A Note on Speed
Reading edition
We have used the modern method of expressing aviation speed—the Mach number. Mach 1.0 is the speed at which sound travels through the air. On an average day at sea level, the speed of sound, or Mach 1.0, is about 760 miles an hour. At higher, colder altitudes on the same day, it is less. For example, at 35,000 feet it might be only 660 miles an hour. Since most of the flying described in this account is at high altitude, Mach 1.0 is, on an average day, about 660 miles an hour. The speed is also expressed in terms of fractions of a Mach number. Thus Mach .5 is half of Mach 1 or half of 660 miles an hour—about 330 miles an hour. Speeds above Mach 1.0 are also expressed in whole Mach numbers and fractions of Mach numbers. For example, Mach 1.5 is the equivalent of one and a half times the speed of sound, or about 1,000 miles an hour. Mach 2.0—or twice the speed of sound—is twice 660 miles an hour, or about 1,320 miles an hour. Mach 2.5 is about 1,650 miles an hour. Mach 3 is about 2,000 miles an hour.
ALWAYS ANOTHER DAWN ►
“There is no liberty except the liberty of someone making his way towards something.”
—ANTOINE DE SAINT EXUPÉRY
CHAPTER 1 ►