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AE-705 Introduction to Flight Lecture No. 13 Chapter-07
AE-705: Introduction to
Flight
Udit Vohra
Aerospace Engineering Department
PEC University of Technology, Chandigarh
GLIDING
CLIMBING
CEILING
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
• Gliding Flight
• Climbing flight
• Operative Ceilings
Layout
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
Art of silent flight
Flight without any Thrust
What is gliding flight ?
Forces involved in gliding flight
Smallest value of θ gives the
flattest glide
W
Horizontal
θ
θ
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
Range in a Glide
• Range = distance traversed by an aircraft
Range when θ or ( L D)max
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
• Sink Rate = rate of reduction in altitude = dh
dt
• Min. sink rate max endurance
• V =2WCosθ
CLρS
•dh
dt= -Vsinθ = -
2WCosθ
CLρSCosθ (
1
𝐿 𝐷)
Sink Rate during Glide
From L = 1
2ρV2SCL = WCosθ
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
Min. Sink Rate
𝐝(dh/dt)𝐝𝐂𝐋
= 0
dh
dt= - 2W
ρS( CD
CL 3 2 )
dh
dt= -Vsinθ = -
2WCosθ
CLρSCosθ (
1
L D)
L
D=
CL
CD
Cosθ~ 1
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
Sink Rate of Schweizer SGS 1-26 Glider
http://www.5c1.net/Glider%20Performance%20Airspeeds.htm
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
Maintain Altitude in the air
Without flapping wings or engine power
Gliding & Soaring
Three methods of launching
Winch launch Aerotow Motor Gliding
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
What can happen when engine fails?
Certainly this is not
going to happen
So what else
can happen
The aircraft can
glide…
Lets see how
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
AIR CANADA 143
https://www.youtube.com/watch?v=oKbpR28l9xM
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
CLIMBING FLIGHT
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
Climb
position
A320 Thrust
levers
https://www.google.com/search?q=thrust+levers+a320&source=lnms&tbm=isch&sa=X
&ved=0ahUKEwjg6MXJ-MHUAhVCO48KHdX9D_8Q_AUIBigB&biw=1570&bih=748
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
Some Important Considerations
Aerodynamics of climbing flight differs from gliding flight
Thrust comes into consideration
Climb differs for different a/c
Depends on engine type
http://amileofrunway.blogspot.in/2015/07/hang-gliding-over-new-zealands.html
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
ENGINE RATINGS
MTT MCT MCL MCR
max thrust that the
engine can deliver
for five minutes at
standard SL
atmosphere
maximum thrust
certified for en-
route climb
maximum thrust
that the engine
can deliver with no
time limit
thrust allowable
for unlimited flight
duration at the
design altitude
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
EQUATIONS OF MOTION
φ
φ
T
D
L
W
Forces involved in climb
horizontalClimb angle
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
• (R/C) is the vertical component of the TAS
• Affected by the climb angle
sin φ = (T – D) / W
R/C = TAS · sin φ
φR/C
TAS
Steady Climb
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node100.html
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
Typical Climb Profile for Transport Jets
The climb at a const. IAS until a certain MACH
Climb is continued at const. MACH no
Climb profile for an A320 is:
Below FL100
(due to ATC) Above FL100 until
reaching M.78
(crossover altitude)
Until the end of
climb
250kt / 300kt / M.78
CLIMB AT CONSTANT IAS/MACH
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
First part of the climb (const. IAS), TAS as the aircraft climbs
Second part of the climb (constant MACH), TAS as the aircraft climbs
TAS
Theoretical R/C
TROPOPAUSE
25%
9%
30%
R/C
PA PA
Real R/C
Two parts of Climb
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
Why Planes fly at a specific altitude?
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
CLIMB AT MAXIMUM ANGLE SPEED
altitude to be reached over the shortest distance
CLIMB AT MAXIMUM R/C SPEED
altitude to be reached within the shortest time
http://www.experimentalaircraft.info/flight-
planning/aircraft-performance-3.php
Climb Speeds
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
TAS
R/CVx : Best Climb angle speed
Vy : Best R/C speed
VyVx
Vx v/s Vy
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
As an aircraft climbs TAS Drag & R/C
Results in a long and inefficient climb
% Climb
capabilityFL330
IAS
FL290
FL250
FL200
100
90
80
70
60
50
CLIMB AT CONSTANT IAS
Climb Speeds
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
TAS
POWER
VxP VyP VxJ VyJ
Power vs. TAS
max diff. for piston
Max diff. for
jet
Min power req (piston)
Min power req
( jet)
power required
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
Vx = Best Angle of Climb Speed
Vy = Best Rate of Climb Speed
Vx < Vy
Vx ( jet) > Vx (piston)
Vy ( jet) > Vy (piston)
Vx and Vy change with altitude !
Important Points
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
Optimum Climb Speed (OCS)
In terms of efficiency and operative costs
Usually higher than the best R/C speed (Vy)
Factors affecting OCS:
OCS ↑ when weight ↑
Fuel price ↑ OCS ↓
Maintenance and crew costs ↑ OCS ↑
Why ? Find out yourselves and upload on Moodle !
Optimum Climb Speed
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
Altitude gain per 100ft of horizontal distance
Ratio of horizontal distance to vertical distance
Climb gradient is affected by wind
Climb gradient is improved with a headwind and reduced with a
tailwind
Climb Gradient
http://slideplayer.com/slide/1540042/
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
Climb gradient ↓
Pressure Altitude ↑
Rate of climb ↓
Climb gradient ↓
Temperature ↑
Rate of climb ↓
Climb gradient ↓
Weight ↑
Rate of climb ↓
How does it
happen ?
Find out
yourself..!!
Report on
Moodle
Factors Affecting Climb
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
Impractical to perform a continuous and slow climb during Cruise
ATC !!
Why ??
Solution – Step Climb
Step Climb
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
Ceiling is the altitude at which R/C has reached some minimum value
What is a Ceiling ?
Absolute
Service Combat Design
Propulsion
Based on
R/C Based on Propulsive and structural
properties
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
Ceiling is the altitude at which R/C has reached some minimum value
What is a Ceiling ?
Absolute
Service Combat Design
Propulsion
Based on
R/C Based on Propulsive and structural
properties
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
ABSOLUTE CEILING
The aircraft cannot climb above the absolute ceiling
It is determined by the aerodynamic & propulsive properties of the aircraft
R/C = 0
Operative Ceiling
http://www.boldmethod.com/learn-to-fly/performance/vx-vy-altitude-and-where-they-meet/
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
PROPULSION CEILING
The altitude that the available thrust provided by the engines permits to reach
It is usually lower than the absolute ceiling
SERVICE CEILING
At this altitude the aircraft has a maximum ROC of 100 fpm
DESIGN CEILING
Maximum altitude that the aircraft can reach due to structural limits
Other Ceilings
We will see this later on
in V-n diagram
AE-705 Introduction to Flight Lecture No. 13 Chapter-07
Absolute ceiling: R/CMAX = 0 fpm
Service ceiling: R/CMAX = 100 fpm
Cruise ceiling: R/CMAX = 300 fpm
Combat ceiling: R/CMAX = 500 fpm
Combat ceilings are basically
meant for highly maneuverable a/c
Eg – MiG 29, F-16
http://joeclarksblog.com/?p=2929
Ceilings based on max R/C