Uploaded July 2021 | Updated September 2026, 1 week ago

---

Let's add a horizontal tail to the aircraft and look at the influence Angle of Attack has on the pitching moment.

Jump Ahead:
00:00 Intro
01:10 Adding the Tail
01:57 The CG*
04:14 Q Stands for "Dynamic Pressure"**
05:34 Lift vs Angle of Attack
08:42 Equations for Lift of Wing and Tail
11:11 Balancing the Torque (or Moment)
15:20 Sizing the Tail to Balance the Moment
15:48 Summary

For level flight, the lift from wing and tail must add up to the weight of the aircraft.

We have a linear relationship between Angle of Attack and Lift 𝐶𝐿𝛼.

For level flight, we need the total moment to be zero.

With the assumptions we’ve made, we balance the aircraft with an equation:

Spoiler Alert… we’re going to have to break one of those assumptions...in the next video!
(youtu.be/1bQT9YUvtkw)

*Notice how CG stands for "Center of Mass". ;)
**Clearly Aero Engineers need to retake kindergarten