circular helix
The space curve traced out by the parameterization
is called a circular helix (plur. helices).
Its Frenet frame is:
Its curvature and torsion are the following constants:
A circular helix can be conceived of as a space curve with constant,non-zero curvature, and constant, non-zero torsion. Indeed, one canshow that if a space curve satisfies the above constraints, then thereexists a system of Cartesian coordinates in which the curve has aparameterization of the form shown above.
An important property of the circular helix is that for any point of it, the angle between its tangent and the helix axis is constant. Indeed, if we consider the position vector of that arbitrary point, we have (where is the unit vector parallel to helix axis)
Therefore,
as was to be shown.
There is also another parameter, the so-called pitch of the helix which is the separation between two consecutive turns.(It is mostly used in the manufacture of screws.)Thus,
and is also a constant.