Quick V-Tail Sizing
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Home > Articles & Tips Index > Model Design > Quick V-Tail Sizing

[Courtesy of Mark Drela, drela "at" mit.edu, March 2000]

The issue of V-tail size and angle came up several times at the last meeting. Below is a short blurb on converting a conventional tail to an equivalent V-tail and vice versa.

- Mark

To convert a conventional tail into a V-tail:

A_vtail = A_vertical + A_horizontal

angle = arctan[ sqrt( A_vertical / A_horizontal ) ]

Notes: "A_vtail" is the area of both halves together, rotated flat. "angle" is the V-tail's dihedral angle from the horizontal.

To convert a V-tail into a conventional tail, use the reciprocal formulas:

A_horizontal = A_vtail * [ cos(angle) ]^2

A_vertical = A_vtail * [ sin(angle) ]^2

These formulas are strictly correct only for large tail aspect ratios, since they do not account for the local interference and lift cancellation at the V-tail roots during yaw or "rudder" application. But they are much better than guessing.

 


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