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Grokhovsky Inflatable Gliders
 
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As part of the landing systems studies, the Bureau of Experimental Constructions headed by Grokhovsky proposed various configurations of inflatable gliders.
 
Systems on board aircraft and gliders were tested. Soon this working group would propose a highly original solution: the use of inflatable gliders,Grokhovsky inflatable gliders (Гроховский надувные планеры). Work in this direction was started by Grokhovsky in 1934. According to their design, these rubber gliders could be used by mountaineers and for disembarkation in places of difficult access. After landing, the plane could be collected and stored in a bag, and could easily be returned to be used again.
 
Experiments in the development of the inflatable model began with the creation of an inflatable wing. The works were carried out at the Leningrad factory “Krasni Triugolnik” (Red Triangle), one of the oldest industries in Saint Petersburg, specialized in the production of rubber products. The wing built, officially called the “Pneumatic Wing”, had the structural elements and spars also made of rubber and was tested by the glider pilot V. Petushkov, who was tied to it by means of belts.
 
Petushkov stood on the bed of a truck firmly tied to the wing. The truck picked up speed and soon the wing took off, taking its "pilot" into the air. After flying a certain distance, he was able to land gently on his legs.
 
This first flight was followed by others from the bed of the truck. Later it was decided to try tying the pilot to the car using a long rope. As the truck began to move, the pilot with wings was towed through the air. This flight could go on for several minutes, until the truck stopped. Initially the flights were not very "elegant", but little by little Petushkov was learning to master the wing. During one of the flights, when landing the "pilot" did not touch the ground correctly and the glider landed on the wing. In other circumstances, the pilot would have been injured, but the inflated wing totally cushioned the blow.
 
As a second step, a simple inflatable glider was created with minimal control elements. According to Grojovski : - "this inflatable glider in a mountainous region will be able to absorb impacts of considerable force and its low weight will allow it to rise above the air flows".
 
The glider was designed in a short time and its construction was commissioned to the Leningrad factory “Promtexnika”. The new glider was notable for its simplicity. It lacked ailerons and rudders as the control would be done by twisting.
 
In a straight line the glider flew smoothly and could be easily towed by a U-1 or U-2 biplane. This glider was tested in flight by Grokhovsky himself and several members of his collective. A film is preserved in the Krasnogorski archives where it is shown how the inflation and the towed unloading of this glider was carried out.
 
The problems arose in the turns. The lateral twists deformed the glider and the forces applied to the controls as well. The elastic fuselage absorbed all the pressures applied on the controls, making the flight uncontrollable. It was clear that the fuselage structure had to be combined in order to guarantee the necessary structural strength.
 
In 1935 the glider was shown to the country during the flypast in Tushino. Soviet newspapers promoted success and soon references to the Russian inflatable glider were found in the Western press.
 
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The Western press echoed the Soviet achievement.
 
Given the lack of financing to continue the project, the glider was transferred to the Moscow Aviation Institute (MAI) as a possible way for its development. Grokhovsky was hopeful that the young engineers would be interested in the development of this technology. Once in the MAI, the glider was deposited in a warehouse and remained there until it was decommissioned.
 
At the Grokhovsky Institute these works were continued. Under the direction of Ivan Titov, Grokhovsky's replacement, the most developed of these gliders was created, the amphibious “X Congress of the VLKSM”.
 
It was a single-seater glider with a high-wing monoplane configuration. The fuselage at its rear was made up of a rigid tube to which the tail and landing pad were attached. Wooden controls were located in the cockpit.
 
The pilot sat on an inflated “pillow”. This version incorporated not only rubber, but wood and metal to the construction.
 
Despite this, a high level of portability was achieved. The glider weighed only 77 kg and could be stored in a 1 x 1 x 0.5 meter bag.
 
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Unpacking the inflatable glider at a demonstration.
 
Preparation for the flight took about 20 minutes using a manually operated filling pump.
 
The construction was carried out in the factory "Krasni Triugolnik", being ready for 1935. The "fuselage" was prepared to allow the glider to land both on land and on the water.
 
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Inflatable amphibious glider named in honor of the X Congress of the VKLSM.
 
The first flight on this glider Grokhovsky wanted to carry out personally. The Leningradenses were able to observe how on a summer afternoon a motor boat advanced over the waters of the Neva River towing a glider that floated touching the water with its wings. As speed increased the wings began to rise and soon the glider rose slightly above the water. Bridges over the river prevented the flight from being long, but the objective had been achieved.
 
The tests were continued by Factory No.47 pilot Georgi Shmith. During the tests, carried out at the Leningrad Flying Club, the glider was towed by a Polikarpov U-2 aircraft at a height of 60 - 100 meters. After being released, it remained in flight, traveling about 1 kilometer before landing. Other successful tests were carried out.
 
With these results Grojovsky began to think about the possibility of making an inflatable plane.
 
 
 
 


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