# Taper sweep angle

Is the Taper sweep angle the same as the sweep angle?

So I know that the sweep angle is the angle from the vertical line from the leading edge to leading edge wing line.

• "So I know that the sweep angle is the angle from the vertical line from the leading edge to leading edge wing line."-- I can't quite understand what this is saying, but it appears to be incorrect. Mar 28 at 16:16
• Re "Taper sweep angle" --I know what taper is, and what sweep (or sweep angle) is, but have never heard of "taper sweep angle"-- Mar 28 at 16:17
• Hi, yeah I’ve never heard of Taper sweep angle but I came across it when a teacher said it
– Mags
Mar 28 at 17:09
• Could it be that the teacher meant "sweep angle" and said something like "... taper, erm, I mean, sweep angle ...". Or was the language spoken not English, so there might be potential for misunderstanding terms or translating them? Mar 28 at 17:35
• Then it is totally possible the teacher has no idea of what he/she is talkin about... Mar 29 at 11:53

"Taper angle," "taper sweep angle," etc., have no widely accepted definition.

Sweep angle could be defined as the angle of the leading edge or of the trailing edge, but it's traditionally that of the 25% chord line, because that's close to the aerodynamic center. In other words, that definition reduces how any taper present might affect what the sweep results in.

When taper is defined as just a tip-to-root ratio, not anything about angles, then the effects of sweep and taper can be discussed more independently.

Taper angle is more of a machining term, which might be the easiest described as the tip angle of a cone formed by a tapered section of a pipe (or tube). Well, maybe not that clear but anyway. For a wing we could logically use the same kind of definition:

Taper angle would be the angle two imaginary lines, drawn along leading edge and trailing edge and extended beyond the wing tip, make when they intersect.

But as stated in comments, this is not a common aviation term, if one at all...

• So, the angle between LE and TE? That would be more precise than taper ratio, which depends on wingspan. Mar 28 at 21:41
• Oops, I was sloppy writing that, I'll fix it. Thanks @CamilleGoudeseune Mar 29 at 8:57

Image source, earlier used in this answer

The sweep angle $$\Lambda$$is the angle that the quarter chord line makes with the lateral axis of the aeroplane. As can be seen in the pic, the leading edge and trailing edge of the wing have different angles relative to the lateral axis, due to the taper.

Wing taper $$\lambda$$ is the ratio between chord at the wing root and chord at the wing tip - this ratio does not define an angle yet, only when multiplied by the wing span.

The leading edge angle $$\Lambda_{LE}$$ of a tapered wing with zero sweep angle is defined by: $$tan (\Lambda_{LE}) = \frac{¼(c_r - c_t)}{½ b}$$ And of the trailing edge $$tan (\Lambda_{TE}) = \frac{¾(c_r - c_t)}{½ b}$$ So the "taper sweep angle" could be defined as $$\Lambda + \Lambda_{LE}$$ for the leading edge, and $$\Lambda - \Lambda_{TE}$$ for the trailing edge. I've never have heard Taper Sweep Angle referenced before, but it could be coined this way.