78 Dossier | Suter Industries efficiency and optimising the carburation. Because, while getting the fuel/air mixture perfect in gasoline engines is important for combustion modulation, in a spark-ignited kerosene engine, it’s less critical. Certainly, for efficiency, it’s incredibly useful, but not so much for combustion control.” Suter adds, however, that knock sensors are straightforward to integrate, so for mission-critical applications it can retrofit one into the SDI-288’s ECU. If vibrations indicative of knock detonations are detected, the ECU can throttle-back power and speed to make sure the UAV isn’t damaging the engine. Kehe adds: “It’s worth mentioning that we not only also measure but also control for CHT. By adjusting the engine’s running to target the narrow temperature range that heavy fuels need, we can optimise both efficiency and combustion stability. “That’s not an easy task for the ECU or the programming of it, and would be made easier if the 288-SDI had water cooling, but air cooling is, for sure, the best approach for the fixed-wing customers we mainly serve, just by not needing radiators and hoses, and so on.” Future As mentioned, Suter’s next aviation engine product will almost certainly be a HF TOA 330-SDI, with specifications to be released once the company has reached a modicum of satisfaction in how its mechanical and SDI systems have been optimised into the core platform. “There’s other projects in the pipeline, but we don’t want to spread ourselves too thin. We’ll react primarily to the market in terms of what we’ll invest time and engineering in,” Kehe says. “For instance, there’s no water-cooled heavy-fuel works in our r&d portfolio, so no HF TOW just yet, but it’s certainly possible, and we’d start simulating one once a serious customer asks. But I think we’re focused more on next-generation sizes of the engine – both bigger and smaller versions, for bigger and smaller UAVs.” Going forwards, Suter plans to continue funding an aggressive r&d schedule through series production of its engines, with around 200 units targeted for 2025, and companywide expectations that the figure will ramp up in subsequent years. This is based on the high prevalence of customers querying how many engines can be produced per month. The company is satisfied that its current manufacturing capacity will be capable of handling demand growth, with the main bottleneck not revolving around constructing the engines, but the breakin and final testing procedures that every unit goes through. The planned second facility will integrate extra break-in dynos over time, which Suter anticipates will enable unit output capacity to be raised to 40 engines per month (or beyond, should demand merit such expansion). “Customers are satisfied with how the TOA 330 and HF TOA 288-SDI are running, but we’re not fully satisfied, so it’s important to us that we don’t stop development,” Giussani muses. “Maybe it’s the racing DNA talking, but we know we can get more out of both engines. Maybe more durability, more performance, more efficiency, less weight. We don’t just want to make engines that run safely and have a good TBO. We want to be the best.” February/March 2025 | Uncrewed Systems Technology CNC machining systems: Quaser Waterjet cutters: Hermle AG Metalworking tooling: BIG KAISER 3D coordinate measuring machines: Wenzel Testing equipment: Kristl, Seibt & Co Gesellschaft Servos: Volz Air filters: DNA Big-end bearings: Koyo, FAG Main bearings: SKF, FAG, NSK Seals: Freudenberg Valves: Moto Tassinari Alternator: Plettenberg Oil: API TC Key suppliers Suter plans to fund aggressive r&d through series production of its engines, with around 200 units to be manufactured in 2025, and that figure is expected to grow in subsequent years
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