|The word supersonic may bring to mind Sega's Sonic the Hedgehog game and how Sonic can run faster
than the speed of sound. But to my mind "flying horses, balloons, angels, and booms"; that's what
supersonic is made of.
Supersonic is made of two little Latin words. Latin and Greek words are the
common building blocks for many science, engineering, and technology words.
Super means above or beyond and sonic means sound. Put the two together and
supersonic means beyond the speed of sound.
So, how fast is that? Well, it depends. Sound
waves usually travel about 760 miles per hour. Those sound waves
can go slightly faster or slower through the air depending on altitude
(how high), air pressure (how heavy the air is), temperature or a
combination of all those. To see if something is moving faster than
sound, a math problem would use 760 mph as a start and then
correct for what the air is really like around the object.
Knowing the speed of sound lets you figure out how far away a thunderstorm is. When lightning strikes,
the light moves so fast it reaches your eyes almost instantly. It takes about 5 seconds for the sound
of the thunder to travel a mile. Visit this website to set up a thunderstorm distance experiment.
The Air Force Thunderbirds are another flight team that uses supersonic F-16
jets. You can visit both websites to learn about women military officers
assigned to these teams. Blue Angels or Thunderbirds.
Now imagine being a test pilot of a supersonic aircraft. A test pilot basically
performs lab experiments on the aircraft as they are flying. After taking off
the runway and climbing to a safe altitude it is time to see how fast your jet
can go. As you fly, scientists would want to keep a record of your speed to
learn as much as they can. It would be difficult to
radio all those digits of your increasing speed in miles per hour and too awkward to
say "times the speed of sound" over and over again. To make things easier, a new
word was made from another popular source, a scientist's name. Ernst Mach took
the first picture of the supersonic shockwave of a bullet in 1887. His last name was
used for that shortcut word for "the speed of sound” called the Mach Number.
Mach 1 means the jet is flying 1 times the speed of sound. Mach 1.5 is one and
a half times the speed of sound. Mach 2 means twice the speed of sound. Have
you heard of the word hyper? It is a little Greek word for over- as in over
the top. How fast do you think hypersonic is? Officially it is something going
at least five times the speed of sound or about 3,800 mph. Check out NASA's
X-43 that can go Mach 10.
When a jet goes faster than the speed of sound some really cool things begin
One thing is a sonic boom. A plane going 760 mph is moving so fast the air pushes together until it can
move out of the way. This makes pressure waves in the air like the wake of a boat on water. If the
shockwave reaches your ear it makes a loud noise or boom. Watch Dr. Kristen Dardin, a NASA
Engineer who studies sonic booms, use a balloon to show you how it works.
It was named Pegasus after a winged horse in Greek Mythology. At 7,000
mph that's one fast pony.
If conditions are just right, a special cloud can form around the aircraft,
like this Navy F-18. The water vapor cools exactly where the shockwave is
being formed. The popular Discovery Channel show MythBusters flew with
the Blue Angels in Navy F-18's to see if sonic booms can really break glass.
Watch the TV show here.
Look under "Schedules" to find out if they will be
performing at a local air show this year. Don't forget
to take your picture with Penelope Pilot. Maybe you can see, touch, feel, or
hear a supersonic aircraft in person. When you do, remember to think about
flying horses, balloons, angels, and booms!