M11.1 Flashcards
Lateral Axis
Pitch Axis
The lateral axis is oriented horizontally and runs from wing-tip to wing-tip.
Pitch motion occurs when the aircraft rotates about this axis. The control surface responsible for pitch is the elevator
Where are elevators located and what are there purpose?
usually located on the tail or the horizontal stabilizer
control pitch by varying the aircraft’s angle of attack. Pitching involves the aircraft’s nose moving up (pitching up) or down (pitching down).
Longitudinal Axis
Roll Axis
The longitudinal axis runs from the nose to the tail of the aircraft
Roll motion occurs when the aircraft rotates about this axis
What are the control surfaces responsible for roll.
The control surface responsible for roll is the aileron.
Where are ailerons located and how do they roll the aircraft
located on the wings, are used to control roll by creating differential lift between the wings. Rolling involves the aircraft tilting to one side (banking) or the other.
Vertical Axis
Yaw Axis
The vertical axis is oriented vertically and runs through the centre of gravity of the aircraft.
Yaw motion occurs when the aircraft rotates about this axis
What are the three primary flight controls?
What can be done to increase efficiency during roll
Ailerons
Elevators
Rudder
On larger commercial aircraft, roll spoilers (and/or speed brakes) may be added to increase the efficiency of the flying control surface.
Where are ailerons located?
What axis does it effect
Outbound trailing edge effects the longitudinal axis
What is the edge on the wing by the Upwards and downwards deflection of an aileron?
The upward deflection of the right aileron reduces the camber of the wing resulting in decreased lift on the right wing.
the downward deflection of the left aileron results in an increase in camber and a corresponding increase in lift on the left wing.
The differential lift between the wings results in the aircraft rolling to the right.
If the airspeed doubles what happens to the pressure felt on the control surfaces?
Aileron
Pressure felt quadruples
Energy in the air is proportional to the square of the airspeed.
Why are some large aircraft equipped with inboard and outboard ailerons
if the airspeed is doubled, the pressure felt on the control surface is quadrupled. This effect means that the force required to move the surface at high speeds increases
In order to combat this, some larger aircraft are equipped with inboard and outboard ailerons. During take-off, landing, and low speeds, both sets of ailerons deflect in response to a roll command giving maximum leverage.
As aircraft speeds increase, the outboard (low-speed) aileron is locked out. Roll control is then exercised through the use of roll spoilers and the inboard (high-speed) ailerons which are smaller and positioned in a more rigid section of the wing.
What is a roll or flight spoilers used for?
used to supplement aileron control by reducing lift on the wing with the upgoing aileron. This action also counteracts the effect of lift-induced drag that causes adverse yaw
The deferential operation is liked to the alieron control system
The reduce the amount of aileron deflection
Where are elevators located and what way do they control
Elevators are located on the trailing edge of the horizontal stabiliser and affect longitudinal or pitch control around the lateral axis. This position is furthest away from the aircraft’s centre of gravity to exert greater leverage.
What are the three main regions of high speed flight and there speeds?
Subsonic Mach numbers less than 0.8
Transonic Mach numbers from 0.8 to 1.2
Supersonic Mach numbers from 1.2 to 5.0
What is subsonic flight
Subsonic flight is a phase of flight in which an aircraft operates at speeds below the speed of sound.
Mach 0 to 0.8
How does air behave at subsonic flight
the behaviour of air can be approximated as incompressible.
Incompressible flow is an idealisation used in aerodynamics when the airflow speed is much less than the speed of sound
It’s important to note that air is not truly incompressible, but rather the degree of compression at subsonic speeds is negligible when compared to the compressibility effects observed at higher speeds
What is transonic flight?
combination of subsonic and supersonic airflow.
As it reaches the upper surface of the wing, the air velocity reaches the critical Mach 1 threshold, leading to the formation of a shock wave
What is a normal shockwave and when does it first occur
typically forms at a 90-degree angle to the airflow, positioned approximately midway between the wing’s leading and trailing edges. This phenomenon is referred to as a “normal shock wave.” And first happens in transonic flight
What are the effects of the normal shock wave during transonic flight?
Transonic flight can pose stability challenges due to the presence of this shock wave, which can result in airflow separation from the wing. Additionally, the shock wave’s effects cause the center of lift to shift rearward, resulting in a nose-down pitch tendency.
What is supersonic flight?
all speeds around the aircraft are higher than the speed of sound. Supersonic speeds typically span from Mach 1.20 to 5.0
the entire aircraft is subjected to supersonic airflow.
The air is compressible, and compression effects develop.
Where is the shockwave located on supersonic flight?
the shock wave that was initially formed over the aircraft’s wing during transonic flight has moved all the way to the rear and has affixed itself to the aircraft’s trailing edge.
How does the coefficients of lift and drag differ during sub and supersonic flight?
During supersonic flight, the coefficient of lift is less than the value in the subsonic range. The coefficient of drag is higher than the subsonic value but less than the transonic value.
What is the critical Mach number?
The critical Mach number of an aircraft is the lowest Mach number at which the airflow over some point of the aircraft reaches the speed of sound, but does not exceed it.
When an aircraft approaches MCrit, it encounters compressibility effects, and shock waves begin to form.
What is the local Mach number?
The curved upper surface of the wing causes an acceleration inflow compared to the lower surface. As a result of this, the air on the top of the wing is travelling faster than the forward speed of the aircraft itself.
