Large reaction helix limit ($U=O(n^{-1}),{\Omega }_1\to \omega ,{\Omega }_2=O(n^{-1})$)

As the length ratio of an opposite-handed reaction helix tends to infinity, its translation and rotation tend to zero as $1/n$, while the finite first helix rotates at almost the full motor rate. Small motions of the long rotor balance finite force and torque. The common propulsion vanishes in this limit of the additive model.