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
-
- 1 / 373
-
Cartes-fiches
Hight speed aerofoil = thin, small Nose is sharp ==> wie ist die sepparation vom aerofil
separation occurs closer to the leading edge
Wo stallt das Flugzeug zuerst?
the wing stalls at the root first while simultaneously keeping the ailerons in clean airflow => allows the control of rolling motions
The lower the taper ratio (teh higher the taper), the higher the
The lower the taper ratio (teh higher the taper), the higher the tip stall tendency
The lower the taper ratio (teh higher the taper), the higher the
The lower the taper ratio (teh higher the taper), the higher the tip stall tendency
Vs1g ist IAS oder TAS
Vs1g ist IAS => with increasing altitude IAS doesn't change, only the TAS
Vs1g
minimum horizontal flight speed => able to maintain steady horizontal flight and remains controllable
=> engines to be idle and C.G. to be as far forward as possible
==> Horizontalflug
\(Vs1g = \sqrt{2 L (oder W)\over p * s * Cl max }\)
load factor is and expressed in?
load factor: describes the lift to weight ration ind expressed in g's ( a load factor of 2 equals 2g)
VSR
Reference stall speed => usually equal to Vs1g
VS
Vs = minimum calibrated airspeed at which an reopen remains controllable, but does not require horizontal flight
Vs1g * 94% = Vs n = loadfactor \(Vs = Vs1g * \sqrt{n }\)
Stall Warnings, 2 Arten
1. Natürliche Warnung: Schütteln = buffeting 2. künstliche Stallwarnung: elektrisch oder akustisch oder visuell
Stall warning => wann kommt die Warnung
5-10 its above the respective stalling speed
Stalling warning Staupunktschalter
=> Unterdruck oder Klappe, welche is deflected into the upward active position when von unten angeströmz
Stall Warnings: Stickshaker and stickpusher
stickshaker: beginnt zu rütteln => da man das buffeting nicht spürt Stickmuster: Wenn kritischer AOA erreicht, drückt der Stick automatisch nach vorne
load factor ist
Lift durch weight
Forward C.G. = more lift is required + stalling speed is higher => Flap?
increases the max CL and reduces the stalling speed
Cobtamination Stall?
Contamination increases stall speed and lowers the critical AOA = reduction of boundary layer => more energy due to higher friction
Stall trip ?
Stolperkante => provozieren einen Stall = man merkt vor dem richtigen Stall dass ein stall kommt => kann auch Schwankungen einbauen = Strömungsabriss am Innenflügel zuerst = bessere Wirkung der Aileron
Kurve, Stall? wie wirken wir entgegen?
Elevator back pressure is applied to keep the nose up and to increase the lift = more drag => Power must be increased => Lift alleine genügt nicht mehr => upward lift Komponente muss verstärkt werden durch thrust
In der Kurve kommt der Load factor ins Spiel, wie rechen wir diesen aus?
n = L/W oder \(x = { 1 \over cos (a) }\) => Lastvielfachtes = load factor n
the mass has xy influenxe on bank angle or turn radius as it is eliminated
the mass has no influence on bank angle or turn radius as it is eliminated
Rate of turn
indication of how long it takes to turn and is expressed in degrees/second = 3 Grad/ s => 180 Turn takes one minute
The staal speed rises with increaseing x and thus with increasing y
The staal speed rises with increaseing load factor and thus with increasing bank angle
20 Grad Querrneigung
30 Grad Querrneigung
45 Grad Querrneigung
90 Grad Querrneigung
vgl. Bild
Festigkeit?
Widerstandsfähigkeit gegen Kräfte => Belastungsgrenzen = keine strukturellen Schäden
Steifigkeit
Widerstandsfähigkeit gegen Biegen, Verdrehen => Aeroplastische Effekte
Wie ist der Zulassungsfaktor für Normale (kategorie)
+ 2.5 bis -1.0 Load factor
Skidding turn
centrifugal force is too great and tends to throw the be toward outside of the turn ==> bank angle must be increased by deflecting the ailerons into the direction of the turn to counteract the centrifugal forces caused by lift
slipping turn
bank angle is too steep for the rate of turn => centrifugal force is too weak = unbalance the equilibrium = slips into a turn = reduce rthe bank angle by using the aileron opposite to the turn's direction = increases centrifugal forces
Short period
Time to dump to half amplitude => quickly dampend to almost zero
Phugoid
Long period oscillations => significant variations in both the airspeed and altitude => slow change in pitch by equally slow change in pitch by equally slow changes in airspeed ==> AOA a each instant along the flight patch is constant
A aircraft with too high stability has xy manoeuvring and vice versa => reasonable balance between stability and manoeuvrability
A aircraft with too high stability has poor manoeuvring and vice versa => reasonable balance between stability and manoeuvrability
Sweepback Wing wo beginnt stall
The wingtips will first stall = tendency to pitch up when stalling and it will lead to deep stall => If horizontal tail is in the turbulent air flowing => it will lose efficiency = not able to get out of the stall
The short period oscillation should always be xy damped
The short period oscillation should always be heavily damped
Decreasing sweepback xy stall speed
Decreasing sweepback descreases stall speed
A lower weight means lower stalling speed, but the stalling angle is
is a property determined by the profile => not dependent on weight
Extending the trailing edge flapes during flight from Take off position to fully down will result in (Lift / Drag ?)
a small increases in lift and a large increase in drag
The Nacelle
der Flugzeugrumpf
which boundry layer produces more friction drag
A turbulent boundry layer produces more friction drag than a laminar on
Wing fence?
prevents the outward drift of the boundary layer and thus reduces the tendency to tip stall = allow to fly a higher AOA
The lowest value of wing lifft occurs (WO CG und Thrust)?
Aft C.G. and take-off thrust
