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Why does induced drag increase as airspeed decreases?
Induced drag increases as the angle of attack of a wing increases. Induced drag therefore increases as airspeed decreases, as the angle of attack must increase to maintain the lift required for level flight. The smoother the surface of the wing, the less is the friction.
Why does increasing speed also increase lift?
Fast air has low pressure. So when plane’s speed increases, the speed of the air over the wing does too. This means that the pressure above the wing drops. Since the air below the wing is moving more slowly, the high pressure there will push up on the wing, and lift it into the air.
What is the minimum thrust required?
Consequently we can see that the minimum thrust required occurs when L/D is a maximum. Again, since L = W, the maximum value of L/D occurs when drag is a minimum. Hence the minimum thrust required occurs at the minimum drag flight condition which is the same as the maximum L/D flight condition.
What drag decreases with speed?
In aviation, induced drag tends to be greater at lower speeds because a high angle of attack is required to maintain lift, creating more drag. However, as speed increases the angle of attack can be reduced and the induced drag decreases.
Does decreasing velocity increase lift?
Conversely, as the aircraft is slowed, the decreasing velocity requires increasing the AOA to maintain lift sufficient to maintain flight. There is, of course, a limit to how far the AOA can be increased, if a stall is to be avoided. Figure 5-6. Drag versus speed.
How does airfoil increase speed?
The air entering low pressure area on top of the wing speeds up. The air entering high pressure area on bottom slows down. That is why air on top moves faster.
How can induced drag be reduced?
Considering the induced drag equation, there are several ways to reduce the induced drag. Wings with high aspect ratio have lower induced drag than wings with low aspect ratio for the same wing area. So wings with a long span and a short chord have lower induced drag than wings with a short span and a long chord.
What happens to induced drag as AOA increases?
In any case, as AOA increases, induced drag increases proportionally. To state this another way—the lower the airspeed, the greater the AOA required to produce lift equal to the aircraft’s weight and, therefore, the greater induced drag. Conversely, parasite drag increases as the square of the airspeed.
What is the difference between power required and thrust required?
Vy – It’s All About Power Vx is all about excess force (thrust) – but Vy is all about excess power (horsepower). Power is work done per unit of time. So, you can compute power required by multiplying your total drag (force required) by your airspeed (distance over time). Power Required = Thrust Required X Airspeed.
What is thrust required?
Thrust is the force needed to overcome the resistance of air (drag) to the passage of an aircraft. Turbofan: most of the thrust is generated by a large fan at the front of the engine; a small percentage is generated by jet efflux.
What happens when the thrust of an engine is reduced?
If the revolutions per minute (rpm) of the engine is reduced, the thrust is lessened, and the aircraft slows down. As long as the thrust is less than the drag, the aircraft travels more and more slowly until its speed is insufficient to support it in the air.
What happens to the thrust required with altitude?
While it is obvious that thrust available will decrease with altitude the impact on thrust required is less clear cut. We know the drag curve will be equal to the thrust required curve for unaccelerated flight.
What happens when the drag is greater than the thrust?
As long as the thrust continues to be greater than the drag, the aircraft continues to accelerate. When drag equals thrust, the aircraft flies at a steady speed. The relative motion of the air over an object that produces lift also produces drag.
How does a configuration change affect the thrust curve?
A configuration change is in many ways the opposite of a weight change. Lowering the landing gear or extending the flaps greatly increases parasite drag while having a relatively smaller impact on induced drag. As a result, the thrust required curve is moved up and to the left.