johnnypep Posted September 24, 2014 Posted September 24, 2014 I've been getting a vibe lately that my hobby is perhaps beginning to wear on the nerves of 2-3 of my closest neighbors. If my suspicions are correct, the sound produced by my lift charges are a lot more troublesome than those of my shell breaks. Is there a way to attenuate or abate the sound that emanates from a mortar tube? On a 3" round shell (I've yet to shoot anything larger) the sound is best described as a "thick, deep & resonating boom," and nothing like the "cracking" sound I hear when others lift similar-size/weight shells. Is it possible my BP is too hot, am I lifting too hard, are the shells too heavy or could it even be the type and length of mortar tube I'm using? BTW, I was using 3" ID carbon-fiber wrapped ABS pipes of 16-20 inches in racks until a few weeks ago when I decided that burying them up to about 6" above the ground might absorb some of the sound (& certainly improve the safety of using said material). No appreciable reduction in decibel level was noticed. Too, about a month or two ago, I began to limit the number & frequency of my test shots to about 3-5 shells (in volley fashion) about once every week or two, and within a half-hour of sunset. This, of course, is an effort to preempt a possible open complaint, or even a confrontation, from someone living nearby. Fortunately, I live in a small neighborhood several miles outside city limits, where all homes are situated on 2 acre lots. I'm currently in the process of acquiring a State Display Operators License, & am not yet BATFE approved, therefore I test-fire everything as it's made. I'm just trying to remain as low-key as possible until I'm totally legit. I feel that in order to do so, I need to find a way to tone down the ground-level noise a bit and am looking for some input/advice.
mkn Posted September 24, 2014 Posted September 24, 2014 Hi JP, Don't P.O. the neighbors, they could make things very difficult for you. 2 acres sounds quite limited interms of safety anyway, I would be worried about a problem shell or fall out. I don't think you can do much about harnessing the sound that would be effective for the efforts. Not what you wanted to hear, but 2 acres is not enough for safety. Matt
dagabu Posted September 24, 2014 Posted September 24, 2014 Yes, I have been in the HVAC business for decades now and we use a simple device to attenuate the sound coming from the air handlers (booming). Find a section of the largest tin vent pipe you can, 16"? Then find a sheet of expanded steel or chicken wire or hardware cloth and roll that up to about a 14" circle the same height. Now for the fun part... Get a short roll of fiberglass, unfaced, insulation and put a single layer of it into the large pipe, make sure its snug, save the rest for later. Carefully roll up the hardware cloth or whatever you choose and insert that into the large pipe making a fiberglass sandwich. Use zipties or tape (no bolts!) to hold the top and bottom together. Place the muffler over your tube and fire the mortar as usual. Caveats: The pipe may open up and make a mess, that is the safety pressure release, go lean on your lift or make the shell tighter in the mortar. The insulation will shred and make a mess. Clean it up and use more insulation to replace the lost stuff. Messy? Yes, but it is effective. 1
pyrokid Posted September 24, 2014 Posted September 24, 2014 A shell here and there won't hurt anyone as far as fallout radii are concerned. This isn't a municipal display. My impression is that the OP is blinded by his love for fireworks. He hasn't adequately considered how his neighbors might perceive his test shoots. I would advise that he tone it down a bit so as to be a good neighbor. Once per month maybe.
BurritoBandito Posted September 24, 2014 Posted September 24, 2014 Perhaps it wouldn't hurt to sit down with your neighbors to discuss the issue. It may very well be a matter of poor timing for them (just laid the baby down for a nap, work night jobs and sleep in the day, etc.). Or maybe they just feel disrespected because they've received no warnings of the loud noises. If all else fails, find a better site to fire.
rogeryermaw Posted September 24, 2014 Posted September 24, 2014 (edited) maybe worth a try? what i did was to call my local sheriffs dept. according to them, the only law covering my test shooting was noise ordinance. so from 6p to 10p, i'm all good to fire. i'm not doing salutes so it really isn't that loud but out where i live, i hear hunters sighting rifles and people shooting tannerite regularly so that may be why no one calls the laws. hope it stays that way as i just got my coreburner set from dag. going to launch(hopefully)one after work this evening. @dag a mortar tube suppressor? love it!! stealth mode fireworks! Edited September 24, 2014 by rogeryermaw
Maserface Posted September 24, 2014 Posted September 24, 2014 Best option is to talk to them, we had a neighbor call the police on us without first contacting us- being licensed, on plenty of land, and within noise ordinance laws (if they even exist), all she did was start herself a war. If she had just called and asked nicely, she might be getting more sleep
dagabu Posted September 24, 2014 Posted September 24, 2014 maybe worth a try? what i did was to call my local sheriffs dept. according to them, the only law covering my test shooting was noise ordinance. so from 6p to 10p, i'm all good to fire. i'm not doing salutes so it really isn't that loud but out where i live, i hear hunters sighting rifles and people shooting tannerite regularly so that may be why no one calls the laws. hope it stays that way as i just got my coreburner set from dag. going to launch(hopefully)one after work this evening. @dag a mortar tube suppressor? love it!! stealth mode fireworks! And no need for a class lll license.
Jakenbake Posted September 24, 2014 Posted September 24, 2014 No need for a class III license with a tax stamp either...Back on topic the "muff" will work nicely since the shell is traveling subsonic velocities (I'm assuming). The more fiberglass you can wrap in there the more effective result. A longer launcher tube will help the flash somewhat and gain a bit of velocity on the shell. Hmmm now i want to get the crono out and do some testing.
MrB Posted September 24, 2014 Posted September 24, 2014 A longer launcher tube will help the flash somewhat and gain a bit of velocity on the shell.Longer tubes, and slower / less lift charge should make it less noisy. But nothing like the suppressor Dagabu suggested. Thats probably the most effective way to deal with it. Well, the actual noise, that is. I agree with those suggesting a talk to the neighbors. But i actually have a third suggestion. Nobody likes this suggestion, but it's the one i'd go with. Quit making pyro until you got the paperwork in order. If your in the process of getting the paperwork done, having a pissed of neighbor call the cops on you will put a huge pin in the wheel, wait until you are ok with the legal issues, and then talk to the neighbors. At which point it's a simple matter of letting them know it will happen, but that you can be flexible about when, just to try and not mess up their days completely.B!
dagabu Posted September 24, 2014 Posted September 24, 2014 Longer tubes, and slower / less lift charge should make it less noisy. But nothing like the suppressor Dagabu suggested. Thats probably the most effective way to deal with it. Well, the actual noise, that is. I agree with those suggesting a talk to the neighbors. But i actually have a third suggestion. Nobody likes this suggestion, but it's the one i'd go with. Quit making pyro until you got the paperwork in order. If your in the process of getting the paperwork done, having a pissed of neighbor call the cops on you will put a huge pin in the wheel, wait until you are ok with the legal issues, and then talk to the neighbors. At which point it's a simple matter of letting them know it will happen, but that you can be flexible about when, just to try and not mess up their days completely.B! +1
Arthur Posted September 24, 2014 Posted September 24, 2014 Do NOT annoy the neighbours or your wife, There will probably be some noise nuisance regs that they can get you on, and the angry wife just rings EOD and claims you are b0mb making.
gregh Posted September 25, 2014 Posted September 25, 2014 I am lucky to have neighbors that love fireworks. I have to call them all before I test anything. That way they can go out and watch too.
Arthur Posted September 25, 2014 Posted September 25, 2014 (edited) OK nutty idea, totally untested, try it in a big space (if at all)! Take a long tube, 4" too long for the shell, with the bottom plugged properly. Drill 20% of the tube wall away as say 1/4" holes for the top 4" so that the "spare" pressure as the shell gets to the top of the tube vents gently through the holes just before the ball gets to leave the mortar with a bang. -You spread the sound pulse out til it's longer but less loud. Think seriously whether your plot is big enough for your testing, would you survive a muzzle break. Survive meaning more survive the effect of frightening the neighbours, testing usually means that there is a possibility of failure. Edited September 25, 2014 by Arthur
Zingy Posted September 26, 2014 Posted September 26, 2014 I really like Dagabu's idea. There are two other options. One is to stack old de-rimmed tires, so the mortar is in the center of the stack, of tires. staking the tires, around the circumference, of the tires, if necessary, so they do not topple. I have noticed at PGI, old truck tire are used, to contain the five gallon plastic buckets. for the cremora fireballs, as a safety mechanism. The second is to hang some type, of curtain, like welding blankets, which would be the most ideal. You could probably use old carpeting. You could use more the one of the options, perhaps all three.
otto Posted September 27, 2014 Posted September 27, 2014 Step 1: Engage your neighbors. Mine love it as long as they know it's coming. I've invited them for years to the commercial shoot on the the 4th. Most just enjoy from the comfort of their own lawns. As for testing, if it's going to be extensive or very loud, I let 'em know. The folks that keep horses next door are the most appreciative; the rest are kind of "Aw, whatever." Of course, my nearest neighbor is 1/4 mile down the road. That said, Wednesday night Sporting Clays at Kenny's is a neighborhood tradition. I'm just not as predictable. If you must........ Step 2.:If it's an issue I'd take the suppression thing to the fence. Do some research on firearm suppressors (which are illegal in any way shape or form unless properly licensed in the US) for the theory. Never got around to making anything like that, just one of my curious expeditions in the Al Gore International Library. Depending on your mortar size, I'm thinking a steel drum with tires inside for baffles. For durability maybe some chain link fence retaining the insulation of your choice inside. The tires should provide enough security in the event of a muzzle break. A smaller bore to adequately pass the shell (I'm thinking a secured lid with a safely sized hole for shell exit) leaves more room for sound suppression,lessens the muzzle blast escaping into your neighbor's sound space and contains/maintains the integrity of the interior suppression material. Additionally, drilling multiple holes near the muzzle of the mortar, known as "porting" in firearm circles, can also lessen, redirect and reduce perceived loudness of muzzle blast. Caveat for Step 2: I never tried this. Just applying what I know against a new situation.
mikeee Posted September 27, 2014 Posted September 27, 2014 How about a compressed air mortar lift system out of a long tube. I used to launch potatoes quite a distance with a compressed air spud gun.
schroedinger Posted September 27, 2014 Posted September 27, 2014 Maybe you also could just burry the mortar at the bottom of a funnel shaped hole (with the mortar beeing the stem). This way most of the sound should be directed upwards. I would make the hole at least 1 m deep.
Sparx88 Posted September 27, 2014 Posted September 27, 2014 Getting along with the neighbors is paramount. I had 2 of the 3 come to me around 10 years ago after I set off a suspended 75 grammer. It was the last time I would do anything like that. And my neighbors all shoot and hunt and like to have celebrations for celebrations, but there is a line. With me shooting 3" shells on the weekends only, (just decided that would be best), which are the noisiest, no problem. But I still keep it spread out though, I may go a month without anything at all etc. A lot of the time when they get to shootin guns on a saturday or sunday, we'll go out and answer back with some noise of our own paying homage to the sound barrier party. Then when evening comes the color goes up. Just gotta go and talk to them and let them know you are doing it as a hobby and mean no harm and apologize for any stress it may have caused and ask for a time and day they would be most comfortable with. Even a phone number from them, (which we all have each others anyway) so to tell them you will call the day you'll be doing it. Maybe invite them to watch. Just try not to embarrass yourself
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