General / Misc Aircraft stuff (ACFT) Flashcards
What are the thresholds of the 3 different weight turbulence categories, and what is the extra exception?
Light is anything up to 7000kg, medium is anything from 7000 to 136,000kg, and heavy is anything about 136,000kg. The exception is the Airbus A380, which is given the turbulence category “super”.
What is “climb gradient”?
Climb gradient is the ratio of height gained to distance traveled, expressed as a %.
What is a typical approach angle, and what has this led to in aircraft design.
A typical approach angle would be 3 degrees, and this has led to many aircraft manufacturers designing their aircraft to have glide points of 3 degrees, to make a normal landing possible in the case of engine failure.
What is an ICAO standard turn, and what is it used for?
An ICAO standard turn is 3 degrees per second, at a bank of no more than 25 degrees. This is used for many maneuvers in instrument flight, including a holding pattern.
Rule of thumb for feet/minute to meters/second.
200ft/minute = 1m/s.
What are the 4 forces acting on an aircraft in flight, and how are they created?
Weight: created by the action of gravity on the mass of the plane.
Lift: created by the motion of air over lift surfaces (wings).
Thrust: created by the engines doing whatever it is that sort of engine does.
Drag: created by the air resistance of the air the plane is flying through.
What is the empennage?
The tail part of an airplane, and all of the things attached to it.
What is an aircraft’s auxiliary power unit?
A small secondary engine on board an aircraft intended to power the secondary systems, but which can also be used to generate lift in the event of engine failure.
What is meant by the term “steady flight”?
A level flight in which speed and altitude remain constant, due to lift, gravity, thrust and drag all being balanced.
What are the lift and drag formulae?
L = 1/2 X velocity squared X rho (air density) X surface area of wings X coefficient of lift. Drag is the same but with the word lift swapped for drag.
What is the difference between static and dynamic pressure, and how are they related?
Static pressure is always present, and is the pressure created by the weight of air above the location, and energy of the air molecules from temperature.
Dynamic pressure is only present when an object is in motion relative to the air, and it acts in the direction of movement. It is proportional to the density and squared speed of the moving air.
The sum of static and dynamic pressure will always remain the same in a given system.
If humidity decreases, what happens to air pressure and why?
It increases, because water vapour is less than air.
What proportion of lift in generated from high pressure pushing up on wings vs. low pressure pulling up on wings.
1/3 to 2/3 respectively.
What are the frontmost and rearmost parts of the wing called?
The leading edge and the trailing edge.
What is a chord line?
A straight line directly connecting the frontmost part of the leading edge and the rearmost part of the trailing edge.
What are the areas above and below the chord line called?
The upper and lower camber, respectively.
What is the name for the position of the wing, relative to the movement of air, at which the wing is almost aerodynamically unstable.
The critical angle of attack.
What is the flat part of the upper camber called?
The laminar wing, or the laminar surface.
What are the 2 different types of drag?
Parasite drag and induced drag.
What are the 3 different types of parasite drag?
Skin friction drag, form drag and interference drag.
What causes induced drag?
Turbulent airflow created by the movement of the wings relative to the air.
What is meant by the “aspect ratio” of a wing?
The ratio of wing length to wing depth.
How can a wing’s aerodynamic properties be adjusted to compensate for a low aspect ratio?
By adding winglets (sticky-up bits at the ends of the wings).
What’s a slat?
An extendable device on the leading edge of a wing which can be folded out when desired. It has a narrow slot which focuses the airflow approaching the wing, putting it under higher pressure, and generating lift by causing the air flow to remain stable and laminar for longer.
What are flaps?
Extendable surfaces at the backs of wings which can be deployed to change the wings’ surface area, and therefore increase lift.
Which factors will limit a plane’s highest possible speed? 3 answers.
The structural strength of the airframe, the plane’s ability to generate enough thrust to overcome its weight and drag, and the critical Mach speed.
What factors will limit a plane’s lowest possible speed? 2 answers.
Lift coefficient and weight.
Which factors will influence a plane’s maximum load?
Size of fuselage, structural integrity, thrust generation capability and coefficient of lift.
What is an aircraft’s “service ceiling”?
The height at which an aircraft is not able to climb by more than 100ft/minute.
How do indicated and true air speed vary with height.
Each 1000ft of elevation causes indicated air speed to read about 2% higher than true air speed.
What does the term “transonic” mean?
A speed between an aircraft’s critical Mach number (up to 1, in theory), and Mach 1.3.
What is the difference between highest and lowest possible speed, and minimum and maximum speed?
Highest and lowest are physical limitations, minimum and maximum are legislative restrictions.
What is the maximum maneuvering speed?
The fastest an aircraft can go with all ailerons, spoilers, rudders and other control surfaces engaged, without breaking any of them.
Which factors decide maximum operating altitude? 2 answers.
Either your Mach number and stall speed approach one another as altitude goes up, in which case you can’t rise without stalling or going supersonic, OR you don’t have a pressurized cabin, in which case you can’t fly so high you can’t breathe, OR you have a pressurized cabin, in which case you can’t fly so high that you wouldn’t have time to get down to a safe breathing altitude in the event of a loss of cabin pressure before your onboard oxygen ran out,.
What are trims?
Aerodynamic control surfaces which can be manually set to lock into position, relieveing strain from the pilot.
What is the difference between autothrust and autothrottle?
Autothrust just changes what the engine is doing, autothrottle actually makes the throttle levels in the cockpit move around accordingly.
Which components of an aircraft help to ensure vertical rotational (yaw) stability?
The tail and dorsal fin always. Sometimes, aircraft will be fitted with a computer called a yaw damper system, in which case that.
Which component of an aircraft helps to ensure latitudinal rotational instability (pitching).
The tailplane.
What features of aircraft can counteract unintended longitudinal rotation (rolling), and how doe they work? 4 answers.
1: High wing position. This works because when a plane is rolling, it is physically like it is swinging on a pendulum, and by putting the wings higher, the centre of gravity is kept higher, which effectively shortens the string of the pendulum, reducing the duration of the roll.
2: Dihedral wings. This means slightly V-shaped wings, and this works because they are not quite horizontal normally. Therefore, when the plane rolls, the lowered wing actually becomes more horizontal than the other, meaning that it generates lift more efficiently, and therefore rolls back.
3: Swept back wings. These work because, if the aircraft rolls, it will also start to slide in the direction of roll. This puts more air flow over the lower wing, increasing its lift and undoing the roll.
4: High keel surface. This also works on the above-mentioned sliding effect: as the aircraft slides into its roll, air is directed at the keel surface, pushing it into a reverse roll.
What is a keel surface?
A surface facing perpendicular to the direction of the aircraft, above the centre of gravity.
