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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Flashcards
Tailplane
horizontal stabilizer
If the increased downwash at the tail plane due to extending trailing edge flaps is considered in isolation:
a nose up pitching moment will be generated
Negative tail stall
when a negative tail stall occurs, the aeroplane will show uncontrollable pitch down moment
Which aeroplane configuration together with icing increases teh risk of tailplane stall
extended trailing edge flaps
What us the aeroplanes pitch changing tendeny when entering the ground effect ?
reduced downwash creates nose-down moment
what is the only influence on the load factor in a coordinated turn
bank angle
Taper Ratio
the tip chord divided by the root => A tapered wing will have a smaller chord at the tip than at the root
The transition point located on the wing is the point where
The boundary layer changes from a laminar flow to turbulent flow
The deceases downwash upon entering the ground effekt gives:
a) increase in the effective angle of attack => b) reduces the induced angle of attack
c) Smaller induced angle of attack => deacreas in induced drag
Aspect Ratio of a wing
ratio between wingspan and the average chord = mean geometric chord
Wing area: wingspan multiplied by average chord
==> high aspect ratio = long, narrow wings
==> low aspect ratio = shirt, stubby wings
Converging streamlines means:
higher flow velocity and lower static pressure
Damping of the phugoid is normally very xy
Damping of the phugoid is normally very weak
Normale Reihenfolge: manoeuvre point, CG, neutral point
CG, neutral point, manoeuvre point
A swept wing has an increased tendency to stall first near the ?
A swept wing has an increased tendency to stall first near the tips => Loss of lift at the tips moves the C.G. forward, gives a nose up pitching moment
Vortex generators
Vortex generators are rows of small, thin aerofoil shaped blades which projects vertically into the airstream => free stream flow of high energy air to mix with and add kinetic energy to the boundary layer => The higher energy level delays the boundary layer separation and thus the stall.
1) The lift and drag forces, acting on a wing cross section:
depend on the pressure distribution about the wing cross section
) Aspect ratio of a wing is the ratio between:
Aspect ratio of a wing is the ratio between: wing span squared and wing area
9) When trailing edge flaps are extended whilst maintaining straight and level flight at constant IAS:
C.p.??
the centre of pressure moves aft
10) During a flight when the trailing edge flaps are lowered to the fully extended position:
the wing CP moves aft and the L/D ratio decreases
12) With changing weight of the aircraft in turn
weight has no affect on the turn radius
13) For an aircraft with a right hand propeller, the slipstream rotation will cause:
yaw to the left
14) Why is a propeller blade twisted from root to tip?
To maintain a constant angle of attack along the whole length of the propeller blade
15) With a constant speed propeller, which of the following statements is true?
Pitch angle increases with increasing TAS
16) A windmilling propeller produces more drag than
16) A windmilling propeller produces more drag than a feathered propeller.
C-G.?
22) CG: point, at which the weight acts
23) Torque effect Propeller
23) Torque effect: 90° in Propellerdrehrich
An aeroplane is said to neutrally stable. This is likely to:
be caused by a centre of gravity, which is towards the rearward limit => the aft limit of C.G. is always forward of the neutral point
augment
vermehren
Propeller resultant force is => and was passiert mit dem Propeller?
1. Thrust 2. tangential force ==> Thrust bending and centrifugal force
was ist was
0. Relative airflow/Speed=> sum of the flight speed (TAS) vector and rotational speed vector 1. TAS 2. AOA (rel. Airflow zu Chord) 3.Helix ( Angle between the rotational speed and rotation speed vector) 4. Pitch angle (Angle rotation speed and Chord)
Geometric Pitch? Effective Pitch? Slip?
Geometric: Should advance in one revolution (theoretical) Effective: actually Slip: Difference
Windmilling propeller
failed engine => not stop => driven by the airflow => result is negative AOA => negative thrust(Drag) and negative tangential (IF force is lower than the engine internatial friction = stops)
Propeller blade twist => wie ist der Propeller aufgebaut
Root ist er Dick und AOA ist gross => AOA wird gegen aussen immer kleiner und V schneller => Optimum 75%
WO ist die Rotation speed höher beim Propeller? Optimum?
Blade tip ; An irgend einem AOA highest trust => Muss man schauen, dass AOA from the blade root to the blade tip ist gleich ==> Pitch angle is high at the root and low at the blade
Propeller werden in 2 Gruppen aufgeteilt
bild
Fixed pitch propeller ? Efficiency?
Propeller Pitch cannot be change d during engine operation => Propeller efficiency is low because the AOA is higher than the optimum AOA => reduction in TAS increases the Propeller AOA and drag; At low speed er hat einen zu grossen AOA für diese V
Propeller efficiency
ratio between propulsive power (Power available) to the BHP of the engine
To provide ineciency of a fixed propeller ? what can we do?
Low pitch for T/O = high trust during T/O and claiming High Pitch for Cruise
Verschiedene Untergruppen der Variable Pitch propeller
bild
efficiency of teh variable pitch propeller
Even with the optimum AOA efficiency is not constant over TAS Because OF => efficiency decreases at higher or lower speed
