With our electric drive as a replacement for a classic internal combustion engine, we have been encountering it more and more often in our lives lately. Slowly but surely, it is beginning to have a firm foothold in almost all sectors of land transport. In contrast, similar projects appear in the aviation industry, even sporadically on a global scale. The idea of Czech designers Martin Štěpánek, Pavel Urban and aircraft modeler Jaroslav Mach is even more unique in this respect.
Paradoxically, several coincidences helped the creation of the originally competitive Phoenix U-15 Electra electro flight. In 2008, Martin Štěpánek discovered a competition for an environmentally friendly aircraft on the website of the voluntary organization CAFE Annnounce. Coincidentally, at the same time he met the already mentioned modeller Jaroslav Mach, who led him to the idea of developing the first Czech electric glider. After a discussion with designer Pavel Urban, it became clear at the time that it was on the verge of technical possibilities, but feasible. After obtaining this information, Martin Štěpánek together with his colleague Ing. Josef Rydl decided to leave Urban Air, start his own company Phoenix Air and devote himself to the development of the U-15 Phoenix aircraft. Since the idea of a development center soon took over the aforementioned Urban Air company and today they have to take care of the production themselves, they turned to the experienced designer Pavel Urban with the development of the aircraft.
During the design and subsequent development of the new aircraft, Urban relied primarily on the proven UFM-13 Lambada machine. Already in December 2008, the first strength tests of the fuselage took place, and the following year in July, the first test flight. They managed to enter the CAFE/NASA Green Flight Challenge on December 31, 2010, literally at the last minute. At that time, they were deprived of the first place only by a month’s delay of the supplier of competitive batteries. Despite the fact that they were forced to install a standard Rotax engine in the machine for these reasons, they managed to get a beautiful 3rd place. Another award that this aircraft received was the 1st place in May in the Outstanding LSA (Most Beautiful Light Sport Aircraft Design) competition in Florida, USA. Following these successes, Phoenix Air began to focus more on launching series production of the Phoenix U-15 Phoenix, which is powered by a conventional internal combustion engine (HKS 700E, Rotax 912 or Jabiru 2200) and its subsequent export to foreign markets. This aircraft is currently very popular, especially in the United States and France, where Volez magazine wrote about it in 2009.
However, let’s go back to the prototype of the electric version of the U-15 Electra. In July 2014, during a test flight, the battery life, engine tuning and other technical features of this machine were monitored on it. Then, due to the technological limitations of the time, the machine was stored on ice for a certain period of time. However, only for a while, already in 2017, a consortium of Czech companies and Pure Flight specialists returned to this project and the whole idea was modernized. The new aircraft differs from the original fiberglass prototype mainly by the all-composite construction with carbon fibers and also by the partially changed shape of the front and rear of the fuselage, wings and interior. Batteries with a total capacity of 35 kWh are installed in the fuselage, which together with other optimizations currently allow up to 2.5 hours of flight. The result is a two-seater low-flying aircraft newly named as Φnix (read fíniks), which is completely manufactured in the Czech Republic, except for batteries imported from Japan. The second generation, on which the designers from Pure Flight are already working, should provide 5-6 hours of flight time in the future.
So far, the biggest obstacle still remains the weight limit of 600 kilograms of take-off weight, which the machine must meet according to the rules of the European Aviation Safety Agency. The good news is that the Pure Flight group has already secured the necessary permission for Φnix to be able to fly normally, and development continues with valuable aerial data. In order for the future customer not to have to solve the problem of charging the batteries, Pure Flight is also developing a mobile charging station (so-called wall box) with an output of 13 to 16 kW in parallel with the electro flight. She should be able to charge the plane from scratch in just three hours. Pure Flight is currently also trying to lay the foundations for the electrification of Czech airports by negotiating with smaller international and sports facilities for the possibility of installing their own wall boxes. The result of the entire comprehensive project of the Pure Flight consortium should be a network of airports with chargers, which will also use the selected protocol to communicate with the aircraft and the pilot will have an overview of where and how he can land when he needs to recharge his machine’s batteries.