![]() P = power (W) Example - Aeroplane and Airfoil Lift - Drag and required Thrust Powerįor an aeroplane with velocity 100 m/s, wing area 20 m 2, a drag coefficient 0.06 and a lift coefficient 0.7 - the lifting force acting on the airfoil can be calculatedį L = 0.7 1/2 (1.2 kg/m 3 ) (100 m/s) 2 (20 m 2 )į D = 0.06 1/2 ( 1. The thrust power required to overcome the drag force can be calculated The drag force acting on a body in fluid flow can be calculatedĪ = body area (m 2 > ) Required Thrust Power to overcome Drag Force On real aircraft, as with your automobile, there is usually a fuel reserve and the pilot makes sure to land the plane with fuel still on board.The lifting force acting on a body in a fluid flow can be calculated So, the lift, drag, thrust, and fuel consumption rate also continually change. The weight constantly changes as fuel is burned. Extra fuel is expended in climbing to altitude and in maneuvering the aircraft. An aircraft’s flight is not conducted at a single ground speed but varies from zero at takeoff, to cruise conditions, and back to zero at landing. In reality, calculating the range is a complex problem because of the number of variables. On this page, we have taken a very simple view of aircraft range–for academic purposes. Since they are surrounded by air, even cars are affected by aerodynamics. Anything that moves through air is affected by aerodynamics, from a rocket blasting off, to a kite flying. ![]() The rules of aerodynamics explain how an airplane is able to fly. The combat radius would be half of the range as specified here. Aerodynamics is the way objects move through air. To avoid confusion about the “range” of a military aircraft, the military often specifies the combat radius of the aircraft. The range of a military aircraft is often specified for a round trip (since you don’t normally want to land in enemy territory to be re-fueled!). On this page, we are assuming that the mission of the aircraft is one-way, such as an airliner flying from city A to city B, where the aircraft can be re-fueled. Humans have been interested in aerodynamics and flying for thousands of years, although flying in a heavier-than-air machine has been possible only in the last. Aerodynamics is the study of forces and the resulting motion of objects through the air. Some care must be used when specifying range. The word comes from two Greek words: aerios, concerning the air, and dynamis, which means force. A summary of information needed to determine the range is given on a separate page. The maximum flight time depends on how much fuel is carried by the aircraft and how fast the fuel is burned. We call this distance the maximum range R of the aircraft. The maximum distance that the aircraft can fly is then equal to the ground speed times the maximum time t max. The drag then slows the airplane, which decreases the lift and, eventually, the airplane comes back to Earth. When the airplane runs out of fuel, the engine stops. There is a time limit, or maximum time, that an airplane can stay aloft, which is usually determined by the fuel load. d = V * t Maximum DistanceĪirplanes, unfortunately, cannot stay in the air forever. Our general rate equation then becomes a distance equation: the distance flown is equal to the ground speed times the time aloft. The amount is the distance d the airplane has flown, the rate is the aircraft’s ground speed V, and the time is the time t aloft. The general rate equation is “rate times time equals amount”. Assuming a constant ground speed, we can use a simple rate equation to determine how far a cruising aircraft flies in a given span of time. ![]() From the solution of the thrust equals drag relation we obtain two values of either lift coefficient or speed, one for the maximum straight and level flight speed at the chosen altitude and the other for the minimum flight speed. The ground speed remains constant as long as the wind speed is constant. The figure below shows graphically the case discussed above. ![]() If we take into account the relative velocity of the wind, we can determine the ground speed of a cruising aircraft. However, if the forces become unbalanced, the aircraft moves in the direction of the greater force. Since there is no net external force on the aircraft, the aircraft maintains a constant airspeed as described by Newton’s First Law of Motion. Home > Beginners Guide to Aeronautics Range – Constant VelocityĪs discussed on the airplane cruise slide, an airplane can maintain a constant speed and level flight, in which the lift is equal to the weight, and the thrust is equal to the drag. ![]()
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