage’s skin and wing body, which houses the GNSS antenna, radar and comms systems. Zylon has RF transparency, as carbon fibre would typically block the passage of comms signals. However, carbon fibre is still used in the winglets and flaperons for its added strength. Electron Beam Processes was at the show to display the benefits of electron beam welding (EBW) in parts manufacturing across a range of engineering fields. “For UAVs, EBW can be used for many products within a vehicle’s design, but it is most useful for propulsion vessels, engine parts and structures that are typically made from titanium, nickel alloys and aluminium, as well as other parts made from combinations of various lightweight metals,” Adrian Pragnell explained. “The process enables welding of similar as well as dissimilar materials within their respective materials group, using a concentrated flow of electrons in a vacuum atmosphere. This provides cleanliness and stability in the stream of electrons, producing very high integrity welds with very low heat input and thus low distortion across the weld.” With EBW, distortion tends to be measured in microns, in contrast to typical welding which produces distortions upwards of 0.5-1 mm (depending on the size of the structures being welded). EBW also welds without intermediary materials such as filler wire, making the weld narrower and giving it a similar strength integrity to its parent materials. The company also performs non- destructive testing of manufactured parts, including radiography and fluorescent penetrant inspection, to check before shipping that parts will not fail in service. Trident Foams attended the show to promote its structural foam products, which include its Tricast range of polyurethane materials that are suitable for cutting and manufacturing as foam cores for propellers and wings. “Polyurethane is better for sculpting – once we cut it from our own blocks, it gives better opportunities for re- manufacturing in aerofoils for UAVs,” said Rebecca Kenyon. The company also offers several new PET (polyethylene terephthalate) structural foams in its Airex materials range. Airex T90, T92 and T10 can all withstand processing temperatures of up to 150 C for manufacturing with prepreg composites, and can also be used for USV decks and superstructures. At the time of writing, however, Airex T10 was not yet fully available and could only be supplied in bulk quantities. SHD Composites produces a wide range of materials for use in multiple markets including UAV manufacturing. Aimed at providing fire retardancy, it has a new series of bio-resin systems that are derived from the waste products of the sugarcane industry. “The bio-resin is a PFA (poly- furfuryl-alcohol) system, which makes it naturally fire-retardant, as it has a very high glass-transition onset – that can be very useful for UAVs working in explosive environments or seeking ATEX certification,” said Simon Howarth. “That means it can withstand temperatures of up to 330 C before the resin starts to lose its mechanical properties. “We are conscious that weight is critical for UAVs, so if customers want lightweight spread-tow fabrics, we can provide them with our bio-resin systems at 50-60 g per square metre, plus the fibre weight, for about 100 g per square metre.” The bio-resin composites, designated FR308 and PS200, are cured at between 12 and 130 C for one to one-and-a-half hours, in an autoclave or an oven, or they can be press-cured. Ascent Aerospace exhibited its HyVarC metal-carbon composite for aircraft manufacturing. “Invar-36 is a popular high-nickel alloy, used in 80-90% of tooling moulds, but it’s very heavy,” said Colin Birtles. “So our new HyVarC is a mixture of that alloy and carbon fibre, which makes it 50% lighter, gives it much shorter lead times February/March 2019 | Unmanned Systems Technology Some of the structural products from Trident Foams