# What are the names of the forces acting upon the side of a vessel?

People often refer to the four forces in navigation as weight, lift, thrust and drag. Are there separate names for the forces acting upon the side of a craft?

• What do you mean by "side"? left and right? Remember that drag and lift are just arbitrary decomposition of the total of aerodynamic forces such that lift is vertical and opposed to weight. – Manu H Apr 17 '16 at 14:28
• @ManuH I sure wish the industry would come up with a term to differentiate the two definitions of lift. It would avoid much confusion – TomMcW Apr 17 '16 at 19:30
• @ManuH Lift is NOT vertical and opposed to weight. Lift is perpendicular to the airflow. – Federico Apr 18 '16 at 6:53
• @Federico does this mean lift and weight have the same direction when the airplane is upside down, i.e. with a negative load factor (e.g. during an aileron roll)? – Manu H Apr 18 '16 at 7:50
• @ManuH depends. usually no, as you will have an AoA such that the lift will be negative (in the aircraft reference frame) and thus still pointing up. – Federico Apr 18 '16 at 7:57

As we engineers are extremely boring people, and given the fact that a name seems not to be available, we generally refer to them simply as "side forces".

Or, at least, I never encountered a different term on any of the textbooks that I have read.

• Lateral and sometimes transverse or cross- are also used to qualify these forces. – mins Apr 17 '16 at 9:32