Wing placement fuels question

Question: I’ve noticed that the wings aren’t placed in the middle of the plane but at nearly the rear of the plane. Why is this? – Christian, California

Answer: I would not say that wings are near the rear of the plane, but they are not always in the exact middle as designers seek the best location for the loading envelope and to improve fuel efficiency.

Wing placement is decided based on fuel efficiency and on the loading capabilities ( weight and balance). Wings create lift, keeping the plane in the air. They are balanced by the small wing in the tail, the horizontal stabilizer. This wing is upside down, so the lift is created downward. By balancing the two points of lift, the pilots can maintain control of the airplane.

As the payload ( passengers, cargo and fuel) is added, the location is important to ensure the pilot remains capable of maintaining control with the horizontal stabilizer.

Q: Can you explain windshear and the effects that has on airplanes? – Timothy Nealon, Ph. D San Antonio

A: Windshear is the amount of change in wind direction or velocity over a short distance. This can be a source of turbulence as the airplane travels through a changing air mass.

One example of windshear’s effect on an airplane could be a change in the ground speed. As a tailwind becomes a headwind, the ground speed would slow down. In extreme cases, a change in direction can cause a loss of airspeed with a resulting reduction in lift.

There have been a number of windshear accidents, caused by the combination of a change in wind direction with a vertical component ( microburst) pushing the airplane into the ground. The last one of these was US Air 1016 in July 1994. Normally the cause of windshear and microburst are thunderstorms.

Technology has dramatically improved the ability to detect wind shear that could pose a risk to the airplane. Airliners have wind shear detection equipment onboard to warn pilots when the conditions are present for windshear. Pilots are trained to avoid these conditions.

FRANK PETERS/ GETTY IMAGES Fuel efficiency and loading help determine wing placement.