Climbing + Descending Flashcards
Forces acting in steady climb
In a steady climb at a constant speed the forces must be in equilibrium so:
- Total thrust must balance the drag and RCW
- Lift must balance W1
Weight components in a climb
Weight is split into 2 components:
- W1 (which acts at a right angle to the flight path)
- RCW (rearward component of weight which acts opposite and parallel to the flight path)
Note: as the climb becomes steeper the RCW increases and the W1 decreases
Deriving the EP curve
The rate of climb at any given speed is determined by the excess PA over PR, when comparing a PA and PR curve the shaded area between the 2 curves is the excess power, this excess power can then be plotted against TAS to give the EP curve (or excess power curve)
Where does the speed for maximum ROC occur on the EP curve
Peak of the EP curve
Where does the speed for maximum angle of climb occur on the EP curve
Where a line drawn from the origin of the graph is at a tangential to the curve
Vx
max angle of climb speed
Vy
max rate of climb speed
Normal climb speed vs Vx and Vy
Normal climb speed is usually done at max power and so normal climb speed will most likely be higher than Vx and Vy
What factors effect climb performance
- Power applied
- Airspeed
- Flap / undercarriage extension
- Manoeuvring
- Altitude
- Temperature
- Wind
- Weight
Climb performance effect of power applied
Decreased power = decreased climb performance
Since the amount of excess power over power required is reduced
Climb performance effect of airspeed
Flying faster or slower than the recommend airspeed can reduce climb performance
Climb performance effect of Flap /undercarriage extension
Extended flaps / undercarriage will decrease climb performance because the L/D ratio is reduced (as drag is increased)
Climb performance effect of weight
Increased weight = decreased climb performance due to the PR to maintain any given speed in level flight increases so there is a smaller excess available for climbing
Climb performance effect of altitude
Increased altitude = decreased density = decreased airframe and engine performance so climb performance is reduced
Climb performance effect of wind
Headwind and tailwind components effect the climb angle but not the ROC (so the altitude gain is the same but headwind reduces the distance traveled over the ground in a given time and tailwind increases it)
Climb performance effect of manoeuvring
Any manoeuvring in the climb e.g. turning, will absorb some of the excess power available and climb performance is reduced
Climb performance effect of temperature
At any altitude where where the air temp is higher than the standard figure the climb performance is reduced due to decreased density
Absolute ceiling
As altitude increases the PR and PA curves move closer together , if the climb is continued the PR / PA curves will coincide and all PA will be needed to keep the a/c in level flight. The point where the curves coincide is called the absolute ceiling
Service ceiling
Is reached when the ROC has been reduced to 100 ft / min and occurs at a lower altitude then the absolute ceiling
Ways to descend
- Glide (throttle is closed so theres no thrust produced)
- Power on descent
Forces acting on a a/c in a steady glide
There is no thrust
- Drag is balanced by the component of weight parallel to the flight path
- Lift is balanced by the component of weight that is perpendicular to the flight path
Forces acting on an a/c in a steady power on descent
- Drag is balanced by the thrust and the component of weight parallel to the flight path
- Lift is balanced by the component of weight that is perpendicular to the flight path
What determines the glide angle at any given speed
The L/D ratio. If the L/D ratio is high the glide angle will be shallow and vice versa . The glide angle is in dierct proprtion to the L/D ratio.
How is the greatest range (and shallowest angle) in the glide achieved
When the a/c is flown at the AoA for the best L/D ratio (speed at the peak of the L/D curve), If glide speed is lower or higher than recommend the L/D ratio will be not as good and the glide angle will be steeper
Effect of weight of glide performance
Weight has no effect on glide angle
Decreasing weight means the AoA for the best L/D ratio will occur at a lower airspeed, and so the ROD will be slightly lower and the time taken to reach the ground will be longer
Effect of wind of glide performance
Headwind reduces the glide distance over the ground but doesn’t effect the glide distance through the air mss. Net flight path is steeper in headwind and shallowing in tailwind
