Principles of Flight (POF)
Principles of Flight FS 15 Klasse:AV14 Dozent:Manfrian Weiteres Lernmaterial unter: www.tinyurl.com/av14fs15
Principles of Flight FS 15 Klasse:AV14 Dozent:Manfrian Weiteres Lernmaterial unter: www.tinyurl.com/av14fs15
Kartei Details
| Karten | 126 |
|---|---|
| Lernende | 127 |
| Sprache | English |
| Kategorie | Technik |
| Stufe | Universität |
| Erstellt / Aktualisiert | 29.05.2015 / 14.04.2024 |
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if \(c_p=0\) the pressure is the same as the pressure
with increasing aspect ration the lift curve slope ...
Total Drag = .....
Profile drag: skin friction drag + pressure drag due to separation
+
Induced drag
if a wing is swept back the critical Mach number....
Explenation
increases
Explenation:
-The airfoil only "sees" the flow component normal to the leading edge \(M_{crit}\over cos(\Omega)\)
-The flow "sees" a thiner airfoil
by sweeping back the wing \(C_{lmax}\)...
explain the coffin corner
Description
In aviation, coffin corner (or Q corner) refers to the point at which the Flight Envelope boundary defined by a high incidence stall intersects with that defined by the critical Mach number. In other words, coffin corner occurs when, for a specific gross weight and G-force loading, the aircraft has climbed to an altitude where the speed differential between the onset of low speed stall buffet and the onset of high speed Mach buffet approaches zero.
As an aircraft climbs towards the altitude that defines its coffin corner, the margin between stall speed and critical Mach number becomes smaller and smaller until the Flight Envelope boundaries intersect. At this point, any change in speed would result in exceeding one or the other of the limits. In the most critical case, simply turning the aircraft could result in exceeding both limits simultaneously as, in a turn, the inside wing slows down whereas the outside wing increases speed. Likewise, encountering turbulence could result in a "beyond limits" change in airspeed.
When flaps are deflected downward the lift coefficient increases because:
1. ....
2. ....
1. camber is increased
2. virutal increas of the angle of attack due to rotation of the chord line
by deflecting a flap downward the lift curve slope ....
explain a deep stall
when the turbulent air of the flow separation at the wings hits the tail. Therefore the flow at tail is also turbulent and the contol over the airplanes longitudinal axis is impossible
aerodynamic ceeling
Altitude at which lines of low speed stall intersects with high speed stall (shock induced).
This point is called Coffin corner.
.
plain flap
-
split flap
-
slotted flap
-
fowler flaps
manipulating the boundary layer
1....
2....
1 blowing bleed air into the boundary layer
2 sucking air from the boundary layer
both methods should decrease the velocity gradient in the boundary layer witch delays flow speparation
deflecting a flap/controll surface downwards ... lift
movement about the x-axis
rolling, lateral motion
movement about the y-axis
pitching, longitudinal motion
movement about the z-axis
yawing, directional motion
Define static stability
If the forces on the body caused by a disturbance tend initially to return the body toward ist equilibrium position the body is statically stable.
Define statically unstable
If the forces and moments are such that the body continues to move away from its equilibrium position after being disturbed, the body is statically unstable
Define dynamic stability
A body is dynamically stable if, of its own accord it, eventually returns to and remains at its equilibrium position over time.
An airplane that is statically stable is also dynamically stable
An airplane that is dynamically stable is also statically stable
stable or unstable
an airplane is trimmed if
the moment about the center of gravity is zero
Define the zero lift line
Consider a wing at an angle of attack such that lift is zero. With the wing in this orientation draw a line through the trailing edge parallel to the relative wind. That is the zero lift line.
Define the absolute angle of attack
The angle between the zero-lift line and the relative wind. \(\alpha_a=\alpha+|\alpha_{L=0}|\)
For an airfoil at \(\alpha_a=0\)
the point where \(M_{cg}=0\) is called
An airplane with this characteristic about the pitching moment is
This airplane is....
In general adding a fuselage to a wing shifts the aerodynamic center ....
In general adding a fuselage to a wing shifts the aerodynamic center forward, .... the lift curve slope
In general adding a fuselage to a wing contributes a ... increment to the moment about the aerodynamic center.
Two interference effects that influence the tail aerodynamics
1. The airflow at the tail is deflected downwards by the downwash due to the finite wing
2. Because of the retarding force of skin friction and pressures drag over the wing, the airflow reaching the tail has been slowed
the tail volume ratio is ...
the ratio between a volume wich defines the position and size of the tail and a volume which charaterizes the size of the wing.
the tail setting angle \(i_t\) must be ... to balance the airplane
if the center of gravity is at the neutral point ....
the airplane is statically neutral.
if the center of gravitiy is behind the neutral point
the airplane is statically unstable
