DeltaHawk DHK180 | Dossier primary sealing and a lower ring serving as a backup), which sit at ringlands in the steel piston crown; their shape is typical for compression-ignition piston rings from a proprietary material. Two more rings sit at the bottom of each piston. The lowest is an oil-control ring, while the higher is called a ‘scraper ring’ in-house, which serves as an air seal and for added oil control. “But the biggest reason for those extra rings is because of two-stroke ports: your oil-control ring can’t cross your ports, not without exposing your crankcase,” Webb says. “Some four-stroke diesels get around that by using very short pistons, but we can’t do that: our pistons need to be around 4 in long. So, the compression rings do cross the ports – the piston crown has to drop below the ports to allow intake and exhaust – but the extra rings are always below the ports and provide critical extra oil control.” The way ahead DeltaHawk emphasises that the DHK180 is an introductory engine, intended as a product but also as a proving ground for its technical IP. New models with substantially higher power and lower weight will be introduced in the coming months using the same V-4 architecture, followed by models with more cylinders and higher power in the near future. “We have already tested 200 HP and 235 HP versions of the engine, with the exact same weight and form factor. All it took was some turbo changes for increased MAF, with no changes to the engine block,” Webb says. “We’ve had requests from several UAV manufacturers for higher-altitude performance, particularly from defenceoriented folks wanting 20,000-30,000 ft, and we can do all that with turbocharger changes on the same block.” Also being developed is a V6 engine that will produce over 300 HP, without being dissimilar in maximum volume to the DHK180 (some ancillaries will be moved around to compensate for a longer block). The company has further irons in the fire for future development, with one of the larger categories for these being optimisations for cleaner power outputs. While already a relatively clean design, owing to the absence of oil in its fuels, the DHK180 is being trialled with bigger alternators for hybrid applications. DeltaHawk also expresses interest in burning not only sustainable aviation fuels, but particularly hydrogen for zerocarbon horsepower, pending the right investor and customer to ensure it is developed with an end in mind. This precise sentiment was expressed to us previously by other companies privately (in UAVs and other applications), possibly indicating a large shift towards clean fuels in the next generation of UAVs and their powertrains. 75 Uncrewed Systems Technology | February/March 2024 DHK180 Two stroke Compression ignition Forced induction (turbo- and supercharged, or twin-charged) Direct injection Liquid cooled Mechanically governed Aluminium block Steel liners Displacement: 3.3 L Bore x stroke: 10.2 x 10.2 cm Dimensions: 84 x 61 x 56 cm Dry weight (including ancillaries): 162 kg Maximum power: 180 HP (134.2 kW) Maximum torque: 492 Nm at 2600 rpm Maximum speed: 2700 rpm Cruising SFC: 7.3 gal/hr (27.6 L/hr) at 135 HP Maximum SFC: 10.8 gal/hr (40.9 L/hr) at 180 HP Fuels: Jet A and Jet A-1 (certified); JP-8, D1, D2 and F-24 (not yet certified) TBO: est. 3000 hours, possibly longer (not yet officially verified) Some key suppliers Starter: Hartzell Engine Technologies Alternator: Plane-Power Oil filter: Champion Aerospace Coolant: Maxima Oil: Philips Specifications As of February 2024, DeltaHawk has also announced a DHK200 and DHK235, with the same dimensions and weight as the DHK180
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