Lift, Drag, Thrust and Weight

There are four fundamental forces acting on an aircraft. They are namely lift, drag, thrust and weight. The weight of the aircraft is what everyone is familar with (and what women are most conscious of !!). It is just a measure of how heavy the aircraft is and it is due to the downward forces of gravity acting on it.

The lift is an upward acting force that overcomes the gravitational weight of the aircraft. The lift force keeps the aircraft airborne and sustains flight. To generate lift, the aircraft has to be in motion and the engines provide the required forward thrust force. A larger thrust force propels the aircraft to a higher flight speed and, to a certain extent, generates a larger lift force.

Finally, the drag force is the resistive force that retards the aircraft's foward motion. As long as the aircraft is in motion, the drag force is present due to the general shape of the aircraft and the viscosity of air. If you place your open palm out the window of a moving car (done safely of course !!), you will feel the drag force acting on your palm.

From a certain point of view, the aerodynamist is aware that there is a constant conflict (or competition) among these four forces. It is logical to minimise the empty weight of the aircraft which can be done by using lighter but stronger materials (carbon fibre composites) for the aircraft's fuselage and wings, like what we see on the A380 or B787 Dreamliner. The weight of the aircraft is relatively constant and it is like a burden which does not contribute to the bottomline of a company.

To increase the profit margin for the aircraft company, the designer always aims to maximise lift force so that the aircraft can carry a heavier payload or more fuel. The aircraft can then carry more passengers (which contributes to $$$$) or fly a longer range (increased endurance). Increasing lift contributes directly to the useful work that the aircraft is designed for and basically makes shareholders happy.

An aircraft that sits on the tarmac is not going to generate revenue for the company. It has to deliver the goods from point A to B. It has be in motion and the thrust force generated by the engines does that and at the same time produces the required lift force to fly from point A to B. Naturally, it is desired that the aircraft can fly as far as possible (increased range) and one way is to increase the fuel load. However, doing so will increase the weight of the aircraft, reduce the revenue generating passenger and cargo load. You may argue that we can increase lift force by increasing the surface area of the wing. You are right but there is a catch. Doing so will also increase the drag force as there is increased friction with air. I guess you are starting to sense the conflicting nature between the four forces now.

To complicate this conflicting nature, the drag also depends on how fast the aircraft flies and on the thrust force. With increased thrust comes increased speed and lift but at the expense of higher drag force. The drag force is just a resistive force that arises when the aircraft is in motion. Streamlining, having less protruding structures from the fuselage and having winglet on the end of each wing reduces drag.

I guess in life, we are constantly faced with either internal or external conflicts and difficulties. Much like the aircraft which has to attain a balance between lift, drag, thrust and weight, you too need to reach a fine balance between these four forces in your life. You need to trim off extra weight and drag in your life and strive to keep it lean. You need to increase your lift and thrust to propel you to achieve higher feats in life.

You may be burdened with too much weighty and draggy issues, like anger, a bad habit, impatience, hanging around bad company, being generally pessimistic in life, procrastination.... The list is endless.....These negativity slow and weigh you down, preventing you from seeking and achieving your desired goals.

On the other hand, you may have a certain sporting, music or art talent, a passion for a hobby, developed specialist knowledge in some subjects, being generally curious, led a morally good life, having good mentors...... Again the list is endless.... These characteristics push and propel you to attain your goals.

The goals that you aim for can be simple things from baking a cake to earning your first million dollars. From landing your first dream job to getting the A+ in your paper. But along the way, you are constanly bombarded, pushed, pulled, tripped and driven by these four forces in your life. If you cared about your life, you constantly seek to balance them as you prod along in your journey. Some try to seek the answers by reflecting internally, seeking solace in religion, re-adjusting their own expectations and developing inner strength. Others search for their answers externally, looking for other people's affirmation and meeting their expectations. Some lose hope, just give up, and turn to crime and drugs.

So what's your LIFT, DRAG, THRUST and WEIGHT? Only YOU can answer that...!