Flight Forces

Question 1

Name the numbered forces acting on a conventional aircraft.

Answer 1

1. Lift
2. Drag
3. Weight
4. Thrust

Question 2

In straight and level flight, what are the two flight force couples?

Answer 2

1. Lift and Weight
2. Drag and Thrust

Question 3

Which force couple gives a nose-down pitching moment on a conventional aircraft?

Answer 3

The Lift and Weight couple.

Question 4

Which part of the aircraft is used to overcome the nose-down pitching moment of a conventional aircraft?

Answer 4

The Tailplane.

Question 5

If the center of gravity of an aircraft moves backward, would it cause a nose-up or nose-down pitching moment?

Answer 5

Nose-up pitching moment.

Question 6

If an aircraft changes from level flight to a climb at the same speed, what happens to the four forces?

Answer 6

• Lift: Decreases
• Thrust: Increases
• Drag: Stays the same
• Weight: Stays the same

Question 7

What single factor does the best ‘glide angle’ depend on?

Answer 7

The lift-to-drag ratio.

Question 8

What two factors determine the glide range of a gliding aircraft?

Answer 8

1. The glide angle (or lift-to-drag ratio)
2. The altitude (or height)

Question 9

What effect would an increase in weight have on the range of a gliding aircraft?

Answer 9

It stays the same.

Question 10

When in a level banked turn, the lift force must balance which two forces?

Answer 10

1. The aircraft weight
2. The centrifugal force

Question 11

If an aircraft changes from level flight to a banked turn at the same speed, what happens to the lift and thrust?

Answer 11

• Lift increases to balance the aircraft weight and centrifugal force.
• Thrust increases to keep the speed constant due to increased drag.

Question 12

If an aircraft wants to maintain the same radius of turn in a steady banked turn, what must happen to the angle of bank if velocity increases?

Answer 12

The angle of bank must increase.

Question 13

What will happen to the minimum stall speed of an aircraft in a banked turn?

Answer 13

The minimum stall speed increases.

Question 14

What is the main problem caused by the large increase in lift when an aircraft goes into a high-angle banked turn?

Answer 14

The high lift can cause structural damage.

Question 15

What are two problems associated with a high-angled banked turn?

Answer 15

1. The minimum stall speed increases, causing the aircraft to stall in a turn.
2. The wings could be damaged or ripped off.