Yesterday, I talked about the problems of loading an airplane improperly. With a forward or aft cg, especially if loaded outside the limits, you are going to have control problems. Now for the rest of the story, as Paul would say…
When you start carrying a little extra weight, you know, that extra 10 or 20 pounds from the holidays, you have a tendency to move not as spritely as normal. The little extra weight is a problem for your bones to carry and it takes extra effort for your muscles to move the mass.
One can say the same thing of an overloaded airplane. When a pilot exceeds the certified operating weight, he or she is looking for trouble. This is the kind of trouble as what happened to this hapless pilot flying in South America. He committed two serious mistakes: the first was putting too much in the airplane; the second was exceeding the allowable aft limit of the cg. As you can see from the video, the consequences were disastrous.
(Found at https://www.youtube.com/watch?v=ZWC2XJYgcJU.)
It is clear from the video the pilot exceeded the aft cg limit. This is obvious by the airplane bouncing lightly on the nosewheel with the tail very low. You can also see how easily the nose rotates up after he starts his takeoff. As the airplane flies past the camera, the pilot is not holding the elevator aft; it is neutral to only slightly aft and the airplane is flying barely above stall.
In addition to possibly crashing on takeoff, there are other performance issues to concern a pilot. These include increased takeoff distance, high rotation speeds, lower climb rates, and shallower climb gradients.
A pilot flying an overweight airplane also needs to keep in mind the change in climb speeds. The best rate of climb will decrease more rapidly with altitude. Conversely, the best angle of climb speed increases dramatically with the higher altitudes. From the June 7 blog dealing with climb speeds and altitude limits, it is obvious the airplane’s service and absolute ceilings will be lower.
As if those are not problems enough, a pilot flying an overloaded airplane in a landing also has similar issues. The airplane requires more runway because of higher approach speeds. The higher landing speeds are necessary because the wing has to generate more lift to keep the airplane flying. This translates into a touchdown at high-speed requiring more distance to stop the airplane. Additionally, the heavier weight is hard on the landing gear, the wheels, and the brakes.
Pilots constantly must maintain awareness of the performance issues associated with heavier operating weights. Every chance a pilot has to cut the weight of his or her airplane, there will be a corresponding increase in performance on the other side of the equation.
Anytime you can increase performance, that is a good thing.
©2011 J. Clark
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