Touchstone for the Future

p>Thinking ahead, the accumulation of knowledge for a new breakthrough in the creation of the next generation of aircraft is an important aspect of the efforts among TsAGI scientists. One of the prime examples of such efforts is the testing of a reference model of a typical transport-class aircraft wing, the first phase of which was recently completed at the Institute. We met Petr Karkle, an expert in the field of aeroelasticity from TsAGI, to discuss how the experiments of today can help to get prospective ideas off the ground.

— Mr. Karkle, please tell us more about the reference model: why is it called so and what is so special about it?

— The model is called reference because it has been designed and manufactured in full compliance with the specifications of a typical full-scale aircraft wing. By doing so, we intend to narrow down the diversity of results and measurements. This is critical for verification and validation, or, put another way, testing of the computational methods.

The model is dynamically scaled, i.e., it allows for research of such aeroelasticity phenomena as flutter and buffeting. In addition, it is flexible and is capable of successfully reproducing any deformation, which may happen to an actual wing — bending, torsion, and other structural oscillations — in a wind tunnel during an experiment. Altogether, this allows us to obtain test results that are as close to full-scale flight conditions as possible.

— You have mentioned a typical full-scale wing. Which aircraft can it be installed on?

— This type of wing is an example of good design and is already in use in several non-domestic aircraft. We also plan to use it as a component of future Russian airliners.

— How has the first testing phase of the wing model gone? What was the key focus of the Institute’s efforts?

— TsAGI’s ADT T-128, a transonic wind tunnel, has been used as an experimental basis for the research. We have studied the wing model in terms of static aeroelasticity, measured its deformations under different angles of attack and determined its pressure distribution patterns. We have also determined characteristics of the special-shaped aileron, which is one of the key aircraft controls. All of the above enables us to enhance contemporary methods and algorithms for computation of oscillating aerodynamic forces applied to a wing during flight, and evaluate innovative design concepts.

Generally speaking, though, the first and foremost result of the initial phase is the verification of a math model, that is, confirmation of the conformance between the calculations and the conditions of a real-life aerodynamic experiment.

— What goals do you and your colleagues pursue in these efforts? What practical use will the results you obtain have?

— Our primary tasks are the testing of measuring equipment, optimization of the experimental technique, and thorough research of such phenomena as flutter, reversal, divergence, and buffeting. Achieving them will allow us to optimize the wing shape in respect to its elasticity and prepare guidelines for enhancing characteristics of existing aircraft, which, in turn, will become an excellent stepping stone for the future of science and technology. So, when TsAGI finally faces the task of researching a new aircraft technology, we will already have the charicteristics of the appropriate wing model for experiments, relevant testing techniques, and the results we wish to acquire.

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