The tailless experimental glider known as “Biezlonzherokka JAI” or “Stringerless Glider” (Russian: ХАИ Безлонжеронка) was designed and built under the direction of Professor Serguei Ivanovich Kuzmin at the Kharkov Aviation Institute (JAI) in 1934. Its development was with the collaboration of engineers AA Lazariev and Ye. S. Balinski.

The Stringerless Glider was designed in a tailless flying wing composition with fluted wings with empennage at the ends. The entire construction was made of wood.

The wing stood out for the marked aspect of 13. The center plane was characterized by a structure of four spars on which the cabin was located.

The removable consoles featured a remarkable dihedral and specific wing profile. As a distinctive detail of the project, it is worth highlighting the total absence of a stringer in the construction of these consoles, which was reflected in the name of the glider. These sections were built using a honeycomb structure with an outer covering around stringers. The lightened wing veins served as the basis for the thin covering layer. The wing consoles were fixed by means of duralumin pieces to the steel supports fixed to the spars of the center plane. This construction method would be the basis for the further development of modern three-layer structures.

The extreme empennages consisted of a fixed keel and rudders. The control of the apparatus was achieved by means of double-section mobile elements covering a large part of the span (60%). The outer section of the ailerons was capable of turning upward at a greater angle than the inner, thereby achieving increased control at large angles of attack.

The glider control system in the center plane was rigid and in the wing by ropes. When installing the consoles to the center plane, the control of the surfaces of these sections was automatically connected.

The glider featured an open cockpit for the pilot, located above the small centerplane, which ended with a tall fairing headrest.

The JHA project without stringers was completed in March 1933. Its construction was started at the Kharkov Aviation Factory with the direct participation of KA Kalinin. Later the works were transferred to the JAI workshops with the participation of KA Kalinin, IG Nieman and S. Ya. Zholkovski. In June the glider was successfully tested in the institute’s laboratories.

The JHA without spars first flew the 14 September of 1934. The tests, developed by the pilot VD Kozulya, showed excellent stability. The sparless JHA was able to hold the course with the stick free and could execute various manoeuvres.

Wingspan: 13 m
Length: 3.2 m
Height: 1.5 m
Empty weight: 160 kg

In January 1932, the JHA chair of aircraft construction began on its own initiative the development of tailless flying wing aircraft. The head of the chair IG Nieman considered this scheme from the point of view of aerodynamics and a good basis for in-depth studies.

Pavel Georgievich Bening, one of the engineers from the KA Kalinin construction bureau, was invited as the main builder of the group. The group was reinforced with the addition of AA Krol, AA Lazariev, SI Kuzmin, among others.

In January 1933 work began on the design and the calculations showed the aerodynamic resistance should decrease by 5%. When designing the model, the manufacturers decided to abandon the use of a long fuselage, forcing the implementation of a swept wing with a permanent center of pressure profile. The wingtips were provided with vertical surfaces with the rudders.

In order to verify the conception of the system and its calculations, it was decided to proceed with the construction of a glider with a similar scheme to that of the future airplane and of proportional dimensions. This glider had to allow, economically, to be able to test the concept and introduce the necessary modifications in the development and testing process.

The new glider was named “Osoaviajimoviets JAI” (Russian: ХАИ Осоавиахимовец ХАИ).

The “Osoaviajimiviets JAI” was designed as a single-seater glider in a tailless flying wing configuration. The construction was of wood with plywood coating.

The wing exhibited sagging and ended in vertical surfaces that included the aerodynamically compensated rudders.

The wing trailing edge featured full-span control surfaces that could perform the function of operating as ailerons or flaps.

On the longitudinal axis was the open cockpit for the pilot, with an aerodynamic fairing that made a smooth transition to the center plane.

A central wooden ski was used as the landing gear, supported by small skids under the vertical planes of the wing tip.

The project and plans for the tailless monoplane glider were ready in July 1933. Constructively it differed from the projected plane in its lower dimensions, the absence of an engine and landing gear. During the landing, an ash ski placed in the lower part of the apparatus was used. The cabin lantern was removable and made of celluloid.

The construction was sponsored by the Osoaviajim of the Ukrainian Soviet Socialist Republic, hence the name finger to the glider. The glider was designed by Bening and its construction began at the Kharkov Photomusical Factory in late 1933. Among the group of carpenters and cabinetmakers, M. Lass, AP Glinski and Grebenyuk stood out among others. When construction was at 90% completion, the decision was made to move it to the GVF Aviation Repair Shops in Kharkov (JARM), located in Sokolniki.

Once the “Osoaviajimoviets JAI” was finished, it was transferred to the JARM track.

On the 6 of February 1934 the first flight took place with BN Kudrin controls. After being launched with the use of an elastic band, the flight passed without great difficulties.

The first tests showed the excellent stability of the device in the air, but they must have been suspended as the weather conditions worsened. Only in May could they be continued by the pilot LS Ryzhkov. Originally, six roll-off flights were developed with takeoffs with elastic bands, in which heights of 10 meters and distances between 200 and 300 meters were achieved, making some small turns.

When the stability of the plane became evident, it was approved to carry out towed flights, originally from a car and later using a Polikarpov U-2. Sharp turns, dips, and reversals were tested on these flights. Subsequent flights were developed with towing from a Polikarpov R-5 at altitudes between 1,100 and 1,500 meters.

In mid-May, Ryzhkov managed to complete 26 closed loops in the “Osoaviajimoviets JAI” of which one started in the opposite direction, after the pilot inverted and made a 180º turn.

These manoeuvres were observed by members of a delegation from the Academy of Sciences of France led by J. Perren academic. Professor Gross, a member of the delegation, declared that the new tailless glider was a brilliant achievement of Soviet technique.

The glider also performed eights and combat evolutions, spinning and landslides. The diameter of the turns of the dead loop did not exceed 8 – 10 meters, the radius of the turns about 8 meters, the spirals 5 – 6 meters, which was quite difficult even for sports aircraft.

The tests demonstrated the excellent stability of the glider, its good response to the controls and the simplicity of the handling. It was also shown that the glider wing had a large reserve of strength, so the future JAI-4 was lightened.

In August 1934 the “Osoaviajimoviets JAI” was shown at the 2nd International Exhibition in Copenhagen and in September in Paris.

The model would be continued in the two-seater “PP Postyshev” or JAI-2.

Wingspan: 10.9 m
Wing area: 22 m²
Length: 3.75 m
Height: 1.1 m
Accommodation: 1