Uncrewed Systems Technology 044 l Xer Technolgies X12 and X8 l Lidar sensors l Stan UGV l USVs insight l AUVSI Xponential 2022 l Cobra Aero A99H l Accession Class USV l Connectors I Oceanology International 2022

78 I n UST 12 (February/March 2017) we featured the A33i UAV engine, a spark-ignited single cylinder two-stroke developed through a collaboration between Power4Flight, Currawong Engineering and Cobra MOTO, the latter of which aptly spun off the Cobra Aero division to develop the engine and the business around it. In the years since we published that article, A33i has received positive feedback from its customers and significant technical updates from its developers. Nonetheless, Cobra Aero has moved on to bigger and more powerful things. As Power4Flight’s Bill Vaglienti recounts, “I was at AUVSI Xponential 2017 with Sean [Hilbert, president of Cobra Aero], which I think was a couple of months after Ian Bamsey’s A33i article came out, and we were walking around, looking at all the engines when I asked him, ‘What would be the best engine configuration?’ He said, ‘An inline, triple, liquid-cooled engine’, then gave me a persuasive list of reasons why. Eighteen months later, I said, ‘Let’s build one.’” Sure enough, Hilbert, Vaglienti, Ross Hoag (CEO of Power4Flight) and their teams spent the subsequent three- and-a-half years working on an inline three-cylinder, liquid-cooled engine for the high-end UAV market. That engine is the A99H, a spark-ignited two-stroke running primarily on heavy fuel but also capable of running on gasoline, and developed using the latest innovations in metal manufacturing additive (AM), ECU systems and more. It displaces 99 cc, outputs up to 7 kW (8.1 bhp), and weighs 3.65 kg in its nominal configuration. While the companies have hinted at the A99’s development over the past few years, the engine’s full unveiling has now arrived. In addition to being shown to the public for the first time at AUVSI Xponential in April 2022, we sat down with Cobra Aero and Power4Flight to Rory Jackson talks to the developers of this inline three-cylinder engine about its advantages over other designs June/July 2022 | Uncrewed Systems Technology Three-pot power The A99H two-stroke, spark-ignited engine runs on heavy fuel and produces 7 kW (Images courtesy of Cobra Aero)