Without a single full lengthed spar going through the whole length, how do folding wings and removable wings be designed such that they maintain structural integrity in flight and other motions involving declarations and accelerations? For example, this is the folding wing of a Sonex Onex aircraft. I'm sure it's safe but how come it is? What is that mechanism I see to the left of the hinge? Is that something for locking the wing in position?