Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Module 11 > High Speed Effects > Flashcards

High Speed Effects Flashcards

1
Q

When is air considered compressible?

A

At abouve or equal to 0.4 Mach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

When air compressibility effects felt?

A

As aircraft approaches initial Mach no. Dues to build up of pressure concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define compressibility effects?

A

Undesirable effects felt in the transonic range

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How can pressure concentration form?

A

As a shockwaves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are some issues with pressure concentration.

A

-sudden rise in drag
-reduction in lift
-uncommanded changes in trim and stability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a shockwave?

A

Sound or pressure wave resulting from air being disturbed as the aircraft moves through it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where do sound or pressure waves radiate from?

A

Source of disturbance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens to shockwaves if the aircraft is slower than the speed of sound?

A

The shockwave travels ahead at the speed of sound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What happens to pressure wave when the aircraft is at the speed of sound?

A

They can’t get away from the aircraft and begin to compress & accumulate forming a bow shockwave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What happens to the shockwave when the aircraft is abouve the speed of sound?

A

Shockwaves get overtaken and radiate behind the aircraft

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

When do normal shockwaves form?

A

In transonic range at MCrit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What angle does a normal shockwave form at relative to the path of the airflow?

A

90 degree angle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does a supersonic aero foil typically include?

A

Sharp/pointed leading edge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does a pointed air of oil allow for?

A

Allows bow wave to attach and slope backwards to form an oblique shockwave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Is airflow forward of an oblique shockwave above or below Mach 1?

A

Above

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Is airflow slower or faster after passing thru a shockwave?

A

Slower

17
Q

Going thru an oblique shockwave airflow will…?

A

Have a slight increase in temp and pressure

18
Q

Are expansion waves considered shockwaves?

A

No

19
Q

How are expansion waves formed?

A

When airflow changes direction around a curve/corner away from preceding airflow direction

20
Q

In an expansion wave is there a change in useful energy or total pressure?

A

No change

21
Q

What decreases from expansion waves?

A

Static pressure,density & temperature all decrease

22
Q

What are the two types of supersonic profile?

A

-double wedge profile
-circular arc profile

23
Q

In a double wedge profile what is the net lift at 0 degrees angle of attach?

A

No net lift

24
Q

What is the advantage of a double wedge profile?

A

Produces lift with only a slight angle of attach

25
Q

What happens in a circular arc profile to wave pattern at supersonic?

A

It decreases

26
Q

Where is the centre of list on a circular arc profilenwhen flow is supersonic?

A

50% chord line

27
Q

Does longitudinal stability increase or decrease on a circular arc profile with supersonic flight and why?

A

Increases as distance between centre of gravity and centre of lift is higher

28
Q

What is wave drag?

A

The portion of total drag due to shockwaves

29
Q

What do shockwaves turn useful energy into?

A

Heat energy

30
Q

What compensates for shockwaves energy waste?

A

Additional engine thrust

31
Q

What are the two ways to reduce wave drag?

A

-using vortex generators
-applying the area rule

32
Q

What does a vortex generator reduce?

A

Wave drag

33
Q

What does a vortex generator increase?

A

Parasite drag

34
Q

Aerodynamic heating is what?

A

Heating of the airframe caused by friction with air

35
Q

When is aerodynamic heating significant?

A

At supersonic speeds

36
Q

What material is used for high speed aircraft and why?

A

Titanium because of its coefficient of thermal expansion and weight

Module 11 (64 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions