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Variable Geometry Rotor


Updating of the Variable Geometry Rotor (VGR) Blade Diameter Change Mechanism Combined with the System of the Centrifugal Force Compensation and Extension of the Range of the Blade Twist Change

Tech Area / Field

  • SAT-AER/Aeronautics/Space, Aircraft and Surface Transportation

8 Project completed

Registration date

Completion date

Senior Project Manager
Ryzhova T B

Leading Institute
Georgian Technical University, Georgia, Tbilisi


  • The Boeing Company, USA, PA, Philadelphia\nPolitecnico di Milano / Dipartimento di Ingegneria Aerospaziale, Italy, Milan\nAgustaWestland, Italy, Samarate

Project summary

Propeller driven airplanes with vertical takeoff and landing (VTOL) are more economic and ecological than jet VTOL. That’s why the creation of a rotor optimal in the whole process of flight is actual.

The fixed pitch rotors (FPR) are not optimal at the all stages of flight. The solution to this problem is possible only by the application of the variable geometry rotor (VGR) due to the possibility of simultaneous change of the diameter of the rotor and also of the setting angle and twist of blades in dynamics.

The VGR especially gives the possibility of optimization of the VTOL flight, provision of maximum diameter and minimum twist in hover mode and the contrary minimum diameter and maximum twist during the cruise flight.

Category of technology development: Demonstration Of Technology. Technology area: SAT-AER.

The Project objective is the updating of the mechanism of the VGR blade diameter change combination with the system of compensation of centrifugal forces and extension of the twist range. With this aim have been developed several versions of mechanisms from which together with the Collaborators will be selected the optimal one for fabrication and tests. The accuracy of scientific conclusions on means of the acting model will be demonstrated. The prerequisites of certification of the VGR and Brand Management with the strategic aim will be considered. For the estimation of possibilities and limitation for promotion of the VGR to the market will be carried out by preliminary SWOT analysis.

Despite the multitude of works of famous companies and scientists of various countries the VGR problem has not been solved yet. There are patents, which did not find the real realization mainly because of a complication and insufficient reliability of technical solutions.

The Project team is competent in the mentioned field. They worked in the ISTC Projects G-060-2 “Variable Geometry Rotor (VGR) and Its Control Means (Actuators)” and G-916 “Controlled Rotor with Compensation of Action of Centrifugal Forces”.

During the execution of G-060-2 Project the original variable geometry rotor (VGR) was created with combination of the diameter and twist change during flight. The approach priority has been protected by the patents of the Russian Federation and Georgia.

The control mechanism units for the rotor diameter and blades twist change have been developed. The versatile program of the VGR model tests on the especially designed stand has been carried out. The tensometric and dynamometric measurements of the rotor thrust at various loads have been conducted.

The priority direction of the applied investigations of G-916 Project was the experimental proof of possibility of at least partial discharge of the mechanism of the rotor diameter change from action of centrifugal forces. In the compensation system of centrifugal forces was used accumulation of energy of the centrifugal forces action in hydro-pneuomo-accumulator during the extension of blades with its subsequent use for partial discharge of the mechanism of the rotor diameter change during the retraction of blades. Several designing versions of the system have been developed from which taking into account the opinions of the Collaborators the optimal one was selected and manufactured. The synchronism of the VGR functioning has been proved.

The work results on both Projects were reported and approved at the authoritative international scientific-technical conferences, patented and published in scientific articles. In Georgia and Romania has been published the monograph in Russian and English.

This Project as the previous ones will conduce to the implementation of the ISTC objectives and tasks helping the scientists and specialists connected with weapon more orient their capabilities to the peaceful activities and also to their subsequent integration into the international scientific community. The Project will be conducive to the solution of national and international scientific and technical problems, particularly in organization of many work places in the Republic and in creation of conditions on development of aviation without aerodromes.

The scope of activities is characterized by definite 8 tasks.

As in the previous Project in this Project the big and significant role will be played by the Foreign Collaborator, Mr. Leo Dadone, Senior Technical Fellow of the Boeing Rotorcraft Company, Philadelphia, Pen., USA who has a big experience in experimental and designing aspects of helicopter technology, head of various experimental and designing works in helicopter construction. As in the previous Projects Mr. L.Dadone will take active part in the specification of plans, in concrete designing developments and in information search. On the side of the European Union the Foreign Collaborators are an outstanding scientist Jean-Jacque Philippe, Honorary Advisor of ONERA scientific center engaged in investigations and developments of helicopters and VTOL. A great assistance will be rendered very competent Collaborators: Dr. Giuseppe Pagnano, Head of Research & Technology Innovation Co-Ordination, Intellectual Property Manager of Agusta Westland (Italy) and Dr. Klausdieter Pahlke, Head Rotorcraft Program, Program Directorate Aeronautics of DLR/ONERA (Germany).

The technical approaches and methodology are conditioned by the fact that this Project relates to the category of demonstration of technologies. The scientific investigations and designing developments will be directed to the updating of the reliable mechanism of the VGR diameter change combining with the system of compensation of centrifugal forces and the extension of the blade twist range change. This will give the possibility of development of such an approach of demonstration of new designs and technologies, which will conduce to the wide commercialization of the VGR.


The International Science and Technology Center (ISTC) is an intergovernmental organization connecting scientists from Kazakhstan, Armenia, Tajikistan, Kyrgyzstan, and Georgia with their peers and research organizations in the EU, Japan, Republic of Korea, Norway and the United States.


ISTC facilitates international science projects and assists the global scientific and business community to source and engage with CIS and Georgian institutes that develop or possess an excellence of scientific know-how.

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