Development of a Simple Morphing Wing Using Elastomeric Composites as Skins and Actuators

Abstract

Morphing wings are desired for their ability to reduce drag, to change flight characteristics, and perhaps to reduce weight by eliminating flap/aileron mechanisms. Development of two generations of a morphing wing project is documented. The work shows how a relatively low cost but realistic morphing wing test-bed can be fabricated. Wing skin, actuator, and actuator attachment development are discussed, as well as possible auxetic skin behavior. Aerodynamic characterization of the wing will be discussed in another paper. A very simple morphing wing was fabricated in generation one. The nose was able to elastically camber down approximately 25 deg and the tail 20 deg. Actuation was provided by three pneumatic “rubber muscle actuators” that produce high contractive/tensile forces. Upper and lower wing skins were fabricated from carbon fiber/polyurethane elastomer laminates. Lower skin buckling, actuator air leaks, and actuator attachment problems were resolved in the second generation. A finite element model of the second wing was developed and is being used to refine the morphing wing test-bed. The second wing fabrication methodology enabled smooth elastic cambering with no buckling or waviness in the skins. The nose cambered down 14 deg and the tail cambered down to 13 deg, and is capable of larger deformations. Improved leak-free biomimetic actuators and attach points now include no metal parts and have higher actuation forces due to new braided sheaths and functionally gradient matrix properties.

Reconsidering the McKibben muscle: Energetics, operating fluid, and bladder material

“…Some groups have employed adhesives like epoxy (Woods et al, 2011) and custom swaging processes (Woods et al, 2012) to fortify the fitting tensile and sealing properties. These actuators have been proposed for many different applications ranging from humanoid robots (Tondu et al, 2005;Verrelst et al, 2005) to aerospace systems (Peel et al, 2009;Woods et al, 2011).…”

In-flight Folding Wingtip System: Inspiration from the XB-70 Valkyrie

“…A corrugated skin concept for similar actuated wingtips was also investigated [20]. A demonstrator of new smart actuation and skin was also made for a wing profile camber morphing [21]. Lastly, a sub-scaled demonstrator was flown recently as part of the Spanwise Adaptive Wing (SAW) project [22,23].…”

In-flight Wingtip Folding: Inspiration from the XB-70 Valkyrie

“…A corrugated skin concept for similar actuated wingtips was also investigated (Ursache, Melin, Isikveren, & Friswell, 2008). A demonstrator of a combination of a new actuation and smart skin was also made for a wing profile camber morphing (Peel, Mejia, Narvaez, Thompson, & Lingala, 2009). Lastly, a sub-scaled demonstrator was flown recently as part of the Spanwise Adaptive Wing (SAW) project (Kamlet & Gibbs, 2018;Warwick, 2018).…”