Flight Training - May 2011 - 50

INSTRUCTOR REPORT»

IF THE RIDER PUTS IN LESS EFFORT, PROVIDING LESS POWER, THE BICYCLE SLOWS DOWN.
business the Wright brothers were in before their experiments at Kill Devil Hill changed everything. The example of a bicycle allows the CFI to incorporate the “Keep it Simple” (KISS) approach to an otherwise potentially complex concept. So when your next student starts looking vaguely perplexed as you try to explain the importance of pitch and power, try this. While in level, unaccelerated flight, open the discussion of pitch and power with the student. It is perfectly reasonable to allow the student to fly the airplane as you conduct this lesson. In fact, it may be more beneficial than if you do the flying yourself. Explain that the airplane works very much like a bicycle. As the student looks at you and begins to consider your qualifications to be acting as PIC, continue on to explain that when the airplane is in a level cruise, a climb, or a descent, the pitch and power combination works in exactly the same way it would if the two of you were on a bicycle, instead of flying an airplane. The student will be trying to find the connection here. So don’t let the comparison linger too long, or confusion may be the result. Charge onward and complete the explanation.

In order to travel over level ground at a specific speed, the bicycle rider has to put in a certain amount of effort. It’s not hard to pedal a bicycle over flat ground, and it’s not hard to maintain a specified speed. But the effort has to be constant. If the rider puts in less effort (providing less power) the bicycle slows down. If the rider puts more effort into pedaling, the bicycle speeds up. Because it has the limitation of being a bicycle, it cannot climb or descend at will as an airplane could. But if we do exactly the same experiment in the airplane, we will get the same result. If we reduce power even a little bit while maintaining altitude through pitch control, the airplane will slow down. If, on the other hand, we increase power even slightly—and retrim the airplane to maintain level flight—our speed will increase. The larger lesson being reinforced is that the combination of a particular power setting and pitch attitude will result in a specific airspeed in level flight. While the student may not understand that entirely, or may not accept it as a fact, the use of a bicycle running over level ground provides a simple, repeatable example the student can understand easily, and transfer that understanding to their understanding of the airplane in flight. If our student is adapting to the lesson well and you feel like moving into some more advanced bicycleCLOSE CALLS: LESSONS LEARNED SAFETY SEMINAR
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related material, you can introduce climbs and descents at a constant airspeed, too. By going back to the bicycle, this concept can be introduced on the ground or in the air with equal success. Because the previous in-flight demonstration showed the student the undeniable link between bicycles and airplanes, as well as pitch and power, his ability to mentally shift into this discussion will be relatively easy. By recalling the bicycle rider on level ground, moving at a specific speed, the student has an easily imagined scenario to work with. Suggest to the student that if that bicyclist wants to maintain the same speed while climbing a hill, more power will be required. The steeper the hill, and the higher the speed, the more effort will be necessary. We can demonstrate this in flight by simply advancing the power and pitching up to maintain airspeed. The airplane will indeed climb. The more power we apply, the higher the pitch attitude can be. The situation is exactly like our example of a bicycle rider climbing a hill. Conversely, to travel downhill the bicyclist can lower his level of exertion and still maintain his speed. Gravity replaces the energy previously provided by the rider. The same phenomenon comes into play when flying the airplane. While flying straight and level, a reduction of power will cause the airplane to nose over to seek out the speed the airplane was trimmed for. The lower the power setting, the lower the nose will sink—but the speed will remain relatively constant. Pitch and power, it’s as easy as riding a bike.
Jamie Becket is a flight instructor and author based in central Florida

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Flight Training - May 2011

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