Issue 40 Unmanned Systems Technology October/November 2021 ANYbotics ANYmal D l AI systems focus l Aquatic Drones Phoenix 5 l Space vehicles insight l Sky Eye Rapier X-25 l FlyingBasket FB3 l GCS focus l AUVSI Xponential 2021

61 autopilots for them, and at Aermacchi I was responsible at first for engineering r&d and later the departments of experimental manufacturing and flight testing. “After the Berlin Wall fell, we partnered with Yakolev in Russia to develop the Yak/AEM-130, but after that partnership was dissolved in 1999 we continued developing that design into the Aermacchi M-346 Master jet trainer and combat aircraft. The Rapier UAV’s control architecture is very much inspired by the same fly-by-wire architecture, flight control computer, safety-critical software, aerodynamics and other technologies in the M-346.” The Rapier is positioned as a competitor to small UAVs in its weight class, such as the Insitu ScanEagle, as well as others far above its weight class, such as Textron’s RQ-7 Shadow. That is no accident. Much of the drive behind creating the Rapier were requests for a 25 kg MTOW aircraft that could offer similar endurance and survey performance as aircraft weighing 200-250 kg. As a result, it has been designed for a range of survey missions. Defence- focused uses include mapping and studying Italy’s geographical characteristics, as well as operations across ISR (intelligence, surveillance and reconnaissance), law enforcement and clearing test ranges. Notable civil and government operations include search & rescue, disaster monitoring and environment impact surveys. System overview The interior of the fuselage is divided into five sections that correspond approximately to the subsystems mounted in them. From front to back, these are the nose sector, payload sector, ejector sector, fuel sector and engine sector. While a few of those are self- explanatory, the nose sector contains the Rapier’s antennas, and the ejector sector contains the landing subsystems. “Placing flight-critical systems in the nose risks losing them to bird strikes; if we lose the antennas, we can still perform a controlled landing with the INSs,” says Francesco Schettini, technical director and engineer at SES. For example, he points out that putting the flight control computer in the nose could be catastrophic if a bird hits the front, as it could lead to the total loss of the UAV. The MTOW has been a key development target since the X-25’s inception, not only for the regulatory importance of that number but also to minimise the logistical footprint and operating costs, for example in terms of fuel and spare parts. Development of the X-25 has also followed regulatory guidelines to keep it free of International Traffic in Arms Regulations (ITAR), meaning far shorter procurement times and fewer export limitations for the aircraft and its spare parts than ITAR-restricted UAVs. With much of the hardware and all of the autopilot software being owned by SES, the company also aims to offer fast and streamlined maintenance services for small tactical UAVs. SES says this maintainability, and being able to optimally manage the obsolescence of subsystems, are important when one considers that what they supply is expected to be used over long periods of time and in critical defence and civilian agency operational theatres. Structure and aerodynamics The Rapier has been designed in accordance with the requirements for light UAS airworthiness laid out in NATO’s STANAG 4703 as well as in DO178-C, to ensure reliability and robustness of the structure, software and hardware. Its configuration consists of a high aspect-ratio wing with a span of 3.6 m, and a twin-boom tailplane with an inverted-vee shape, the nose-to-tail length of the craft being 2.4 m. The hull is made from multi-layer carbon Sky Eye Systems Rapier X-25 | Digest The Rapier has been designed for missions including mapping, ISR, law enforcement, search & rescue, and environment impact surveys Unmanned Systems Technology | October/November 2021 The X-25 is constructed from numerous carbon composites, features four control surfaces, and is powered by a 29 cc single-cylinder engine from Currawong