gliding climbing ceiling

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


• Gliding Flight

• Climbing flight

• Operative Ceilings

Layout


GLIDING FLIGHT


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


Range in a Glide

• Range = distance traversed by an aircraft

Range when θ or ( L D)max


• 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


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


Sink Rate of Schweizer SGS 1-26 Glider

http://www.5c1.net/Glider%20Performance%20Airspeeds.htm

Glider Flight, Schweizer 1-26.mp4


Maintain Altitude in the air

Without flapping wings or engine power

Gliding & Soaring

Three methods of launching

Winch launch Aerotow Motor Gliding

Glider Winch Launch.mp4

AeroTow.mp4

STEMME Sky Sportster S6.mp4


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


AIR CANADA 143

https://www.youtube.com/watch?v=oKbpR28l9xM

C:/Data/dee/official/acads/aactive_sem/AE705/lectures/Capsule 07_Perfo_Climb_Turn/Lect13_Climbing_Ceilings/Gimly Glider.mp4


CLIMBING FLIGHT

http://www.airliners.net/open.file?id=780915&size=L&sok=JURER (ZNGPU (nvepensg,nveyvar,cynpr,cubgb_qngr,pbhagel,erznex,cubgbtencure,rznvy,lrne,ert,nvepensg_trarevp,pa,pbqr) NTNVAFG ('+"777"' VA OBBYRNA ZBQR)) beqre ol cubgb_vq QRFP&photo_nr=23


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


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


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


EQUATIONS OF MOTION

φ

φ

T

D

L

W

Forces involved in climb

horizontalClimb angle

Climbing.mp4


• (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


TAS

DRAG

DMIN

THRUST (JET)

Drag vs. TAS


http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node100.html

http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node100.html


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


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


Why Planes fly at a specific altitude?

Why Do Planes Fly So High.mp4


CLIMB SPEEDS


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

Max angle climb vs ROC.mp4


TAS

R/CVx : Best Climb angle speed

Vy : Best R/C speed

VyVx

Vx v/s Vy


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


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


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

Why Vx & Vy Change With Altitude.mp4


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


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/


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


Impractical to perform a continuous and slow climb during Cruise

ATC !!

Why ??

Solution – Step Climb

Step Climb


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


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/


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


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


SUSTAINED LEVEL TURN + PULL UP

Next Class on Wednesday 4th October

gliding climbing ceiling

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