Lecture #1

Ehsan Roohi

Sharif University of Technology

Aerospace Engineering Department

1

Definition Historical Background Parts of an Aircraft Stability Aerospace Terminology Forces on Aircraft Lift & Drag Airfoils

2

Goal

3

4

Tail Wing

Modern Ornithopter

5

Had a Fuselage, Tail, wings!

He proposed using an engine for thrust,

None available at that time.

6

Crashed and died on a flight in 1896

7

The first successful flight on December 17, 1903

8

9

10

Aerodynamics &

Performance

Stability &

Control

Propulsion

Structures

Design

11

The longitudinal axis

extends lengthwise

through the fuselage

from the nose to the tail.

Movement of the

airplane around the

longitudinal axis is

known as roll and is

controlled by movement

of the ailerons.

12

. فرام شذ است ياقع در بخش خارجی بالا( الراوا) کىترل غلتش ب يسیل شپرایشپرا، عکس یکذیگر مرد بر برداری قرار می گیروذ، بذیه ترتیب ک یکی ب سمت بالا رفت ي

دي بال، سبب اختلاف در برآ ي متعاقب آن، اختلاف در اوحىای مؤثر بر ريی. دیگری ب سمت پاییه می آیذ .ایجاد یک گشتاير غلتشی می شد

The vertical or normal axis passes vertically through the center of gravity.

Movement of the airplane around the vertical axis is yaw.

Yaw is controlled by movement of the rudder.

13

بر ری یک اپیوای هتعارف، پذالای کترل گردش ب یک رادر هتحرک هتصل ستتذ کت دتد بتر انت اى . عودی اار اات

چیي اثری یتک . عول رد رادر، ابب تغییر ض ل اطح پایذار کذ عودی ایجاد یک اطح هحی هی ضد . یری جابی پذیذ هی آرد

.یک گطتار جابی ایجاد هی کذ یری جابی،

The lateral axis extends crosswise from wingtip to wing tip.

Movement of the airplane around the lateral axis is known as pitch.

Pitch is controlled by movement of the elevators.

14

.بخص عقب دم افقی اپیوا للا ضذ تا یک بالابر را ض ل دذ .توایل بخص عقب بالابر ب اوت بالا ابب ایجاد یک احای هفی در دم افقی هی ضد

. اات( برآی هفی)یک یری ب اوت پاییي (ب ااط یری حاصل)پیر اعوال فطار بر دم افقی

. ب اوت پاییي، زای حول بال افسایص هی یابذ بابرایي، تیج ایی توایل بالابر ب اوت بالا، یک گطتار پیچطی

.اات ک ابب بالا رفتي دهاغ افسایص برآی کلی هی ضد

Elevators control pitch

angle

Ailerons control roll angle

Rudder controls yaw angle

Flaps increase lift and drag

Canard is a horizontal

control surface placed near

the nose.

15

747بییىگ

Empty Weight = What the aircraft or spacecraft weighs

when it is nominally empty (may include trapped fuel )

Fuel Weight: That required to do the mission plus

required reserves

Crew Weight: Weight of crew and associated equipment

(parachute, oxygen, etc.)

P/L= Payload Weight = Weight the aircraft was designed

to carry. (passengers weight, baggage for aircraft)

GW=Gross Weight= The nominal weight for a standard

mission before the aircraft (or spacecraft) takes off.

GW = Crew weight+ P/L + Fuel Weight + Empty Weight

16

◦ Wing Loading = Aircraft Weight/Wing Area

◦ Power Loading = Aircraft Weight/ Nominal Engine Power

◦ Aspect ratio, AR = (Wing Span)2 / Wing Area

◦ Taper ratio = Root Chord/ Tip Chord

◦ Specific Fuel Consumption, sfc = (Fuel Weight)/ (Power x Hour)

◦ Empty Weight Fraction = Empty Weight/ Gross Weight

◦ Payload Fraction = Payload Weight/ Gross Weight

22

,m

N

ft

lb

Watt

N

HP

lb,

17

The engine provides the thrust, using propellers

(piston engines or turboprop), fans (turbofans), or

high velocity jets (turbojet).

Thrust is needed to overcome drag. At steady level

flight, thrust equals drag.

If thrust does not equal drag, the vehicle will

accelerate or decelerate.

Aircraft without engines providing the thrust is a

glider, and will need other energy sources (e.g.

thermal currents) to stay aloft.

18

•These are the result of the pressure forces and viscous

forces exerted by the air molecules on the aircraft.

•The component along the flight direction is called drag.

•The component normal to the flight direction is called lift.

Viscous forces can

act both normal, and

tangential to the

surface.

Pressure Forces act normal

to the aircraft surface.

19

In steady level flight lift produced by the entire aircraft surface equals

weight.

Much of the lift is produced by the wing.

The tail surface (stabilizer and elevator) will usually produce a

downward directed lift.

If lift does not equal weight, the aircraft will climb or descend.

20

تىتا در . ویريیی عمد بر جتت پترياز : تعریف جامع ویريی برآ ب صرت زیر ارائ می شد . یک پرياز افقی یکىاخت، ویريی برآ دقیقا برابر با ویريی يزن، عمدی ي ب سمت بالاست

Lift is usually non-dimensionalized, so that geometrically similar configurations (e.g. a 1/10 scale of an aircaft and the full size aircraft) can be easily compared one to one.

The lift coefficient is defined as: where L is the lift force, S is the wing area, V is the velocity of the aircraft, and r is the density of air far upstream of the aircraft.

Two geometrically scaled models will have identical lift coefficients if they operate at identical Mach number, Reynolds number (definition later) and angle of attack (angular orientation of the aircraft relative to the direction of flight).

SV

LCL

2

2

1

r

21

It is defined as: where D is the drag force, S is the wing planform area, V is the velocity of the aircraft, and r is the density of air far upstream of the aircraft.

Two geometrically scaled configurations will have an identical drag coefficient if other conditions are identical - Mach number, Reynolds number, angle of attack.

SV

DCD

2

2

1

r

22

Mach number is the ratio between the speed of

the aircraft (relative to the ambient air, which itself

may be moving), and the speed of sound in the

ambient air far upstream of the aircraft.

a

VM

23

24

It is a measure of how strong the inertial forces (e.g. pressure forces) acting on a fluid particle are, compared to the viscous forces acting on it.

It is defined as:

Here r is the density, V is the velocity, L is any characteristic length of the vehicle. Also, m is the viscosity of the fluid, a fluid property.

m

r LVRN

25

26

2 .تحت عىان فشار دیىامیکی شىاخت می شد کمیت

2

1Vr

. تلیذ یری برآ، تیج ادتلاف فطار بیي اطح بالا پاییي بال ااتایي ادتلاف فطار یس بر طبق رابط برلی با تفات در ارعت ستبی تا ری د اتطح

. بال ارتباط دارداز ایي ر هیساى یری برآی تلیذ ضذ، ب تفات در ارعتای سبی بتیي اتطح بتالا

.پاییي بال ابست اات

27

هقاطع تخت یا هتقارى، در صرتی ک سبت ب رااتای جریاى زای داضت باضتذ، .تلیذ برآ داذ ود

تاى ب پراز درآرد؛ البت اگر آى را ستبت بت جتت حتی یک ت آجر را یس هیض ل آجتر، هبتای هااتبی .حرکت، زای دار گرفت با ارعت زیاد حرکت دین

چترا کت در هقایست بتا یتری بترآ، یتری پستای . برای یک بال دت یستت

.قابل تجی تلیذ هی کذ( بازدارذگی)

28

دطی هستقین ک لب حول لب فرار را ب ن هتصل هی کذ: دط تر

یا دط هتاط، دطی فرضی اات ک بیي لب فرار لب حول تراین هیطد ر قط ری دط هتاط، در فاصل دط احا .هسای از صفحات بالا پاییي قرار هیگیرد

. بیطتریي هیساى احراف دط هتاط از دط تر، هقیاای از هیساى احا ب دات هی دذ [100%×(e/c)] .ضداحا عوها ب صرت درصذی از تر بال بیاى هی

29

بالچ ای دگا . ک و اجساء آى ب کار گرفت ضذ اات BAe 146اپیوای ای برآ ب اوت بالای بال باز ضذ اذ تا پسا را افسایص کاذ . کاهلا باز ضذ اذ

. داد برآ را از بیي ببرذ