Climbing and Descending

Question 1

The angle between the longitudinal axis and the horizontal is the … angle (greek letter?)

but the flight path of the aircraft will be … because we are flying with an angle of attack, alpha

Answer 1

pitch

theta

less steep

Question 2

The angle between our flight path and the horizontal is called the … or …

which is greek letter …

Answer 2

flight path angle

climb angle

gamma

Question 3

Mathematically Theta =

Answer 3

alpha + gamma

Question 4

describe weight apparant drag, and what is the formula for it?

Answer 4

in a climb weight continues to act vertically downwards, parallel to gravity. But now lift is a force that is no longer aligned with weight, because lift acts at right angles to the flight path, not the horizontal. Lift is now only required to balance the component of weight acting perpendicular to the flight path (green dotted line)

Another component of weight is acting parallel to the flight path, acting in the same direction as drag – referred to as weight apparent drag

The amount of weight apparent drag will depend on the steepness of the climb and is represented by the red line

Using trigonometry, its value is W sin gamma

Question 5

To maintain speed in the steady climb, the available thrust must balance both … drag and … drag, and the formula for its value is:

available thrust = …

Answer 5

aerodynamic

weight apparent

drag + W sin gamma

Question 6

the amount of weight we can balance (and therefore the FPA we can achieve) will depend on how much … we have over our ….

Written mathematically: excess thrust = …

Excess thrust is equal and opposite to weight apparent drag so we can write:

(T – D) = W sin gamma,

so; sin gamma = …

Answer 6

excess thrust

aerodynamic drag

(T – D) (D is aerodynamic drag)…

(T – D)/W

Question 7

W sin gamma =

(2 things)

Answer 7

weight apparant drag

thrust

Question 8

load factor in a climb is always less than … because …

Answer 8

one

lift is less than weight in a climb

Question 9

in a climb, we can find the value of lift from the weight component acting perpendicular to the longitudinal axis

lift =

Answer 9

W cos gamma

Question 10

when given thrust to weight ratio and lift to drag ratio, what is the formula for best climb angle?

(sin gamma)

Answer 10

(thrust/weight) - (drag/lift)

Question 11

If we again assume that at small climb angles the hypotenuse and the long side of the triangle are effectively equal, the following formula can be used for climb gradient:

Climb Gradient (%) = …

Answer 11

Sin gamma x 100

Question 12

when considering factors that affect max climb angle, what is the formula to use?

Answer 12

Remember that max climb angle we can achieve depends on excess thrust!

Sin gamma = (T – D) / W

Question 13

what speed will the bext climb angle be achieved at and why?

Answer 13

excess thrust (T – D) will be greatest if drag is minimised, so the best climb angle will be achieved by flying at the min drag speed Vmd

Question 14

The forces in a descent are very similar to those in a climb. The difference is that the component of weight that gave us weight apparent drag is now helping to propel us down the slope, and is given the name …

The value of this force remains …, and its value depends on …

Answer 14

‘weight apparent thrust’

W sin Gamma

the angle of descent (gamma)

Question 15

Because a component of weight is now acting in the direction of thrust in a descent, if speed is remaining constant, thrust must be … and is represented by the formula:

Thrust = …

Answer 15

less than drag (how much less depending on the size of W sin gamma)

D – W sin gamma

Question 16

In a descent, lift is less than weight and is calculated as: …

Answer 16

W cos gamma (the same as a climb)

Question 17

Although it is not actually the case, the exam questions assume that there is no thrust in the descent and that we are gliding

With zero thrust, our … is the only force balancing the aerodynamic drag. In the steady descent the two are equal and we can say:

D = …

Answer 17

weight apparent thrust

W sin gamma

Question 18

What speed should we glide at for range?

Answer 18

Vmd

Question 19

why is gamma minimised when drag is reduced?

Answer 19

more drag means a steeper angle of gamma is required to balance the drag and maintain speed

Question 20

in a descent Sin gamma = weight apparent thrust / W

But at small angles we can again assume that lift = weight, and because weight apparent thrust equals drag, the equation can be written as:

Sin gamma =

This shows that the best glide angle any particular aircraft can achieve depends entirely on its best …, and nothing else – glide angle is independent of …

Answer 20

drag / lift

lift to drag ratio

weight

Question 21

if we want to glide for endurance, we want to stay airborne for as long as possible.

the only way to achive this is to …

this is done by slowing speed below … which increases drag but the shallow drag curve shows that we can

We will go …, and our rate of descent in ft per minute will be less, increasing the amount of time before we hit the ground

Answer 21

decrease rate of descent

slow down a lot while only increasing drag (and therefore glide angle) a little

much more slowly down a slightly steeper glide path