Bow Test Parameters
October 28, 2010
Ever wonder what the guidelines are for our bow tests? Wonder no more.
In an effort to simulate "real world" bowhunting conditions, Petersen's BOWHUNTING has adopted the following protocol for setting up bows for its High Grade reviews:
Bows are tested with a draw length of 29 inches and a draw weight of 65 pounds. All bows are set up with a single brass nock and QuikTune 3000 arrow rest. With the exception of these two items, every bow is tested just as it would be shipped to the dealer or customer.
The draw weight of 65 pounds (+/- 1 pound) is verified using a calibrated Chatillon digital force gauge, backed up by an Easton Bow Force Mapper System handheld unit.
The manufacturer's 29-inch draw length is also verified. Draw length is the sum of the brace height, power stroke and a constant of 1.75 inches. Brace height is measured with calibrated Mitutoyo 8-inch Dial Calipers. The power stroke (the distance the archer actually moves the string) is measured with a force draw system, which is a combination of a modified Apple Bow Drawing Machine, Chatillon force gauge, calibrated 36-inch steel rule and trammel point. The three numbers are added and must equal 29 inches (+/- 1/2-inch).
While the bow is still on the force draw system, the cams are marked at full draw. The bow is then paper tuned by hand with the test arrow before being placed on a Hooter Shooter portable shooting machine. Once properly set on the Hooter Shooter, the bow is drawn to the cam marks indicating full draw. The front of the bow's handle is set approximately three feet from the first gate of an Easton Professional Chronograph. An infrared lighting system on the chronograph allows for indoor testing. Speed is calculated by averaging the results of five shots, all of which must be within +/- 2 feet per second of one another.
All bows are speed tested using two arrows weights — 375 grains and 425 grains. Kinetic energy is calculated for each arrow using the following formula: Arrow Weight x Arrow Speed x Arrow Speed/450240.