Hexagonal Rack

[dbroome]

To go along with the fireworks launching sytem I am designing (link to thread (http://www.pyrouniverse.com/forum/showthread.php?t=1409)), I have put together a hexagonal rack. Here is a small picture of the finished product, but I have also done a complete write-up with pictures of the construction here (http://www.davidbroome.com/page.asp?SID=1&Page=154).

I'd love to hear any tips for making it better!

http://www.davidbroome.com/TBFireLaunch/b12t.jpg

[graybeard]

A lot of guys have invested a great deal of time and money in this type of rack, where you have all your mortars in one tight group. Many have created workshop masterpieces. Recently, building giant racks has created a lot of excitement on the site, almost to the point of becoming a fad. In my opinion, this type of rack presents some very serious safety hazards. Many who have built this type of rack, have the tubes canted out in various directions. How do you safely load this type of rack without having loaded tubes directed at your head or upper body ? How do you safely walk around a loaded rack like this ? When the show is over, how do you safely approach and ensure that all of your tubes are clear ? If you suspect a hangfire, or become aware of a misfire in one or more of the inner tubes, how do you clear it without reaching across hot tubes, which may or may not, be clear ! Another issue is that the distance of your required clear safety zone is increased because the tubes are angled out in various directions. Proper procedure requires that you have a designated and conrtolled fall out area downrange of your mortars. With the mortars angled in various directions, fallout will be dropping in various directions. I think we need to keep in mind, that the professionals worked out the concept of single straight rows of mortar racks, for a very important reason, which is safety. With straight racks, in straight rows, you can work with them safely, by approacing and loading on the back side of the row. You have one fallout area to be concerned with, rather than having fallout dropping in various directions.

[johnny_boomboom]

Graybeard,

I see some of your points about safety... although this racks does not appear to be angled so multi-directional angling should not be a concern. Loading ...if you work from the center out it is not a problem. But after the show there is a major saftey concern, checking the guns for hangfires and mis-fires would be a problem... and that is enough of a problem to consider this in design to be in effect unsafe.

If you are angling racks they need to only in one plane, to ensure you can approach the rack from a non-angled side.

[St1dinoh]

is this design detachable? do the segments seperate from each other... if so this would eliminate most of these concerns.

you are still left with the problem of inspecting them after the shoot, that will always be dangerous. so you should be carefull when doing that. but i do like the design. looks like a lot of work went into that. just be carefull to not lean over any loaded and/or hot tubes and you should be ok.

greybeard is right these massive "cake" racks are a bit concerning to work with. i have a 75 shot box and quite frankly i get nervous when it's going off...

lets face it....that first tube could flowerpot, blow the corner out, and all the tubes fall out of the rack, possibly pointing directly at people. yet another reason to maintain a good distance between the rack and anything flamable/living :D . always place the rack with the idea that it's pointing directly at your audience. so just in case it does...the breaks are still outta reach.

[Dan]

Greybeard, I agree with you on the fact that these racks are getting bigger and bigger, and some angles are getting crazy.

I DO use a few 50 shot fan racks, just like you are talking about, but the difference is my angles are minimal, less than 5 degrees. I also fuse/wire mine in "flights". I never let them all go up at once or fused all together. I usually have each row of 5 shots fused, so really my 50 shot rack takes 10 of my firing panel cues to shoot off. So if something goes "wrong" in one of the flights, I can opt to NOT shoot the remaining rows, rather than a single fuse lighting everything up no matter what happens.

I think any large racks should be shot that way.

Dan

[dbroome]

You all make good points and I want it to be as safe as possible. To address the specific concerns:
1) no mortars are angled
2) all six segments are detachable, so you can get to the inner mortars without leaning.
3) Loading will be done from center out

All shells will be lit with e-matches, and I will have my finger on the power source button. The first hint that something isn't going right, and she gets unplugged.

To check after the show, I had anticipated approaching the racks, removing one and starting at the back, work my way to the front making sure all are clear. Then moving on to the next rack.

What is the accepted procedure for doing this, regardless of rack design?

And how do you mitigate the "flowerpot" scenario as described by St1dinoh in a straight rack (or in any rack)?

Obviously I want to be as safe as possible, so I would appreciate any other ideas...

[St1dinoh]

the only way i've seen people design with a flowerpot in mind, is to put braces/dividers between each tube that are attached to the side support slats. this will allow one tube to blow up and detach itself from the rest of the rack, but the rack still maintains as much strutual integrity as possible. so you may have to leave out one or 2 tubes per row, but the dividers provide extra strenght and will contain the tubes in the event of the side wall loss.

[carp]

For flower pots and other mortar catastrophe's.

Racks should be perpendicluar to the crowd if possible. The end boards are going to be your strongest point, they should face the crowd. When lighting by hand, the safest place to be is beyond the end board of the rack putting the end board and other mortars between you and the mortar that is firing. ANother solution is a barricade between the crowd and the mortars. Do not have your mortars all wedged in real tight in the rack(two schools of thought on this one). Tight minimizes more of the risk of a mortar getting bounced out(rare from the pros I;ve talked to) but also beats the crap out of the racks and adds more risk to a rack really falling apart, even under regular firing with no incidents. We had a club shoot over the weekend. I took 3 9 shot racks with fiberglass mortars (in tight at the bottom). I ran 5 sets of shells through them mixing up firing 1,2, and 3 shells at a time. Some mortars were damaged where the wood met the side of the mortar. Obvious, upon inspection, that having them in tight was the cause. No CATOs no flower pots. The mortars were not from Colin.


Separating each mortar also helps keep a whole rack of mortars from spilling on to the ground.

With chain fusing there is more risk! than firing individually.

Checking racks afterwards:

First and foremost a cool down period before you check them.

Spotters for the mortars to actually watch the mortars as they fire to help make sure they all did. Tough with fast firing finales.

Some put tape over the mortars. Some tape cardboard disks over the mortars, as a method to help identify mortars that didn't fire.

Some use things similiar to a mechanics mirror(mirror on a rod) so you don't risk sticking any body parts over the mortars. But, if one goes up and hits the rod while it's in your hand, not good, but better than a shell hiting your head.

I'm sure the pros on this board can add alot more.

[graybeard]

I guess it's an optical illusion in your photo, but it sure looks like the tubes are all angled out from the center. Carp made this point while I was typing mine, but I'll reinforce what he said. A standard procedure to help protect your spectators (and yourself) from a blowout in a rack, is to set up your rows of mortars perpendicular to the crowd. In most 1.3 shoots, your AHJ will insist on that. With a straight rack that is built right, a blow out will usually result in a tube falling out front or back. When your mortars are lined up perpendicular to the crowd, and one or more mortars falls out and fires a shell parallel to the ground, the direction of travel is more likely to be at a right angle to the spectators. With the circular rack shown, it would be more possible that a blow out could result in a shell being fired in the direction of your spectators. One point on Pyro terminology; A 'flowerpot' is when a shell goes off in the tube and the stars shoot out of the tube like a mine, without damaging the tube or rack. A 'blowout' is when the shell goes off in the tube, wrecks the tube, destroys the integrity of the rack, allowing one or more mortars to fall out.

[dbroome]

I see. I'm not opposed to rearranging the sections to be more safe. From what you are saying, I would be better off taking my 6 sections and instead of arranging them in a hexagon, arrange them in a straight line and then make that straigt line be perpendicular to the crowd?

And to be extra careful, I should insert a separator piece of wood between the mortars so that each mortar is enclosed by wood on all 4 sides?

Then all other safety concerns would be me loading correctly and checking tubes after the show carefully?

And just so I am aware, what is the likelyhood of a properly loaded shell in a fiber glass mortar having the sort of blowout that would cause rack failure/mortar spillage?

[graybeard]

dbroome, You have it right. Placing a block between each mortar, top and bottom, adjacent to the side slats, secured with screws and glue on both sides, will help prevent the whole row from falling out during a blow out. As to your question about blow outs in fiberglass mortars; an Excal shell placed upside down and fired, generates incredible explosive force. Why take the chance ?

[dbroome]

I agree, I don't like taking chances. My curiosity stems from the fact that before I built my rack, I looked at the mortar rack plans on this site and the racks for sell on the various sites linked from here, and the various racks in people's galleries, and a VERY small % of them had each mortar enclosed on 4 sides. Almost universally they had rows of mortars that were placed side by side.

Which is why I copied that configuration in my design. If this were a common occurrence, I would have thought everyone's racks would be built as is suggested here.

[carp]

... a VERY small % of them had each mortar enclosed on 4 sides. Almost universally they had rows of mortars that were placed side by side.

Which is why I copied that configuration in my design. If this were a common occurrence, I would have thought everyone's racks would be built as is suggested here.

I do it to cover my butt. I also don't want to be rebuilding racks if NFPA 1123 ever makes it a requirement. I feel the added protection is worth it and some states require it. Also don't want to get my stuff to a shoot and have the Fireworks Inspector say I can't use my racks or decides to make me bury them to use them(also required in some states).

Just remember, it's not if something will happen, it's when.

[shrapnel]

Doesn't NFPA also state no more than 15 mortars per rack? or is that only for 1.3? How many tubes will that hex rack hold?

[dbroome]

It is actually 6 racks, and each hold 25 (or at least they do if you don't remove some to place the brace pieces). Is their a place to download the NFPA so I can read it and see what it says?

[carp]

Doesn't NFPA also state no more than 15 mortars per rack? or is that only for 1.3? How many tubes will that hex rack hold?

Do you mean for chain fusing?

3" and under = max 15, 4" =12, 5,6 Inch =10, no chain fusing above 6".

Hmm.. I wonder if it would be wise for those doing 1.4g shows to follow these rules. Say the fire department/police etc stopped by before during or after the show. They notice you have racks of mortars. They know racks for 1.4g are not a common thing at the "fireworks store", and decide that they want to hold you to 1123. Suppose you have an accident and violated the rules of 1123. Wonder if that would stick on someone shooting a backyard shoe in Indiana or another 1.4g friendly state.

[DennyMo]

Is their a place to download the NFPA so I can read it and see what it says?
Yes, if you're willing to shell out the bucks to buy it. NFPA standards aren't cheap. A better idea would be to go to your local fire department, and ask them if they have a copy of it you can review.
And just so I am aware, what is the likelyhood of a properly loaded shell in a fiber glass mortar having the sort of blowout that would cause rack failure/mortar spillage?
Slight, but don't assume that your shells will be loaded properly every time - especially if you're not the only one doing the loading.

[graybeard]

I'm sure that a lot of guys are probably thinking; " why should I worry about professional standards, I'm only shooting consumer goods". If you think about it, as soon as you get to that point where you are building mortar racks and chain fusing multi shot cake boards, you have entered into the realm of the professional pyrotechnician. The first thing most everyone wants to do after building their first multi shot mortar rack, is chain fuse all of the shells. Once that fuse is lit, those shells are going somewhere. You're not going to stop anything until the last shell fires. If your rack is built poorly and blows out or tips over, You, and your spectators, will be in a lot more danger if you are unaware of, or not following well established safety procedures. For example, a lot of guys have built multi shot racks, but have no idea how to safely clear a misfire or hangfire in their rack. My recommendation would be to get a copy of the PGI shooters manual. Everything is presented in a 'how to' style with diagrams and explanations. NFPA 1123 is a must have if you're are shooting 1.3 but it is in the form of a list of requirements and does not offer much 'how to' type information.

[shrapnel]

Try this Guys, all free.

http://www.nfpa.org/freecodes/free_access_agreement.asp?id=NFPA112300&cookie%5Ftest=1

[DennyMo]

Try this Guys, all free.

http://www.nfpa.org/freecodes/free_access_agreement.asp?id=NFPA112300&cookie%5Ftest=1
Excellent, glad to see that I was only partly wrong.:rolleyes: