1/24/2024 0 Comments Feet of altitude geometrySumming the forces in the above figure along the thrust axis we find:īut this equation is a static relationship which does not allow acceleration i.e., does not allow a change in kinetic energy. This will be the angle of climb, θ, which will be considered positive in a climb and negative in a glide or descent. In this study we must add an angle to our previous illustration of the balance of forces on the airplane. This is our job in the sections that follow. This is the job of the engineer who designs the airplane to be able to meet the pilot’s needs in such a situation. The pilot in the above situation is not going to stop think about her or his aircraft’s power available or power required performance curves. The ultimate control of the aircraft in such a circumstance will require the coordinated use of both controls to regulate both speed and altitude during this most difficult phase of flight. The proper response, adding power, will result in a climb to recover from the altitude loss. This will, however, merely increase the angle of attack and result in a reduction in speed, possibly leading to stall and certainly leading to further loss of lift and altitude. If a sudden downdraft causes a loss of altitude the pilot must take immediate action to regain the lost altitude or run the risk of an unplanned encounter with the ground short of the runway! Pulling back on the control to bring the nose of the aircraft up is the most common instinctive response since the aircraft is descending with the nose down. For example, on an approach to landing the pilot is attempting to hold a steady descent toward the runway. This is, of course, not entirely true since the two controls are used simultaneously however, this is the analogy that will best serve the pilot in a difficult situation. One of the most difficult things for a flight instructor to teach a new pilot is that the throttle controls the altitude and the control stick or yoke controls the speed. To maintain our 55 mph (keeping kinetic energy constant) as we move up the hill we must add power. If a car is traveling at, say, 55 mph (since none of us would think of driving at speeds over the limit!) and we start up a hill holding the accelerator (throttle) steady, the car will decelerate as it climbs the hill, trading kinetic energy for potential energy. If we think about a car going over a hill, however, the process is not hard to understand. These, of course, are vehicles limited to the altitude of the road or water surface. Most of us are conditioned by experience with cars, boats and bicycles to think of speed increase as a consequence of adding power. The concept of adding power to increase altitude (climb) is usually not intuitive. This can be determined from the power performance information studied in the last chapter. The maximum rate of climb at a given speed will then depend on the difference between the power available from the engine at that speed and the power required for straight and level flight. To climb at that same speed then requires extra power and the amount of that extra power will determine the rate at which climb will occur. We are aware that a certain amount of power is required for straight and level flight at a given speed. The engine provides the needed energy for climb and the engine energy output per unit time is power (work per unit time). Rate of climb then involves the change of potential energy in a given time. In climbing, the aircraft is increasing its potential energy. One of the questions above involved the rate of climb. In a glide we are converting potential energy into velocity (kinetic energy) which will give us needed lift for flight. In climb we are turning kinetic and internal (engine) energy into an increase in potential energy. To look at altitude changes we need to think in terms of energy changes. How fast can I get from altitude A to altitude B? How far can I glide after my engine fails? If I take off 600 feet from the end of the runway, can I clear the trees ahead? The question to be answered now is how do we get the aircraft from one altitude to the other? This discussion must include the investigation of possible rates of climb and descent, the distance over the ground needed to climb a given altitude and the range of the aircraft in a glide. We know that from the straight and level data we can determine the theoretical maximum altitude, or ceiling, for a given aircraft. We must now add another dimension to our study of performance, that of changes in altitude. Through the basic power and thrust performance curves considered in the last chapter we have been able to investigate the straight and level flight performance of an aircraft. Altitude Change: Climb and Guide Introduction
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |