Lesson 4 - adding forces, reducing a system of forces to a center point
Now you know that force is a vector quantity (as well as Torque). Several forces can be applied to mechanical system and it's usually a good step to simplify the system of forces, reducing them to one resulting force and one resulting torque. In order to do that we have to find a geometrical sum of force vectors.
The system of four forces applied to the airplane:
- Thrust force Ft
- Gravity force Fg
- air Drag force Fd
- air Lift force Fl
- replace them all with one equivalent force R
There are two basic approaches how to find resulting vector. First one is graphical approach, also known as "parallelogram rule". For two vectors A and B, move one of them to make its origin coincident with second vector's origin. Then resulting vector R can be found as a diagonal of the parallelogram formed by these two vectors, that diagonal which comes out of the common vector origin (fig. 1.4.2).
If we have more than two vectors, we can arrange them as a polygon line in such a way that each new vector comes out of the end of the previous one. Then we connect the start and end point of the polygon line - this is resulting vector R.