Thursday, October 18, 2007

Fascination With Aircraft

Cessna 560 corporate jet on landing approach to Centennial Airport (KAPA/APA).
This plane is owned by US Bancorp Equipment Finance of Portland, OR.
CLICK HERE for registration information.

I find airplanes fascinating. The mere fact that a vehicle weighing many tons can actually fly is quite amazing, even though I understand the science behind it. My office is near Centennial Airport, giving me the opportunity to watch at fairly close range, as private jets and small propeller-driven planes come and go.

I took the photo above on my way home from work today. I like the fact that you can clearly see the wings configured for landing, along with the landing gears locked down. Because airplanes are moving at a relatively slow speed when taking off and landing, the pilot alters the shape of the wings to provide more lift at these lower velocities.

On the leading edge of the wings are slats that move forward and down to create a greater curvature on the front of the wing. Flaps are on the rear of the wings, and extend backwards and down. Both flaps and slats are extended during takeoff and landing. Next time you fly in a jetliner, notice this during takeoff, and notice that once the plane is climbing, the flaps and slats are retracted. Of course, the landing gears are pulled up almost as soon as the aircraft leaves the runway in order to reduce the drag of air friction.

On the top of the wings are spoilers. These are panels that extend up from the top surface of the wing. The pilot can use spoilers to slow the plane down after landing, as well as using one or the other to roll the plane toward one direction or the other during flight.

Another control surface on the back of the wings are ailerons, used to help turn the plane during flight. The tail has elevators that move to orient the direction of the nose of the craft, as well as the rudder which helps to steer the plane.

In my younger, less informed days, I actually caused a plane I was on to get out of takeoff queue because of ailerons. This was shortly after Northwest Airlines Flight 255 bound for Phoenix crashed into a freeway overpass in Detroit a short distance from the runway. The crash was caused by the flight crew's failure to extend the slats and flaps, causing the plane to not have enough lift for takeoff. All on board were killed, except for a four-year-old little girl. The crash occurred the evening of August 16, 1987.

Anyway, I was on a Southwest Airlines plane in queue for takeoff from Houston's William P. Hobby Airport, and noticed what I thought was a flap sticking up off the wing. With the Detroit crash in my mind, I thought better to be a living fool than a dead person who kept his dignity. I rang the flight attendant bell, and asked was that "flap" supposed to be sticking up. She didn't know, but called to the flight deck. The captain pulled the plane to the side of the taxiway and came back to ask me if there was a problem. I told him, "I don't know, but I bet you can tell me. Is that a flap that is not down, like the one that caused the crash in Detroit?" He looked out the window and said, "Oh, that. No sir, those are called ailerons, and they are fine. But thanks for letting us know."

When he returned to the flight deck, he came on the PA and announced, "We just pulled over for a visual equipment check, and we will be taking off in just a few minutes." Nice job, Randy!

One new feature you see on many planes nowadays are winglets. These are the vertical extensions you see on the tips of the wings. Aircraft engineers have found that these wing extensions reduce the whirling vortices of air that spin off the wing tips during flight, thus reducing drag and increasing fuel economy. Many airlines use the winglets as billboards to advertise their web sites or airline name to the passengers inside the plane.

If you look at the large version of my picture above, you can also see a wire extending from the top of the tail to the fuselage. This is a communications aerial or antenna. Although the terms are commonly used interchangeably, aerials are usually flexible wire, while an antenna is a rigid device.

My airplane piloting experience is limited to balsa wood gliders as a kid, but that doesn't stop my enjoyment and admiration of airplanes.

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