Calculation of Lift and Drag of a Supersonic Wing

Question 1

It is a linearized, first order theory based on sweeping assumptions which
nevertheless give quite good results provided that the Mach number is not
too low and the airfoil section is not too thick.

Answer 1

Ackeret Theory

Question 2

For supersonic flows, the airfoil sections should have the following characteristics:

Answer 2

1. Thinness
2. Sharp Leading Edge
3. Maximum Thickness at Half Chord
4. Symmetry

Question 3

Thinness
To minimize flow deviations due to thick airfoil sections which bring about shock losses, a supersonic airfoil should be of __________

Answer 3

thin cross sections

Question 4

Sharp Leading Edge
It is necessary to keep an _________ on the airfoil section and to avoid losses due to a normal, detached shockwave.

Answer 4

attached bow shock wave

Question 5

Sharp Leading Edge
This can be done by employing low thickness to chord ratio to
create a ___________ which is necessary to ensure shockwave attachment at low supersonic speeds.

Answer 5

small leading-edge angle

Question 6

It ensures expansion behind the maximum thickness point which is similar in value to the compressions ahead of it and to illustrate that this is conducive to low values of drag.

Answer 6

Maximum Thickness at Half Chord

Question 7

Symmetry
For supersonic flows, a positive camber results in a ____________ which follows that at any given incidence the lift is reduced by the camber of the airfoil section

Answer 7

positive zero lift angle of attack

Question 8

Symmetry
At slow speeds, the effect of camber is to _____ the value of drag.

Answer 8

increase

Question 9

Supersonic Airfoil Sections

Answer 9

1. Wedge
2. Double Wedge
3. Biconvex
4. Flat Plate

Question 10

This airfoil has a positive camber.

Answer 10

Wedge

Question 11

Wedge
The positive pressure increment relative to the free stream value on the ___________ is greater than the _________ happening in the upper rear surface.

Answer 11

front upper surface; negative pressure increment

Question 12

Wedge
Since the lower surface of the airfoil experiences no pressure
increment, anywhere on its surface, there will be a ___________ on the airfoil, which means a ___________

Answer 12

net downward force; negative lift at zero angle of incidence

Question 13

the zero-lift angle of attack must be ____________.

Answer 13

positive

Question 14

To achieve zero lift, the airfoil must be ______________ to counter the inherent
negative lift at zero incidence.

Answer 14

tilted positively (nose-up)

Question 15

For a given thickness to chord ratio, minimum wave drag is
achieved using the __________

Answer 15

double symmetric double wedge airfoil or a diamond airfoil.

Question 16

generate the same amount of lift as compared to a
flat plate, however more wave drag is generated by this type of
airfoil section.

Answer 16

Diamond airfoils

Question 17

• Occurs in compressible (usually supersonic flow), caused by the formation of shock waves
  and expansion fans.

Answer 17

Wave Drag

Question 18

whose
upper and lower surfaces are formed by equal circular arcs as
shown by the figure below.

Answer 18

biconvex section

Question 19

such profiles produce more wave drag as compared to
the double wedge sections of the same thickness to chord ratios.

Answer 19

Biconvex

Question 20

The best wing section in theory for a supersonic flow is an infinitely ___________ because it satisfies all the requirements presented
above more than any other possible wing.

Answer 20

thin, flat plate

Question 21

it is not a practical solution since the thinness of the airfoil
section is subject to the structural requirements of an aircraft.

Answer 21

Flat Plate

Question 22

The first trans-oceanic supersonic passenger flight was a ____________ that took off from ___________ in_______________.

Answer 22

Concorde Flight; London Heathrow Airport; January 21, 1976

Question 23

More than ___________ flew supersonically until __________and__________ took the Concorde out of service in
2003.

Answer 23

2.5 million passengers; British Airways and Air France

Question 24

means flight that is faster than the speed of
sound.

Answer 24

Supersonic flight

Question 25

The speed of sound in Earth’s atmosphere varies depending on ___________- and other atmospheric conditions.

Answer 25

temperature

Question 26

Mach number

Answer 26

1. Subsonic 2. Transonic 3. Supersonic 4. Hypersonic

Question 27

* All current commercial aircraft are subsonic, with Mach number less than 1.

Answer 27

1. Subsonic

Question 28

* Flight near Mach 1 is called _____________ * Aircraft typically fly at such speeds only briefly while they accelerate from subsonic to supersonic or vice versa. * They do not cruise near Mach 1 because they would experience high drag.

Answer 28

transonic.

Question 29

* faster than Mach 1. * The Concorde cruised at about Mach 2.02 (roughly twice the speed of sound) when not over land. * Some military aircraft fly at even higher ______________ speeds.

Answer 29

supersonic

Question 31

* Flight faster than Mach 5 is known as ______________. * ___________ flight is currently limited to experimental aircraft and missiles as well as spacecraft reentering the atmosphere from orbit (the space shuttle during reentry flew at about Mach 25).

Answer 31

Hypersonic

Question 32

Demise of the Concorde

Answer 32

1. A very costly project. 2. Expensive to operate. 3. High subsonic noise levels during takeoffs and landings and sonic boom. 4. Failed to make Concorde flights a sustainable business. 5. Filling the seats on Concorde flights with paying customers was not easy. 6. Impractical for carrying cargo or mail, given the limited cargo space.

Question 33

Of the 20 Concordes ever manufactured, 14 were sold to the state-owned carriers of the two countries involved in building the planes: 7 to _________ and 7 to ___________

Answer 33

British Airways; Air France.

Question 34

High-Speed Flights DISADVANTAGES:

Answer 34

1. Cost 2. Noise 3. Profitability

Question 35

High-Speed Flights Advantages

Answer 35

1. Speed 2. Range

Question 36

High-Speed Flights (Limitations)

Answer 36

LIMITATIONS 1. Circadian Dysrhythmia 2. High Altitude 3. Radiation 4. Noise (Sonic Boom)

Question 37

* It is caused by the desynchronization of the normal sleep and wakefulness cycle of the body with local time. The problem presents itself to travelers as lowered efficiency, inability

Answer 37

Circadian Dysrhythmia

Question 38

is the internal biological clock that regulates body functions based on our wake/sleep cycle. It can be disrupted by changes in sleep pattern. Aircrew members may experience circadian rhythm disruption (specifically “jet lag”) as they work.

Answer 38

`Circadian rhythm

Question 39

In order to fly fast, aircraft must fly high where the _________-

Answer 39

air density and aerodynamic drag are less.

Question 40

Modern jet aircraft cruise just below the tropopause (38,000 ft) but supersonic aircraft will fly considerably higher, up to ____________-.

Answer 40

60,000 ft

Question 41

Galactic radiation consists of

Answer 41

high energy particles and heavy particles.

Question 42

The principal regulatory concern surrounding supersonic aircraft is the _____________, a shock wave of pressure created by compression of sound waves as the air is displaced by the airframe traveling at or above Mach 1.0.

Answer 42

sonic boom

Question 43

is used to refer to the shocks caused by the supersonic flight of an aircraft.

Answer 43

sonic boom

Question 44

generate enormous amounts of sound energy, sounding much like an explosion.

Answer 44

Sonic booms

Question 45

is the reason why supersonic flights are not allowed over populated areas.

Answer 45

Sonic boom

Question 46

Factors Affecting Sonic Boom:

Answer 46

a) Aircraft Weight, Shape, and Length b) Aircraft Altitude c) Aircraft Maneuvers d) Location in Sonic Boom Carpet e) Attitude