ADMIX
admix
admix
Kartei Details
Karten | 90 |
---|---|
Sprache | English |
Kategorie | Physik |
Stufe | Andere |
Erstellt / Aktualisiert | 08.12.2016 / 15.09.2022 |
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The CI-alpha curve of a positive cambered aerofoil intersects with the vertical axis of the
CI-alpha graph:
above the origin.
CI alpha curve - positive cambered aerofoil... above the origin.
Considering a positive cambered aerofoil, the pitch moment when CI=0 is:
negative (pitch-down).
CI = 0, positive cambered aerofoil = negative.
The critical angle of attack:
remains unchanged regardless of gross weight.
Critical AoA bleibt unverändert ohne Rücksicht auf das grobe Gewicht.
When the lift coefficient CI of a symmetrical aerofoil section is zero, the pitching moment is:
zero.
CI of a symmetrical aerofoil section 0 = pitching moment is also 0.
When lift coefficient CI of a negatively cambered aerofoil section is zero, the pitching moment is:
nose up (positive)
negatively cambered aerofoil = pitching moment positive!
The LIFT FORMULA can be written as:
L = CL * 1/2 rho * V² * S
L = CL * 1/2 rho * V² * S
Which of the following variables are required to calculate lift from the lift formula?
Dynamic pressure, lift coefficient and wing area.
Zur Berechnung des Auftriebformels benötigen wir:
Dynamic Pressure, lift coeffiecient and wing area.
Assuming standart atmospheric conditions, in order to generate the same amount of lift as altitude is increased, an aeroplane must be flown at:
a higher TAS for any given angle of attack.
Unter Berücksichtigung der Standart Atmosphäre, zwecks Erzeugung der selben Summe des Auftriebs wobei die Höhe steigt, muss das Flugzeug mit
einem höheren TAS zu gegebenen AoA fliegen.
Regarding the lift formula, density doubles, lift will
also double.
density ~ lift
Bsp: Dichte verdoppelt = Auftrieb verdeoppelt sich auch.
Regarding the lift formula, if airspeed doubles, lift will:
be 4 times greater.
Airspeed double - lift 4times greater.
Airespeed verdoppelt sich, Auftrieb vervierfacht sich.
If the lift generated by a given wing is 1000 kN, what will be the lift if the wing area is doubled?
-> lift: 2000 kN.
Wing area doubles, lift doubles.
If the wing area is increased, lift will
increase because it is dircetly proportional to wing area.
Lift ~ wing area.
(proportional)
AIRSPEED : AERODYNAMIC FORCE:
If the airspeed doubled, whilst maintaining the same control surface deflcetion the aerodynamic force on this control surface will:
becomes 4 times greater.
Airspeed 1 : Aerodynamic force 4.
The lift coefficient CI versus angle of attack curve of a symmetrical aerofoil section intersects the vertical axis of the graph:
at the origin.
curve of a symmetrical aerofoil section = at the origin
The lift coefficient CI versus angle of attack curve of a negatively cambered aerofoil section intersects the vertical axis of the graph:
below the origin.
curve of a negatively cambered = below the origin.
The lift coefficient CI versus angle of attack curve of a positively cambered aerofoil intersects the horizontal axis of the graph:
to the left of the origin.
curve of a positively cambered = to the left of the origin.
Regarding a positively cambered aerofoil section, whicht statement is correct?
The angle of attack has a negative value when the lift coefficient equals zero.
A nose down pitching moment exists when the lift coefficient equals zero.
positive cambered aerofoil section:
NEGATIVE value AoA
A nose down pitching moment.
Regarding a symmetric aerofoíl section.
The angle of attack is zero when the lift coefficient eqauls zero.
The pitching moment is zero when lift coefficient equals zero.
symmetric aerofoil section:
AoA is zero, when CI = 0
Pitching moment is zero, when CI = 0.
The correct drag formula can be written as:
D = CD 1/2 RHO V²* S
Widerstandsformel:
D = CD 1/2 RHO V²* S
The polar curve of an aerofoil is a graphic realtion between:
CL and CD
CL and CD
"Lift and Drag"
The frontal area of a body, placed in a certrain airstream is increased by a factor 3.
The shape will not alter. The aerodynamic drag will increase with a factor 3.
airstream 3 : drag increase 3.
Aerodynamic drag:
A body is placed in a certrain airstram. The airstream velocity increases by a factor 4. The aerodynamic drag will increase with a factor : 16!!
airspeed 4 : aerodynamic drag 16
density of airsream decreases to half:
A body is placed in a certrain airstream. The density of airstream decreases to half of the original value. The aerodynamic drag will increase with a factor: 2!
density airspeed halbiert = aerodynamic drag verdoppelt.
The aerofoil polar is:
a graph of the realtion between lift coefficient and drag coefficient.
aerofoil polar = graph lift and drag coefficient.
When an aircraft with a typical aerofoil is in level flight at low speed and high angle of attack, the normal axis is:
nearly vertical.
low speed, high AoA = normal axis nearly vertical
comparing the lift and drag coefficient for convential aeroplanes:
CL is much greater than CD.
CL > CD!
Increasing dynamic pressure will have the following effect on the total drag of an aeroplane:
at speeds above the minimum drag speed, total drag increases.
increasing dynamic pressure at speeds above minimum drag speed, total drag increases.
Increasing air destiny will have the following effect on the drag of a body in an airstram
(angel of attack and TAS are constant):
Drag increases.
increasing density = increasing drag.
Minimum Drag of an aeroplane in straight and level flight occurs at the:
maximum CL-CD ratio.
Minimum Drag : maximum CL-CD ratio
Variables Drag Fromula:
Which variables are requirede to calculate drag from the drag fromula?
Dynamic pressure, drag coefficient and wing area.
relevatn variables for drag formula:
dynamic pressure, CD, Awing
A positive cambered aerofoil generates zero lift:
at a negative angle of attack.
Positiv cambered airfoil + negative AoA = zero lift!
Assuming ISA Conditions, and no compressibility effects, if an aeroplane maintains straight and level flight at the same anlge of attack at two different altitudes, the:
TAS is higher at the higher altitude.
different altitudes, same AoA: higher TAS at higher altitude.
Assuming ISA Conditions, and no compressibility effects, if an aeroplane maintains straight and level flight at the same anlge of attack at two different altitudes, the:
IAS is the same at both altitudes.
two different altitudes, same AoA = IAS is the same.
Assuming ISA Conditions, and no compressibility effects, if an aeroplane maintains straight and level flight at the same anlge of attack at two different altitudes, the:
TAS is lower at the lower altitude.
Altitude ~ TAS
An Aeroplanes AoA is the angle between:
speed vector and lonitudinal axis.
AIRPLANES AoA is between:
speed vector and lonitudinal axis.
Which of the following planforms gives the HIGHEST local profile lift coefficient at the wingroot?
Rectangular
Highest lift coefficient = Rectangular!
The fundemental difference between the areodynamic charecteristics of two and three-dimensional flow is that, in a three-dimensional flow about a wing:
a spanwise component exists in addition to the chordwise speed component.
in 3-D: a spanwise component + chordwise speed component!
flow on the upper surface:
The flow on the upper surface of the wing has a component in wing root dircetion.
flow above the wing has a component in wing root direction.
Airplane accerlerates from 80 to 160 with load factor 1.
The induced drag coefficient alters with factor 1:16
and induced drag with factor 1/4.
Acceleration: doubles
CDi: 1/16
Di 1/4
increasing AR on induced Drag:
it is reduced because the effect of wing-tip vortices is reduced.
increasing AR # decreasing induced Drag.