Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

POF > Stalling > Flashcards

Stalling Flashcards

1
Q

Reducing IAS does what do CL

A

CL need to increase to maintain level flight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Straight Wing Stall

A

Distinct Symptoms (nose drop/buffering)

  • Lift reduces
  • Total drag much greater from large increase in form drag
  • CP moves aft
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

You stall what you gonna do

A

REDUCE AOA
DO NOT USE AILERON OR RUDDER UNTIL YOU UNSTALL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Factors Contributing To Wing Drop

A

Manufacturing differences between each wing
Small Lateral imbalances in lift prod
Loss of lift at tip rather than root (moment)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Ellipetical Wing Stall Category

A

Same vortex spanwise = same downwash spanwise
All area of wing working equally as hard

! Sudden stall - controls become ineffective quickly
! Large roll rates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Stalling With Tapered Wings

A

Mid section vortex least so least downwash here (greatest EAOa at mid section)
Stall starts in mid section
Not as bad as Ellipetical wing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Stall With Swept Wing

A

Less vortices at tip - EAOA greatest at tip
Tip will stall first
CP moves forward and inwards
AC pitches further up (Deep stall)
Increased Downwash on tailplane adding to the deep stall conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Deep Stall

A

Wake of wing impinges tail surfaces making them ineffective

Worse on high T tail planes
A/C with sweepback wings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Anti Stall Devices

A

Vortilon - Generate vortex to help spanwise flow
Wing Fence - Physical barrier to spanwise flow
Reduce camber/washout towards tip to reduce local CL and prevent tip stall
Cross Section - Thicker more progressive inboard stall
Nacelle Stakes - Located on engine tight vortex to reenergise
Stall Strips - Used on tip to sharpen LE at root

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Wing Loading on stall speed

A

Greater Wing Loading = Higher Stall Speed
Lower Wing Loading = Lower Stall Speed

Weight/area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Flaps/Slats on Stall Speed

A

CLMAX increased + VS speed decreases
LE - Increase stalling Angle
TE - Reduce Stalling Angle
Slates/Slots - Increase delaying flow separation to higher AOA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Measures to delay flow separation

A

Vortex Generators
Engine nacelle strakes (lift vanes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Sharper vs Larger radius leading edge

A

Sharper LE the tighter the radius of turn more energy consumed

Large radius from LE less energy loss by flow

Stagnation point moves backward onto underside of aerofoil as alpha increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Critical Angle Of Attack

A

Highest achievable AOA before the stall
No the actual stall
Maximum lift produced at the critical angle
AC will always stall at the same critical angle of attack

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Aspect Ratio on stalling angle

A

High aspect ratio produces same lift with less span wise flow/less downwash = shallower effective airflow

High aspect ratio the effective angle of attack = low wing angle of attack

Low aspect ratio produces more span wise flow and more downwash for same lift = small effective angle of attack and therefore stalling angle of attack is much larger

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Rectangular Wing on stalling

A

Stalls at the roots first then the tips

Shallower effective airflow at wing root produces a greater effective angle of attack and therefore stalls first

Spread from root to the tip as alpha increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Why does a sweep back wing pitch up at the stall

A

Wings CP moves forward and inwards
Increased downwash on horizontal stabiliser (inner wing has to produce more lift increasing downwash airflow onto tail)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

CS25 Stall Criteria

A

Nose down pitch that cannot be readily arrested
Buffeting of magnitude to deter further speed reduction
Pitch control reaches aft stop no more pitching

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Deterrent Buffet

A

Point at which buffet becomes a strong and effective deterrent

Vertical accelerations of 0.5g+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Engine nacelle (Lift vanes)

A

Reduces upwash ahead of wing delaying onset of seperation locally in area of wing influenced by nacelle

Create large vortex over upper surface which reenergises boundary layer locally delaying separation to high alpha

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Cross section on stalling

A

Sharper thinner leading edge stalls more sudden (high-speed wing)

High-thickness chord ratio with greater leading edge has a more gradual stall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

VS1

A

Minimum steady flight speed in obtained config

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

VS0

A

Stall speed in landing config

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

EASA regs for MEP aircraft in class B

A

VR = 1.1vs1
T/O Screen = 1.2vs1
L/D(vref) = 1.3vs1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
EASA regs for stall speeds in class A
VR = 1.1vs1 VSRI (T/O Screen) = 1.13VSR1 VSRD (Landing) = 1.23VSRD 10% 13% 23%
26
EASA C25 Reg for stall warning speed
VSW must be 5kt or 5% greater
27
What happens towards the stall
AOA is increasing Stagnation point moving rearward Kinetic energy airflow over the wing is reducing Seperation point moving forward Adverse pressure gradient increasing
28
What causes a swept wing to pitch up at the stall
Roots are having to generate more lift are tips have stalled More downwash on tailplane Increasing AOA on horizontal tailplane Increased downforce Causing nose to pitch up
29
Swept wing “pitch up” phenomenon
Cp moves forward with AOA Beyond critical AOA CP continues to move forward due to swept wings stalling at tips Further nose up pitch
30
Centre of pressure of straight wing at stall
CP moves forward with AOA Beyond critical AOA the CP moves aft Nose down pitch moment
31
Swept Wing CP movement at stall
Swept wing moves forward with AOA Beyond critical AOA keeps moving forward Further nose up pitch
32
Common method to reduce tip stalling
Modify cross section Washout and reduced camber at tips to reduce local CL
33
Landing Gear effect on stall speed
Extension increases stall speed Creates a drag force which forms an arm with CG causing a nose down pitching moment Increased downforce produced by tailplane the counter so more lift needed Speed needs to be increased
34
Where are stall speed determined
With the least favourable cg position. The most forward cg limit This leads to downwards force which needs to be compensated for Higher stall speed at aft cg
35
How are minimum controls speed determined (conditions)
Cg on aft limit will provide small arm and least ability to oppose yawing moments on engine failure
36
Flapper Switch
Mounted on LE - on/off device that activates audio warning when AOA exceeds set value Works by: AOA increasing stagnation point moves down and aft once stagnation point is behind flapper switch airflow pushes flapper switch into its up position
37
AOA Vane
Pivots around its own axis to align with airflow Angle is detected relative to longitudinal axis electrically Processed by computer to give a calculated wing AOA and provide continuous display of aoa and trigger warning on approach to stall
38
Fixed Prob Stall warner
Two ports which measure pressure When aoa increases airflow into each port differs Different pressure sensed at each port sent to computer to determine AOA Works even if pitot tube freezes
39
Rotating Probe
Probe with two ports that rotates to null out pressure difference at both ports. Orientation is then measured by computer to calculate wing AOA.
40
Stick Shakers Role
At computed AOA stick shaker forcefully vibrate control yoke to stimulate light buffet in ac with no natural buffet Operates until pilot reduces AOA
41
Low Mounted Engine hazards at the stall
Below ac CG therefore full power at the stall could pitch up
42
CS23 Stall Measured by
Engines at idle/throttle closed CG at max stall speed - forward limit and max mass
43
Vr
Speed at which pilot begin to apply control input on T/O 1.1 x vs1
44
VToss (50ft)
Speed you must be at 50ft after take off 1.2 x VS1
45
VREF
Landing speed 1.3 x VS0
46
Minimum speed at 35ft after take off on CS25
1.113 x VSR1
47
Minimum landing speed C25
Referred to as Vref 1.23 x vs0
48
CS23 Single engine Vr speed
For must not be less than VS1
49
CS23/25 rules for stall warning speeds
Must be activated 5kt or 5% above relevant stall speed and operate until above the limit
50
Airbus 3 AOA protection systems
Alpha protection Alpha Floor Alpha Maximum
51
What do you do if you experience buffeting after lowering the flaps
Return flaps to previous setting
52
Vne
Never exceed speed used on smaller ac - CS23
53
Vmo
Maximum operating speed/maximum operating Mach number - used on cs25
54
Vmc
Minimum control speed - calibrated airspeed of ac below which directional or lateral control of ac can no longer be maintained after failure of one engine. Maintain straight flight with bank angle of no more than 5 degrees with max thrust on engine
55
Vmca established conditions
Max take off power Aeroplane trimmed for takeoff Unfavourable CG position Max seal level take off weight Critical take off config (gears ups) Ground effect negligible
56
Washout
To stall the root first
57
3 AOA protections in normal Law of a320
Alpha protection Alpha floor Alpha maximum
58
Power increase from idle in stall will do what to clmax and the stall speed
CLMAX unchanged Stall speed will decrease
59
Angle of sweep on stall speed
Swept wing less efficient at producing lift than straight wing therefore as cl decreases speed must increase. Decrease in clmax from swept wing increases the stall speed
60
Vortilons
Fixed aerodynamic devices on ac winds to improve handling at low speed - energises the boundary layer over the wing turbulent flow Usually fitted under the wings leading edge Help improve aileron performance at high AOA also
61
What does weight do to critical alpha
No effect on critical alpha only the design of the wing will change the critical alpha

POF (25 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions