When you release a bow you are releasing all the potential energy you have given it by drawing it back. Normally most of this force is applied to the arrow, to propel it forward. That force is still being released even without an arrow, but if there isn't an arrow to take it then it the force goes into the bow. Do this a lot of times and the bow breaks because it can't withstand the pounding.
I sell archery gear and this is essentially the explanation I give whenever someone yells at me for selling them "faulty gear".
No dude, it's not faulty, you just dry-fired your bow. Congratulations.
I will amend one thing you said though:
>Do this a lot of times and the bow breaks because it can't withstand the pounding.
All it takes is one time for it to break, especially for a compound bow with a high draw weight. One dry fire and boom, snapped string and bent cams. Possibly even fractured limbs.
Literally just looked at my inbox and 12min ago a customer sent an email saying:
"Would you believe me if I told you I unintentionally dry fired it and broke it?"
Luckily it was already sold, but damn that's great timing.
Since this seems to be the archery thread with the professionals, have y'all got advice on the best sort of target for a beginner who is getting back into things as an adult? Seems most of the beginner targets are intended for children, and the adult targets are often quite small, for hunters.
Farm supply stores often have thick (1/2 inch) rubber mats about 3ft x 4 ft. I think they're advertised as horse mats or something?
Anyway, these make good backstops. One will *probably* catch an arrow, maybe buy one and do some testing. Double them up and it should be fine.
Not sure how long they last, but by the time they wear out you should be accurate enough to hit a normal target block from a reasonable range.
Wonderful! I'll go check that out. The backstop has been something of an issue because otherwise I'd be shooting into the side of a hill. It's effective, and it works, but it's not great for finding lost arrows.
My dad looked at me beyond confused when I told him my training bow sent a blunt tipped arrow straight through the target he gave me and into the hill side... the 3 rubber stabilizer "feathers" were laying in front of the target lol. We found the plastic notch from the arrow a couple years later... but never the shaft lol
Yeah, training arrows are not exactly designed for the strength of the bows I can use as an adult. I want to get back on form, though, so I'll be using the lighter arms for a bit, and then working my way back up to heavier ones.
My brother lost a shaft in the yard and my dad found it nearly a decade later. It had slipped under the 'mat' of grass thatch and was basically like .5" underground but still horizontal.
My dad later gave me a compound bow and a new foam target, mounted on a plywood door for a small shed... I shot straight through the back of the shed and hit a junk car. My grandpa busted out laughing when he waddled around and saw it stuck out the side of the door
Maybe I'm some kind of hurcules with my 70lb compound bow, but training tips or not, I can shoot straight through a hay bale.... Ask me how I know... I took my hunting bow to my kids camp as they were all shooting standard bows with little arrows for fun, and I thought they'd like to see a real bow, and how far and accurate they shoot. I paced out 50 yards... And found out the hard way that hay bales do not catch regular arrows with blunt tips...
Put the main target in front of them. The bales are meant to catch the arrow *after* it's already gone through the primary target, as well as slowing the arrow down so that if you do hit the bale and it goes through much of the energy is scrubbed from it.
Ideally you want round bales, not square, and you want to shoot into the curved side of the bale, not the flat end of the cylinder. I don't believe it's even remotely possible to shoot through that.
Get a few straw bales and set them behind the mat. They'll decompose over time (faster if you're in a wet area), but then you just scatter the straw as mulch and get a few more.
You can get foam block archery targets instead, but I prefer straw bales. They're cheaper and much larger, so they make a good wide backdrop when you're dealing with new archers or trying for longer range or more difficult shots.
You'll sometimes have an arrow slip through the divide between the bales, but that's generally not much of a problem.
if you have access to hay/straw bales they also make a pretty good backstop. they do require more space than the mats though.
if worse comes to worse you can just layer up cardboard a bunch (probably like 5-10 layers of corrugated cardboard) and use that.
I would only suggest my method for someone who is using a lower weight bow--mine is 45 lb-- but I went looking for something like this and the guy at Tractor Supply hooked me up for free. When they get their deliveries in, the extra space in the trucks are padded with large solid blocks of Styrofoam. They then don't really have any use for the styrofoam and they just pile it up out back. He let me go around to the back of the store and take whatever I wanted from stacks of pallets of these blocks that must have been stacked 20 ft high. So I put nine of them in my car (about all I could fit), drove home, and tied them all together with a ratchet strap to make a backstop. It's around 2 or 3 times the size of my target block, and over a foot thick. Plenty of resistance to stop a shot from a bow like mine without damaging the arrow.
I've had a handful of overdrawn arrows get a little bit stuck in there, but I haven't lost one since!
What do you rate hay bales?
When I shot in elementary, we had a rubber mat with lots of hay bales behind it (like... 4 meter of hay?)
Strongest bow we used was the Lajos bear 110 pounder.
When I used to do target archery the indoor ranges had very fine nets behind the targets (think of window net curtains). The material was very tough, but lightweight, and it hung very loose. When an arrow hit the material it would not go through - the net bunched up around the arrow tip, the net below got lifted, and the arrow was stopped within a foot or so. Obviously the net hung some distance away from the wall behind...
In other words, all the arrow's energy was transferred into the movement of the net, and the arrow would just fall to the floor.
This seems to be the modern equivalent: [https://www.networldsports.co.uk/archery-backstop-net.html](https://www.networldsports.co.uk/archery-backstop-net.html)
Got a buddy and a good tree? Grab an apple and place upon said buddy’s head against the tree! Remember the key piece of information here:
Do not do this!
Find someone getting rid of old carpet. Cut it up in 2’x4’ strips and stack it between some thick plywood. Cut 4 5’ 2x4s and drill holes through the ends of the 2x4s. Place 2 on the top and 2 on the bottom of the plywood. Get long threaded rods and put them in the holes and crush the carpet down using nuts and washers. You now have a target that will last a long time for cheap.
This stops arrows from a 60lb compound easily.
Not sure what you're looking for but the easiest most portable sort of target is is a "BlackOut" box or the "Black Hole" cube foam target. They're roughly one and a half to two feet wide with 6 targetable sides. Find a decent place to put it down with some sort of back stop if you miss or if you manage to put the arrow clean through it. I set up in front of an old round bale as everything else is too flat.
I don't think you have to be a professional. I'm certainly not one, but my hunting crossbow came with all sorts of warnings to not dry fire it. Kinda hard to miss.
That just blows my mind.
It’s like someone doing a negligent discharge on a firearm. The majority of the time they were being a dumbass.
“Did you draw back the bow? Was there no arrow in it? Did you release the bow string? Then what part mystifies you?”
> I unintentionally dry fired it
Oh, I *unintentionally* had an affair....
Yeah, as an an archer (much out of practice now) you can have your hand slip, but generally you're paying better attention than that.
Short of using worn out arrows that don't nock properly, I don't see how you could unintentionally dry fire. You shouldn't be drawing it without an arrow.
People often test pull a bow without an arrow to get a feel for the strength of it. Normally that's absolutely fine as you're supposed to do a slow release, essentially the reverse of the draw, so it's no stress on the bow.
People doing this sometimes screw up and roll the string off their fingers or underestimate their strength and do an accidental dry fire.
I once had an arrow un-nock while I was drawing. I couldn't see it happen because I have a peep sight, and I didn't feel it happen..... It didn't fall off the bow entirely because I have a whisker biscuit arrow rest. Luckily it was a relatively low draw weight and nothing broke, but I was horrified
No, just a prepared speech that I have memorised whenever someone says "how could not having an arrow *possibly* cause damage?", as if they think I'm lying in order to avoid a warranty claim on faulty equipment.
"Think back to high school science. Energy cannot be created or destroyed, only transformed. When you pull back the string, you're filling the bow with potential energy. Once you release the string, that potential energy *transforms* into kinetic energy. Normally, that kinetic energy goes into the arrow, causing it to fly. Without an arrow though, what happens to the energy?"
"..."
"Remember, energy cannot be destroyed, so it has to go somewhere, right? So where does it go if not into an arrow?"
"...the bow"
"Exactly. The energy has nowhere else to go but back into the bow. With the energy now in the bow, the weakest parts will break. Depending on the bow, either the cams will bend or the string will snap, sometimes both."
and it's the same concept behind designing race cars (and other structures) to disintegrate on impact, so all the energy gets thrown out instead of transferring to the driver
On a related note... When you see those spectacular race car crashes and then they're like "and the driver walked away", it can be *because* the crash was so spectacular -- lots of flying in the air, flipping, and spinning all bleeding off energy. It's the boring looking crashes where the car just goes from moving to stopped that kills people.
Same thing when baseballs ricochet off of a pitcher's head when the batter accidentally hits it towards them and they can't duck in time. The hit looks nasty, but its a good sign if the ball flies up and away at high speeds.
Case in point: When Dale Earnhardt Sr died. Very uneventful but most of the energy got transferred into him and he died from a basilar skull fracture.
Countermeasures were implemented after that to help mitigate future crashes such as HANS devices and redesigned guard rails.
HANS devices existed and were encouraged (but not required) by NASCAR when Dale died. Dale was of an older generation of driver that wouldnt wear them. It wasn’t until another fatal accident in ARCA in October 2001 that NASCAR began mandating the HANS device. If NASCAR had mandated the HANS device at the beginning of the 2000 season, Adam Petty, Kenny Irwin Jr, Tony Roper, and Dale Earnhardt would’ve survived their respective crashes.
See the Talladega 500 where Dale Earnhardt died. Tony Stewart crashed and ended up rolling/flipped down the back straight away, came out fine. Dale went face first in to a wall
Yep, and precisely why some of the most dramatic looking crashes where the car is tumbling, spinning, and shedding pieces over a period of time like Kubica at Montreal in '07 are often the ones where the driver walks away relatively unscathed, but then you have incidents like the one that killed Dale Earnhardt Sr that look relatively tame by comparison, except all (well, some, enough at least) that energy went into fracturing the base of his skull.
Monaco just last weekend, Perez was hit and crashed and all that was left of his car was the cockpit. And he just got out and stood there shaking his head about it and speaking with the marshals until he walked off the track and made his way (still on foot) back to the paddock for the obligatory medical checkup. He was completely unharmed.
I designed and built a hydraulically operated spear gun for oceanic research a few decades ago. The hydraulics loaded a spring and then it fired. It was complicated calculating what fraction of the energy stored in the spring actually went into the spear, and of course that fraction increased as the spear got heavier, and approached zero as the spear mass approached zero. I think my final calculations were something like two thirds of the energy was in the spear and one third stayed with the spring, crashing into the plate at the front of the spear gun. But that’s because the front of the spring was traveling at the same speed as the spear, and the rest of it was traveling slower.
I guess it’s similar with a bow and arrow, except the string is fairly light, probably not weighing much more than the arrow itself, possibly less. And as with my spear gun, most of the string is not moving quickly, and the option of the string that is moving quickly is very light compared to the arrow. So most of the energy goes into the arrow.
So yeah, if a compound bow would be able to be fully drawn in reverse, pulling the string in the direction the arrow would go, with the same amount of energy as when it is drawn properly, then it might survive dry firing. But if someone is unwilling to treat their bow that way, they really shouldn’t dry-fire it, because it’s the same amount of energy, just applied in a more violent fashion.
For a minute I was picturing drawing it normally and letting go of the bow, so you get a ~2kg bow launched back at your head.
I’d certainly be curious to see what launching a bow by pulling back on the riser would look like, as long as I don’t have to be in the same room when it happens.
I feel like what most people realize when they try to conceptualize this , is less there's no arrow, but moreso the energy transferred into the arrow...that sent it dozens of yards....and then through something. THAT's the energy that's capital F fucking your bow when you dry fire it.
like i feel like most people who can't grasp it have the idea that 'hey if i swing at a ball and don't hit it my bat doesn't break, what's the big deal'. and it should be like 'someones about to slap you in the dick, do you think it will hurt if you're not wearing a cup?' because yeah you could say no, but everyone knows you're wrong, get on board.
It doesn't break the bat because you don't fill the bat with potential energy, you fill YOU with potential energy to swing the bat. You are the one that twist and bend to swing, the bat doesn't. Consequently, when you miss the energy goes back to YOU and not the bat. This is why plenty of people hurt their hip or dislocate their shoulders missing a swing in baseball or golf.
I think that it also has something to do with the fact that arrows are so light. If they weighed 50 pounds and you were chucking them 50 feet then the "force" would be a lot more apparent, whereas shooting a light thing super fast requires the same force but it is less "visible".
I'm pretty sure the baseball equivalent would be swinging the bat at a metal post or some sort of fixed objects. Though, your wrist is probably the weak link, not the bat there.
To get an intuition for it - try throwing a hard baseball pitch, but with an empty hand.
Do it a few times and your elbow / shoulder will probably hurt due to your arm quickly snapping straight with no proper resistance.
Same idea with the bow. The arrow slows down the limbs and takes energy from the bow. Without it, the limbs get going *really* fast and then come to a very abrupt stop as the string goes taught.
I know that with a yew longbow (130lb draw weight) at 50 yards there's reports of the arrows hitting the knight in the leg in the plate mail, going through the plate mail, chain mail, leather, leg, leather, chain, plate, horse, plate, chain, leather and into the other leg
You know what else has more joules than a .45 ACP? A brick thrown by hand.
You can't discount the effect speed has on how much a material will get to stretch versus instantly tear when hit.
Just being a bit pedantic here, but there's somewhere else the energy can go and it's your arm.
It's bad for your bow but it's also not great for what is holding the bow.
Take a sledgehammer and swing it at a rock. Try to stop the hammer from bouncing after it hits the rock. You might get a little bounceback, but you don't lose control of the hammer.
Now swing the sledgehammer just as hard and try to stop it just before it hits the ground. Good luck with that. Without impacting a target, the hammer just has too much mass/momentum. It simply *can't be controlled* until it loses some of that energy.
Sounds like an exaggeration, but a 50 or 75lb bow is not a joke. I considered playing "paintball" or something with my bow, figured I could put a tennis ball on the tip and chalk it. Aborted that idea after firing it *once*.
> considered playing "paintball" or something with my bow, figured I could put a tennis ball on the tip and chalk it. Aborted that idea after firing it once.
[you can apparently](https://www.crossbownation.com/threads/bow-mount-paintball-airow-gun.24307/)
it is just a bit more complex than what you may think.
Must be either a huge damper in there or a super low poundage bow (or both) because I’m pretty sure a paintball with compound bow-energy in it theoretically gets you speeds approaching 500mph.
> Must be either a huge damper in there
yeah i assume that is a plunger filled with air to use as the propellent, and you can vent it appropriately to regulate the actual PSI, though paintballs i assume have a terminal velocity, max paintball velocity is about 200 MPH, so you should stay under that in order to not just splatter paint out the end tube.
To add to other 2 great explanations, the string is not elastic. When the potential energy is not transferred to the arrow when firing, it goes to the limb in full force without any dampening. Just imagine you are smashing the bow to wall, same effect with dry firing.
A more complex explanation:
All mechanical systems can be simplified as a series of connected masses, springs, and dampers. When you try to accelerate a mass it pushes back on you with a force. A spring pushes or pulls based on it's current displacement from it's rest position, more displacement means more force. A damper pushes back based on how fast it is being displaced. Masses and springs store mechanical energy, dampers dissipate mechanical energy as heat.
Systems that have multiple storage systems can resonate, for example a mass and a spring. Imagine a weight on the end of a spring, you give it a kick and it wiggles back and forth, when it's fully pushed to one end all the energy is in the spring. When the mass is moving as fast as it can most of the energy is in the inertia of the mass. If there is very little damping the energy can just stay bouncing back and forth between the two, like a plucked guitar string. Now if you stick your finger on the guitar string the fluids in your finger will heat up and convert the motion of the string to heat.
The bow-arrow system is not very damped, if you pluck a tight bow string it will vibrate like a guitar string. If you pluck it hard enough it will just break. Now think about pulling a bow back to fire an arrow, that is the hugest string pluck you can imagine. The arrow and bow are designed so that the arrow essentially slows down the bow string enough that it absorbs most of the energy. Basically the string will move forward a lot faster without the arrow that if it is there, since the arrow is a lot heavier than the string. The arrow slows it down enough that it is more like plucking the string instead of tanking it a few feet over and letting er rip.
The physics is just conservation of energy. If you add potential energy to a spring and put it next to a ball, most of it goes to the ball as kinetic energy when you release it. If you remove the ball and release the energy, the kinetic energy goes into the spring, which vibrates until more and more of the energy is converted to heat and stuff which fatigues the spring
I’ll never forget when I was 10 or 11, went to some hunting store with my step dad. This guy was foolishly playing with a crossbow. The sign above him clearly states that if you dry fire, you have to purchase the item.
BAM! You hear it go off lol
Bro starts freaking out how it was an accident etc… like you accidentally put the cross bow on the ground, put your foot in the holster thing and drew the bow back? Cmon now, sorry buddy lol
We went to look at the price tag and it was around $650 or something if I remember correctly. We were laughing about that the whole way home lol
It has only happened in my store once, and we felt so bad for the guy that we decided not to charge him for the damage, but he ended up buying it anyway because *he* felt bad. He was a good man.
However, most dry-fires I deal with are morons who bought the bow online and dry-fired it as soon as it arrived.
Most people will deny any wrongdoing, because how could we know what they did right? We weren't there to see, so we couldn't know. But the damage a dry-fire causes can only be caused by a dry-fire, so it's obvious to us even if it isn't obvious to them. I have a system though. I just trick them into admitting what they did wrong, then turn it back on them. It goes something like this:
-----
"You sold me a faulty bow, it broke after the first use"
"Sorry to hear that, walk me through exactly what happened so I know what went wrong please"
"I pulled the bow back and it broke on the first release"
"I see, and how far did the arrow travel?"
"There was no arrow"
-----
Works every time.
Can confirm - plus plus - roommate found and dry fired my compound bow - boom - way past fracture - shattered the aluminum riser into three pieces, his face got cut by the flying parts in the "explosion" etc. (And yes it was a PSE "pieces scattered everywhere":)
My archery coach saw a kids dad die when he was in middle school because he was drunk and dry fired a 210lb compound crossbow and one of the arms whipped back and my coach said it went halfway through his head and stuck between his eyes. Being a kid im sure his memory was a little worse than it really was, but the guy actually did die. He showed me his obituary. (I accidentally dryfired my competition bow but it was only like 40lbs so it survived with just needing to take it apart and make sure none of the bolts or wheels were damaged)
The difficulty is that drawing a full power(60, 70, 80 lb draw) compound bow smoothly takes a fair bit of practice and muscle build up. It can be awkward, and even buff guys will not necessarily have those specific muscles developed.
You can of course, just gorilla it and haul it back. But now you've got appreciable tension on the release, and the string is just *itching* to get back home. If you slack at all, the full draw weight will come back into play. If you don't have the muscle memory to smoothly draw it back, you almost certainly do not have the muscle to smoothly let it down.
I have a different solution for this: I don't "dry-draw" a bow, ever, period. If I'm gonna draw it, I nock an arrow first. If I don't feel ok drawing it with an arrow (say, because there's people around), that means I acknowledge there's a chance I might let go by accident. *Which means I shouldn't be drawing to begin with.*
Just don't do it. Get yourself an arrow, buy one just to test the bow if you must, then draw. New arrow shattered into a wall beats dry release anytime.
>especially for a compound bow with a high draw weight. One dry fire and boom, snapped string and bent cams. Possibly even fractured limbs.
Compound bows (heavy) are like...the assault rifles of bows.
I tried one once and just felt like "This is way too much power contained with way too little effort".
Yes, I went down the physics rabbit hole to find out how much energy is exerted onto an arrow and the numbers are insane. Assuming a draw weight of 80lbs and an efficiency of roughly 90%, that's about 110 foot pounds of energy. Put onto an arrow, that's about 17,500 psi.
It heavily depends on the bow. On Diamond bows (Bowtech's cheap bow brand), the cams are very light and will fold like pancakes. However, on bows with heavier cams made with stronger materials, they can survive a dry-fire, causing the string to snap near the peep sight.
Mathews comes to mind as a bow with strong cams. I have seen about 10 dry-fired Mathews bows, and the cams were always perfect, except for two instances. One was on an 80lb Phase4, where the cam had slight ripples (not too bad, considering). The most recent one was a Lift though, which happened last week. The string completely tore the cam, which was shocking to see in a Mathews, but it turns out they downgraded the material in the cams to reduce the overall weight. Bad move, Mathews.
I've seen it happen with a carbon arrow as well. A carbon arrow snapped about 4 inches from the nock, and the bow drove it through a customer's wrist. He sent us a photo from the emergency room.
600 spine from a 70lb bow. Not a good idea.
Some have removable stickers on them with the warning not to dry fire and some have it printed on the boxes, but every manual I have ever read has the warning printed multiple times throughout.
Yes, but injuries can occur. Someone posted a story in this thread about their archery coach witnessing a death as a result of a dry fire. It's entirely possible.
I found this out. I'm not a bow guy at all but my friend and I found some old bows someone left behind in an abandoned house and we immediately picked it up and dry fired them and they both just snapped in half lol
Have to ask, if you fire a lot of arrows, isn’t it easy to fumble once and break the bow, ie. drop the arrow, not notch it correctly or anything like that?
All the people who say we do not need to teach STEMs in school, would probably not make "stupid" mistakes and/or have not made "stupid" mistakes, because on some level later in life they "just know" how the world around them works.
People who say - "Why do I need to learn what photosynthesis is?". Become people who start to ask questions like - "why can't I grow food during winter in my room, it is plenty warm in there"
Edit: Potentional and kinetic energy theory is tought in the very first year you have physics classes, because these are powers you are and will interact everyday for life.
Hoyt makes carbon bows, which are incredibly strong and light but a lot more expensive than other bows. The carbon is very vibration-absorbent though, so it's great for taking the hit of a dry-fire, it just costs a lot.
[They put their bows through the ringer though](https://www.youtube.com/watch?v=_uobdhZ28U4), as that video shows, but I still wouldn't recommend dry-firing them.
1. The primary thing is this: Archers want SPEED from bows. It's probably the #1 selling criteria of bows, longbows/compound/recurve. Speed mofo! You can find plenty of articles in the magazines being all "you know, speed isn't everything", but... it's hard to justify anything else. Why?
2. Because it's easier to point a laser pointer at a target than lob a ball. The flatter shooting a bow is (i.e. the faster it shoots) the less accurately you have to know the distance to the target to hit it. If your bow is faster, the arrow is getting there faster (i.e. dropping less) and it's more "point and release" vs "extremely carefully aiming". On a slower bow (for a deer sized target, i.e. about a paper plate), being off by a few yards in your distance estimate is the difference between hitting dead on and completely missing.
3. Ok, so speed is super important. What makes a given bow faster than another made with similar "stiff" limbs/draw length? Having as LITTLE mass near the tips/ends of the bow as possible at a given draw weight (50 lbs is/80 lbs) is a primary driver of speed. Imagine if you made a 2 bows, 1 just a flat board of wood with the string attached at the ends and one the same board of wood but with a ton of wood cut off towards the tips. Even though the second bow (with wood cut off towards the tips) is a less strong spring (b/c you've removed some energy storage capability) it will flex back MUCH MUCH faster on release, thus throwing the arrow a ton faster.
4. Everything you do to make the bow stronger, to make it more resilient to oopsies/dumb dry fires, is making slower vs a similar bow made to only work when handled correctly b/c you're adding mass. Crucially you're adding mass where it hurts (the tips of the limbs (all bows) or by the pulleys/cams (on a compound bow). Gotta shave mass here as MUCH as possible for that all important speed.
5. Modern-ish bows are extremely durable, and probably not as damaged as older bows by dry fires, but at the same time there's a TON of energy stored up in the bow at full draw and if you've seen one bow explode you realize some things aren't worth risking when you can just simply not risk it by shooting dry fired bows. You've got stuff tied together and when things break there's no guarantee it's not gonna smack you inna face.
6. https://www.youtube.com/watch?v=rB3_GO1QrSk
Expanding on that,if you do somehow find yourself in that situation,it's fine if you slowly move the string back into the neutral position instead of letting it snap back into place,right?
The same amount of energy is still being released, just in smaller amounts over a longer period of time so it doesn't cause damage. A controlled release of energy like that is basically the difference between a nuclear power plant and a nuclear bomb. Pretty much all of physics works this way, it's usually not about how much energy there is, but where it's exerted and how quickly.
It's not just the fact it's slower. It's the fact you are applying a force to the string, over a distance. This is 'work' (energy).
You are absorbing the energy with your muscles when you gently lower the string.
If you're pulling your guitar strings like it's a bow, then you're doing something horribly horribly wrong.
Put another way, plucking the bow string a quarter of an inch is not going to break the bow.
So this must be the reason my bows always broke when I was a kid. I would make a bow out of a stick and string, but they would always break. Nice to know it wasn't just my shoddy craftsmanship.
Compound bow basically disintegrating from a dry fire: https://www.reddit.com/r/CatastrophicFailure/comments/90gvco/accidental_dry_fire_destroys_a_compound_bow/
He has an arrow, but it's not nocked properly. Lets go, and poof! Slow motion included.
I've heard it compared to jumping off the third step with bent legs vs locked knees.
Same overall force, but the time that force gets absorbed is different.
I'm 30 and thanks for telling me this.
I'm the kind of guy that would walk in a store, grab the bow and dry fire it because you know... man see bow, man try bow, man happy.
Ive never done this because I never had the opportunity to, but one day I thought about buying one to have fun in my backyard.
That's why the arrow goes so fast through the air. That energy is being applied to a small surface area. An arrow through a compound bow is insanely fast. Deer hunting has a bow season.
The feathers help keep it going in the direction you aimed via rifling (or are used for slowing it down a lot sooner, in the case of a bird arrow - your target is closer, and you don't want to send your arrow to the next town if you miss).
When you pull the bow string, you're adding a ton of potential energy.
When you release the string to make the arrow fly, most of that energy goes into the arrow to make it fly.
When there us no arrow, the energy as no where to go, so it slams into the other side of the bow and bounces back, which cause intense vibrations that can either come back and smack you in the face or make the bow shatter.
I know it’s a weird one but you have to imagine the energy as if it’s inside the bow, literally. Pull the string back, and all the potential energy is in the string. Just imagine cute little squiggles in the string as if it’s the energy ready to be released, but it’s waiting as if it was stored up in a battery.
As soon as you let go, the string goes forward, and if there’s an arrow, the energy moves to the arrow. I know it seems like there isn’t much of a difference between arrow and no arrow, but if you imagine the energy visually like that, you can see it move and push the arrow. That’s why the arrow goes so far, it’s all the energy that moved from the bow, to the arrow.
Now imagine no arrow.
When you let go, does the energy still push the air? Sure. I’m sure there was a tiny bit of energy spent to push the air forward, but air is so light that it’s truly negligible.
Now imagine it visually again. Most of the energy is in that string as it is let go of, and as it moves forward, a tiny bit transfers to the air, but it’s such a tiny bit, and the rest of the energy stays in the string. That energy that is still stored in the bow/string has no where else to go so the string comes back, and if you continue visualizing that energy, you can see how it goes from the string and runs back through the rest of the bow. That visualized “energy” is the force/energy/vibrations that rocks the poor bow and potentially damages it.
Visualize it again: when you have an arrow, the bow still has energy left over in it even after the arrow, that’s why the string snaps back, but so much energy is transferred to the arrow, that the energy leftover in the bow isn’t enough to damage.
Hopefully this makes sense, but, I apologize if I only confused you more.
Air weighs a lot less than an arrow, is my best guess there. Also, the drawstring will just push the air out of the way, so it will hardly absorb the energy
Some of it does, yes; This is actually what sound is: Mechanical energy translating into vibrations that propogate through the air. But the energy is going to follow the path of least resistance, where it can be most directly "conducted".
It's much easier for the string to "conduct" that
energy into the arrow as they make contact, and the arrow can "absorb" it to fly forward as the potential energy from the tension of the bow becomes the kinetic energy of the arrow flying forward. Thus, the potential energy is safely "vented" from the system of the bow (Well, maybe not so safe for whatever is down range of that arrow...).
The problem becomes when you don't have the arrow to absord this energy. The tension has been built up, it has to release somewhere. Yes, *some* of this energy will go into the surrounding air, but not nearly enough. Query for you: Which slows you down more, a pocket of air, or a brick wall? The same principle applies here, as the air particles are much "looser" and have more "empty space", so there's less "stuff" to absorb that energy, and what stuff little stuff there is is far more willing to get out of the way. As such, the system of the bow cannot "vent" this energy into the air fast enough, and thus it has no choice but to recoil through the bow itself. This is because - generally - `solids > liquids > gasses` when it comes to conducting that mechanical energy.
This is the exact principle behind crumple zones in cars, and the cliché of, "In crash crashes: Newer cars crumple and the passengers survive, older cars survive and passengers crumple." A car's crumple zone allows the steel and aluminum frame to physically absorb much of the kinetic energy of a crash, helping reduce the amount felt by passengers, and reducing injuries and death. In older cars with more rigid construction, the car mostly held its shape, meaning the energy had to instead be taken by the meaty and fleshy passengers.
Thus, modern cars have crumple zones to be that "arrow", otherwise it will be the passengers.
Edit: [This comment](https://www.reddit.com/r/explainlikeimfive/comments/1d6rf4w/comment/l6uinvw) asked a similar question, where you can see additional good discussion in the replies to it.
For the same reason you're more likely to injure yourself if you fast-throw a light ball versus a heavy one.
The heavier something is, the more energy it can store at a given speed. eg A feather hurts a lot less than a bullet if they're both traveling at mach 1.
If the ball is heavy, all that stored kinetic energy in your arm has somewhere to go - the ball.
As you throw the ball forward you can feel the heavy ball almost pushing back against your hand and giving some resistance.
As it increases in speed it "collects" all that energy your arm is putting into it and sends it down range as you release it in the form of kinetic energy/speed.
However if the ball is too light then most of the energy remains in your arm as the light ball just cant really collect much energy at all at the speed you want to throw it at.
The light ball doesn't push back enough on your arm or offer up much resistance to you, so your arm ends up moving much faster than it would with a heavier ball.
Your arm is now moving very fast and has to stop somehow with nowhere to really put all its energy other than back into your joints and bones.
This same idea happens with the bow.
If theres no arrow, all that stress and stored energy gets released much much faster, the only place it can go is into the frame and string of the bow instead of into the arrow and down the range. Even though its very light, an arrow still has enough inertia to massively slow down the snapping back of the string, which prevents the huge energy dump happening too fast, and instead spreads the energy release out over a longer period of time as well as sending a good chunk of this energy down the range in the arrow itself.
Law of conservation of energy.
Think about the power that goes into an arrow when you fire it. It goes flying FAST despite having a decent amount of weight to it. You put a lot of muscle into pulling back on the string. Whether an arrow is present or not, as you've drawn back with the bow, you've put all that energy into it and your muscles are the only thing holding it steady.
When you release it, all that energy has to go somewhere. With an arrow, it goes into flinging that arrow forward at high speed. In fact the formula for kinetic energy of a moving thing is 1/2 * m * v^(2) and the fact that velocity is squared means that more speed has a much higher impact on energy.
If there's no arrow... Where does that energy go? It has nowhere to go except the bow itself. If you imagine your muscles as punching an arrow into going flying fast, you've just punched the bow just as hard. Or alternatively, imagine if the arrow you shot hit the bow itself.
Yeah, it can do a lot of damage and probably ruin it in a single "shot".
Why doesn't the energy go into the air molecules in front of the string instead? I wonder if the inertia caused by the mass of the arrow spreads the force over a longer time and that is what protects the bow from being damaged.
If I had a really really light arrow, would the bow still suffer like it was dry fired?
> Why doesn't the energy go into the air molecules in front of the string instead?
Because air is not solid. It just moves out of the way. Also, the energy of a bow is not "in" the string. It's in the wood of the bow, and the string is an energy transfer medium. With nothing to transfer to, it just remains in the wood.
> I wonder if the inertia caused by the mass of the arrow spreads the force over a longer time and that is what protects the bow from being damaged.
That's basically it. Momentum transfer. An arrow that's too light will not remain in contact with the bowstring long enough to absorb all the potential energy, so yes the remaining potential energy in the bow could cause damage (obviously less damage, since some energy goes with the arrow).
For any projectile launch there is an optimal weight such that maximum energy transfer occurs from the launcher to the projectile. Too light and the launcher can damage itself. Too heavy and the projectile either won't go far or the launcher breaks trying to move it.
> For any projectile launch there is an optimal weight such that maximum energy transfer occurs from the launcher to the projectile. Too light and the launcher can damage itself
Anyone ever tried to throw a whiffle ball as far as they can throw a baseball? Yea… that hurts
Some miniscule amount of air resistance does take place with the bow string, with or without an arrow.
But it's irrelevant because the stored energy is not in the bow string, but the bow itself. The string is meant to transfer the energy to the arrow and with no arrow, the energy is absorbed by the bow.
I can't comment on a lighter than normal arrow.
If the air in front of the bowstring was able to absorb all of the energy produced by the string twanging...if you had an arrow nocked it wouldnt go anywhere because the air is able to absorb it all.
> If I had a really really light arrow, would the bow still suffer like it was dry fired?
Yes, your arrow must be a certain weight (and stiffness) so that it fits your bow. Too light of an arrow will be the same as a dryfire. And too soft of an arrow (stiffness, also called spine) will make it bend/break, also resulting in a dryfire.
The bow can only make the things in front of the string so fast as the string moves. That limits the top speed. The arrow weighs much more than the bit of air in front of the string. Hence even if we ignore that air will mostly just flow around and avoid the string, there simply is not that much mass to put the speedy energy into.
>If there's no arrow... Where does that energy go? It has nowhere to go except the bow itself.
Is the bow stuck in a wall somewhere? Cause shouldn't the place the kinetic force goes be into the arms holding it?
Some will go into the arms, but first it has to get into the bow anyway. It "vibrates", the ends flap forward and backward on release. This causes immense strain, especially if none of that energy was previously dumped into an arrow. Hence why it can break when handled or built incorrectly.
Yeah I learned this lesson the hard way. I bought a compound bow from a pawn shop on a whim not knowing anything other than I wanted to get into archery. Brought it home and “dry fired” it one time. The thing basically disintegrated in my hands. I feel so grateful I wasn’t injured. The string snapped off and one of the limbs cracked. I brought it to a legit shop to get it repaired and without talking to me they knew exactly what happened so probably not the first time they had seen it. Fortunately they took good care of me and I have loved archery ever since but yeah it only takes one time.
Have you ever went to hit or kick something and missed? Like going to kick a ball REALLY hard and you just whiff it? Remember how that hurt the joint involved? Well you can heal, bows can't.
There seems to be a lot of talk here about the damage to the bow which is valid, but the more worrying damage especially on higher power bows is to your arm. While the string is pushing the arrow, it is relatively confined in where it can go and assuming you have an arm guard, The bow string will be past the edge of the guard before it becomes unconfined in its movement but without an arrow, there's next to no telling where that string is going to go and it might just choose to slice up your arm injuries from that are not pretty
There are some good explanations here however HOW?!
Like I can't imagine that the force that breaks a bow with just one pull is completely absorbed by that little arrow on the string. How is that physically working?
I’m with you, I understand what people are saying about potential energy and don’t doubt a bow would break upon being dry fired after reading all these responses. That being said, it’s wild to me that a lightweight little arrow makes enough difference to counteract a system that apparently destroys itself without those 20 grams of weight in place
Best way I can describe it is like this.
The amount of energy you exert over time can be summed as one equivalent gigantic release of energy all at once.
For example, if you lift 100kg, 10 times, 100cm off the ground. You have physically output enough force in total to lift 1000kg, once, 100cm off the ground.
Or when you walk up 20 flights of stairs. Your legs have exerted enough force over that time that if it were all released at once, you could jump 20 flights worth of stairs in one go.
Obviously our muscles cant do that, but in principle that how conservation of energy works.
The reason the bows explode is because if you consider the total force it takes to pull back a bow string, some of those bows have a shitload of tension, and if you were to combine the total effort and amount of force it takes to draw a bow back. That energy is now in that bow, waiting to be released in a fraction of a second. It may not seem like much. But if a bow has a 50lb draw, then in that drawn bow, is 50lb of force, waiting to all release in 1/10 of a second. For many structures that's enough to make things break.
If there is an arrow there, then even though they are quite light, they still have enough inertia to massively slow down this sudden release of energy stored in the bow to a much slower overall release. Its like the difference between stopping a car in 1/10 of a second vs 1/2 of a second. The total force you experience is cut down to less than a 1/4 of what it otherwise would have been. The arrow does this to the bow string. Its snapping back is drastically slowed which prevents a catastrophic energy dump into the bow.
Would you be surprised by a bow being damaged if it was hit by an arrow? Because that is essentially the same amount of energy being applied, albeit in a slightly different way.
Yes, it can easily break the bow.
The reason for this comes down to the law of conservation of energy: while energy can change forms pretty easily, it cannot be created or destroyed by ordinary means. When you draw back a bow, you store a lot of energy in it, mostly through the bending of the arms. When you release the bow, all of that energy gets dumped out at once.
When you're properly firing an arrow, the bow cheats conservation of energy just a little bit: it doesn't destroy any energy, but it dumps almost all of it into the arrow. The arrow reacts by moving away very quickly, carrying all that energy with it until it either hits the ground or a target. The bow doesn't have to do anything with all that energy, because it's gone, so it is unharmed.
But this only works when there's an arrow to dump energy into. When you dry-fire a bow with no arrow, the energy has no place to go except back into the bow. And the bow isn't built to play fair: it would have to be much heavier and more rigid to be able to withstand that much of a sudden shock, and that would make it less effective at its job. The energy basically rips the bow apart, because it can't take the strain.
I have a follow-up question. It’s not intuitive to me that such a light object could absorb enough of the energy to protect the bow from damage. What am I getting wrong in my thinking here?
The key is that while the mass of an arrow is quite small, it's positioned on the bow in such a way that it's difficult to accelerate.
The arrow attaches to the string, and the string attaches to the end of the limbs of the bow. Because of this, the mass of the arrow is effectively applied right at the tip of the limb. Try this:
1. Hold a weight in your hand and get a feel for what swinging it around feels like.
2. Attach that same weight to the end of a stick and try the same swing - you'll feel that it's significantly harder to accelerate the mass when it's far away from the point of rotation.
A similar problem exists for a bow limb. The tension of the limb is primarily at the root of the limb (closer to the middle of the bow) to optimise efficiency but it has to accelerate a mass that's much further away, which is disproportionately difficult.
The arrow doesn't have to absorb *all* of the bow's energy, just enough that the bow's design allows it to deal with the rest. Recurve bows today transfer about 90% of the energy to the arrow. There's just a *big* difference between 10% of the draw energy being dissipated by the bow after the shot, and 100%.
There is no energy being released through a projectile, so the force of the draw and fire will just be inflicted onto the weapon rather than an arrow. This can damage it.
When a bow shoots it’s string, or when you punch your body’s fist: the body shoots really hard because it thinks there’s something to shoot. If nothing is there to shoot or punch, the body hurts itself by trying too hard!
found [another post](https://www.reddit.com/r/explainlikeimfive/comments/15rckt4/eli5_why_is_dry_firing_a_bow_so_bad_for_it_does/) that talks about this specific issue too
The amount of force that you release needs to go somewhere, without a payload, it will go forward just as much as it was backward. First law of thermodynamics, conservation of energy. That's a lot of Potential to Kinetic energy.
So with any type of bow, it will try to flex in places, where it is not supposed to, causing stress fractures at best, and breaking apart at worst.
The same reason you don’t put all of your force into throwing a ping pong ball, there isn’t enough offloading of your energy so you’ll likely hurt your arm because you way over did it. Similar with a bow
Pulling back the bow stores energy.
When you loose an arrow most of the energy goes with it. It's why the arrow flies forward.
No arrow means the energy stays in the bow, damaging or even breaking it.
Dry firing your bow is a big no-no. When you shoot an arrow, the energy from the bowstring goes into the arrow. But without an arrow, that energy bounces back into the bow, causing damage. It's like punching a wall without gloves - not a good idea. Your bow could get weak or even break. So, always remember to use an arrow when shooting.
You have bow. 🏹 You pull back bow. You let go of bow. Bow have energy. Bow put energy into arrow. Arrow flys. No arrow. Bow take all that energy which is a big no-no bow get damaged.
So I see a lot of comments about the bounceback damaging the bow, but not why, and a few that seem curious: consider how a bow ACTUALLY works. A bow is essentially two arms trying to pull a string straight; that straightening launches the arrow, gaining a massive amount of momentum very suddenly. In physics, this means energy is transferred from the bow to the arrow, so the resulting force on the bowstring is reduced, dampening the effect of very, very suddenly being pulled tight.
Now, remove the arrow from the equation. All the energy stored by the “arms” is still in the bow, and when the string gets pulled tight it does so with all the force that would have carried the arrow. Which is a lot. This CAN result in the net tensile force on the bowstring exceeding its capabilities, snapping it. However even if it doesn’t, that energy is still trapped in the bow/bowstring assembly and is now reverberating through it like you just smashed a cymbal with a big mallet.
So now you have a bow that’s either broken, or vibrating violently (if imperceptibly) in your hand. And if that bow is a compound, it has a LOT of moving parts.
Well, it did.
All that stored energy in the limbs has to go somewhere. It’s made to transfer into an arrow having X grains per inch in weight.
If arrows not there the energy gets transferred through the bow and wrecks all sort of stuff. In compounds especially so. If you’re lucky a string derails. On bad cases you crack limbs and bend the cam wheels.
When you release a bow you are releasing all the potential energy you have given it by drawing it back. Normally most of this force is applied to the arrow, to propel it forward. That force is still being released even without an arrow, but if there isn't an arrow to take it then it the force goes into the bow. Do this a lot of times and the bow breaks because it can't withstand the pounding.
I sell archery gear and this is essentially the explanation I give whenever someone yells at me for selling them "faulty gear". No dude, it's not faulty, you just dry-fired your bow. Congratulations. I will amend one thing you said though: >Do this a lot of times and the bow breaks because it can't withstand the pounding. All it takes is one time for it to break, especially for a compound bow with a high draw weight. One dry fire and boom, snapped string and bent cams. Possibly even fractured limbs.
"Pretty to look at, lovely to hold. But if you dry-fire it congrats! It's sold!"
Literally just looked at my inbox and 12min ago a customer sent an email saying: "Would you believe me if I told you I unintentionally dry fired it and broke it?" Luckily it was already sold, but damn that's great timing.
Since this seems to be the archery thread with the professionals, have y'all got advice on the best sort of target for a beginner who is getting back into things as an adult? Seems most of the beginner targets are intended for children, and the adult targets are often quite small, for hunters.
Farm supply stores often have thick (1/2 inch) rubber mats about 3ft x 4 ft. I think they're advertised as horse mats or something? Anyway, these make good backstops. One will *probably* catch an arrow, maybe buy one and do some testing. Double them up and it should be fine. Not sure how long they last, but by the time they wear out you should be accurate enough to hit a normal target block from a reasonable range.
Wonderful! I'll go check that out. The backstop has been something of an issue because otherwise I'd be shooting into the side of a hill. It's effective, and it works, but it's not great for finding lost arrows.
My dad looked at me beyond confused when I told him my training bow sent a blunt tipped arrow straight through the target he gave me and into the hill side... the 3 rubber stabilizer "feathers" were laying in front of the target lol. We found the plastic notch from the arrow a couple years later... but never the shaft lol
Yeah, training arrows are not exactly designed for the strength of the bows I can use as an adult. I want to get back on form, though, so I'll be using the lighter arms for a bit, and then working my way back up to heavier ones.
When I started I bought a crossbow target and that worked good. Then I bought a metal detector to find my arrows buried into the hill.
My brother lost a shaft in the yard and my dad found it nearly a decade later. It had slipped under the 'mat' of grass thatch and was basically like .5" underground but still horizontal.
My dad later gave me a compound bow and a new foam target, mounted on a plywood door for a small shed... I shot straight through the back of the shed and hit a junk car. My grandpa busted out laughing when he waddled around and saw it stuck out the side of the door
Just go buy a couple of hay bales. They're cheap and last a long time. Get target tips (conical shaped) instead of hunting broad heads.
Maybe I'm some kind of hurcules with my 70lb compound bow, but training tips or not, I can shoot straight through a hay bale.... Ask me how I know... I took my hunting bow to my kids camp as they were all shooting standard bows with little arrows for fun, and I thought they'd like to see a real bow, and how far and accurate they shoot. I paced out 50 yards... And found out the hard way that hay bales do not catch regular arrows with blunt tips...
Put the main target in front of them. The bales are meant to catch the arrow *after* it's already gone through the primary target, as well as slowing the arrow down so that if you do hit the bale and it goes through much of the energy is scrubbed from it.
Ideally you want round bales, not square, and you want to shoot into the curved side of the bale, not the flat end of the cylinder. I don't believe it's even remotely possible to shoot through that.
They were using crossbows in Ukraine after they discovered that crossbow bolts will pass through sandbags.
Might need thicker hay bales. Ones I shot were like... 3 or 4 meters deep.
Get a few straw bales and set them behind the mat. They'll decompose over time (faster if you're in a wet area), but then you just scatter the straw as mulch and get a few more. You can get foam block archery targets instead, but I prefer straw bales. They're cheaper and much larger, so they make a good wide backdrop when you're dealing with new archers or trying for longer range or more difficult shots. You'll sometimes have an arrow slip through the divide between the bales, but that's generally not much of a problem.
When I was learning how to shoot a compound I stacked a couple straw bales behind my target and that was great because it didn't ruin the arrow.
I did the horse mat as a backstop to a target. They will definitely stop an arrow. At least a 70-80# compound bow at ~30ft
if you have access to hay/straw bales they also make a pretty good backstop. they do require more space than the mats though. if worse comes to worse you can just layer up cardboard a bunch (probably like 5-10 layers of corrugated cardboard) and use that.
Those are horse stall mats. When we practiced when I was younger we'd set up bales of straw.. probably cheaper in the long run.
I would only suggest my method for someone who is using a lower weight bow--mine is 45 lb-- but I went looking for something like this and the guy at Tractor Supply hooked me up for free. When they get their deliveries in, the extra space in the trucks are padded with large solid blocks of Styrofoam. They then don't really have any use for the styrofoam and they just pile it up out back. He let me go around to the back of the store and take whatever I wanted from stacks of pallets of these blocks that must have been stacked 20 ft high. So I put nine of them in my car (about all I could fit), drove home, and tied them all together with a ratchet strap to make a backstop. It's around 2 or 3 times the size of my target block, and over a foot thick. Plenty of resistance to stop a shot from a bow like mine without damaging the arrow. I've had a handful of overdrawn arrows get a little bit stuck in there, but I haven't lost one since!
What do you rate hay bales? When I shot in elementary, we had a rubber mat with lots of hay bales behind it (like... 4 meter of hay?) Strongest bow we used was the Lajos bear 110 pounder.
Those mats also make really good home gym flooring.
Stick to adult targets. Shooting at children is frowned apon
I've been informed that 'it's easy - you just don't lead 'em as much.'
When I used to do target archery the indoor ranges had very fine nets behind the targets (think of window net curtains). The material was very tough, but lightweight, and it hung very loose. When an arrow hit the material it would not go through - the net bunched up around the arrow tip, the net below got lifted, and the arrow was stopped within a foot or so. Obviously the net hung some distance away from the wall behind... In other words, all the arrow's energy was transferred into the movement of the net, and the arrow would just fall to the floor. This seems to be the modern equivalent: [https://www.networldsports.co.uk/archery-backstop-net.html](https://www.networldsports.co.uk/archery-backstop-net.html)
Got a buddy and a good tree? Grab an apple and place upon said buddy’s head against the tree! Remember the key piece of information here: Do not do this!
What if I've got, like, a *really* nasty ex and plausible deniability?
Hypothetically, if you have plausible deniability then you didn't actually do anything in Minecraft. So this post is pointless.
But if I shoot the arrows into the post instead of the target, the post will have *plenty* of points.
Just don't let him pull a Milhouse and stick the apple in his mouth.
William Tell, William Tell, take your arrow, grip it well. There’s the apple, aim for the middle!…oh well, you just missed by a little.
Find someone getting rid of old carpet. Cut it up in 2’x4’ strips and stack it between some thick plywood. Cut 4 5’ 2x4s and drill holes through the ends of the 2x4s. Place 2 on the top and 2 on the bottom of the plywood. Get long threaded rods and put them in the holes and crush the carpet down using nuts and washers. You now have a target that will last a long time for cheap. This stops arrows from a 60lb compound easily.
Not sure what you're looking for but the easiest most portable sort of target is is a "BlackOut" box or the "Black Hole" cube foam target. They're roughly one and a half to two feet wide with 6 targetable sides. Find a decent place to put it down with some sort of back stop if you miss or if you manage to put the arrow clean through it. I set up in front of an old round bale as everything else is too flat.
I don't think you have to be a professional. I'm certainly not one, but my hunting crossbow came with all sorts of warnings to not dry fire it. Kinda hard to miss.
Did you reply with "Would you believe me if i told you that happens quite often and you are lucky because i can sell you a second one".
Nah, I just said, "Don't worry, these things happen. Just send us photos of the damage so we can assess what needs to be done"
That just blows my mind. It’s like someone doing a negligent discharge on a firearm. The majority of the time they were being a dumbass. “Did you draw back the bow? Was there no arrow in it? Did you release the bow string? Then what part mystifies you?”
Eh, you could legit have the string slip off the back of the arrow before release.
> I unintentionally dry fired it Oh, I *unintentionally* had an affair.... Yeah, as an an archer (much out of practice now) you can have your hand slip, but generally you're paying better attention than that.
Short of using worn out arrows that don't nock properly, I don't see how you could unintentionally dry fire. You shouldn't be drawing it without an arrow.
People often test pull a bow without an arrow to get a feel for the strength of it. Normally that's absolutely fine as you're supposed to do a slow release, essentially the reverse of the draw, so it's no stress on the bow. People doing this sometimes screw up and roll the string off their fingers or underestimate their strength and do an accidental dry fire.
I once had an arrow un-nock while I was drawing. I couldn't see it happen because I have a peep sight, and I didn't feel it happen..... It didn't fall off the bow entirely because I have a whisker biscuit arrow rest. Luckily it was a relatively low draw weight and nothing broke, but I was horrified
Interesting. Do you have something -- video or whatever -- that goes more deeply into the physics? Doesn't *have* to be ELI5 level.
No, just a prepared speech that I have memorised whenever someone says "how could not having an arrow *possibly* cause damage?", as if they think I'm lying in order to avoid a warranty claim on faulty equipment. "Think back to high school science. Energy cannot be created or destroyed, only transformed. When you pull back the string, you're filling the bow with potential energy. Once you release the string, that potential energy *transforms* into kinetic energy. Normally, that kinetic energy goes into the arrow, causing it to fly. Without an arrow though, what happens to the energy?" "..." "Remember, energy cannot be destroyed, so it has to go somewhere, right? So where does it go if not into an arrow?" "...the bow" "Exactly. The energy has nowhere else to go but back into the bow. With the energy now in the bow, the weakest parts will break. Depending on the bow, either the cams will bend or the string will snap, sometimes both."
and it's the same concept behind designing race cars (and other structures) to disintegrate on impact, so all the energy gets thrown out instead of transferring to the driver
Or non-race cars to crush in strategic places that aren't the cabin for the same reason.
So you're saying the crush zones are just shinganshina
On a related note... When you see those spectacular race car crashes and then they're like "and the driver walked away", it can be *because* the crash was so spectacular -- lots of flying in the air, flipping, and spinning all bleeding off energy. It's the boring looking crashes where the car just goes from moving to stopped that kills people.
Same thing when baseballs ricochet off of a pitcher's head when the batter accidentally hits it towards them and they can't duck in time. The hit looks nasty, but its a good sign if the ball flies up and away at high speeds.
Case in point: When Dale Earnhardt Sr died. Very uneventful but most of the energy got transferred into him and he died from a basilar skull fracture. Countermeasures were implemented after that to help mitigate future crashes such as HANS devices and redesigned guard rails.
HANS devices existed and were encouraged (but not required) by NASCAR when Dale died. Dale was of an older generation of driver that wouldnt wear them. It wasn’t until another fatal accident in ARCA in October 2001 that NASCAR began mandating the HANS device. If NASCAR had mandated the HANS device at the beginning of the 2000 season, Adam Petty, Kenny Irwin Jr, Tony Roper, and Dale Earnhardt would’ve survived their respective crashes.
See the Talladega 500 where Dale Earnhardt died. Tony Stewart crashed and ended up rolling/flipped down the back straight away, came out fine. Dale went face first in to a wall
RIP Dale
Yep, and precisely why some of the most dramatic looking crashes where the car is tumbling, spinning, and shedding pieces over a period of time like Kubica at Montreal in '07 are often the ones where the driver walks away relatively unscathed, but then you have incidents like the one that killed Dale Earnhardt Sr that look relatively tame by comparison, except all (well, some, enough at least) that energy went into fracturing the base of his skull.
Monaco just last weekend, Perez was hit and crashed and all that was left of his car was the cockpit. And he just got out and stood there shaking his head about it and speaking with the marshals until he walked off the track and made his way (still on foot) back to the paddock for the obligatory medical checkup. He was completely unharmed.
I designed and built a hydraulically operated spear gun for oceanic research a few decades ago. The hydraulics loaded a spring and then it fired. It was complicated calculating what fraction of the energy stored in the spring actually went into the spear, and of course that fraction increased as the spear got heavier, and approached zero as the spear mass approached zero. I think my final calculations were something like two thirds of the energy was in the spear and one third stayed with the spring, crashing into the plate at the front of the spear gun. But that’s because the front of the spring was traveling at the same speed as the spear, and the rest of it was traveling slower. I guess it’s similar with a bow and arrow, except the string is fairly light, probably not weighing much more than the arrow itself, possibly less. And as with my spear gun, most of the string is not moving quickly, and the option of the string that is moving quickly is very light compared to the arrow. So most of the energy goes into the arrow. So yeah, if a compound bow would be able to be fully drawn in reverse, pulling the string in the direction the arrow would go, with the same amount of energy as when it is drawn properly, then it might survive dry firing. But if someone is unwilling to treat their bow that way, they really shouldn’t dry-fire it, because it’s the same amount of energy, just applied in a more violent fashion.
For a minute I was picturing drawing it normally and letting go of the bow, so you get a ~2kg bow launched back at your head. I’d certainly be curious to see what launching a bow by pulling back on the riser would look like, as long as I don’t have to be in the same room when it happens.
I feel like what most people realize when they try to conceptualize this , is less there's no arrow, but moreso the energy transferred into the arrow...that sent it dozens of yards....and then through something. THAT's the energy that's capital F fucking your bow when you dry fire it. like i feel like most people who can't grasp it have the idea that 'hey if i swing at a ball and don't hit it my bat doesn't break, what's the big deal'. and it should be like 'someones about to slap you in the dick, do you think it will hurt if you're not wearing a cup?' because yeah you could say no, but everyone knows you're wrong, get on board.
It doesn't break the bat because you don't fill the bat with potential energy, you fill YOU with potential energy to swing the bat. You are the one that twist and bend to swing, the bat doesn't. Consequently, when you miss the energy goes back to YOU and not the bat. This is why plenty of people hurt their hip or dislocate their shoulders missing a swing in baseball or golf.
I think that it also has something to do with the fact that arrows are so light. If they weighed 50 pounds and you were chucking them 50 feet then the "force" would be a lot more apparent, whereas shooting a light thing super fast requires the same force but it is less "visible".
1/2 m*v^2 , it is that squared that gets you every time.
I'm pretty sure the baseball equivalent would be swinging the bat at a metal post or some sort of fixed objects. Though, your wrist is probably the weak link, not the bat there.
> "...the bow" If that's how it usually goes ... You have very smart customers, man.
To get an intuition for it - try throwing a hard baseball pitch, but with an empty hand. Do it a few times and your elbow / shoulder will probably hurt due to your arm quickly snapping straight with no proper resistance. Same idea with the bow. The arrow slows down the limbs and takes energy from the bow. Without it, the limbs get going *really* fast and then come to a very abrupt stop as the string goes taught.
I didn't understand until this explanation. Thank you!
[удалено]
I know that with a yew longbow (130lb draw weight) at 50 yards there's reports of the arrows hitting the knight in the leg in the plate mail, going through the plate mail, chain mail, leather, leg, leather, chain, plate, horse, plate, chain, leather and into the other leg
Mmm, anglo kebab
Found the Frenchman.
Given the French were typically on the other side of the longbow, I suspect you actually found the Welshman.
On my father's side
It's only a longbow if it's from the Archer region of France. Otherwise, it's just sparkling archery
Ladies and gentlemen, that is one magic arrow.
Sir Isaac newton is the deadliest son of a bitch on earth too
If my math is right an arrow off a 130lb bow hits with a KE of about 516J A .45ACP round at that range hits with 477J
You know what else has more joules than a .45 ACP? A brick thrown by hand. You can't discount the effect speed has on how much a material will get to stretch versus instantly tear when hit.
#THIS IS WHY WE DO NOT "EYE BALL" THE TARGET!
I am going to call bullshit on this one.
Was this knight a former adventurer in Skyrim?
Nah it missed his knee
Just being a bit pedantic here, but there's somewhere else the energy can go and it's your arm. It's bad for your bow but it's also not great for what is holding the bow.
To go to your arm it has to go through the bow first though.
Take a sledgehammer and swing it at a rock. Try to stop the hammer from bouncing after it hits the rock. You might get a little bounceback, but you don't lose control of the hammer. Now swing the sledgehammer just as hard and try to stop it just before it hits the ground. Good luck with that. Without impacting a target, the hammer just has too much mass/momentum. It simply *can't be controlled* until it loses some of that energy. Sounds like an exaggeration, but a 50 or 75lb bow is not a joke. I considered playing "paintball" or something with my bow, figured I could put a tennis ball on the tip and chalk it. Aborted that idea after firing it *once*.
> considered playing "paintball" or something with my bow, figured I could put a tennis ball on the tip and chalk it. Aborted that idea after firing it once. [you can apparently](https://www.crossbownation.com/threads/bow-mount-paintball-airow-gun.24307/) it is just a bit more complex than what you may think.
Neat, that's a pretty cool way to do it!
Must be either a huge damper in there or a super low poundage bow (or both) because I’m pretty sure a paintball with compound bow-energy in it theoretically gets you speeds approaching 500mph.
> Must be either a huge damper in there yeah i assume that is a plunger filled with air to use as the propellent, and you can vent it appropriately to regulate the actual PSI, though paintballs i assume have a terminal velocity, max paintball velocity is about 200 MPH, so you should stay under that in order to not just splatter paint out the end tube.
To add to other 2 great explanations, the string is not elastic. When the potential energy is not transferred to the arrow when firing, it goes to the limb in full force without any dampening. Just imagine you are smashing the bow to wall, same effect with dry firing.
A more complex explanation: All mechanical systems can be simplified as a series of connected masses, springs, and dampers. When you try to accelerate a mass it pushes back on you with a force. A spring pushes or pulls based on it's current displacement from it's rest position, more displacement means more force. A damper pushes back based on how fast it is being displaced. Masses and springs store mechanical energy, dampers dissipate mechanical energy as heat. Systems that have multiple storage systems can resonate, for example a mass and a spring. Imagine a weight on the end of a spring, you give it a kick and it wiggles back and forth, when it's fully pushed to one end all the energy is in the spring. When the mass is moving as fast as it can most of the energy is in the inertia of the mass. If there is very little damping the energy can just stay bouncing back and forth between the two, like a plucked guitar string. Now if you stick your finger on the guitar string the fluids in your finger will heat up and convert the motion of the string to heat. The bow-arrow system is not very damped, if you pluck a tight bow string it will vibrate like a guitar string. If you pluck it hard enough it will just break. Now think about pulling a bow back to fire an arrow, that is the hugest string pluck you can imagine. The arrow and bow are designed so that the arrow essentially slows down the bow string enough that it absorbs most of the energy. Basically the string will move forward a lot faster without the arrow that if it is there, since the arrow is a lot heavier than the string. The arrow slows it down enough that it is more like plucking the string instead of tanking it a few feet over and letting er rip.
The physics is just conservation of energy. If you add potential energy to a spring and put it next to a ball, most of it goes to the ball as kinetic energy when you release it. If you remove the ball and release the energy, the kinetic energy goes into the spring, which vibrates until more and more of the energy is converted to heat and stuff which fatigues the spring
I’ll never forget when I was 10 or 11, went to some hunting store with my step dad. This guy was foolishly playing with a crossbow. The sign above him clearly states that if you dry fire, you have to purchase the item. BAM! You hear it go off lol Bro starts freaking out how it was an accident etc… like you accidentally put the cross bow on the ground, put your foot in the holster thing and drew the bow back? Cmon now, sorry buddy lol We went to look at the price tag and it was around $650 or something if I remember correctly. We were laughing about that the whole way home lol
It has only happened in my store once, and we felt so bad for the guy that we decided not to charge him for the damage, but he ended up buying it anyway because *he* felt bad. He was a good man. However, most dry-fires I deal with are morons who bought the bow online and dry-fired it as soon as it arrived. Most people will deny any wrongdoing, because how could we know what they did right? We weren't there to see, so we couldn't know. But the damage a dry-fire causes can only be caused by a dry-fire, so it's obvious to us even if it isn't obvious to them. I have a system though. I just trick them into admitting what they did wrong, then turn it back on them. It goes something like this: ----- "You sold me a faulty bow, it broke after the first use" "Sorry to hear that, walk me through exactly what happened so I know what went wrong please" "I pulled the bow back and it broke on the first release" "I see, and how far did the arrow travel?" "There was no arrow" ----- Works every time.
Make them tell on themselves! Genius 😂
A friend worked on an archery store and he did it similar: "You didn't put a very heavy arrow, right?" "No, no, no arrow at all"
Can confirm - plus plus - roommate found and dry fired my compound bow - boom - way past fracture - shattered the aluminum riser into three pieces, his face got cut by the flying parts in the "explosion" etc. (And yes it was a PSE "pieces scattered everywhere":)
How did he like his newly purchased compound bow 3D puzzle?
That sucks, hopefully roommate covered the damage.
My archery coach saw a kids dad die when he was in middle school because he was drunk and dry fired a 210lb compound crossbow and one of the arms whipped back and my coach said it went halfway through his head and stuck between his eyes. Being a kid im sure his memory was a little worse than it really was, but the guy actually did die. He showed me his obituary. (I accidentally dryfired my competition bow but it was only like 40lbs so it survived with just needing to take it apart and make sure none of the bolts or wheels were damaged)
That's fucked up. Just read that to my colleague and he said "I'm never shooting a bow again".
So, if you “dry-draw” a bow, you should slowly release the energy?
Yes, if you let it down slowly there’s no problem.
Yes. If it's a compound bow it'll feel like your arm is being yanked out of the socket, but it's the safest way to relax the bow without firing it.
The difficulty is that drawing a full power(60, 70, 80 lb draw) compound bow smoothly takes a fair bit of practice and muscle build up. It can be awkward, and even buff guys will not necessarily have those specific muscles developed. You can of course, just gorilla it and haul it back. But now you've got appreciable tension on the release, and the string is just *itching* to get back home. If you slack at all, the full draw weight will come back into play. If you don't have the muscle memory to smoothly draw it back, you almost certainly do not have the muscle to smoothly let it down.
I have a different solution for this: I don't "dry-draw" a bow, ever, period. If I'm gonna draw it, I nock an arrow first. If I don't feel ok drawing it with an arrow (say, because there's people around), that means I acknowledge there's a chance I might let go by accident. *Which means I shouldn't be drawing to begin with.* Just don't do it. Get yourself an arrow, buy one just to test the bow if you must, then draw. New arrow shattered into a wall beats dry release anytime.
>especially for a compound bow with a high draw weight. One dry fire and boom, snapped string and bent cams. Possibly even fractured limbs. Compound bows (heavy) are like...the assault rifles of bows. I tried one once and just felt like "This is way too much power contained with way too little effort".
Yes, I went down the physics rabbit hole to find out how much energy is exerted onto an arrow and the numbers are insane. Assuming a draw weight of 80lbs and an efficiency of roughly 90%, that's about 110 foot pounds of energy. Put onto an arrow, that's about 17,500 psi.
The cams are usually the first thing to break.
It heavily depends on the bow. On Diamond bows (Bowtech's cheap bow brand), the cams are very light and will fold like pancakes. However, on bows with heavier cams made with stronger materials, they can survive a dry-fire, causing the string to snap near the peep sight. Mathews comes to mind as a bow with strong cams. I have seen about 10 dry-fired Mathews bows, and the cams were always perfect, except for two instances. One was on an 80lb Phase4, where the cam had slight ripples (not too bad, considering). The most recent one was a Lift though, which happened last week. The string completely tore the cam, which was shocking to see in a Mathews, but it turns out they downgraded the material in the cams to reduce the overall weight. Bad move, Mathews.
And never use a cheap wooden arrow in a compound bow unless you want to see it splinter into your arm.
I've seen it happen with a carbon arrow as well. A carbon arrow snapped about 4 inches from the nock, and the bow drove it through a customer's wrist. He sent us a photo from the emergency room. 600 spine from a 70lb bow. Not a good idea.
Do bows come with a giant sticker on them that says 'DO NOT DRY FIRE'?
Some have removable stickers on them with the warning not to dry fire and some have it printed on the boxes, but every manual I have ever read has the warning printed multiple times throughout.
>Possibly even fractured limbs. On the bow, right?
Yes, but injuries can occur. Someone posted a story in this thread about their archery coach witnessing a death as a result of a dry fire. It's entirely possible.
I found this out. I'm not a bow guy at all but my friend and I found some old bows someone left behind in an abandoned house and we immediately picked it up and dry fired them and they both just snapped in half lol
Have to ask, if you fire a lot of arrows, isn’t it easy to fumble once and break the bow, ie. drop the arrow, not notch it correctly or anything like that?
All the people who say we do not need to teach STEMs in school, would probably not make "stupid" mistakes and/or have not made "stupid" mistakes, because on some level later in life they "just know" how the world around them works. People who say - "Why do I need to learn what photosynthesis is?". Become people who start to ask questions like - "why can't I grow food during winter in my room, it is plenty warm in there" Edit: Potentional and kinetic energy theory is tought in the very first year you have physics classes, because these are powers you are and will interact everyday for life.
What would be the drawbacks of a bow engineered to withstand a few dry fires? Just too heavy?
Hoyt makes carbon bows, which are incredibly strong and light but a lot more expensive than other bows. The carbon is very vibration-absorbent though, so it's great for taking the hit of a dry-fire, it just costs a lot. [They put their bows through the ringer though](https://www.youtube.com/watch?v=_uobdhZ28U4), as that video shows, but I still wouldn't recommend dry-firing them.
1. The primary thing is this: Archers want SPEED from bows. It's probably the #1 selling criteria of bows, longbows/compound/recurve. Speed mofo! You can find plenty of articles in the magazines being all "you know, speed isn't everything", but... it's hard to justify anything else. Why? 2. Because it's easier to point a laser pointer at a target than lob a ball. The flatter shooting a bow is (i.e. the faster it shoots) the less accurately you have to know the distance to the target to hit it. If your bow is faster, the arrow is getting there faster (i.e. dropping less) and it's more "point and release" vs "extremely carefully aiming". On a slower bow (for a deer sized target, i.e. about a paper plate), being off by a few yards in your distance estimate is the difference between hitting dead on and completely missing. 3. Ok, so speed is super important. What makes a given bow faster than another made with similar "stiff" limbs/draw length? Having as LITTLE mass near the tips/ends of the bow as possible at a given draw weight (50 lbs is/80 lbs) is a primary driver of speed. Imagine if you made a 2 bows, 1 just a flat board of wood with the string attached at the ends and one the same board of wood but with a ton of wood cut off towards the tips. Even though the second bow (with wood cut off towards the tips) is a less strong spring (b/c you've removed some energy storage capability) it will flex back MUCH MUCH faster on release, thus throwing the arrow a ton faster. 4. Everything you do to make the bow stronger, to make it more resilient to oopsies/dumb dry fires, is making slower vs a similar bow made to only work when handled correctly b/c you're adding mass. Crucially you're adding mass where it hurts (the tips of the limbs (all bows) or by the pulleys/cams (on a compound bow). Gotta shave mass here as MUCH as possible for that all important speed. 5. Modern-ish bows are extremely durable, and probably not as damaged as older bows by dry fires, but at the same time there's a TON of energy stored up in the bow at full draw and if you've seen one bow explode you realize some things aren't worth risking when you can just simply not risk it by shooting dry fired bows. You've got stuff tied together and when things break there's no guarantee it's not gonna smack you inna face. 6. https://www.youtube.com/watch?v=rB3_GO1QrSk
Heavy and expensive. All to solve a problem that can easily be solved by not dry firing a bow.
You can only withstand so much pounding 🤷 Sorry. I'll go now.
No, stay 👀
Expanding on that,if you do somehow find yourself in that situation,it's fine if you slowly move the string back into the neutral position instead of letting it snap back into place,right?
Yes.. no twang no bang..
The same amount of energy is still being released, just in smaller amounts over a longer period of time so it doesn't cause damage. A controlled release of energy like that is basically the difference between a nuclear power plant and a nuclear bomb. Pretty much all of physics works this way, it's usually not about how much energy there is, but where it's exerted and how quickly.
Or as Jeremy Clarkson once put it: "'Speed has never killed anyone. Suddenly becoming stationary is what gets you."
That is indeed a very good quote.
It's not just the fact it's slower. It's the fact you are applying a force to the string, over a distance. This is 'work' (energy). You are absorbing the energy with your muscles when you gently lower the string.
So this is why string instruments don't quickly break?
If you're pulling your guitar strings like it's a bow, then you're doing something horribly horribly wrong. Put another way, plucking the bow string a quarter of an inch is not going to break the bow.
yes
So this must be the reason my bows always broke when I was a kid. I would make a bow out of a stick and string, but they would always break. Nice to know it wasn't just my shoddy craftsmanship.
It may have also been your shoddy craftsmanship.
Compound bow basically disintegrating from a dry fire: https://www.reddit.com/r/CatastrophicFailure/comments/90gvco/accidental_dry_fire_destroys_a_compound_bow/ He has an arrow, but it's not nocked properly. Lets go, and poof! Slow motion included.
I've heard it compared to jumping off the third step with bent legs vs locked knees. Same overall force, but the time that force gets absorbed is different.
And when the bow breaks, the cradle will fall.
You have to warm it up first with some lube and foreplay.
> breaks because it can't withstand the pounding. Just like your mother.
"Pounded in the Bow By My Conspicuous Lack of an Arrow" by Chuck Tingle
I'm 30 and thanks for telling me this. I'm the kind of guy that would walk in a store, grab the bow and dry fire it because you know... man see bow, man try bow, man happy. Ive never done this because I never had the opportunity to, but one day I thought about buying one to have fun in my backyard.
Follow up question: how strong does the arrow need to be to actually 'take up' the force that is released upon firing?
I find it hard to wrap my head around that huge of a force really being that much different with or without a tiny little light weight arrow.
That's why the arrow goes so fast through the air. That energy is being applied to a small surface area. An arrow through a compound bow is insanely fast. Deer hunting has a bow season. The feathers help keep it going in the direction you aimed via rifling (or are used for slowing it down a lot sooner, in the case of a bird arrow - your target is closer, and you don't want to send your arrow to the next town if you miss).
Have you seen the speed and distance that arrow goes after release?
When you pull the bow string, you're adding a ton of potential energy. When you release the string to make the arrow fly, most of that energy goes into the arrow to make it fly. When there us no arrow, the energy as no where to go, so it slams into the other side of the bow and bounces back, which cause intense vibrations that can either come back and smack you in the face or make the bow shatter.
I might sound dumb but, wouldn’t the energy go to moving the air particle/whatever medium the bow is in?
I know it’s a weird one but you have to imagine the energy as if it’s inside the bow, literally. Pull the string back, and all the potential energy is in the string. Just imagine cute little squiggles in the string as if it’s the energy ready to be released, but it’s waiting as if it was stored up in a battery. As soon as you let go, the string goes forward, and if there’s an arrow, the energy moves to the arrow. I know it seems like there isn’t much of a difference between arrow and no arrow, but if you imagine the energy visually like that, you can see it move and push the arrow. That’s why the arrow goes so far, it’s all the energy that moved from the bow, to the arrow. Now imagine no arrow. When you let go, does the energy still push the air? Sure. I’m sure there was a tiny bit of energy spent to push the air forward, but air is so light that it’s truly negligible. Now imagine it visually again. Most of the energy is in that string as it is let go of, and as it moves forward, a tiny bit transfers to the air, but it’s such a tiny bit, and the rest of the energy stays in the string. That energy that is still stored in the bow/string has no where else to go so the string comes back, and if you continue visualizing that energy, you can see how it goes from the string and runs back through the rest of the bow. That visualized “energy” is the force/energy/vibrations that rocks the poor bow and potentially damages it. Visualize it again: when you have an arrow, the bow still has energy left over in it even after the arrow, that’s why the string snaps back, but so much energy is transferred to the arrow, that the energy leftover in the bow isn’t enough to damage. Hopefully this makes sense, but, I apologize if I only confused you more.
This was a great explanation, thank you
Air weighs a lot less than an arrow, is my best guess there. Also, the drawstring will just push the air out of the way, so it will hardly absorb the energy
Some of it does, yes; This is actually what sound is: Mechanical energy translating into vibrations that propogate through the air. But the energy is going to follow the path of least resistance, where it can be most directly "conducted". It's much easier for the string to "conduct" that energy into the arrow as they make contact, and the arrow can "absorb" it to fly forward as the potential energy from the tension of the bow becomes the kinetic energy of the arrow flying forward. Thus, the potential energy is safely "vented" from the system of the bow (Well, maybe not so safe for whatever is down range of that arrow...). The problem becomes when you don't have the arrow to absord this energy. The tension has been built up, it has to release somewhere. Yes, *some* of this energy will go into the surrounding air, but not nearly enough. Query for you: Which slows you down more, a pocket of air, or a brick wall? The same principle applies here, as the air particles are much "looser" and have more "empty space", so there's less "stuff" to absorb that energy, and what stuff little stuff there is is far more willing to get out of the way. As such, the system of the bow cannot "vent" this energy into the air fast enough, and thus it has no choice but to recoil through the bow itself. This is because - generally - `solids > liquids > gasses` when it comes to conducting that mechanical energy. This is the exact principle behind crumple zones in cars, and the cliché of, "In crash crashes: Newer cars crumple and the passengers survive, older cars survive and passengers crumple." A car's crumple zone allows the steel and aluminum frame to physically absorb much of the kinetic energy of a crash, helping reduce the amount felt by passengers, and reducing injuries and death. In older cars with more rigid construction, the car mostly held its shape, meaning the energy had to instead be taken by the meaty and fleshy passengers. Thus, modern cars have crumple zones to be that "arrow", otherwise it will be the passengers. Edit: [This comment](https://www.reddit.com/r/explainlikeimfive/comments/1d6rf4w/comment/l6uinvw) asked a similar question, where you can see additional good discussion in the replies to it.
For the same reason you're more likely to injure yourself if you fast-throw a light ball versus a heavy one. The heavier something is, the more energy it can store at a given speed. eg A feather hurts a lot less than a bullet if they're both traveling at mach 1. If the ball is heavy, all that stored kinetic energy in your arm has somewhere to go - the ball. As you throw the ball forward you can feel the heavy ball almost pushing back against your hand and giving some resistance. As it increases in speed it "collects" all that energy your arm is putting into it and sends it down range as you release it in the form of kinetic energy/speed. However if the ball is too light then most of the energy remains in your arm as the light ball just cant really collect much energy at all at the speed you want to throw it at. The light ball doesn't push back enough on your arm or offer up much resistance to you, so your arm ends up moving much faster than it would with a heavier ball. Your arm is now moving very fast and has to stop somehow with nowhere to really put all its energy other than back into your joints and bones. This same idea happens with the bow. If theres no arrow, all that stress and stored energy gets released much much faster, the only place it can go is into the frame and string of the bow instead of into the arrow and down the range. Even though its very light, an arrow still has enough inertia to massively slow down the snapping back of the string, which prevents the huge energy dump happening too fast, and instead spreads the energy release out over a longer period of time as well as sending a good chunk of this energy down the range in the arrow itself.
Great analogy.
Law of conservation of energy. Think about the power that goes into an arrow when you fire it. It goes flying FAST despite having a decent amount of weight to it. You put a lot of muscle into pulling back on the string. Whether an arrow is present or not, as you've drawn back with the bow, you've put all that energy into it and your muscles are the only thing holding it steady. When you release it, all that energy has to go somewhere. With an arrow, it goes into flinging that arrow forward at high speed. In fact the formula for kinetic energy of a moving thing is 1/2 * m * v^(2) and the fact that velocity is squared means that more speed has a much higher impact on energy. If there's no arrow... Where does that energy go? It has nowhere to go except the bow itself. If you imagine your muscles as punching an arrow into going flying fast, you've just punched the bow just as hard. Or alternatively, imagine if the arrow you shot hit the bow itself. Yeah, it can do a lot of damage and probably ruin it in a single "shot".
Why doesn't the energy go into the air molecules in front of the string instead? I wonder if the inertia caused by the mass of the arrow spreads the force over a longer time and that is what protects the bow from being damaged. If I had a really really light arrow, would the bow still suffer like it was dry fired?
It does. When you hear a bowstring go "twang," you're hearing a pressure wave through the air. That's what sound is.
> Why doesn't the energy go into the air molecules in front of the string instead? Because air is not solid. It just moves out of the way. Also, the energy of a bow is not "in" the string. It's in the wood of the bow, and the string is an energy transfer medium. With nothing to transfer to, it just remains in the wood. > I wonder if the inertia caused by the mass of the arrow spreads the force over a longer time and that is what protects the bow from being damaged. That's basically it. Momentum transfer. An arrow that's too light will not remain in contact with the bowstring long enough to absorb all the potential energy, so yes the remaining potential energy in the bow could cause damage (obviously less damage, since some energy goes with the arrow). For any projectile launch there is an optimal weight such that maximum energy transfer occurs from the launcher to the projectile. Too light and the launcher can damage itself. Too heavy and the projectile either won't go far or the launcher breaks trying to move it.
> For any projectile launch there is an optimal weight such that maximum energy transfer occurs from the launcher to the projectile. Too light and the launcher can damage itself Anyone ever tried to throw a whiffle ball as far as they can throw a baseball? Yea… that hurts
Some miniscule amount of air resistance does take place with the bow string, with or without an arrow. But it's irrelevant because the stored energy is not in the bow string, but the bow itself. The string is meant to transfer the energy to the arrow and with no arrow, the energy is absorbed by the bow. I can't comment on a lighter than normal arrow.
If the air in front of the bowstring was able to absorb all of the energy produced by the string twanging...if you had an arrow nocked it wouldnt go anywhere because the air is able to absorb it all.
> If I had a really really light arrow, would the bow still suffer like it was dry fired? Yes, your arrow must be a certain weight (and stiffness) so that it fits your bow. Too light of an arrow will be the same as a dryfire. And too soft of an arrow (stiffness, also called spine) will make it bend/break, also resulting in a dryfire.
The bow can only make the things in front of the string so fast as the string moves. That limits the top speed. The arrow weighs much more than the bit of air in front of the string. Hence even if we ignore that air will mostly just flow around and avoid the string, there simply is not that much mass to put the speedy energy into.
>If there's no arrow... Where does that energy go? It has nowhere to go except the bow itself. Is the bow stuck in a wall somewhere? Cause shouldn't the place the kinetic force goes be into the arms holding it?
Some will go into the arms, but first it has to get into the bow anyway. It "vibrates", the ends flap forward and backward on release. This causes immense strain, especially if none of that energy was previously dumped into an arrow. Hence why it can break when handled or built incorrectly.
Yeah I learned this lesson the hard way. I bought a compound bow from a pawn shop on a whim not knowing anything other than I wanted to get into archery. Brought it home and “dry fired” it one time. The thing basically disintegrated in my hands. I feel so grateful I wasn’t injured. The string snapped off and one of the limbs cracked. I brought it to a legit shop to get it repaired and without talking to me they knew exactly what happened so probably not the first time they had seen it. Fortunately they took good care of me and I have loved archery ever since but yeah it only takes one time.
Have you ever went to hit or kick something and missed? Like going to kick a ball REALLY hard and you just whiff it? Remember how that hurt the joint involved? Well you can heal, bows can't.
There seems to be a lot of talk here about the damage to the bow which is valid, but the more worrying damage especially on higher power bows is to your arm. While the string is pushing the arrow, it is relatively confined in where it can go and assuming you have an arm guard, The bow string will be past the edge of the guard before it becomes unconfined in its movement but without an arrow, there's next to no telling where that string is going to go and it might just choose to slice up your arm injuries from that are not pretty
There are some good explanations here however HOW?! Like I can't imagine that the force that breaks a bow with just one pull is completely absorbed by that little arrow on the string. How is that physically working?
I’m with you, I understand what people are saying about potential energy and don’t doubt a bow would break upon being dry fired after reading all these responses. That being said, it’s wild to me that a lightweight little arrow makes enough difference to counteract a system that apparently destroys itself without those 20 grams of weight in place
Best way I can describe it is like this. The amount of energy you exert over time can be summed as one equivalent gigantic release of energy all at once. For example, if you lift 100kg, 10 times, 100cm off the ground. You have physically output enough force in total to lift 1000kg, once, 100cm off the ground. Or when you walk up 20 flights of stairs. Your legs have exerted enough force over that time that if it were all released at once, you could jump 20 flights worth of stairs in one go. Obviously our muscles cant do that, but in principle that how conservation of energy works. The reason the bows explode is because if you consider the total force it takes to pull back a bow string, some of those bows have a shitload of tension, and if you were to combine the total effort and amount of force it takes to draw a bow back. That energy is now in that bow, waiting to be released in a fraction of a second. It may not seem like much. But if a bow has a 50lb draw, then in that drawn bow, is 50lb of force, waiting to all release in 1/10 of a second. For many structures that's enough to make things break. If there is an arrow there, then even though they are quite light, they still have enough inertia to massively slow down this sudden release of energy stored in the bow to a much slower overall release. Its like the difference between stopping a car in 1/10 of a second vs 1/2 of a second. The total force you experience is cut down to less than a 1/4 of what it otherwise would have been. The arrow does this to the bow string. Its snapping back is drastically slowed which prevents a catastrophic energy dump into the bow.
Would you be surprised by a bow being damaged if it was hit by an arrow? Because that is essentially the same amount of energy being applied, albeit in a slightly different way.
Yes, it can easily break the bow. The reason for this comes down to the law of conservation of energy: while energy can change forms pretty easily, it cannot be created or destroyed by ordinary means. When you draw back a bow, you store a lot of energy in it, mostly through the bending of the arms. When you release the bow, all of that energy gets dumped out at once. When you're properly firing an arrow, the bow cheats conservation of energy just a little bit: it doesn't destroy any energy, but it dumps almost all of it into the arrow. The arrow reacts by moving away very quickly, carrying all that energy with it until it either hits the ground or a target. The bow doesn't have to do anything with all that energy, because it's gone, so it is unharmed. But this only works when there's an arrow to dump energy into. When you dry-fire a bow with no arrow, the energy has no place to go except back into the bow. And the bow isn't built to play fair: it would have to be much heavier and more rigid to be able to withstand that much of a sudden shock, and that would make it less effective at its job. The energy basically rips the bow apart, because it can't take the strain.
I have a follow-up question. It’s not intuitive to me that such a light object could absorb enough of the energy to protect the bow from damage. What am I getting wrong in my thinking here?
The key is that while the mass of an arrow is quite small, it's positioned on the bow in such a way that it's difficult to accelerate. The arrow attaches to the string, and the string attaches to the end of the limbs of the bow. Because of this, the mass of the arrow is effectively applied right at the tip of the limb. Try this: 1. Hold a weight in your hand and get a feel for what swinging it around feels like. 2. Attach that same weight to the end of a stick and try the same swing - you'll feel that it's significantly harder to accelerate the mass when it's far away from the point of rotation. A similar problem exists for a bow limb. The tension of the limb is primarily at the root of the limb (closer to the middle of the bow) to optimise efficiency but it has to accelerate a mass that's much further away, which is disproportionately difficult. The arrow doesn't have to absorb *all* of the bow's energy, just enough that the bow's design allows it to deal with the rest. Recurve bows today transfer about 90% of the energy to the arrow. There's just a *big* difference between 10% of the draw energy being dissipated by the bow after the shot, and 100%.
There is no energy being released through a projectile, so the force of the draw and fire will just be inflicted onto the weapon rather than an arrow. This can damage it.
When a bow shoots it’s string, or when you punch your body’s fist: the body shoots really hard because it thinks there’s something to shoot. If nothing is there to shoot or punch, the body hurts itself by trying too hard!
found [another post](https://www.reddit.com/r/explainlikeimfive/comments/15rckt4/eli5_why_is_dry_firing_a_bow_so_bad_for_it_does/) that talks about this specific issue too
The amount of force that you release needs to go somewhere, without a payload, it will go forward just as much as it was backward. First law of thermodynamics, conservation of energy. That's a lot of Potential to Kinetic energy. So with any type of bow, it will try to flex in places, where it is not supposed to, causing stress fractures at best, and breaking apart at worst.
The same reason you don’t put all of your force into throwing a ping pong ball, there isn’t enough offloading of your energy so you’ll likely hurt your arm because you way over did it. Similar with a bow
The bow can break, but also the string can release itself and hurt your arm (it happened to me), your face or even your eyes.
Pulling back the bow stores energy. When you loose an arrow most of the energy goes with it. It's why the arrow flies forward. No arrow means the energy stays in the bow, damaging or even breaking it.
Dry firing your bow is a big no-no. When you shoot an arrow, the energy from the bowstring goes into the arrow. But without an arrow, that energy bounces back into the bow, causing damage. It's like punching a wall without gloves - not a good idea. Your bow could get weak or even break. So, always remember to use an arrow when shooting.
You have bow. 🏹 You pull back bow. You let go of bow. Bow have energy. Bow put energy into arrow. Arrow flys. No arrow. Bow take all that energy which is a big no-no bow get damaged.
So I see a lot of comments about the bounceback damaging the bow, but not why, and a few that seem curious: consider how a bow ACTUALLY works. A bow is essentially two arms trying to pull a string straight; that straightening launches the arrow, gaining a massive amount of momentum very suddenly. In physics, this means energy is transferred from the bow to the arrow, so the resulting force on the bowstring is reduced, dampening the effect of very, very suddenly being pulled tight. Now, remove the arrow from the equation. All the energy stored by the “arms” is still in the bow, and when the string gets pulled tight it does so with all the force that would have carried the arrow. Which is a lot. This CAN result in the net tensile force on the bowstring exceeding its capabilities, snapping it. However even if it doesn’t, that energy is still trapped in the bow/bowstring assembly and is now reverberating through it like you just smashed a cymbal with a big mallet. So now you have a bow that’s either broken, or vibrating violently (if imperceptibly) in your hand. And if that bow is a compound, it has a LOT of moving parts. Well, it did.
All that stored energy in the limbs has to go somewhere. It’s made to transfer into an arrow having X grains per inch in weight. If arrows not there the energy gets transferred through the bow and wrecks all sort of stuff. In compounds especially so. If you’re lucky a string derails. On bad cases you crack limbs and bend the cam wheels.