What is induced drag?
What is induced drag?
Induced drag and its wing tip vortices are a direct consequence of the creation of lift by the wing.
Since the Coefficient of Lift is large when the Angle of Attack is large, induced drag is inversely proportional to the square of the speed whereas all other drag is directly proportional to the square of the speed.
The effect of this is that induced drag is relatively unimportant at high speed in the cruise and descent where it probably represents less than 10% of total drag. In the climb, it is more important representing at least 20% of total drag. At slow speeds just after take off and in the initial climb, it is of maximum importance and may produce as much as 70% of total drag.
Finally, when looking at the potential strength of wing tip vortices, all this theory on induced drag must be moderated by the effect of aircraft weight. Induced drag will always increase with aircraft weight.
Explain the Fohn wind.
Explain the Fohn wind.
A Fohn wind is a warm dry wind that blows down the lee side of a mountain.
Initially, the air temperature cools dry-adiabatically (3°C/1000 ft), until its dew point temperature is reached. Condensation occurs as the air is further forced up the mountain range, resulting in the air cooling saturated-adiabatically (generally considered in the mid-latitudes to be 1.8°C/1000 ft). Clouds and precipitation form. When the air mass reaches the top of the mountain range it has lost a significant amount of its water content and so has a much lower dew point temperature.
As the air then begins to descend down the lee slope of the mountain the compressed air is initially heated saturated-adiabatically, and in effect the direct reverse to the cooling effect on the windward side occurs. As the air continues leeward and downward from the mountain range, the air, now no longer saturated, is heated dry-adiabatically.
The resultant wind is dry and warm giving clear conditions at airfields on the lee side of the mountain range.
The Foehn Effect also may be associated with mountain wave activity.
What is the movement of the center of pressure during/approaching a stall?
What is the movement of the center of pressure during/approaching a stall?
Center of pressure moves forward when approaching a stall.
How are contrails formed?
How are contrails formed?
Their formation is most often triggered by freezing water vapour from the exhaust of aircraft engines.
Does windshear show on the weather radar?
Does windshear show on the weather radar?
No
Describe the movement of the center of pressure with varying angle of attack.
Describe the movement of the center of pressure with varying angle of attack.
The Center of pressure position is dependent of the angle of attack. As the angle of attack increases the center of pressure moves closer to the leading edge.
During what phase of flight is lift the greatest?
During what phase of flight is lift the greatest?
For a commerical aeroplane: During take off. At this point the aircraft has it it's maximum weight, and accelerating in the vertical plane requiring the highest ammount of lift to counteract the weight.
What sort of weather would you find at an occluded front?
What sort of weather would you find at an occluded front?
Low pressure weather, unstable weather.
What is VMBE?
What is VMBE?
The maximum brake energy speed.
It is a function of the gross weight, altitude, temperature, runway slope, wind component, and braking configuration.
V1 must be less than VMBE.
You are flying at FL350 and the temperature reads -30°C, is the aircraft at its optimum temperature?
You are flying at FL350 and the temperature reads -30°C, is the aircraft at its optimum temperature?
No because it is warmer, according to ISA temperature should be -55°C