On Tuesday, 3 February 2026 at 11:00 in the Main Building of the Polish Aviation Museum in Kraków, the world’s only example of the Acro Viper aerobatic aircraft will be ceremonially introduced to the exhibition. Following a comprehensive restoration, this extraordinary prototype — an ambitious project by Polish designers — will join the Museum’s permanent exhibition, becoming yet another testament to Polish courage, engineering and passion for aviation. FREE ADMISSION!
The story of the Acro Viper is one of great vision and determination. The initiator of the aircraft’s construction was Paweł Kwieciński, a United States-based physician by profession, pilot and aviation enthusiast. In 1991, he met in Zurich with Jerzy Śmielkiewicz, then director of the Experimental Glider Production Enterprise PZL Bielsko (PDPSz PZL-Bielsko). Together they decided to create a modern aerobatic aircraft that could compete with the Western Extra 300 while being an entirely composite construction.
Outstanding specialists from the Bielsko-Biała aviation community were brought into the project. Jerzy Śmielkiewicz was responsible for the concept and main design, Adam Kurbiel for the airframe structure, and Wiesław Gębala for technology. Paweł Kwieciński took on the entire funding of the venture, importing composite materials from Germany and equipping the machine with a six-cylinder Lycoming engine, modern avionics and a Hartzell propeller.
The ambitions of Acro Viper’s creators are best reflected by the performance parameters which, already at the design stage, were intended to place the aircraft at the very top of aerobatic machines of its era. The design, powered by a Lycoming AEIO-540 engine producing 300 HP, was characterised by a maximum speed of around 380 km/h, with a permissible speed reaching as high as 425 km/h. Equally impressive was the rate of climb — 15 m/s, indicating a very good power-to-weight ratio and potential for performing advanced aerobatics.
For comparison, the Extra 300, regarded as the world standard in this class, achieves a maximum speed of approximately 407–410 km/h and a rate of climb of 16 m/s. Comparing these data clearly shows that the Acro Viper — despite remaining a prototype project requiring certain changes and refinement — came close in its parameters to the best Western designs.
It is precisely these numbers that make the Acro Viper worthy of being seen not as a curiosity or an unfinished experiment, but as a bold attempt to create a new-generation Polish aerobatic aircraft, capable of genuinely competing with the icons of world sport aviation.
*The photographs shown depict the Acro Viper aircraft after restoration but before assembly — without wings and without the rudder, horizontal stabiliser and elevator
Construction work begun in the early 1990s took a long time and proceeded during the difficult period of economic transformation. Although the prototype was completed, the aircraft never entered serial production. The Acro Viper’s maiden flight was made by Wiesław Cena; flight tests revealed structural problems that required far-reaching modifications — including a change of layout from low-wing to mid-wing and enlargement of the rudder. New wings made of carbon fibre were even produced, but the prototype was not flight-tested with them.
The Acro Viper was an exceptionally modern project for the realities of the early 1990s — an entirely composite construction was an ambitious and rarely used solution in this class of machines at the time. The wings were made of glass-fibre and carbon-fibre composite, while the fuselage of Kevlar and carbon-fibre composite, which was intended to ensure high structural strength while reducing weight. It is worth emphasising that the use of Kevlar in sport and aerobatic aviation was at that time an expression of thinking about the aircraft in terms of a construction of the future.
This thread also carries an important Polish connection: Kevlar was invented in 1965 by a team led by Stephanie Louise Kwolek — an American chemist of Polish descent, one of the most outstanding figures in the world of materials science. Symbolically, this intertwines the story of the Acro Viper with the broader narrative of the Polish contribution to the development of modern technologies.
It is hard to resist reflecting that had it not been for the tragic death of designer Adam Kurbiel in an accident in 2000, the fate of the Acro Viper could have been entirely different. The prototype, which during its first flight revealed a number of structural defects, simultaneously had enormous development potential. There is a high probability that with further design work the aircraft would have been refined, and after finding an investor it could have had a real chance of entering serial production as a modern Polish aerobatic aircraft. However, that was not to be. Today, the only existing example can be viewed from 3 February at the permanent exhibition of the Polish Aviation Museum in Kraków.
Before the Acro Viper could be presented to the public as a museum exhibit, it underwent a thorough restoration carried out by the Museum Artefact Conservation Department of the Polish Aviation Museum. The scope of work included, among other things, reconstruction of the rudder, sealing of technological openings in the fuselage, sanding and painting of the structure, as well as engine installation and a new propeller spinner. Thanks to these efforts, the aircraft regained a cohesive appearance and an exhibition form worthy of its history. The ceremonial introduction of the Acro Viper to the exhibition on 3 February 2026 will be not only a presentation of an extraordinary exhibit, but also a symbolic reminder of the bold, often underappreciated projects of Polish designers.
