Transonic drag

Hey folks,

Just a few notes on transonic drag.

The phenomena of a sonic boom (and supersonic drag) is similar to
that of a wake of a ship.

The ship is travelling faster than the speed of waves on the surface of
the water.  As the ship moves along, a shockwave forms.  The wake trails
out from the bow of the ship and as the wake travels past an observer,
that observer would 'hear' the wake.  (detect the waves as they pass by)

Now, as you may notice, the water behind a ship, inside the barriers of
the wake, is much less turbulent than either the wake itself or the water
around it.  Supersonic and hypersonic airframes take advantage of this by
projecting a nose cone of the aircraft forward.  The 'wake' or shockwave
forms (a cone in this 3D case) around the nose while the rest of the
aircraft falls inside the cone of the shockwave.  Thus the wings and tail
are *NOT* subjected to supersonic airflow even when the aircraft is
travelling supersonic.

The transonic drag that forms as one hits Mach 1 is felt as the plane goes
into transition from normal airflow (where air flows over each part of the
craft) to the shockwave airflow.  You can imagine each part of an aircraft
forming its own shockwave thus making for very turbulent air.  Once the
speed of sound is exceeded, there is only the one shockwave.

Transonic drag is MUCH heavier than supersonic drag.  This is why some
aircraft require afterburners to go hit the speed of sound, yet cruise
supersonic without the burners.

Hope this makes sence,

Scott 2G Kellogg
God!  It's hard to describe without diagrams!