Almostparadise Posted November 12 Posted November 12 Ive been making a few cylinder shells recently and they seem to be quite a bit louder on the launch than the same 3" and 4" diameter ball shell. Im wondering if lengthening the mortar tube 6" + or - (in addition to the tubes being buried) would dampen the sound enough to make them sound closer to the ball shells launch. Another thing is that I do not know how adding another 6+ inches would change how they lift and perform in the air?
FiroweWorks Posted November 13 Posted November 13 What is the tube length you're already using? It can increase lift height by adding length to tubes. But, after continuing to add length to a tube for the same size shell, it eventually becomes pointless and won't make a noticeable change in launch height.
cmjlab Posted November 13 Posted November 13 I always assumed that cylinder shells are a bit louder since their typically heavier than ball shells, and their shape compared to a ball shell - i have no science to back that up though. How much lift are you using? 1
Almostparadise Posted November 13 Author Posted November 13 (edited) 10 hours ago, FiroweWorks said: What is the tube length you're already using? It can increase lift height by adding length to tubes. But, after continuing to add length to a tube for the same size shell, it eventually becomes pointless and won't make a noticeable change in launch height. 3" mortar is 18" and 4" is 24". 10 hours ago, cmjlab said: I always assumed that cylinder shells are a bit louder since their typically heavier than ball shells, and their shape compared to a ball shell - i have no science to back that up though. How much lift are you using? I use just shy of 10% of shell weight. More lift = more sound i suppose. I just was not aware if there were any negative consequences to lengthening the mortar tube. I think I'll give it a try with one of them. I use steel pipe just because I have a free source so I'm going to cut a 24-in long 3-in tube and see if there's much of a difference and then go from there. Edited November 13 by Almostparadise
Arthur Posted November 13 Posted November 13 If you look at YT vids many a Maltese cylinder shell is longer than the mortar is deep, so that the shell actually sticks out of the tube
Almostparadise Posted November 13 Author Posted November 13 (edited) 27 minutes ago, Arthur said: If you look at YT vids many a Maltese cylinder shell is longer than the mortar is deep, so that the shell actually sticks out of the tube Really?? I'll have to check that out. I'm wondering if that is by design or if it's just the way it works out at times. Very interesting. Edited November 13 by Almostparadise
Carbon796 Posted November 13 Posted November 13 (edited) Adding 6" in length probably won't affect the sound much, if at all. You may get slightly more altitude. I used to shoot 6" multi breaks from a 60" steel buried gun. ( Steel guns should always be buried or barricaded. Especially for multibreaks or shell that have flash based components or boosters. ) Our 8" gun was similar in length iirc. I don't personally think they were any quieter than a standard 6x gun. Cylinder shells just leave the gun with a kick. The 10% by weight rule. Is for ball shells. Part of the additional length of Maltese shells is due to the lifting style/method used. Which is different from traditional American/Italian styled shells. Edited November 13 by Carbon796
Almostparadise Posted November 16 Author Posted November 16 On 11/13/2024 at 9:58 AM, Carbon796 said: Adding 6" in length probably won't affect the sound much, if at all. You may get slightly more altitude. I used to shoot 6" multi breaks from a 60" steel buried gun. ( Steel guns should always be buried or barricaded. Especially for multibreaks or shell that have flash based components or boosters. ) Our 8" gun was similar in length iirc. I don't personally think they were any quieter than a standard 6x gun. Cylinder shells just leave the gun with a kick. The 10% by weight rule. Is for ball shells. Part of the additional length of Maltese shells is due to the lifting style/method used. Which is different from traditional American/Italian styled shells. Okay, that gives me something to think about. So the 10% weight rule is for ball shells, is there a rule for cylinder shells?
cmjlab Posted November 16 Posted November 16 Generally 1oz per pound up to 10 lbs, then 1/2 oz per pound after that, is what is written in the Fulcanelli Articles (Pyrotechnica IV and VI). My math isn't great but I think that's approximately 6%, if you prefer percentages. 1
Mumbles Posted November 26 Posted November 26 It's 6.25% if you want to be specific. The cylinder shell rule of thumb tends to be a good starting point, but you really need to kind of dial in what works for you and what works for your BP. It tends to work best for the size of shell described in Fulcanelli of roughly 1-20lbs. It breaks down a little bit on the outside of that range. I use roughly that rate, but with some caveats. For instance, I've had better luck using 4FA rather than 2FA for smaller shells (3" and below, sometimes 4" single breaks). I generally round up to at least the next half ounce, if not full ounce, if I want to be extra sure or I'm shooting out of an unknown gun at PGI or a club shoot or something. It tends to break down a little bit for pretty big shells. For some it is easier to use a rule of 3/4oz per pound. 20lbs is the point that rule and the original ounce per pound up to 10lbs, and then 1/2oz per pound after that break even. For extremely large shells, like 60-80lb+, 1/2oz per pound across the board might be more applicable. Getting into the larger sizes is when you may want to start considering alternatives, like 1FA instead of 2FA, or using a lift sabot. Lift sabots themselves are a whole thing unto themselves and are best done by leaning on the experience of others and testing yourself. It's also a thing I'd want to dial into a specific gun. They use significantly less BP generally, but also only see real advantages and utility in my opinion with larger shells. Just as an example, here's some of the recommended lift amounts based on the various rules of thumb for an 80lb shell 45oz (Fulcanelli) 60oz (0.75oz/lb) 40oz (0.5oz/lb) 25.6oz (sabot) To get back on topic a little bit, there is an article is Best of AFN V on page 57 about the effect of mortar length and lift height that might interest you.
msantosh1989 Posted November 27 Posted November 27 (edited) Hi guys... I have something to ask related to this topic. I have made some 3 inch ball shells recently (1st time making ball shell). My mortar length is 21". I initially used 10% lift charge. Which did not give sufficient lift. So subsequently I increased the lift charge to 20%. Still I am not happy with the altitude. My lift charge is not ball milled, but finely sieved and 4-12 mesh granules. There was 1-2mm gap between the shell and the mortar - inside. I am attaching some videos. Please have a look and hope you can throw some light. My questions are 1. What should I do to increase the altitude? 2. Does adding more layers to the shell to make it more confined to the mortar negatively impact the shells? Will that destroy stars? 3. If the quality of my lift charge is the issue, can I boost it with some flash powder? (Ignore the quality of stars in shells 1 and 2. I randomly filled them with whatever old stuff I had) Welcome any other suggestions... Shell 1.mp4 Shell 2.mp4 Shell 3.mp4 Edited November 27 by msantosh1989 1
Zumber Posted November 27 Posted November 27 17 minutes ago, msantosh1989 said: Hi guys... I have something to ask related to this topic. I have made some 3 inch ball shells recently (1st time making ball shell). My mortar length is 21". I initially used 10% lift charge. Which did not give sufficient lift. So subsequently I increased the lift charge to 20%. Still I am not happy with the altitude. My lift charge is not ball milled, but finely sieved and 4-12 mesh granules. There was 1-2mm gap between the shell and the mortar - inside. I am attaching some videos. Please have a look and hope you can throw some light. My questions are 1. What should I do to increase the altitude? 2. Does adding more layers to the shell to make it more confined to the mortar negatively impact the shells? Will that destroy stars? 3. If the quality of my lift charge is the issue, can I boost it with some flash powder? (Ignore the quality of stars in shells 1 and 2. I randomly filled them with whatever old stuff I had) Welcome any other suggestions... Shell 1.mp4 24.23 MB · 0 downloads Shell 2.mp4 16.75 MB · 0 downloads Shell 3.mp4 17.38 MB · 0 downloads 1-use more lift till you get desire height, height of shell in video is not too low if still you wish you could add a bit more. 2-additional layer to the ball makes shell burst a bit more than present no of layers if your prime is hot enough stars may survive and shell will spread far. 3- milling bp is most best option, if you can't mill just sure all chemicals are fine enough atleast to pass 100 mesh screen, In India two types of charcoal available one is normal and other is ball milled air float which is best for lift. Sieve all ingredients 5 times through 80 mesh screen and don't make granules bigger 2 mm is good choice for 3 inch shell and also keep amount of binder not more than 2 percent as binder affects burn rate. Flash boosting isn't good idea it increases sound unnecessary during launching of shell plus it may destroy shell if it is not reinforced well and will cause shell to burst in a morter sometimes not every time. 1
msantosh1989 Posted November 27 Posted November 27 6 minutes ago, Zumber said: 1-use more lift till you get desire height, height of shell in video is not too low if still you wish you could add a bit more. 2-additional layer to the ball makes shell burst a bit more than present no of layers if your prime is hot enough stars may survive and shell will spread far. 3- milling bp is most best option, if you can't mill just sure all chemicals are fine enough atleast to pass 100 mesh screen, In India two types of charcoal available one is normal and other is ball milled air float which is best for lift. Sieve all ingredients 5 times through 80 mesh screen and don't make granules bigger 2 mm is good choice for 3 inch shell and also keep amount of binder not more than 2 percent as binder affects burn rate. Flash boosting isn't good idea it increases sound unnecessary during launching of shell plus it may destroy shell if it is not reinforced well and will cause shell to burst in a morter sometimes not every time. Thanks Zumber. Binder in my lift was 5%. I will reduce it the next time to 2%.
Zumber Posted November 27 Posted November 27 I use 2 to 3 percent for lift and upto 6 percent for stars. 1
Mumbles Posted Thursday at 10:27 PM Posted Thursday at 10:27 PM I would second the suggestion to use a finer granulation for the lift grains. I mentioned it in my previous post, but I use 4FA in 3" shells and below. 4FA is -12+20 mesh. You could go even finer than this without a problem. I've used 2Fg as well, which is around -16+30. The issue you're describing is the exact reason I started using a finer grain. 2FA (-4+12) just didn't have enough kick. Either the weight of the shell was too low to really get the pressure in the mortar up, or it was burning too slow to really get going. This effect seemed to be exaggerated in the winter or colder months as well.
Almostparadise Posted Saturday at 02:19 PM Author Posted Saturday at 02:19 PM (edited) To follow up. I with the 3". It's a seamless steel tube 30" long, it's beefy! I cut a thick tapered plug from a dead oak tree and pounded it the bottom w a mini sledge hammer. The inside is now 27". Buried in the ground it's easy to notice the difference in sound. The tone is noticeably deeper. A "Tha-Wump!" Instead of a "Ca-Boom" sharp cracking sound. While still loud, the deeper launch sound, to my ears anyways, sounds alot less threatening. I am plenty far from other houses but not far enough to escape the sound. It's been 3 years since there were any complaints and that suits me fine. The 4" is next. It's cut to 40" so I'll get 36" inside after I plug it. I don't mind that it's going to weigh as much as a small elephant. ☺️. I also plan on a side by side launch, simultaneous with both original fiberglass and longer steel tube to see how that extra 9" affects the height. Edited Saturday at 02:22 PM by Almostparadise
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