POF
T1
T1
WIth a turbofan ngines have no critical engine except the outher ones at a 4-engined aeroplane. By a crosswind T/O which one is the critical one?
the engine one on the windward side is the critical engine
3 options how to fly after an engine failure (small aircraft)
1.=> keeping the wings level => Rudder + aileron towards good engine=> The ball is centered => sideslip greates a large amount of drag
2. bank towards the good engine => ONLY AILERON => Rudder neutral => sideslip greates a large amount of drag
3. slighz bank and moderate rudder towards goo engine => straight ahead with minimum drag => no sideslip
=> minimum drag, no sideslip ====> the ball of the turn and slip indicator is not centered, but there is no sideslop => Bank angle max. 5 degrees
how to fly after engine failure big aircraft
a) larger power surplus
b) jet aeroplanes is linked with spoiler deflection which increases drag
=> then rudder is applied to teh side of teh operating engine which keeps aileron input at almost zero with the spoilers retracted => sideslip towards the side with the dad engine
VMCG
Minimum controlled speed on the ground => Flaps T/O
VMCA
Minimum controlled speed in the air => Flaps T/O, Gear up
VMCL
Minimum controlled speed for landing
Why is an aft, why a forward C.G. limit established?
aft: stability fwd: controllability
The static margin is equal to the distane between:
the CG and the NP
When the CG is close to the forward limit:
very hight stick forces are require for pitch because the aircraft is very stable
Dihedral angle is:
the upward and outward inclination of the main planes to the horizontal datum
helix angle
angle between the rotational speed and relative speed
pitch angle propeller
Angle between rotational speed and chord line
reference point propeller
where the resultant thrust force of a bald acts
Geometric pitch
distance a propeller should advance in one revolution
propeller: feather position
lowest drag for the aeroplane => 90 degrees => used on a failed engine of a multi-engine aeroplane to keep draw as slow as possible
propeller: Cruise pitch
between coarse (high pitch) and fine (low pitch)
propeller: Ground fine
the thrust is approximately zero => aeroplane is not moving
propeller: full reverse
max reverse thrust
propeller: Why is the pitch angle high at the root and low at the blade tip ?
to maintain the optimum AOA from the blade root to the blade tip
If teh aircraft is properöy loaded the CG, the neutral point and the manouvre point will be in the order given, forward to aft?
CG, neutral point, manoeuvre point
accelerate
beschleunigen
equidistant
gleich weit entfernt
obtain
erhalten
increase
zunehmen
dynamischer Druck
1/2 * p(Roh) * v^2
Lift in Newton
dynamischer Druck (1/2 * Roh * v^2) * s (Fläche) * CI (Koeffizient)
Kraft F in N
influence that causes a body to undergo a certain change in movement. ⇒ F (N) = m(kg)* a(m/s^2)
Arbeit (W)
Work (W)= Force x Distance Unit = Joule (J)
Leistung (P)
Power = Force x Velocity Unit = Watt
Gravitationskraft:
9.81 m/sec2
shape of an airfoil
Profil eines Flügels
Vektor:
Vektor: Grösse, welche auch durch ihre Richtung bestimmt ist
Weight:
Weight: the gravitational force onto a body. ⇒ In N
Mass:
Mass: the resistance that a body exhibits in response to a force which acce-lebrates or slows down the body Masse ⇒ Materie in a body
Acceleration
Acceleration: The rate at which the speed of an object changes = Beschleunigung ⇒ a = F / m
Coanda Effekt:
Coanda Effekt: ein strömendes Fluid mit Kontakt mit einer gebogenen Ober-fläche hat die Neigung der Biegung der Oberfläche zu folgen
Dichte (p) =
Masse pro Volumen = Mit zunehmender Höhe = Dichte nimmt ab è Hohe Temperatur + hoher Airport = selten gut p (N/m2) = p (kg/m3) * Rair * T(K) Rair = 287
atmospheric pressure =
weight of air column / area
totaler Druck
• Totaler Druck (pt): statischer (q)+ dynamischer Druck (ps)
Das Trägheitsgesetz = Gerade aus fliegen
Jeder Körper verharrt in Ruhe oder behält eine gleichförmige, geradlinige Bewegung bei, solange keine äussere Kraft auf ihn einwirkt, oder die äusse-ren Kräfte im Gleichgewicht sind d.h. sich gegenseitig aufheben
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Lernkarten
Neutral Static stable
neither the tendency to return, nor the tendency to continue
Negativ Static stable
a tendency to continue in the direction of disturbance
If an aeroplane is statically stable, teh aeroplane may
1. return to the previous flight condition or 2. it might overshoot the original attitude
2 Arten bei der Positive Dynamic Stability
Periodic motion 2. an aperiodic motion
If there is no dampig in the system, an oscillation (Schwingung) is teh result. Such an oscillation indicates xy static stabilitty but xy or xy dynamic stability
If there is no dampig in the system, an oscillation (Schwingung) is the result. Such an oscillation indicates positive static stabilitty but neutral or negative dynamic stability
An aeroplane that has positive static stability can be dynamically xy
An aeroplane that has positive static stability can be dynamically stable, neutral or unstable
Dynamically Indifferent stability
Ist das gleiche wie Dynamically neutral stability
Lateral Stability bedeutet ?
vgl Bild
longitudinal Stability bedeutet ?
vgl Bild
Directional Stability bedeutet ?
vgl. Bild
Was ist die Seitenstabilität
Lateral und Directional Stability
CG
Center of Gravity; Point at which the entire weight of the aircraft is assumed to be zero or balanced. The CG moves with changing load
CP
Center of Pressure; Druckpunkt; Is the point where all of the aerodynamic pressure is taken together => The CP moves with changing AOA
Je grösser der AOA, desto weiter wanderr der CP nach
vorne
Where is the CP denoted ?
on the MAC
When is the Equilibrium is reached
Equilibrium is reached when the sum of all moments is zero
Stabil or instabil?
stabil => AOA wird grösser => Lift wird grösser => CG nach vorne = geht automatisch in den Sinkflug
stabil or instabil
Instabil, weil es kein rückführendes Moment hat => Produziert Lift vor dem CG, jedoch ist der Flügel weniger belastet
Seitebstabilität ist eine Konbination aus:
Lateral Stability (Rollen) und Directional Stability (Schieben)
Anordnung der Flügel hat auf die Stabilität einen EInfluss. Was für einen?
Hochdeker = stabiler
DC 9 = langer Rumpf
Alles was hinter dem CG. ist = rückführendes Moment => Moment bringt es zurück => Gleich ist es beim A321 => Viel ruhiger in der Luft als der A319
pitching moments resulting in a nose down are xy and nase-up moments are xy
pitching moments resulting in a nose down are negative and nase-up moments are positiv
cambered aerofoil creates a negative moment even if the lift is xy
zero
Neutral point of the eroplane or aerodynamic centre of the aerplane is
where the deshabilleising moment of the wing equals the stabilizing moment of the tail and thus the aeroplane shows neutral static stability
the square root
Wurzel
During a steady horizontal turn, the stall speed:
increases with the square root of the load factor.
The centre of pressure (CP) is in its most forward position
when the angle of attack is equal to the stalling angle of attack.
Which of the following is used to activate a stall warning device?
movement of the stagnation point
A spin
spin = Trudel; can develop at or below manoeuvring speed ; occurs with the wings in a stalled condition ; can develop in any attitude
occur
vorkommen
VA
maneuvering speed, maximum speed at which you may apply full and abrupt control movement without danger of structural damage
VSO
stalling speed or minimum speed in landing configuration
VS1
stalling speed or minimum speed obtained a specified configuration
VFE
Flaps extended speed => the maximum speed with flaps extended
VNO
Normal operation Maximum structural cruising speed => This speed should not be exceeded expect in smooth air
yellow sector (Speed)
yellow sector indicated the caution range => only possible in smooth air and only with caution
VNE
Never exceeded speed => operating above this speed is prohibited since it may result in damage or structural failure
Stall?
AOA exceeds the critical AOA and airflow sepatazes at the aerofoil/ wing surface => an Aircraft can be stalled at any speed, altitude or power setting by exceeding the critical angle of attack
How do you feel a stall
buffeting is caused by the vibration of the aeroplane due to airflow separation
The Power On Stall => Höher oder tiefer als power off stall and why
höher => propeller wash (slipstream) increases the total lift in comparison to a power-off stall => A nose high attitude adds a vertical component of the thrust which compensates for some weight
