Samara-based Flying Vehicle
Maple seed Lauan seed
Some plants such as maple, linden, or lauan have seeds with one or multiple wings. Those seeds are called "samara" and can fly rotating their wings. Their flight resembles to the helicopter but they don't have an enzine to rotate their wings. They use aerodynamic force to rotate their wings.
Above figure explains the mechanism. In the section A, the inflow speed due to the rotation is small because of the short distance from the rotation axis. Whereas, the inflow speed in the section B is large because of the large distance from the rotation axis. The inflow speed due to the descent is same for both sections. Therefore the angle of the resultant inflow is different for two sections. In the section A, this angle is large and then the resultant force R, i.e. lift(L) + drag(D), inclines forward generating the forward component of the aerodynamic force. This force acts as a torque to rotate the seed. In the section B, the angle of resultant flow is small and then the resultamt force R points upward generating the upward component of the aerodyamic force. This force acts as the supporting force to fly. In other words, the wing generates torque to rotate the seed in the inner part of the wing and generates lift to support the seed in the outer part of the seed. This mechanism is called "auto rotation"
Samara-based flyer
We are developing samara-based flyers that can fly using auto rotation. This flyer is equipped with camera inside and can take pictures while flying down from the air.