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AfterShock
Reality Strikes Series:
Part one: Blade Center-of-Gravity This Center-of-Gravity (C-of-G as we’ll call it), is a really big deal on crossbows and fast bows. As you’ll see, most mechanical broadhead manufactures don’t even know about its effects and the ones that do would rather keep it quiet than expose any problems with the design. Unless you’re reading this while in orbit on the space shuttle right now, you’re feeling the force of Earth’s gravity at 1g. If you take off in a fast drag car or bike, you may feel up to 2 g’s (twice the force of gravity) and that would make you feel twice as heavy in the direction of travel. Now imagine the acceleration of an arrow and broadhead in today’s fast bows. It’s nothing for bows to accelerate the arrow assembly to many hundreds of Gs. At 400 Gs, a 125-grain broadhead makes the arrow think it has over 7 pounds screwed into the insert! NOTE: This is one reason why it is so critical to have a straight strong arrow and have the bow tuned so that the nock travel is dead straight. At these acceleration forces, arrow trueness and small alignment issues can turn into big accuracy problems as the arrow bends leaving the bow. Most every mechanical on the market today has the C-of-G of the blades outboard (or short of center) of their pivot points. This has real problems when released. The blades want to open during acceleration. To make matters worse, the blades want to shut on impact (or deceleration)! Even if everything works and you don’t break an O-ring or retaining clip at release, this blade flutter wastes energy and hurts accuracy. O-rings and friction clips just can’t be trusted with keeping things closed on release with crossbows or fast bows. Check your favorite mechanical yourself. Take whatever blade retention device off, hold the broadhead pointing straight up and close the blades. If the blades fall open, you’re C-of-G is outboard and physics is NOT on your side.
The HyperShock was designed with an Inboard C-of-G. The blades go past the balance point and Over-Center to get to their closed position. The O-ring is only there to keep the blades closed while handling (or close the blades again after hitting a branch or brush in flight). It has nothing to do with keeping them shut at release. Now the faster the Crossbow or bow, the tighter the HyperShock keeps it blades closed. The opposite is true at impact. The HyperShock blades actually start partial blade deployment during rapid deceleration. This is what you want to have happen. Now physics is on your side. As an added bonus, the HyperShocks inboard C-of-G concentrates more of the broadheads mass down the center of the arrow’s spine. This helps eliminate arrow distortion at release, which in turn helps your available kinetic energy at target and accuracy. Join us next month when the topic will be “Broadhead Aerodynamics” and why you should care. For More Information Contact: AfterShock Archery L.L.C.
Email: info@aftershockarchery.com
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