Can any one explain how to draw a leading edge circle of an aerofoil.

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Discussion Overview

The discussion revolves around how to draw the leading edge circle of an aerofoil, focusing on the center and radius of this circle. Participants explore the geometric characteristics of leading edges in various airfoil designs, including theoretical and practical considerations.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants question the notion of a leading edge circle, suggesting that leading edges are often parabolic or elliptical rather than circular.
  • It is noted that at a specific point on the leading edge, the radius of curvature reaches a minimum, which could theoretically allow for the calculation of a radius and the drawing of a circle.
  • Participants mention that NACA airfoils have a defined "nose circle," indicating a specific geometric feature relevant to their design.
  • The importance of the nose radius is emphasized, particularly for airfoils designed for supersonic flight or those intended to maintain laminar flow.
  • Clarification is provided regarding the location of the center of the leading edge circle, which is said to be one nose radius from the point of minimum radius of curvature, directed inward normal to the surface.
  • It is suggested that having the airfoil coordinates can aid in determining the radius of curvature at various points, especially for NACA airfoils.

Areas of Agreement / Disagreement

Participants express differing views on the nature of the leading edge, with some asserting it is not a circle while others acknowledge the existence of a nose circle in specific airfoil designs. The discussion remains unresolved regarding the exact method for plotting the leading edge circle.

Contextual Notes

There are limitations regarding the assumptions made about the shapes of leading edges and the specific airfoil types being referenced. The discussion also highlights the dependence on airfoil coordinates for accurate calculations.

danny2010
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Can anyone explain how to draw a leading edge circle of an aerofoil. Where is the center and what is the radius of the leading edge circle
 
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danny2010 said:
Can anyone explain how to draw a leading edge circle of an aerofoil. Where is the center and what is the radius of the leading edge circle

It's not a circle. Most model leading edges made of balsa are parabolas, but some are elliptical. In the real world, they're shaped in accordance with whatever airfoil is being used.
 


However, at some point on the LE the radius will be a minimum, at which point you COULD calculate a radius of curvature at that point and draw the radius inward normal to that point and make a circle.
 


And oops! NACA airfoils do indeed have a "nose circle."
 


Right. Nose radius is an incredibly important parameter for certain parts of airfoil design, especially if you are talking supersonic airfoils or airfoils meant to stay laminar as long as possible.
 


Thanx for trying to help me...but i still have a doubt, where will one plot the center and draw the leading edge circle. !
 


The center will be one nose radius say from the point of minimum radius of curvature on the LE. It will be in the direction inward normal to the surface at said point.

If you have the airfoil coordinates you can find the radius of curvature at any of those points. If it is a NACA airfoil you can definitely find those coordinates somewhere.
 

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