Unmanned Systems Technology 026 I Tecdron TC800-FF I Propellers I USVs I AUVSI 2019 part 1 I Robby Moto UAVE I Singular Aircraft FlyOx I Teledyne SeaRaptor I Simulation & Testing I Ocean Business 2019 report

42 Focus | Propellers the specific aircraft’s flight profile, and works as a turnkey replaceable system, rather than needing a dedicated internal architecture to provide hydraulic or mechanical actuation of the blade pitches. They are also often designed to fold back mechanically – a quality that has proven increasingly useful for tiltrotor UAVs. Most tiltrotor UASs are now configured to use three or four rotors for take-off and landing but only one or two for cruise. By folding back the propeller blades and switching off their motors, they are kept from interfering with the airflow, and the vehicle saves significant power and operating costs. As with fixed-pitch propellers, the past few years have seen passive VPP manufacturers developing and maturing larger form factors of their technology. Wind tunnel testing is enabling the optimisation of diameters far above the 60 cm typically seen with these systems – upwards of 100 cm in some cases – with additional design work to produce lighter hubs (using less metal) to compensate for the weight increase that comes with larger blades. Ongoing research is also being conducted to develop passive VPPs with four or more blades, to suit the larger unmanned aircraft coming onto the market. Data continues to be gathered for the ever-growing tiltrotor UAV market, in the interest of optimising passive VPPs between vertical lift, stationary hover and horizontal cruise on a single aircraft. Acknowledgements The author would like to thank Tomas Mejzlik of Mejzlik Modellbau, Dr Wanbo Liu of DARcorporation, Steve Boser of Sensenich, Leslie Koegler and Tyler Russell of KDE Direct, XB Niu of Hawk Aviation Technology Company, Andrew Kondor of Aerovate, and Olivia Wan of T-Motor for their help with researching this article. June/July 2019 | Unmanned Systems Technology CANADA Aerovate +1 807 474 1641 www.aerovate.ca CHINA Anyang Hawk Aviation +86 372 5931 122 www.falconhobby.com T-Motor +86 791 8855 6889 604 www.tmotor.com CZECH REPUBLIC Fiala Prop +420 732 682 554 www.vrtule-fiala.cz Mejzlik Modellbau +420 54321 8888 www.mejzlik.eu FRANCE Helices E-Props +33 (0)4 92 34 00 00 www.e-props.fr INDIA Albatross Flying Systems +91 80 28 44 44 66 www.albatrossflyingsystems.com ITALY FP Propeller +39 0532 732470 www.fp-propeller.com GT Propellers +39 0541 693399 www.gt-propellers.com SPAIN Helices Aerobat Propellers +34 617 772273 www.aerobat.es UK Rockwood Composites +44 (0) 1626 240026 www.rockwoodcomposites.com USA APC Propellers +1 530 661 0399 www.apcprop.com DARcorporation +1 785 832 0434 www.darcorp.com Hartzell Propeller +1 937 778 4200 www.hartzellprop.com KDE Direct +1 888 976 1442 www.kdedirect.com Maxx Products International +1 847 438 2233 www.maxxprod.com McCauley Propeller Systems +1 316 831 4021 www.mccauley.textron.com NorthWest UAV +1 503 434 6845 www.nwuav.com Sensenich +1 813 752 3711 www.sensenich.com Whirlwind Propellers +1 619 562 3725 www.whirlwindpropellers.com Xoar International +1 626 679 1158 www.xoarintl.com Examples of propeller manufacturers & suppliers