INTRODUCTION Aerospace vehicle’s design is a continuous process of applying new ideas to previously studied and established systems. However, looking to the current aircraft design, the new design concepts look remarkably similar to the ones designed 100 years ago, notwithstanding the incorporation of new, lighter materials and modern electronics. This proposal gives insight on a theme that has been studied and demonstrated positive results that will give rise to radically new concepts of aircraft vehicles: Morphing aircraft.
Morphing is a fairly new topic in the aviation world but has been present in several aircraft design throughout the years. The basic idea of morphing has been around since the first aircraft was designed by the Wright Brothers. In order to control the rolling motion of the Wright B Flyer, Wilbur Wright conceived in 1899 a system enabling the control of the wing’s twisting motion utilizing a series of strings/cables. With this system, the pilot had the ability of changing the lift force unevenly to both wings thus creating a rolling motion due to the achieved moment. To this wing twisting system was given the name wing warping. Since the velocities at which aircraft fly have been increasing throughout time, the wing warping system was abandoned, giving rise to the nowadays conventional ailerons, which have a better performance concerning less drag and higher rolling moment.
 Figure 1 - Increased flight envelop due to morphing systems
The most beneficial advantage rising from the use of morphing systems is the optimization of various fields of aircraft systems. As depicted on the left of Figure 2, from a study performed by Next Gen Corporation, the final and ideal objective of the imposition of morphing systems, is to attain a complete optimization of several or even all of the flight phases of an aircraft. This achievement would enable a morphing aircraft to conduct several types of missions, instead of existing one specific type of aircraft designed to perform one specific type of mission, thus increasing the flight envelope of the aircraft (Figure 1 demonstrates how a camber morphing system may increase the flight envelope). This type of ability has been seen throughout the years in the avian species, for birds have the ability to mold and change in a complex way the shape of their bodies to adapt themselves to the current flight phase. The right of Figure 2 shows an example of some of the different configurations a bald eagle can achieve.
 Figure 2 – Left - Comparative scheme between fixed wing and morphing wing aircraft; Right - Bald eagle in various flight configurations
As described, morphing technologies could provide an advantage to the to air transport systems, by greatly decreasing fuel consumption during their missions. Therefore, project CHANGE presents the clear objective of increasing the performance of aircraft flight utilizing morphing technologies in the wings. CHANGE wants to achieve this goal by including in the same wing various morphing systems that will complement each other and increase the performance in two different aspects. The first is the increase of the Lift over Drag ratio, which will undoubtedly decrease the aircraft’s fuel consumption. This will be achieved by using the advantages of the proposed morphing systems to mold the wing to the most suitable (in performance) wing shape for the accordingly flight phase, i.e., for a cruise flight phase it is foreseeable that the wing must have a high lift over drag ratio and since high velocity might not be a key factor. In this flight phase, the wing could have a large wingspan so that it may be flown with a lower speed (due to the decrease of the aircraft’s stall speed), decreasing greatly the amount of fuel spent for the same distance flown. Apart from increasing the aircraft’s performance, project CHANGE will enable the same aircraft to be flown in a larger variety of different missions. The wing will be able to mold itself accordingly to the appointed mission, therefore enabling the aircraft to fly with increased performance in different missions that it was not able to fly prior to the change or that it would fly under performance.
Objectives
The CHANGE project presents the following main objective:
This goal may be divided into several lower level objectives with associated foreseen achievements, as represented in the following list:
Project CHANGE will assess the possibility to integrate several different morphing technologies into one sole wing, using the advantages of all the morphing systems. An aerodynamic and structural assessment will be performed in order to determine if all the considered morphing systems are indeed complementary to one another and what different morphing technologies should be included in the wing to be developed within the Project.
Prior to the manufacture of the wing, a concept model (CAD model) will be created in order to ascertain the aerodynamic and structural properties of the wing, evaluating both the advantages and disadvantages of the each morphing system included in the wing. This concept design will provide to the CHANGE Consortium the necessary information to ascertain which morphing systems are indeed increasing the performance of the wing without an abrupt increase in manufacture complexity.
The morphing assessment software in CHANGE will exhibit the property of providing the user the most favorable wing shape to which the morphing wing shall morph into in order to fly with the highest performance possible. The user shall provide as input to the software the actuator locations and limitations, as well as the mission(s) assigned to the aircraft. The outcome of the software will be the desired wing shape and actuator settings that the wing must endure in order to fly the mission with the best performance possible.
Both the morphing wing and the morphing assessment software will be validated utilizing wind tunnel and flight testing results. The morphing wing and its components, such as the skin, structure and the morphing actuators will be evaluated using these two tests. The morphing assessment software will be validated using the data retrieved from both the performed tests, in which the performance of the aircraft (e.g. lift over drag ratio) will be compared to the results obtained from the software.
Expected Results from CHANGE
CHANGE will take into account a variety of different morphing technologies, namely, telescopic, camber variable, twist variable and sweep variable wings and gather them in a sole wing that will gather the performance increase of all the morphing systems. This will provide the aircraft increased capability to be applied in different missions, previously unattainable and perform them with increased performance.
Project CHANGE presents another focus, a medium to long range impact, in the development of a tool with a software basis with the capability to provide the user the most efficient wing shape of the morphing wing solely by delivering the information of the type of mission that the aircraft will fly. Given the type of morphing systems and actuators of the wing and the type of mission the aircraft will fly, the software will provide to the user the most efficient wing shape possible under those conditions and actuator limitations. The user has then the knowledge on how to change the wing’s shape in order to fly it with the highest performance possible. The software may then be used for the same aircraft in a variety of different missions, enabling the aircraft to fly with the highest performance possible in the assigned missions and flight conditions.
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