maintain the geometry of the airfoil as well as provide effective storing and deployment

of the mechanism.

 Also for the purpose of considering improved maneuverability and performance,

roll maneuvers have been studied using a flexible wing [16]. Numerical studies were

used to consider the aerodynamic loads on a flexible wing at high speeds. Wing twist

is also considered in order to recover the rolling moment lost but has not been tested in

flight. This is due to the challenges involved in implementing a functioning mechanism

for wing twist on a full scale aircraft.

 Research has also been done considering the material aspects of shape changing

with a finite element model of a wing [17]. This considered roll maneuvers using

a piezoelectric material as an actuation mechanism with aerodynamic loads being

applied. Piezoelectric sensors and actuators are useful for this application because they

are light, have a small volume and can achieve various shapes. This technique has

not been tested; however, due to the large deflections that are needed from such small

actuators.

 Numerical studies have considered structural and aerodynamic modeling for

shape changing wings [12]. These considered a generic lambda wing such as used in

unmanned combat air vehicles (UCAV). The different mode shapes were studied to

consider structural modeling. This model was then used to study the roll performance

of the morphing wing. It was shown that this wing with hinge-less control surfaces

shows improved roll performance because of the aerodynamic and structural benefits.

 As mentioned previously, there are several benefits such as improved performance

due to the use of wing morphing. Also, morphing is easily achieved on MAVs because

the wings are constructed of flexible membrane material. The flexible wings can be

grossly deformed via mechanical actuation yet are capable of withstanding flight loads.

The flexible nature of the wing also gives rise to the mechanism of adaptive washout

which permits small changes in wing shape in response to gusty wind conditions.