Quantities Describing Compound Bows
AMO standard draw length is the distance from the string at full draw to the lowest point on the grip plus 1.75 inches / 4.45 cm. Because the draw force may increase more or less rapidly, and again drop off more or less rapidly when approaching peak draw, bows of the same peak draw force can store different amounts of energy. Norbert Mullaney has defined the ratio of stored energy to peak draw force (S.E./P.D.F.). This is usually around one foot-pound-force per pound / 3 joules per kilogram but can reach 1.4 ft·lbf/lbf / 4.2 J/kgf.
Efficiency of the bows also varies. Normally between 70-85% of the stored energy is transferred to the arrow. This stored energy is referred to as potential energy. When transferred to the arrow it is referred to as kinetic energy. The product of S.E./P.D.F. and efficiency can be called power factor. There are two measurement standards of this quantity, AMO and IBO speed. AMO is defined as the initial velocity of a 35 g / 540 grain arrow when shot from a bow with a peak draw weight of 270 N / 60 lbf and draw length 76 cm / 30 inches. IBO speed is defined as the initial velocity of a 22.7 g / 350 grain arrow shot from a bow with a peak draw weight of 300 N / 70 lbf and a draw length of 76 cm / 30 inches.
Brace height is the distance from the pivot point of the grip to the string at rest. Typically a shorter brace height will result in an increased power stroke, but comes at the price of a bow that's less forgiving to shooter error and having harsher string slap.
Read more about this topic: Compound Bow
Famous quotes containing the words quantities, describing, compound and/or bows:
“The Walrus and the Carpenter
Were walking close at hand:
They wept like anything to see
Such quantities of sand:
“If this were only cleared away,”
They said, “it would be grand!”
“If seven maids with seven mops
Swept it for half a year,
Do you suppose,” the Walrus said,
“That they could get it clear?”
“I doubt it,” said the Carpenter,
And shed a bitter tear.”
—Lewis Carroll [Charles Lutwidge Dodgson] (1832–1898)
“Psychologists have set about describing the true nature of women with a certainty and a sense of their own infallibility rarely found in the secular world.”
—Naomi Weisstein, U.S. psychologist, feminist, and author. Psychology Constructs the Female (1969)
“We are all aware that speech, like chemistry, has a structure. There is a limited set of elements—vowels and consonants—and these are combined to produce words which, in turn, compound into sentences.”
—Roger Brown (b. 1925)
“Come with bows bent and with emptying of quivers,
Maiden most perfect,lady of light,”
—A.C. (Algernon Charles)