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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Cartes-fiches
The units of a turning moment are
Newton x meters.
Boundry Layer
the layer where surface friction influences the speed
What is the name of the point, where the laminar to a turbulent changes?
Transition point
What you can say about the turbulent boundry layer
=> greater thickness because the oscillating particles incorporate more outside air into the boundary layer
=> a sharper speed change near the surface
=> higher speed = higher skin friction drag
Where is the max. speed reached? (boundry layer)
at the obstacle's thickness
Form drag
Airflow separaion occurs, when the lower levels of the boundary layer do not have sufficient kinetic energy and the static pressure along the flow increases
=> Form drag = the airflow separates, it is much higher than friction drag
Profile Drag
D Profil = Dform + Dskin friction
Do its lower kinetic energy, the airflow seperates more easily than by a xy boundry layer
turbulent
Average chord
or mean geometric chord => geometric average of tip chord and root chord
A swept back wimh has a higher CL towards its tips. a rectangualr wing?
A rectangular wing has its highest CL at the root
For an aircraft flying at a constant IAS
the drag will be the same at altitude as at sea level
Which of the following will reduce induced drag?
Elliptical lift distribution.
perpendicular
rechtwinklig
If the landing gear is lowered
total drag increases, and Vmd decreases
the aspect ratio
Low aspect ratio increase induced drag => Länge / Breite => kleine Breite 1/2 grosse Breite: 1/5 => low aspect ratio = higher induced drag
The relationship between induced drag and the aspect ratio is:
a decrease in the aspect ratio increases the induced drag.
The induced angle of attack is the result of:
downwash due to tip vortices.
Which statement concerning the local flow pattern around a wing is correct?
By fitting winglets to the wing tip, the strength of the wing tip vortices is reduced which in turn reduces induced drag.
Wing tip vortices cause
downwash behind the wing and an upwash outside the wing tips
the magnitude
die Grösse
The induced drag:
ncreases as the lift coefficient increases.
At high altitudes, what happens with the AOA ?
high altitudes the TAS is greater => this leads to a smaller AOA
At high altitudes, what happens with the dynamic stability?
the dynamic stability decreasing at high altitudes because the damping is reduced => higher TAS => grössere Kraft bei Seitenwind => Rückführende Kraft ist keliner
Aerodynaic centre A.C. of the aerofoil
or neutral point of the aerofoil => the increasing lift is compensated by the shorter moment arm ==> C.G. would be ahead of the wings aerodynamic centre = moment is negative => aeroplane static longitudinal stability
Static Directional Stability => wind comes from right, hat happens
a yawing moment to the right should be created which tends to return the nose into the relative wind
Dorsal Fin?
front of the vertical tail => develops at the dorsal fin which increases the boundary layer anergy => called a strake
A Ventral fin
on the bottom of the fuselage => Increases the fin area and has its greatest effect when flying at high AOA
At a high AOA a decrease in static directional stability of teh aeroplane can be anticipated => it is a results of what?
a result of the reduced contribution (Beitrag) of the vertical tail => Therefore jet fighters are equipped with twin fins
To reduce the effect of seperated fuselage airflow at high AOA flight, some aeroplane are eqipped with ?
with strakes or vortex generators at the forward fuselage => create energies the fuselage's boundry layer thus reducing airflow separation
What increases the lateral stability?
1.) high wing position => creates positive lateral stability
2. dihedral of teh wings => increase in lift at the wing taht is directed towards teh wind in a sidelip => During a sideslip te downward pointing wing is under higher AOA => Higher lift acting
Influence of Wing Sweep, Vertical Tail, Dorsal and Vetral Fin, T-Tail
=> improves lateral stability => the produce a restoring moment during sideslip situation because their C.P. is above the longitudinal axis
When one engine fails, teh lift distribution along the wing span becomes?
asymmetrical
Which one is teh critical engine by a 2 piston aircraft?
the left. because a clockwise rotating propeller creates more thrust at its right hand side with the down going blade => a greater yawing moment is produced when the eft engine fails
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
