Shape
The inlet cone is shaped so that the shock wave that forms on its apex is directed to the lip of the intake; this allows the engine to operate properly in supersonic flight. As speed increases, the shock wave becomes increasingly more oblique (the cone gets narrower). As a result, some inlet cones (for example, on the SR-71) are designed to move axially to maintain the shock-on-lip and allow efficient operation over a wider range of flight speeds. On MiG-21 this movement also makes the opening between the intake (diffusor) lip and the cone smaller, preventing the inside of the intake section from bursting open from dynamic air overpressure at the aircraft's highest speeds above Mach 2.
Read more about this topic: Inlet Cone
Famous quotes containing the word shape:
“Caught by the spectacle my mind turned round
As with the might of waters; an apt type
This label seemed of the utmost we can know,
Both of ourselves and of the universe;
And, on the shape of that unmoving man,
His steadfast face and sightless eyes, I gazed,
As if admonished from another world.”
—William Wordsworth (1770–1850)
“The structure was designed by an old sea captain who believed that the world would end in a flood. He built a home in the traditional shape of the Ark, inverted, with the roof forming the hull of the proposed vessel. The builder expected that the deluge would cause the house to topple and then reverse itself, floating away on its roof until it should land on some new Ararat.”
—For the State of New Jersey, U.S. public relief program (1935-1943)
“We cannot and must not get rid of nor deny our characteristics. But we can give them shape and direction.”
—Johann Wolfgang Von Goethe (1749–1832)