Chapter 18

Question 1

What if the feel is too heavy or too light on the controls?

Answer 1

Then the controls need balancing using aerodynamic balances to increase or decrease the feel.

Question 2

Spring tab?

Answer 2

At low speed the spring will remain ridged and the control surface will defect when the pilot moves the controls. At high speed when the pilot moves the controls, the spring will compress and the tab will defect

Question 3

What are the different types of controls

Answer 3

Conventional
Power assisted
Fully powered

Question 4

Conventional control

Answer 4

The pilot provides all of the force needed to move the control surfaces. This makes it hard to over stress the aircraft since the forces needed to do so are so high.

Question 5

Partially powered controls

Answer 5

The pilot makes some of the force needed to move the controls, hydraulics provide the rest. The pilot still gets a natural feeling. It is still difficult to over stress the aircraft

Question 6

Fully powered controls

Answer 6

The hydraulics provide all of the force needed yo move the controls. It is now easy to overstress the aircraft as the pilot has no feel from the controls.

Question 7

What are the 2 artificial feel systems and their definitions

Answer 7

Spring system - Springs provide resistance to control column deflection
Bob weight - A bobweight pulls the stick forwards to pull the G the pilot must pull against the bobweight. As G increases the bobweight gets heavier and it becomes progressively harder to pull more G.

Question 8

What are the DBW Laws

Answer 8

Normal law: both hard and soft protections
Alternate law: Soft protections only
Direct Law: no protections
Significant failures cause hard protections to be lost

Question 9

Pitch control FBW

Answer 9

Control column movements usually issue a G command to the FBW computer

Question 10

Roll Rate FBW

Answer 10

Control column movements usually issue a roll rate command to the FBW computer.

Question 11

In a roll what happens to the angle of attack on each wing

Answer 11

The angle of attack increases on the down going wing and decreases on the up going wing.

Question 12

What is adverse Aileron Yaw?

Answer 12

When in a roll the aircraft will want to Yaw opposite to the roll due to uneven drag of the high wing. This creates an unbalanced turn.

Question 13

Differential Ailerons

Answer 13

The up going aileron (On the downgoing wing) is rigged to defect further the downgoing aliron which increases drag on the downgoing wing

Question 14

What are the key designs to stop Aileron Yaw in small to medium aircraft?

Answer 14

Differential ailerons - The up going aileron is defected more through the airflow there for causing more form drag.
Frise Ailerons - The leading edge of the aileron is asymmetrically
shaped. When the aileron is deflected upwards, its leading edge
protrudes into the airstream to increase form drag. When the aileron
is deflected downwards, the asymmetric leading edge remains
shrouded by the wing.

Question 15

What are the benefits of Spoilers?

Answer 15

They don’t suffer from flutter problems.
They leave the trailing edge free for flaps.
They cause no twisting moment to the wing.

Question 16

Which way do you have to turn the trim for a nose down.

Answer 16

You will need to roll it forward for nose down and back for nose up.

Question 17

What does trimming nose up do?

Answer 17

More forward CG
Flying slower
More aft neutral control position
Wind the trim wheel towards you.

Question 18

What are the disadvantages to trim

Answer 18

Creates extra trim drag
Elevator efficiency is reduced
As we trim nose up, elevator authority is reduced and eventually lost - the forward CG position must be limited to prevent this.

Question 19

All moving tailplane (Slab tail)

Answer 19

A very powerful control surface used on aerobatic aircraft and fighter jet.

Question 20

What is the difference between an elevator and a all moving tailplane.

Answer 20

The elevator is a camber changing device while the moving tailplane changes the angle of attack.

Question 21

Trimmable Horizontal Stabiliser (THS)

Answer 21

Modern jet transport aircraft are commonly equipped with a variable
incidence tailplane, more commonly known as a trimmable horizontal
stabiliser(THS).
This design uses an electrically powered screw jack to gradually change
the incidence of the horizontal stabiliser. The sole purpose of the change in
incidence is to trim the aircraft in pitch.
Pitch control is effected using conventional elevators attached to the
trailing edge of the THS.