Unmanned Systems Technology 015 | Martin UAV V-Bat | William Sachiti | Sonar Systems | USVs | Desert Aircraft DA150 EFI | SeaCat AUV/ROV | Gimbals

51 two-stroke for UAV use. HFE president Tom West is widely regarded as the North American guru of fuel injection for UAV two-strokes, and he has worked closely with Australian specialist Currawong for a number of years. Fundamentally, the regular EFI version of the DA150 is a more affordable version developed by HFE with model aircraft enthusiasts in mind. However, Desert Aircraft president Dave Johnson notes that there are UAV developers today who are cost-conscious enough to prioritise its price over the superior quality and control offered by the Mil- Spec version. The comparison is $5,861 versus $17,811 (in both instances for the unit complete with EFI, less exhaust and starter/alternator, items that are application-dependent). Johnson notes that while some rival companies only assemble outsourced parts, Desert Aircraft designs and manufactures components, and builds and services its engines at its Tucson, Arizona, factory. This features a state-of- the art CNC machine shop, quality control and r&d departments. The r&d operation features advanced diagnostic equipment and dynamometers, as well as using engine simulation and design software. Clearly, with UAV applications in the future becoming ever more diverse, there is a place for both the Mil-Spec and the regular EFI versions of the DA150. Either way, the user gets the well-proven dependability of the base unit – a coveted characteristic in aviation, be it manned or unmanned. Background Johnson says, “I am a lifelong motorcycle and model airplane fan. When in the early 1990s model airplanes started getting bigger, they started using engines that I was familiar with from the motorcycle world. “Whereas I had knowledge of motorcycle two-strokes, the 40-60 cc engines used then in giant-scale models were converted from the likes of chainsaws. We were figuring out how to put electronic ignition and reed valves onto them, to get better performance. “Around that time I became connected with a German company that was producing engines specifically for model airplanes. I helped them for several years as Desert Aircraft, distributing their engines in North America and servicing them. We then saw different ways of doing things. At that stage we parted company and I created my own range of engines. “For aerobatics, giant-scale aircraft need engines of more than 100 cc, so we started with a 150 cc twin. That is the DA150, which we began designing in 1997 and which first flew the following year. In 2000, that engine powered the winner of the Tournament of Champions giant-scale aerobatic event in Las Vegas. The event had a $400,000 prize fund and attracted the best pilots in the world. “From there the DA150 went into full production and became extremely popular. We were soon selling them as fast as we could build them. We then started expanding our line, with different displacements and single, twin and multiple cylinders – we have a flat four in our range. The 150 to this day is still very popular. There have been very few modifications to it and we have now sold more than 8000 of them.” We asked, when was the DA150 first used in a UAV project? “From around 2002 it has been used in various projects,” Johnson says. “Some we knew about at the time, others we didn’t – people would buy the engine without telling us what Desert Aircraft DA150 EFI | Dossier Unmanned Systems Technology | August/September 2017 The DA150 crank and con rods We started with a 150 cc twin. That is the DA150, which we began designing in 1997, and in 2000 it powered the winner of an aerobatic event