How much downward force is exerted on a DR11 tube?

[CozmicRooster]

Had a couple bottoms blow out of my racks and it was quickly obvious that I hadn?t used long enough screws to secure them. It got me to thinking about the fact that I really had no idea about how much force is exerted when the lift charge ignites. I know there are a variety of answers, so I?m using a standard 60g consumer shell kit at a reference here.

[bani]

Had a couple bottoms blow out of my racks and it was quickly obvious that I hadn?t used long enough screws to secure them. It got me to thinking about the fact that I really had no idea about how much force is exerted when the lift charge ignites. I know there are a variety of answers, so I?m using a standard 60g consumer shell kit at a reference here.

should be able to roughly calculate it from the weight of the shell and the height it flies.

all my dr11 tubes are stapled and i have yet to have a bottom blow out from consumer mortar in ... 8 years?

[displayfireworks1]

You are going to have a serious event trying to save a few dollars on these racks. Just buy fireworks racks from my advertiser and they are ready to go..
.
http://www.pyroboom.com/

[CozmicRooster]

should be able to roughly calculate it from the weight of the shell and the height it flies.

all my dr11 tubes are stapled and i have yet to have a bottom blow out from consumer mortar in ... 8 years?

The rack, not the mortar. Tubes are fine.

[pyroboom]

I'd like to see a picture of your racks. You should be using 1.5" thick wood for the frame. Then adding rails makes it even stronger. We use OSB for the bottom rail. I've also seen where some floor joist made out of OSB, so it handle quite a bit weight.

[Engineer Cat]

Pyroboom makes some quality racks. I just cant justify the purchase with the shipping charges. I know it's not their fault. I would totally buy a few of those ART racks if I was close enough to pick them up.

[Salutecake]

If I'm getting this right the bottom of the rack blew out and not the plug in the dr11 tube? it's a little hard to believe a 1.5 inch of wood with a consumer shell would blow out, a definition of blow out might be in order here. I would hardly believe that the downward force from that consumer shell, set off, on top of a 1.5 wooded base would barely leave an imprint on soft ground, let alone blow it out, unless you were using something like cardboard.
Of course I might be interpreting what you said all wrong.

Plenty of online sources to make your own, as Dave suggested Pyroboom makes nice ones - and you also might find some at your local fireworks store at reasonable prices.

[Fulliautomatix]

Perhaps you could find one of those scales that has a 'maximum deflection' needle that stays in position once the load has been relieved. It would be interesting to see how much force is exerted.

[Arles]

Had a couple bottoms blow out of my racks and it was quickly obvious that I hadn?t used long enough screws to secure them. It got me to thinking about the fact that I really had no idea about how much force is exerted when the lift charge ignites. I know there are a variety of answers, so I?m using a standard 60g consumer shell kit at a reference here.

I can't imagine how that would happen with even minimal length screws... morons fire these things off of their heads and it usually works out okay for them. While I would be curious, I don't think the calculation is particularly useful as a reasonably well built rack will hold up to it. Not to mention, you could also have multiple cans firing at the same time, so you're still relying on assumptions that may or may not be true. A reasonably well built rack will handle it. Most racks I've seen use a 2x4 or similar as a base. Did you put plugs in the bottom of your mortars?

I'll second Pyroboom... I have over a dozen various racks and slice holders from them. All are well constructed and hassle free.

[CozmicRooster]

I wasn’t trying to get overly complicated or in the weeds here. It appears my post was not very clear. The wood is not damaged. It was an angled rack so the bottom was not flush to the ground. I used screws that were too short and the bottom of the rack got pushed loose from the sides. There was only about an inch clearance to the ground so the bottom did not come completely apart. The screws have all been replaced with ones of appropriate length. Using the term ‘blown out’ was probably not the best language to describe what happened.

I was merely curious if anyone knew what the approximate force was that is exerted during a lift charge from a standard 60g consumer shell.

[Arles]

This is for display shells, but may be an interesting read for those of you who are smarter than I am.

http://www.jpyro2.com/wp-content/uploads/2012/08/Kos-743-747.pdf

[CozmicRooster]

This is for display shells, but may be an interesting read for those of you who are smarter than I am.

http://www.jpyro2.com/wp-content/uploads/2012/08/Kos-743-747.pdf

Perfect. Thank you. That’s actually quite informative and interesting.