High Speed

Question 1

Mach number =

Answer 1

TAS/LSS

Question 2

LSS=

Answer 2

TAS/Mach

39 x square root of the temp in K

Question 3

How does compressibility effect the stall speed

Answer 3

Increases it

Question 4

Mfs

Answer 4

Mach number, can be seen in the f/d

Question 5

ML

Answer 5

Local mach numbers, varies due to a/c shape

Question 6

3 categories of ML

Answer 6

Subsonic <1

Sonic = 1

Supersonic >1

Question 7

3 speed regions

Answer 7

Subsonic - all ML are less than 1, above 0.4 and compressibility will occur

Transonic - mixture of ML that are sonic, subsonic and supersonic

Supersonic - ML are all greater than 1 and the whole a/c is supersonic

Question 8

Mcrit

Answer 8

Highest speed you can reach without going supersonic and a shockwave occurring

Border of subsonic and transonic speed region

Mfs number

Question 9

Normal shockwave facts

Answer 9

Perpendicular to the flow
Only forms in the transonic region only 
Supersonic infront, sub behind 
Gets more powerful with speed 
Most violent 
Thickness, 0.0025m never changes 
Extends to a greater height with faster speed 
Can get a wave in front of the leading edge

Question 10

Oblique shockwave facts

Answer 10

Forms on the trailing edge 
Supersonic infront and behind 
Not as violent as normal 
Only occurs at mfs >1- transonic region 
Stretch on forever due to less energy transfer and travel at the same ground speed of the a/c across the ground 
Faster we go the angles reduce

Question 11

Mdet

Answer 11

Speed where the bow wave attaches to the leading edge, the whole wing is supersonic

Question 12

Bow wave

Answer 12

A normal shockwave before the leading edge with oblique on each side

Question 13

Cone

Answer 13

Have to make sure all control surfaces are in the cone

Sinu = 1/mach no

Cone angle = angle from the oblique wave to the flight path

Question 14

Expansion wave

Answer 14

Airflow is forced around tight corners of the a/c, creates wave

Question 15

Changes in mach, ps, density, temp and pt with an expansion wave

Answer 15

Mach increases
Ps,density, temp decreases
Pt remains the same

Question 16

Changes in mach, ps, density, temp and pt with a normal/oblique wave

Answer 16

Mach decreases
Ps,density,temp increases
Pt,decreases

Question 17

Climbing/descending beneath the tropopause

Answer 17

C,T,M

Question 18

Climbing and descending in the isothermal stratosphere

Answer 18

C,TM

Question 19

Climbing and descending in the ozone layer up to the stratospause

Answer 19

C,M,T

Question 20

Climbing below change over CAS

Answer 20

AoA constant
FPA decreases
Pitch decreases

Question 21

Passing the change over altitude when climbing to mach

Answer 21

AoA increases
FPA decreases
Pitch decreases

Question 22

Descending above the change over in mach

Answer 22

AoA increases
FPA in decent - steeper
Pitch - decreases

Question 23

Descending below the change over in CAS

Answer 23

AoA, FPA, pitch remain constant

Question 24

In the event of failure of the mach trimmer what must be done

Answer 24

Mach speed must be limited

Question 25

Temp behind an oblique shockwave

Answer 25

Higher than in-front of it

Question 26

The push over manoeuvre

Answer 26

LF is less tan 1, stall speed reduces Reduces the value of the low speed buffet and increases the value of the high speed buffet

Question 27

Vortex generators

Answer 27

Decrease wave drag | Reenergise the boundary layer

Question 28

Increasing sweepback

Answer 28

Increases the mach drag divergence number

Question 29

Through an expansion wave heat happens to LSS

Answer 29

Decreases