Transcript Basic Nav tests

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Principles of Flight
Principles of Flight
Learning Outcome 3:
Know the principles of stalling
Principles of Flight
Revision
Questions
Which surfaces control an aircraft in the Rolling Plane?
a. Elevators.
b. Ailerons.
c. Rudder.
d. Tabs.
Questions
How do we “Pitch” an Aircraft?
By using:
a. Elevators.
b. Ailerons.
c. Rudder.
d. Tabs.
Questions
What may cause an imbalance in Roll?
a. Tyre Pressures uneven.
b. Rudder Not Central.
c. Wing Fuel Imbalance.
d. A heavy co-pilot!
Questions
On an aircraft with 2 wing mounted engines,
which control would be used to keep straight
if one engine failed?
a. Elevators.
b. Ailerons.
c. Rudder.
d. Tabs.
Stalling
Objectives:
1. Describe the Stall in terms of Lift.
2. State the generally used Critical or Stall
Angle of Attack.
3 Understand the relationship between Stalling and
Airspeed.
4. State where the Pilot obtains information regarding the
Aircraft’s Stalling Speed.
5. List the Factors which affect the Stalling Speed.
Stalling
It is ESSENTIAL that a Pilot understands Stalling.
During Take-Off and Landing, the Aircraft is at
Low Speed.
In Aerobatics the Aircraft experiences High “G”.
What has Stalling got to do
with these?
Stalling
Remember the Lift Formula?
Lift = CL½ ρV2S
If we slow down (reduce V) we must keep Lift the
same (for Straight & Level Flight) by increasing CL.
The Limit is CLMAX, so the Equivalent speed is
VMIN (stalling speed)
Cl Max
Lift = CLMAX½ρV2MINS
o
Crit AOA ~ 15
α
Stalling Speed
Is:
The speed at which a clean aircraft (flaps up),
At a stated weight,
With the throttle closed,
Flying straight and level,
Can no longer maintain height.
The Mechanism of Stalling
BOUNDARY LAYER SEPARATION –
Low AoA
TOWARDS LOWER
PRESSURE - FASTER
TOWARDS HIGHER PRESSURE
PLUS VISCOUS ADHESION -
“ SLOWER”
TRANSITION POINT (PERHAPS)
FROM LAMINAR TO TURBULENT
BOUNDARY LAYER
BOUNDARY LAYER SEPARATION –
Higher AoA
TOWARDS LOWER
PRESSURE - FASTER
TOWARDS HIGHER PRESSURE
PLUS VISCOUS ADHESION “MUCH SLOWER”
SEPARATION POINT
BOUNDARY LAYER SEPARATION – Wing
Stalled
TOWARDS LOWER
PRESSURE - FASTER
SEPARATION
COMPLETE
Factors affecting stalling speed
Aircraft Weight
EFFECT OF WEIGHT
Lift HEAVY WT = CL MAX½ ρ V2 HEAVY STALL S
Lift BASIC WT = CL MAX½
ρ V2 BASIC STALL S
EFFECT OF WEIGHT
Lift HEAVY WT
Lift BASIC WT
CL MAX½ ρ V2 HEAVY STALL S
=
CL MAX½ ρ V2 BASIC STALL S
EFFECT OF WEIGHT
V2 HEAVY STALL
=
V2 BASIC STALL
Lift HEAVY WT
Lift BASIC WT
LIFT HEAVY WT
X
LIFT BASIC WT
V2HEAVY STALL =
V2BASIC STALL = V2HEAVY STALL
V2BASIC STALL
LIFT HEAVY WT
X
LIFT BASIC WT
EFFECT OF WEIGHT
V2
HEAVY STALL
V STALL HVY
V STALL HVY
=
=
=
V2
LIFT HEAVY WT
X
LIFT BASIC WT
BASIC STALL
V STALL BASIC
V STALL BASIC
X
LIFT HEAVY
LIFT BASIC
X
Weight HEAVY
Weight BASIC
Factors affecting stalling speed
Pulling ‘g’
EFFECT OF ‘G’
V STALL HVY = V STALL BASIC
LIFT HEAVY
X
LIFT BASIC
SAME FOR PULLING “g”
V STALL MAN’VRE dV STALL BASIC
X
e.g. Vstall basic = 90kts,
4g loop
V STALL MAN’VRE d 90 x
4 = 90 x 2
d 180kts
“g”
EFFECT OF ‘G’
Danger
Danger
If you pull ‘g’, the stalling speed increases,
e.g. if you pull 4g the stalling speed doubles!
Danger
Danger
Factors affecting stalling speed
Engine Thrust
EFFECT OF THRUST ON STALLING
Lift
Thrust
Flight Path
Weight
EFFECT OF THRUST ON STALLING
Lift
Lift
Thrust
Flight Path
Weight
TR
EFFECT OF THRUST ON STALLING
FLIGHT PATH
Aircraft in level flight have a high nose attitude at the stall,
particularly swept wing aircraft.
If the engine is at high power - two thrust components:
1. Along flight path (countering drag).
2. Vertical (opposing weight).
Therefore less lift required from wings, so:
SLOWER STALLING SPEED (V) AT CLMAX
NATURAL STALL WARNING
Speed
Nose Attitude
Controls
Light Buffet
Heavy Buffet
Nose Drop
Wing Drop
NATURAL STALL WARNING
TURBULENT
AIR MISSING
TAILPLANE
NORMAL FLIGHT
NATURAL STALL WARNING
TURBULENT
TURBULENT AIR
AIR
MISSING
JUST
TOUCHING
TAILPLANE
TAILPLANE
STALL WARNING
NORMAL
FLIGHT
LIGHT BUFFET
NATURAL STALL WARNING
TURBULENT
TURBULENTAIR
AIR
JUST
TOUCHING
COVERING
TAILPLANE
TAILPLANE
STALL WARNING
LIGHT BUFFET
HEAVY
BUFFET
Aircraft Descending
Synthetic Stall Warning
Firefly/Tutor:
Warning Horn
Warning Light (Firefly only)
Tucano:
Warning Horn
AoA Gauge
Stick Shaker
Indexer
Typical – Stall Warning Vane
Vane held down by airflow
Vane lifted up by airflow
Micro-switch not made
Micro-switch made
No stall warning given
Stall warning given
Example of a Stall Warning Vane
EFFECT OF FLAP
Basic ‘Clean’ Situation
α
Relative Airflow
EFFECT OF FLAP
Flap Lowered
Basic
‘Clean’ Situation
α
Relative Airflow
Effective Increase in AoA
EFFECT OF FLAP
Flap Lowered
Maintaining the Same Lift
α
To obtain the same CL the Attitude is Lowered
Effective Increase in AoA
to Reduce the AoA
EFFECT OF FLAP
Cl Max
Without Flap
CL
Critical Angle
AoA
AT STALL: WEIGHT = LIFT = CLMAX ½ρ V2STALL S
EFFECT OF FLAP
Cl Max More
With Flap
Cl Max
Without Flap
CL
Nose
lower
at
Stall
Critical Angle
AoA
AT STALL: WEIGHT = LIFT = CLMAX ½ρ V2STALL S
CONSTANT
IF THIS IS
THIS IS
MORE
LESS
Stall Recovery
STANDARD STALL
RECOVERY
Move stick Centrally forward until buffet stops.
Open throttle at the same time.
Only then level the wings.
Raise nose at a safe speed and climb.
Other Factors Affecting Stalling
Ice:
Alters the ‘Shape’ of the wing, this will reduce Lift.
Damage:
Can also reduce Lift ie after a ‘Birdstrike’.
Summary of Stalling Speeds
What happens to the Stalling Speed if:
Aircraft Weight Increases:
Increase.
If we Lower Flap:
Decrease.
If we are “Pulling G”:
Increase.
If the Aircraft is damaged or had a Birdstrike, it will
probably:
Increase.
Using Engine Thrust:
Decrease.
Stalling
REMEMBER:
An Aircraft can STALL in any Attitude, level,
turning, upside-down etc.
Where would we find our Stalling Speeds?
Pilot’s Notes/Aircrew Manual etc.
Any Questions?
Stalling
Objectives:
1. Describe the Stall in terms of Lift.
2. State the generally used Critical or Stall
Angle of Attack.
3 Understand the relationship between Stalling and
Airspeed.
4. State where the Pilot obtains information regarding the
Aircraft’s Stalling Speed.
5. List the Factors which affect the Stalling Speed.
Questions
What happens to Lift when a Wing is Stalled?
a. Lift Increases as Angle of Attack Decreases.
b. Lift Decreases as Angle of Attack Increases.
c. Lift is Greatly Reduced.
d. Lift Remains unchanged.
Questions
The Critical Angle of Attack is Generally about?
a. 5o.
b. 15o.
o
c. 25 .
d. 35o.
Questions
Which of the following will NOT REDUCE the Stalling Speed?
a. Extra Weight.
b. Larger Wing Area.
c. Flaps Lowered.
d. Flaps Raised.
Questions
Where would you find the information regarding
the Aircraft’s various Stalling Speeds?
a. Pilot’s Notes.
b. Air Traffic Control.
c. Ground Crew.
d. McDonald’s.