[ELI5] why is dry firing a bow so bad for it? Does the arrow really make that much of a difference in that regard?
In: 2366
So when you “fire” an arrow, the energy stored in the bow as you bent it gets pretty much entirely transferred into the arrow and propels it forward. If you dry fire a bow, that energy gets dissipated into the body of the bow and into your arm, potentially damaging the bow, and potentially hurting you.
When you loose an (appropriate for the bow) arrow, effectively all the energy stored in the bow goes into the movement of the arrow. With a properly tuned bow and arrow, the bow should basically be at rest in your hand after the arrow flies, no vibrations or forward movement.
If you dry fire a bow, all that energy is NOT going into an arrow. There’s nothing slowing down the limbs untill they’re abruptly and violently stopped by the string, which itself isn’t elastic. So it’s sort of like you took the bow and smashed it against the wall. I think you can see from that analogy why the bow might get damaged.
I’ve made a video about it [here](https://www.youtube.com/watch?v=gPII-cFUKzY&pp=ygURbnVzZW5zZWkgZHJ5IGZpcmU%3D).
The main things to consider are:
* The energy transferred into the arrow
* The time taken to transfer that energy
While the arrow doesn’t weigh much, the string and limbs don’t weigh much either. That arrow mass makes a difference. Enough energy will be transferred into arrow, reducing the stress on the limbs. The presence of the arrow also means that the transfer is slower, which again reduces the stress on the limbs.
The limbs are not designed to handle an excessive amount of energy being transferred from that side. It can cause cracks and delamination. For a compound bow, the damage is much more severe due to the faster acceleration. The string will almost certain derail from the cams, but there is also a likelihood of more severe damage, such as bent or cracked limbs, or the bow even splitting. We don’t exaggerate when we say that the bow “explodes”.
Acceleration = Force / Mass
The arrow is in fact a LOT heavier than just the string. But a string with no arrow has just as much tension. So the bow and string are going to straighten a LOT faster without an arrow. Then once the string is taut, the bow cannot continue straightening and all that speed it built up needs to stop in an instant.
Shooting bow with arrow: energy is put into the arrow, propelling it forward.
Shooting bow without arrow: energy is into the bow limbs, severely damaging its structural integrity. It can crack/fracture/explode on the spot.
I used to shoot religiously for years. It
100% makes a difference with/without an arrow. Depending on the situation I wouldn’t trust to use that given bow again.
it basically stresses everything in ways its not entirely designed to handle one probably wont do anything but doing it all the time will start to cause unnecessary fatigue of parts overtime.
If you dry fire a compound bow you can dramatically unstrung the bow. The results can be painful.
I throw ball, energy goes into ball, my arm is fine.
I make throwing motion with full force except now my arm slams into wall, arm owie
You ever swing a baseball bat at something hard and it hurts your hand? Same concept. The energy was directed into the wrong object.
Hi I service bows(both recurve and compounds) and instruct archery(LVL 2 USA certified), I’m gonna get a little bit technical.
Bows shoot arrows through energy stored in the limbs, the limbs store energy when they are bent, which is accomplished through pulling on the string, how much energy is stored is dependent on the poundage of those limbs, and how far the bow is being drawn back, my boss always likes to explain it like this. Say you have two identical cars on strips of straight road, one has a longer road than the other and both have to stop before they run out of road, the car with the longer road will reach a higher speed, bow and arrow acts the same, the further back you pull the string, the more energy is stored in the limbs, and the longer the string has time to accelerate the arrow.
So what happens to all that energy when the string is drawn and let go? Well if there’s an arrow there like there should be, the majority of the energy(we know bows aren’t 100% efficient because bows still vibrate and make noise), goes into the arrow, and hopefully your arrow goes into your target.
We all understand some basic physics, energy has to go somewhere or turn into something, so if you let go of a string and there is no arrow, there’s only one place for that energy to go, and that’s the limbs of your bow.
That’s not all though, because you can have an arrow on the bow, and the bow will still act as though it dry fires, if the arrow is stiff but light, the mass of the arrow won’t be able to carry enough energy and the bow will sound very loud(this doesn’t really damage the bow unless done repeatedly), had a absolute unit of a guy with a 32″+ draw(that’s long for an archer), had him shoot the stiffest arrow we had with the heaviest point I could easily find, and the 60LB bow he shot sounded like a small gun going off. If the arrow is too flexible in relation to the energy being transferred, the arrow will snap in half, effectively resulting in a dry fire(also can result in some nasty shrapnel in your hand with carbon fiber arrows). The messy part is the length of the arrow effects it’s stiffness, along with how heavy the arrow tip is. So it’s not just about having an arrow on a bow, it’s about having the right arrow for a bow as well.
Now for what actually happens when a bow is dry fired, best case scenario, nothing, most commonly the bowstring will pop off, or in the case of a compound bow, the string will derail and you’ll need a bow press to put the string back on. Worst case scenario, the limbs of your bow get a crack or splinter and will need to be replaced before you can shoot the bow again.
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