Lecture 10

Question 1

What are the two primary variables related to the operation of a fluid power system?

Answer 1

Pressure and Volume

Question 2

What happens to the air as you approach sonic speeds?

Answer 2

It becomes a compressible fluid

Question 3

Speed of Sound

Answer 3

No pressure waves moving in advance of the aircraft
All pressure disturbances are behind the aircraft

Question 4

Mach number

Answer 4

the speed of the aircraft in relation to the speed of sound

Question 5

Subsonic

Answer 5

any region below the transonic region or below the critical Mach number

Question 6

Transonic

Answer 6

begins with first evidence of localized sonic or supersonic airflows and begins at the critical mach number. ends when all flows around aircraft are fuller supersonic

Question 7

Sonic

Answer 7

right at the speed of sound

Question 8

Supersonic

Answer 8

any speed faster than the speed of sound

Question 9

Hypersonic

Answer 9

any speed above mach 5. plasma effects begin to affect airflow

Question 10

Transonic flow creates the most…

Answer 10

drag on a high speed aircraft

Question 11

Transonic region

Answer 11

When some flows are supersonic and some are subsonic you are
flying

Question 12

What happens to drag as you hit Mcrit

Answer 12

Drag rises quickly as the aircraft hits MCRIT, and then
drops of quickly as the aircraft becomes fully supersonic,
and then the drag begins to rise again

Question 13

Super cruise?

Answer 13

supersonic cruising speed that has the same drag as when the aircraft was still flying subsonic

Question 14

Normal Shock Wave

Answer 14

Perpendicular to the flow direction
causes tremendous drag
Airflow slows from supersonic to subsonic

Question 15

Oblique Shock Wave

Answer 15

Inclined to the flow direction
Creates some drag
Airflow slows from high supersonic to low supersonic

Question 16

These all increase after a shock wave

Answer 16

air pressure, temp, and density

Question 17

How is lift made if Bernoulli’s Principle no longer applies?`

Answer 17

Lift is generated by the AOA

Question 18

Sonic Booms

Answer 18

sounds made from pressure waves or shock waves from supersonic objects

Question 19

What happens to the speed of sound as the air gets colder?

Answer 19

Slows down

Question 20

What produces large shockwaves?

Answer 20

Large and sudden changes in cross-sectional areas

Question 21

How to prevent large shockwaves?

Answer 21

Larger overall cross-sectional area, but smaller wing aspect ratio
Smooth transition from wings to fuselage cross section

Question 22

Whitcomb area rule

Answer 22

a design procedure used to reduce an aircraft’s drag at transonic speeds which occur between Mach .75 and 1.2

Question 23

Why have wing sweep at subsonic speeds?

Answer 23

yaw stability

Question 24

Why have wing sweep at high subsonic speeds?

Answer 24

raise the critical mach number

Question 25

Why have wing sweep at supersonic speeds?

Answer 25

keep wing tips out of shock waves