081 PoF
Principles of Flight
Principles of Flight
Set of flashcards Details
| Flashcards | 60 |
|---|---|
| Language | Deutsch |
| Category | Traffic |
| Level | Other |
| Created / Updated | 17.08.2022 / 08.09.2022 |
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With regards to stability, which 2 categories of stability exist?
- Static stability
- Dynamic stability
Define statically stable for an aircraft
After displacement by a wind gust, the aircraft returns to its initial flight path.
Define statically unstable for an aircraft
After displacement by a wind gust, the aircraft continues to part from the initial flight path.
Define statically neutral (or indifferent)
After displacement by a wind gust, the aircraft continues on the newly obtained flight path
Define dynamic stability
The oscillation decreases with time
Define dynamic neutral stability
The oscillation stays the same (with time)
What is dynamic unstable?
The oscillation increases with time
Define dynamic unstable
The oscillation increases with time
Which aircraft movement is related to longitudinal stability?
Pitch
The position of the centre of gravity is denoted in % in terms of the ... ?
Mean Aerodynamic Chord (MAC)
MAC is defined as: where y is the coordinate along the wing span, S is the wing area, b is the span of the wing, and c is the chord at the coordinate y.
Related to MTOM and CG, how is an aircraft certified?
Always worst case within envelope: aircraft at MTOM and CG full forward.
Which pitching moment is created with CG ahead of CP?
The pitching moment Cm is negative -> Nose down.
How can directional and lateral stability be achieved?
- Large tail
- Dihedral wing
- Swept wing
Does the aircraft in the picture have a dihedral or anhedral wing?
Dihedral: Upward angle of wing (from root to tip).
Name all aircraft axes:
Longitudinal Axis -> X-Axis -> Roll
Lateral Axis -> Y-Axis -> Pitch
Normal or vertical axis -> Z-Axis -> Yaw
What happens if the elevator deflects upwards?
Tailforce lift is directed downwards and results in a Pitch up
By which principle does a fixed stabiliser with moveable elevator operate?
Deflecting elevator changes camber
By which principle does an all moving horizontal stabilator operate?
Change of angle of incidence
Why does aileron deflection result in roll?
Deflecting the elevator downwards, creates more lift, while deflecting the elevator upwards, decreases lift. The result is the aircraft banking towards the side with decreased lift.
Name the parts of an aircraft that control the yaw?
The Yaw is controlled by the vertical stabilizer (fixed) and the rudder (movable).
Rudder deflection to the right results in right yaw and vice versa to the left.
Explain adverse yaw
The wing creating more lift, also creates more drag. Thus, the aircraft will start to yaw towards the wing creating more lift (opposite the direction of roll)
How can adverse yaw be countered?
- By the pilot applying rudder
- Via mechanical corrections:
- Coupling of alieron and vertical
- Differential ailerons
- Frize aileron
Explain the principle and the advantage of differential ailerons
Differential ailerons are a solution to partially overcome the problem of adverse yaw.
The ailerons are geared so that e. g. the upgoing aileron moves more than the downgoing.
What is Yaw-Roll coupling?
While yawing around the vertical axis, the forward wing is producing more lift than the one moving aft. This results in a rolling moment in the same direction as the yaw.
What would Rudder-Linus do if the turn and slip indicator looks like this?
KICK THE BALL!
The plane is flying level but in a slip. The ball has to be centered with stepping on the right rudder.
Why does an aircraft have bendable trim tabs?
The bendable trim tabs are fixed and can only be changed by the mechanic.
Every aircraft is built slightly different, if an acft with controls neutral has a slight tendency in a certain direction (all axes), a trim tab is bent to counteract this tendency. The are attached the control surfaces (rudder, elevator, ailerons)
Name the four types of flaps:
Plain Flap
Spilt Flap
Slotted Flap
Fowler Flap
Sort the flap types "plain", "fowler", "slotted" in order of increasing CL/Alpha:
(Basic aerofoil), plain flap, slotted flap, fowler flap
What is the effect of trailing edge devices (flaps) on lift and what happens to the center of pressure?
Lift gets increased towards the trailing edge of the wing and the center of pressure moves aft.
What is the effect of slats?
extending forward, they energize the boundary layer and increase maximum AoA
How do slats and flaps influence the CL/alpha curve?
What is the primary role of a propeller?
The primary role of a propeller is to convert the mechanical power of a power plant to (thrust)-power in order to propel the aircraft forward.
What's the secondary role of the propeller?
A secondary role of the propeller is to act as an aerodynamic brake in order to shorten landing and roll distances. This is primarily valid for larger and fast aircraft.
What is Thrust?
THRUST = MASS AIRFLOW x ACCELERATION (measured in N)
What is the difference between "tractor" and "pusher" type propellers?
Tractor type "pull" the aircraft fwd, Pusher type "push" the aircraft fwd
What is the helix of a propeller?
the propeller path
What is the difference between geometric and effective pitch?
propeller slip
What is the geometric pitch of a propeller?
Theoretical distance a prop advances in one revolution
What is the effective pitch of a propeller?
Effective distance a prop advances in one revolution
Where is the speed highest of a propeller?
At the tip.
