11.1.1 Aeroplane Aerodynamics and flight controls Flashcards
What are the 3 motions of an aircraft around the 3 axis’?
- Pitch
- Roll
- Yaw
What are the primary flight controls?
- Ailerons
- Elevators
- Rudder
On larger aircraft, what can be added to the wing to increase efficiency?
Roll spoilers
What are the secondary flight controls?
- Slats
- Flaps
- Trim systems
- Flight spoilers
What ailerons are used in high-speed flight?
Inboard ailerons
What will happen to the aircrafts nose if an elevator deflects upwards?
The nose attitude would go upwards
What is a “stabilator”?
A fully-movable aircraft horizontal stabiliser
What type of aircraft are most common to have stabilators?
High-speed military combat aircraft
What are the two types of canards?
- lifting canard
- control-canard
What is a lifting canard?
The weight of an aircraft is shared between the wing and the canard
What is a control canard?
Almost all of the weight is carried by the wings, the canard is primarily used for pitch control during manoeuvres
What is the disadvantage of using lifting canards?
The wings need to be larger or the same size as designed without the canard (due to the requirements stating that the canard would have to stall before the main wings)
What is the purpose of a rudder limiter system?
It limits rudder travel at high speeds in order to prevent rudder/stabiliser overload
At slow speeds (<150kts), what angle will the rudder have full deflection?
30° is permitted
At what speed is the intermediate (15°) travel of the rudder permitted?
Between 150-200 knots
What angle is the minimum travel of the rudder at high-speeds (> 200Kts)?
5.7° deflection
What is a ruddervator?
A combination of a rudder and elevator (v-tail)
What are the disadvantages of a ruddervator?
- larger control surfaces
- no full elevator/rudder deflection at the same time
- aircraft stability is reduced
- more complicated adjustment mechanics
What is a delta wing aircraft?
A tailless Aircraft like Concorde
- the aircraft has elevons (a combination of elevator and ailerons)
What are flaperons?
Some aircraft have them
- they usually work as ailerons but deflect symmetrically downwards when the flaps are extended (known as the aileron droop function)
What are wing flaps usually used for?
Landing - by increasing drag and lift
Take off - on Large Aircraft to increase lift
How do the flaps work on a wing?
When the flaps extend they change the camber of the wing and this increases the coefficient of lift at slower speeds
What are the types of flaps?
- plain
- slotted
- split
- fowler
What type of flap is the most effective?
The fowler flap - up to 95% increase in the maximum lift coefficient
What is the purpose of slots in secondary lift devices?
They prevent an early flow-separation
How much do slats increase the lift by?
Approximately 35%
What is the purpose of spoilers?
They increase drag and reduce lift
What are Air brakes?
Aircraft structure that deploys outwards into the airflow. They are only located where the aircraft structure can withstand heavy air-loads
What is spanwise flow?
When air particles flowing over a swept wing travel in two different angles; down the leading edge and then at right angles over the wing
- thickens the boundary layer at the wing tip increasing the possibility of flow separation (at low speeds/high AOA)
What can be used to prevent/reduce the effects of spanwise flow?
- Wing fences
- Saw-tooth leading edge
What is a vortex generator?
It improves boundary layer control on a wing by taking relatively high energy air from outside the boundary layer and mixing it with low energy air in the boundary layer
How are the number and location of vortex generators determined?
It depends on flight test investigations
What is the purpose of a stall wedge (strip)?
Installed at the wing roots so that with high angles of attack it disrupts the airflow to separate early causing it to stall at the root before the wing-tips (giving ailerons maximum control throughout the stall)
What is the purpose of a trim system?
It compensates for the imbalance of an aircraft
What are the 3 control inputs for the primary flight controls in the cockpit?
- control column
- control wheel (yoke)
- rudder pedals
What is a ruddervator made up of?
A mixer unit that when moving the control column, it rotates the gimbal of the mixer unit
Airbus use side-sticks instead of a control yoke or column. How is the rudder input completed?
Via the rudder pedals still
What are control runs that transmit the pilots input into the flying control system called?
Transmissions
What are the main components of a mechanical control run?
- rods
- cables
On larger aircraft, the pilots require assistance to operate the control surfaces. What provides this assistance?
The aerodynamic balance - reduces the force required to operate
What is the purpose of a horn on an aircraft control surface?
It moves into the wind during deflection for aiding movement
What are the two types of aerodynamic horn balance?
- horn balance
- insert hinge
What is the disadvantage of using a balance tab?
It reduces the efficiency of the control surface
How does a balance panel create differential pressure?
The chambers allow pressure from outside to enter via the slots which in turn produces a force in the panel to assist in the deflection
What is the advantage and disadvantage of using an anti-balance tab?
Advantage:
- it increases the efficiency of the control surface unlike the balance tab
Disadvantage:
- more effort is needed than the balance tab
What is the purpose of a trim tab?
It compensates for the imbalance of the aircraft
