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Arrow Speed - One Archer’s Opinion
Submitted by diybow on Sun, 07/26/2009 - 03:17
What is clearly a marketing competition among bow manufacturers, and a frequent subject of conversation at any gathering of archers, is speed – “bow” speed or “arrow” speed.
First, let’s be clear on how speed is measured by bowyers. There are two measures, from the bowyers’ point of view – AMO and IMO. AMO is tested using a 28” draw and an arrow weighing nine grains per pound of pull weight. IMO is tested using a 30” draw and an arrow weighing five grains per pound of peak draw weight. Uh Oh! What’s the difference? Well, the main difference is that IMO came into being after the advent of compound bows – and the manufacturers couldn’t get enough numbers from the AMO ratings to really sell their bows.
Either of these measures can be applied to any bow. However, any bow is going to come off slower under the AMO than the IMO system.
The fact is these measures serve two purposes. One is to provide a basis of comparison among bows. The other is to provide manufacturers with “bragging rights” to sell their bows. In truth, that’s about all there is and it doesn’t make any difference to the average archer (other than to those that spent a lot of money to get the fastest bow).
Manufacturers run hundreds of tests on their bows, under ideal conditions, with arrows jiggered around to be as close to perfect as possible. They will then boast of the fastest one arrow from their bow. The top shooters using optic sights and all the gadgets may benefit from fast arrows and knowing what is the possible speed. Few of those, however, will ever achieve the advertised speed of their bow.
Archers may benefit from knowing how fast is their bow, with their arrows and their release. There, however, is little reason for the average archer for care about the advertised speed of their bow –none are likely to ever achieve the advertised speed.
There are three factors about the quest for speed that may be real to the average archer. One is that greater arrow speed reduces sighting problems due to arrow drop. [For hunters with sights, greater speed may only introduce more problems on short up or down hill shots due to sight parallax.] The second is that greater speed apparently results in more kinetic energy of the arrow. [Again for hunters, kinetic energy may not be what they really seek. Another physics concept, momentum, may be more important as penetration is their real goal.] The third factor in the quest for speed is arrow weight. Reducing arrow weight to gain speed has two negative aspects.
Less arrow mass produces less momentum out there where it counts. Also, a really light arrow may not have enough mass to absorb the energy generated by the bow. Big deal? - Yes it is a big deal! If the arrow does not have enough mass to absorb a significant amount to the energy generated by the bow on release, the result may be like “dry firing” the bow. A lot of energy left to be absorbed by the bow will result in damage to the bow. [For hunters, the more energy not transferred to the arrow the noisier will be the bow in shooting.]
This archer’s opinion is that speed is an overblown factor in archery, just as is distance in golf. Speed is definitely a consideration in tuning a bow and arrow combination and in adjusting sights. However, the true goal is accuracy. A slow bow and heavy arrows can achieve acceptable accuracy – so long as the bow, arrow and archer are in tune.
What I’ve seen is that the best of the best were just as good last month or last year before they bought that new bow. A few (very few) archers can gain an edge from more speed. However, for most archers, even modestly good equipment is better than are they. Until one reaches the potential of his/her current equipment, more speed is just a waste of money.
One should keep in mind that the famed English military archers commanded battlefields with bows that drew over 100 pounds at full draw and shot arrows weighing well over 1000 grains each. Reasonable accuracy and maximum penetration were the keys. The significance of accuracy in shooting cannot be diminished or replaced by anybody’s equipment or claims. To have another archer miss, at 50 to 100 more feet per second than my arrow speed on my first day doesn’t mean a lot to me – does it to you?