The Akar glider was the first construction of the Aviation Section of the Mechanical Engineers’ Circle of the Warsaw University of Technology, re-established after regaining independence in 1921. Its creator was student Adam Karpiński. The designation SL-1 served as a factory number. Construction of this wooden, fabric-covered glider began in autumn 1922 at the Central Aviation Workshops (CWL) at the Mokotów airfield in Warsaw, intended for participation in the 1st Glider Competition held from 23 August to 13 September 1923 on Litwinka Hill in Czarna Góra near Nowy Targ.
The first hill launch was made on 24 August 1923 by Tadeusz Karpiński, the designer’s brother. The flight lasted 1 minute and 8 seconds. Tadeusz Karpiński and Ryszard Bartel competed on the Akar. The longest flight, made by T. Karpiński, lasted 3 minutes and 6 seconds. Karpiński also achieved an altitude gain of 20 m above the launch point and a flight distance of 3 km. The Akar took 1st place in the competition.
On 8 April 1924, during a gliding expedition of the Aviation Section students to Babia Góra, Tadeusz Karpiński made a flight on the Akar lasting 4 minutes and 5 seconds (a new national record), covering a distance of 2 km and gaining an altitude of 50 m above the launch point. During landing, the glider was severely damaged and was never repaired. It was destroyed in 1925.
The SL-1 Akar was the first successful Polish glider, on which the first Polish gliding records were set and the first gliding competition was won. The presented replica was built by students of the Aviation Scientific Circle of the Warsaw University of Technology in 2014. Larger structural components were manufactured at the “Jeżów” Glider Works. The reconstruction was a very difficult and time-consuming process due to the extremely scarce documentation, limited to just a few photographs.
| Wingspan | 9.3 m |
| Length | 5.5 m |
| Wing area | 12.3 m2 |
| Empty weight | 75 kg |
| Takeoff weight | 145 kg |
| Glide ratio | 9 |
| Sink rate | min. 1.3 m/s |
| Speed | 45 km/h |
