Aerodynamics - Drag - Air Resistance


There are 3 main types of drag that affect an aeroplane. These are Induced Drag, Form Drag and Parasite Drag.

All forms of drag work together to oppose thrust, a reciprocating internal combustion engine with a prop or turbine type engine all generate thrust to overcome the drag. When thrust equals drag the aircraft will not increase speed any more.


Induced Drag

Induced Drag is probably the largest of the three types of drag or air resistance. This of course is effected by the design of the aircraft, so the types of drag effecting a specific design of aircraft may change in how much it effects it. This is probably the most true for parasite drag, however induced drag has the highest effect on an aircraft and aeronautical engineers can do little to avoid it, if only minimise it where possible.

In a previous article beginning with aerodynamics, i mentioned that in aircraft design you dont get something for nothing. There is always a compromise, it is the law of conservation of energy.

Induced drag, is simply the result of an aerofoil or wing generating lift, the more lift you generate the more induced drag you create. Induced drag also effects wing tip vorticies, the wing tip vorticies create drag and are slightly related to induced drag, but more on that later.

Form Drag 

Form drag is caused by the actual shape or cross section of the aircraft, but more specifically the friction of the air moving over the skin of the aircraft.

Parasite Drag

Parasite drag is the simple one, it is the drag created by all the little things like antennas, door handles, navigation lights etc. The more "parasite" type object you have hanging off an aeroplane, the more parasite drag you will get.

more to come........