Force divergent Mach number

T-45A/C TS, ADV & IUT Aero-02

High-Speed Flight

Sg 1, fr 11

Fig 2: Compression

Wave Formation

(1) Approximately 5% above critical Mach

number (0.85 Mach in T-45)

(2) Pressure waves pile up to form normal

compression wave, and flow is slowed to

subsonic.

(3) Rapid rise in drag

Sg 1, fr 12

Force Divergence

(a) Due to heating of air being

Mach Number

compressed

(b) Boundary layer separation

(4) Airflow just in front of compression wave

has highest speed and lowest pressure.

NOTE: The following does not occur in

the T-45.

Sg 1, fr 13

Fig 2: Compression

Waves continue to move aft and attach to the trailing

Wave Formation

edge as aircraft speed increases.

(2 Overlays)

Overlay 1

Area in front of waves continues to send out

pressure warnings.

Overlay 2

As aircraft speed increases, waves pile up and form

Sg 1, fr 14

a bow wave which leading edge catches up to.

Detail of Bow Wave

(2 overlays)

If leading edge radius is small enough or sharp,

the bow wave will attach.

If bow wave does not attach, an area of

stagnation and large drag values will occur.

Until bow wave attaches, part of flow is

subsonic and aircraft remains in the transonic

flight regime; aircraft is not in supersonic flight

Overlay 1

regime until all airflow about it is supersonic.

Overlay 2

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(9-99) Original