As
aircraft exceed the speed of sound, the compressibility of the air around the
wing begins to change. At subsonic speeds, the changes in the density of air
are negligible however at supersonic speeds, the density changes become
dramatic. At supersonic speeds, the air molecules in front of the wing are
unable to move out of the way fast enough. The air molecules then form a cone shaped
shockwave that follows behind the aircraft. The sudden release of pressure from
the shockwave creates a sound that is known as a sonic boom. The shockwave can
be seen forming behind the F/A-18 Hornet (pictured above left).
At supersonic speeds, the drag created by an aircraft becomes exponential. In order to combat the amounts of drag, supersonic aircraft are made to be very sleek and narrow. Since the amount of lift created by a wing increases with speed, supersonic aircraft don't require massive wings in order to stay in flight. Many supersonic aircraft have a distinct delta wing design which can be seen in the SR-71 Blackbird (pictured above center). This design allows the aircraft to be light and sleek and extremely effective at high speeds and altitudes. In order to minimize the effects of the air flowing around the fuselage, supersonic aircraft fly at extremely high altitudes where the air is much less dense. For example the SR-71 Blackbird had a cruise altitude of around 80,000 feet.
Due to the extreme speeds of supersonic aircraft, the air molecules flowing over the body create enormous amounts of friction that can heat the body of the aircraft to over 500 degrees Fahrenheit. Supersonic aircraft must be made of materials that can withstand high temperatures such as titanium or titanium alloys. The SR-71 has a corrugated skin with large panel gaps while it sits on the ground, however in the air at high speeds and temperatures the skin expands and fits perfectly along the body.
Supersonic aircraft require engines that can provide enough thrust to overcome the exponential drag and push them to speeds of 760 miles per hour and beyond. Since supersonic aircraft fly at such high altitudes their engines must be able to take in massive amounts of air to compensate for the lack of air density. The Pratt and Whitney J58 turbo jet (pictured above right) used on the SR-71 could take in 300 pounds of air per second. Each jet engine produce 150,000 Newtons of thrust to propel the aircraft to speeds over 2,200 miles per hour.
At supersonic speeds, the drag created by an aircraft becomes exponential. In order to combat the amounts of drag, supersonic aircraft are made to be very sleek and narrow. Since the amount of lift created by a wing increases with speed, supersonic aircraft don't require massive wings in order to stay in flight. Many supersonic aircraft have a distinct delta wing design which can be seen in the SR-71 Blackbird (pictured above center). This design allows the aircraft to be light and sleek and extremely effective at high speeds and altitudes. In order to minimize the effects of the air flowing around the fuselage, supersonic aircraft fly at extremely high altitudes where the air is much less dense. For example the SR-71 Blackbird had a cruise altitude of around 80,000 feet.
Due to the extreme speeds of supersonic aircraft, the air molecules flowing over the body create enormous amounts of friction that can heat the body of the aircraft to over 500 degrees Fahrenheit. Supersonic aircraft must be made of materials that can withstand high temperatures such as titanium or titanium alloys. The SR-71 has a corrugated skin with large panel gaps while it sits on the ground, however in the air at high speeds and temperatures the skin expands and fits perfectly along the body.
Supersonic aircraft require engines that can provide enough thrust to overcome the exponential drag and push them to speeds of 760 miles per hour and beyond. Since supersonic aircraft fly at such high altitudes their engines must be able to take in massive amounts of air to compensate for the lack of air density. The Pratt and Whitney J58 turbo jet (pictured above right) used on the SR-71 could take in 300 pounds of air per second. Each jet engine produce 150,000 Newtons of thrust to propel the aircraft to speeds over 2,200 miles per hour.