Center of Lift vs. Center of Thrust

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    Center Lift Thrust
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Discussion Overview

The discussion revolves around the concepts of the center of lift (CoL) and center of thrust (CoT) in the context of rocket dynamics. Participants explore the relationship between these two points and their implications for stability and aerodynamic forces during vertical and non-vertical flight.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant proposes that the CoL and CoT are located at the same point on a rocket, as both thrust and lift originate from the engine.
  • Another participant clarifies that the center of lift is determined by the aerodynamic forces generated by various components of the rocket, such as fins and the body.
  • A different participant questions the role of the fins and body when the rocket is traveling vertically, suggesting they primarily contribute to stability and drag rather than lift in that orientation.
  • It is noted that while no lift is generated at zero angle of attack, fins must produce some lift to maintain stability during disturbances.
  • One participant acknowledges their understanding of the concepts discussed.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between CoL and CoT, with some asserting they are the same and others emphasizing the distinct roles of aerodynamic forces and stability components. The discussion remains unresolved regarding the exact nature of these concepts.

Contextual Notes

The discussion includes assumptions about the definitions of lift and thrust, as well as the conditions under which lift is generated. There are also unresolved aspects regarding the impact of angle of attack on the forces involved.

Gbl911
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I have been thinking about the CoL and CoT on rockets. I came to the conclusion that they are in the exact same spot on the rocket since your thrust and lift come from the same thing in the same place, the engine. I read some forums on other websites but didn't get a clear answer. It would be very helpful if someone could clarify this for me.
Thanks
 
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The center of lift (sometimes called center of pressure) is the point of application of aerodynamic force generated by fins, wings, body, etc. There is a CP for each lifting surface and for the total lift generated by the whole rocket.
 
Your saying that the center of lift is calculated from all of the fins, body, etc. But if you are traveling perfectly vertical than the fins, body, etc. are only adding stability and drag, no upward force until it starts traveling non-vertical if I am correct. So I am just saying that the exact upward lift and the thrust are both coming from the engine. But the actual defined CoL is calculated by the fins, body, etc.

Thanks for the reply
 
That's right. When angle of attack is zero, no lift is generated. However, for fins to add stability, they must produce some lift whenever a disturbance occurs. Keep in mind that lift is the component of aerodynamic force perpendicular to the relative wind. The lift vector may point any direction, including sideways or down.
 
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