11.1 - Theory of Flight Flashcards
Theory of Flight
Which form of drag is reduced by boundary layer control?
Induced Drag
which of the statements is true?
Spoiler and speed brakes always reduce lift and increase drag
How are the Leading edge devices deployed?
By the same lever as flap deployment.
Regarding aerodynamic heating. which material looses 80% of its strength at 250c
Aluminium Alloys
What can be said about changes in velocity, pressure and density in a shock wave?
Changes occur suddenly and sharply
What happens to the airflow as an aircraft approaches the speed of sound?
Areas of supersonic airflow increases and shockwaves move closer to the trailing edges.
What is the increase in lift provided by the slat system?
35%
When does the boundary layer loose control with the surface?
When kinetic energy in boundary layer is too low.
What is the critical Mach number
The point at which local airflow reaches Mach 1
When is a control surface correctly balanced
When the centre of gravity of the surface is located on the hinge line
What is done to prevent extreme pressures and temps at the engine compressor during high speed flight
1 normal and 3 oblique shockwaves are formed to slow airflow
What is the disadvantage of an antibalance trim tab
The pilot requires more effort to deflect the control surface
Which tab system uses a lever
Control tab type
How is profile thickness expressed in aerodynamics
as a relationship between actual thickness divided by chord length
What is the name of the most effective flaps
Fowler flap
What is the main function of the stabilator
Eliminate Mach Tuck caused by a shockwave formation
What is the purpose of ailerons
Roll control
Which primary flight controls effect the yaw control of the aircraft
Rudder
Which type of tab arrangement increases the effectiveness of a control surface
Anti-balance tab
Which of the following materials would generally be used to resist aerodynamic heating
Titanium alloy
How does supersonic flight effect the air
The air is compressible
If a mach indicator shows a number of 0.6. What does it mean
The aircraft is flying at 60% the speed of sound
Which of the following statements, regarding transonic flight is correct
Local Mach number is more than the flight Mach number
If the right ruddervator goes down and the left goes up.
The aircraft yaws right
How much does the fowler flap increase lift by more than other lifting devices
95%
What is the Subsonic speed range
Mach numbers less than 0.8
What is the transonic speed range
Mach numbers from 0.8 to 1.2
What is the supersonic speed range
Mach numbers between 1.2 to 5.0
When flying above Mach 1, an oblique shock wave is formed. What happens to air passing through it
As it passes the wave, the velocity is reduced but remains supersonic. Causing slight increase in temperature and pressure
When is an expansion wave formed
When supersonic airflow changes direction around a curve or corner, away from the preceding flow direction
How does the Center of lift/pressure chord position differ between subsonic and supersonic flight
At supersonic speeds the centre of lift is approximately 50% chord position
At subsonic speeds the centre of lift is approximately 25%
What is the portion of total drag due to shockwaves called
Wave drag
What is the function of a vortex generator
Transference of energy from the free airstream to the boundary layer to reduce flow separation
How does supersonic airflow act in a Venturi
It acts opposite to subsonic flow due to nozzle chokes the air and increases pressure
What is the disadvantage of a swept back wing
Increases span wise airflow
