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View Full Version : Why are crossbows so LOUD? What can be done?



BowSniperX
07-18-2013, 09:54 PM
I'm curious as to what makes the crossbow, or any bow for that matter, so LOUD?

Some reach amplitude levels that exceed 80db.

This seems like a huge waste of energy and reveals the hunters location immediately.

Does anybody have any good advice or methods to keep db levels to a minimum?

Thanks!

mrbb
07-19-2013, 12:43 AM
well x bows are so loud due to how they work, first they hold a ton of energy, energy being released makes noise
second, the string typically slaps and drags about the Barrel, the part the arrow/bolt rest in/on, plus the bolt also is being dragged some what along it as it goes down range
third much heavier strings being used and even cables, in a MUCH smaller wheel to wheel set up, and it all hold noise ,
and well it all gets released as the trigger is released in one fast release of energy
Things that can help , well, all the hype of anti sound dampening devices and anti vib , plus heavier bolts/broadheads, , and well maybe even them dampening Nocks??, type things for bows can help a LITTLE on X bows too, just honestly don't expect great gains
if your quiver is still attached to the X bow, that that off, can help right there with noise too!
the only and best true way is to buy a X bow that is most efficient in its materials, and build
From my experience, the reverse limb design X bows are by far the quietiest I have seen , in shooting next to other x bows at the same time, they also balance better, due to the design, they put the weight closer to the shoulder, unlike traditional X bows that have so much far out weight away from shoulder
I personally think, it absorbs sounds better with this design, where as other designs, blast that sound at the very end of the Bow, where most of the limbs/material is still
The good news is, even the fastes bows of any design, x bow long bow compund or ?? bow, they all make noise, and are NO where near the speed of sound, yet can kill deer all the same
the key is to try to take shots as close as possible, and on game that is relaxed, and not on edge, to prevent them from jumping the string, as they say!
this is one of them things so many suggest before buying a bow
SHOOT as MAny as you can, to see hear feel how they work, and not buy blindly, based on a name or some other reason
NOTHING beats shooting bows before buying!

buckstalker17
07-19-2013, 12:58 AM
I can't add much to what mrbb posted pretty much covers it.

hortontoter
07-19-2013, 07:11 AM
The thought of the sound made by shooting your crossbow giving away your postion is a mute one. This is a ONE shot game. The idea, as I'm sure you know, is to wait for a shot that is close and at the correct angle to offer the optimum opportunity for a clean kill. One shot is all your going to get. And if you end up like me, and are picky about the buck/bucks you want to take, your one shot may be a long time coming. I haven't shot an arrow at a deer in two seasons and I hunt a lot. I just haven't had the buck I want inside my 20 yard shooting window. I know 20 yards is close, but the noise you mention is the reason I limit my shots to that range. Any further out and I am concerned with the animal jumping the string causing a bad hit.

Big_Holla
07-19-2013, 08:17 AM
First of all BowSniperX welcome to the forum!!

I do agree, some of them are crazy loud!! Our Ten Point Titan the first time I shot it I about crapped my pants and looked it over to see if something broke. Shocked was the word!! Mrbb about summed it up. I think that short draw cycle and sudden stop with such a short string sends that shock wave throughout the whole crossbow. We added a sound dampening kit made by Limbsavers that helped some but it's still a loud crack when it goes off. I haven't heard much if there is a difference between a cam/eccentric wheel model and a recurve style or not, maybe someone can add to that. I would say there are likely better models though than others that transfer that energy more efficiently which also would help reduce the noise.

mrbb
07-19-2013, 08:19 AM
well again, the fact sound travels at 1200 FPS, and most archery gear is less than 400 fps, in hunting set ups
at 10-20-30-40-even 50 yrds the time it takes for the arrow or bolt to get to a deer, is fractions of a second in difference, meaning a deer can and is almost as likely to jump string at 10 as at 20 as at even 50
sure closer, makes it get there sooner, but its really sub second in difference
a deer has some awesome ears and reflexes, and theye most useable to them when there nervous or alert
thus making shooting at a calm relaxed deer you best game plan, and sticking to ranges your most comfortable at!
the bigget issue with range is drop, and loss of energy, all the more so if you shoot expandable heads

and I personally find very very few broadheads today, that provide practice blades, never fly like real blades in same broadhead
there many times not even in the same shape /size as the real heads
so I never even shoot them any more
I also use older blades as test flyers, and then ONE shot with the real one's to make sure no changes
then re sharpen slightly and hunt with them!
and yep Hortontoter, that ONE shot can be long coming, I average about one shot at a buck every 3 yrs in my home state LOL
so that;s a long wait for sure

BowSniperX
07-19-2013, 05:20 PM
Thanks guys for the excellent responses!

While most of the sound issues can be compensated for, ie) string jump (aim low) etc I find that the overall loss of energy is killing the efficiency of the Xbow. 85db is a lot of potential energy being lost in the elastic to kinetic transfer. Damping can absorb some of the resonance but does nothing to restore the efficiency, It simply absorbs some of the loss. From my experience, damping only lowers the amplitude by a few decibels. It also focuses energy to the location where the damping occurs, this leads to premature limb failure when there is a lot of energy being released.

I prefer my bear compound over my Horton recon however depending on the type of hunt, ie stalk or tree stand, I'll use one over the other. I've had success hunting with a compound from the ground in a spot and stalk scenario but they usually jump the string so I know to aim low. I find that I need to compensate for string jump more with a compound than a crossbow even though the xbow is louder, the compound is slower by 150-200fps in most cases. There is more time to react before impact.

In my opinion, Reverse Draw designs are not necessarily quieter in terms of transient amplitude however they do not "ping" or "reverberate" as much as a traditional crossbow. They still have a transient amplitude that can reach 80db+ but the limb positions in relation to one another dampen the reverberation.

It's sounds like there is not much that can be done to completely eliminate the noise of a bow, which in essence is nothing more than a harmonic oscillator. I guess we should expect some acoustic signature and energy loss with these devices.

mrbb
07-19-2013, 06:33 PM
well, I highly doubt your vertical bow is 150-200 ffps slower than your X bow!
most x bows and compound bows are pretty darn close in real world set ups
odds are more deer maybe jump vertical bows because they catch you drawing the bow, , thus pitting them on more alert
over the yrs I really never bothered to aim low due to worry about string jump
I honestly tried more to not take shots at alert or nervious deer
sure its has happened to me, but in all my bow kills, I have had more never know the arow was coming, than any that dropped any
thus if I aimed low counting on a deer dropping, I would MAYBE not have made the kills I did
I prefer to pick a spot on a calm deer and hope/expect it to hit right where I am aiming

BowSniperX
07-20-2013, 01:13 AM
well, I highly doubt your vertical bow is 150-200 ffps slower than your X bow!

MRBB...you are correct. My compound shoots roughly 230fps while my Horton Recon shoots roughly 330fps. 100fps is still a pretty significant difference.

BowSniperX
07-20-2013, 01:26 AM
The thought of the sound made by shooting your crossbow giving away your postion is a mute one. This is a ONE shot game.

Hortontoter,

I agree to an extent. I've taken two shots, missed the first, connected with the second. Clean kill...Usually this second shot doesn't happen and if it does it happens fast.

My main issue with the noise is in the loss of energy that occurs, not so much in revealing my location to the deer. It just seems like a waste of energy to me. I feel like if the sound was muted without damping then the xbow would be much more efficient ie) faster, safer etc.

mrbb
07-20-2013, 11:19 AM
well your compound bow is on the slow side compared to most of todays newer compounds, and there are many x bows that shoot slow too
so you have to compare apples to apples on speeds, as there are compounds that shoot just as fast as the fast x bows
and noise in the x bos making same speeds isn't all that much louder
it I think just seems a lot louder as the sound is closeer to your ears
and I have also had second shots with the bow several times over the yrs
and even had a second shot chance with the x boy, just didn't take, or actually need it
in a perfect world all archery great would be stealth quiet, but all mopving parts make noise when they move, and all stored energy makes noise too
an example, Outdoor life just did a pretty good test with good info
a PSE Dream season, compound bow, @70 lbs , goes 343 fps, makes 83.45 DB of sound going off
and a Ten point Stealth x bow, at 185 lbs draw weight, @ 351.25 Fps(closest on speed they tested) makes 94.35 DB of sound
that's just 10 DB or so more, sure its louder, but look at how much more draw weight and stoed energy in being held in the bow
the speeds are pretty close through
and 10 DB isn't all that loud a dofference to be honest!
so again all things of speed being considered, a x bow and a compund on Paper are pretty close these days
a lot of the sound is just how we hear it, I think more due to the fact the noise is closer to the shooters ears on an x bow