USE Network launch I UAV Works VALAQ l Cable harnesses l USVs insight l Xponential 2020 update l MARIN AUV l Suter Industries TOA 288 l Vitirover l AI systems l Vtrus ABI

70 Dossier | Suter Industries TOA 288 Engine management system An exhaust gas temperature (EGT) sensor is installed near the underside of each cylinder. For additional key engine management data, the system also includes a cylinder head temperature (CHT) sensor next to both spark plugs. These two sensors track key temperature data relating to the engine’s performance, and enable the ECU to react to signs of overheating in the combustion or exhaust phases. “We’ve programmed different compensation strategies for handling temperature issues – by manipulating the fuel spray, injection timing and ignition timing, for example – to keep within safe heat limits,” Kehe says. “We send all this sensor information by CAN bus or RS-485 to the flight control unit, so that the customer can have their pilot or autopilot reacting to the overheating too.” The developers have opted for an open-loop Alpha-N control strategy for the ECU, using a map of throttle positions against crank speeds for timing and controlling the ignition and injection. Throttle position readings coming from the throttle servo’s feedback signal are sent via CAN bus, to save the weight of a conventional throttle position sensor. This was done to avoid relying on a constantly closed loop for the whole June/July 2020 | Unmanned Systems Technology Suter Aviation is a division of Suter Industries, and was formed to oversee development of the company’s new aerospace engine projects. The division has also formed a strategic partnership between the parent company and CAE (Compass Aircraft Europe), to combine their expertise in high-end two-stroke engines. Suter has long experience of engineering two-strokes for the motorsport world, and provides considerable resources for the partnership, including extensive CAD and CFD capabilities, CNC-machining facilities, and dynamometers and other testing equipment. CAE and Suter Aviation are headed by Dietrich Kehe, who has about 25 years of experience in precision engineering of two-stroke aircraft propulsion systems. He has developed clean-sheet engine designs for many advanced UAV applications. Suter & CAE The engine uses a reed valve to vary air intake as needed for the different operational modes of each flight An open-loop Alpha-N control strategy is used for the engine management, with additional closed-loop functions to help with altitude adjustment and overheating compensation