## Monday, March 19, 2007

### Airbus A380

Today, the biggest passenger aircraft has ever been made in history is making its first test flight from Frankfurt to New York. The test flight is supposedly to test air conditioning system, entertainment electronics and other comfortibilities. Most of the passengers are Airbus employees and reporters. They will be asked to give feedback about the performance during the flight.

I am always amazed with how sophisticated the aeronautics is. First, how could a pair of wings lift such a massive body of an airplane? The material used on the wings must be superstrong and must be precisely and carefully selected and the superconstruction must be very detail and thoroughly. Just look at how much weight they have to bear. Gas tank is resided there, four huge jet enginees hang there too. Not to mention the body (in case of A380, with no passengers it weights 252 tons).

The wheels are also very strong. If we look at how tiny the rods that holding the wheel, we can imagine what a pressure it has to support. As we know, pressure (P) is defined as Force divided by crossection of an area. If the area is small relative to the force, the pressure becomes higher. There is 3 wheel system on most airplanes. One is in the front, the other two are below the wings. If there is 500 passengers with weight of 60 kg each passenger, there will be 30 ton in weight. Baggages can contribute to about the same amount. With other stuff packed into the aircraft (foods, etc.), the total weight can be up to 100 ton. So the total weight is about 352 ton. Assume the pressure is spread evenly to the three wheels. So each wheel bears about 120 tons!

The wing is even more astounding. The span for for A380 is about 78 meters. With such a long span (of two wings), it has to bear massive load. If we look back to high school physics 101, the torc (or torque) is defined as a product of force times length. It is also called Moment of the Force. While flying, these wings experience constant vibration and shock, either from turbulence or others.

The last thing I am also wondered is its avionics, including its control system. With such a complex system, ofcourse we need to have very complex instrumentation and control system too. I recalled when I was still in college, in one of courses I took was Control System Theory and Digital Control System. Those courses made me got big headache. Lots of math involved: Fourier, Laplace, z-transform; higher level integral and differential (including differential equations), etc. Not only that, an aircraft has strict restrictions on how to carry weight. So engineers have to design and decide what materials and components to fit in the plane.

The last but not least, aircraft is one of the top-most and top-notch of all advancements and product of engineering and technolgy humans have ever invented.