Helix Tracing Helical Trajectory

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Discussion Overview

The discussion revolves around the mathematical description of a curve formed by a helix tracing out a helical trajectory, specifically focusing on the concept of a "super-helix" where the axis itself is a helix. Participants explore the mathematical formulation and underlying concepts related to this topic.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant seeks clarification on how to mathematically describe a curve formed by a helix tracing out a helical trajectory.
  • Another participant suggests that any helix traces out a helical trajectory and proposes that the discussion may involve a helix whose axis is also a helix.
  • A mathematical approach is presented, starting with a base helix defined along the z-axis, with equations for x, y, and z that incorporate parameters for radius and pitch.
  • The participant emphasizes the need to find the normal and bi-normal vectors to the base helix to derive the parametric equations for the desired "real" helix.
  • A later reply expresses gratitude for the explanation and indicates a desire to learn more about concepts like "binormal," requesting recommendations for textbooks or standard texts on the subject.

Areas of Agreement / Disagreement

Participants appear to agree on the general approach to describing the helical trajectory, but there is no consensus on the specific mathematical details or the terminology used, such as "binormal." The discussion remains exploratory and unresolved regarding the best methods and resources for learning.

Contextual Notes

Participants express uncertainty about specific mathematical concepts and terminology, indicating a need for further learning and clarification. The discussion does not resolve the complexities involved in describing super helices.

stevenphy2
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hi all,
I am wondering how to mathematically describe a curve formed by having a helix tracing out a helical trajectory? Any idea?
 
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So, I mean the mathematical description of a super-helix.
 
Any helix "traces out a helical trajectory"! Do you mean a helix whose axis is a helix?

I would do it this way: first assuming the "base helix"- that is the one forming the axis of the helix we want- has the z-axis as axis, we can write it as x= R cos(t), y= R sin(t), z= ct[/itex] where "c" controls the "pitch" of the helix. Now, the hard part: Find the normal and bi-normal to that curve. Those you can use as axes to give the same parametric equations for the "real" helix you want, with, say, radius r and pitch d. The parametric equations for that helix will be the sum of the two sets of parametric equations- you get the point on the axial helix and then add the components out to the "real" helix.
 
Last edited by a moderator:
HallsofIvy said:
Any helix "traces out a helical trajectory"! Do you mean a helix whose axis is a helix?

I would do it this way: first assuming the "base helix"- that is the one forming the axis of the helix we want- has the z-axis as axis, we can write it as x= R cos(t), y= R sin(t), z= ct[/itex] where "c" controls the "pitch" of the helix. Now, the hard part: Find the normal and bi-normal to that curve. Those you can use as axes to give the same parametric equations for the "real" helix you want, with, say, radius r and pitch d. The parametric equations for that helix will be the sum of the two sets of parametric equations- you get the point on the axial helix and then add the components out to the "real" helix.

HallsofIvy, thanks. That's what I meant.
I think it is the way to go, but I do not know things like "binormal" etc. I should learn it now. Do you have textbooks to recommend for learning these things? Or standard text which teach you how to do these super helices things? Thanks.
 

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