Big Explosions!

[MrCrowley]

Ahhhh!!!

I bet that would be loud.

Here's the problem. I need it remotely triggered on cue. Is that possible?

Looks like you might have to go with a pneumatic cylinder so you can puncture the disk. Like this:
http://www.spudfiles.com/forums/qctbdc- ... t5847.html

[kissass78]

Sure I know vermiculite. Doesn't that have asbestos in it?

It has to go underground with a remote trigger.

[daberno123]

Joel of Spudtech made something for the same purpose: Thunderpipe FX

You could build a similar one out of PVC for a lot cheaper than a burst disk gun. Not sure about how to make a crater simultaneously.

Just throwing that out as another option, good luck with the movie.

[kissass78]

I envision the thing being less than 4' wide. A reservoir, valve, elbow and cone. That's it. I just need a valve system that can push 100psi out of a 8" tube real fast....

[starman]

Doesn't that have asbestos in it?

Nope, not the stuff you get today. It has many good uses as described here.

[jon_89]

how about something like this. http://www.youtube.com/watch?v=yRw4ZRqmxOc. Without the flare of course.

[kissass78]

Lord have mercy that's it!.....less creamer though.

I tell you, I know that Spielberg used massive air units to get the mortar explosions on SPR's beach landing scene. I don't know how he did it.

[starman]

Here's another one with sawdust...

[youtube][/youtube]

[kissass78]

I can't tell how they launched that up in the air....

[jon_89]

how do they trigger that one? I see a hose going into the tank.

[starman]

It's just a pneumatic cannon with a large QEV valve.

You could always use an electrical solenoid sprinkler valve to pilot your big valve. Switch the voltage on to the solenoid and off she goes. 3 - 9 v batteries will do the trick.

@jon: They are probably piloting the valve with the hose. It was quacking pretty badly there....

[kissass78]

If I have two or three 6" reservoirs hooked into a 6" coupling which in turn attaches to a 2 INCH valve, which goes to an 8 INCH barrel......

....how would that effect the blast? Less diameter = less boom right?

The air coming from three 6" reservoirs though a 2" valve would be slowed considerably right?

I need a big valve or a burst disk I guess.

[clide]

Not many cheap commercial valves will be capable of that kind of blast. The only commercial valve I'm aware of that will be of a large enough port would be an "air cannon" which happens to be an industrial name for what we'd see as a pneumatic cannon without a barrel.

Basically it's a piston valve and a chamber which gets discharged into a silo for loose and dry material to clear blockages.

I'm aware of up to 6" valves (outlet port) for that. Heavy metal and cost a bit.

There is a show called Time Warp on the Discovery channel that records various stuff in slow motion. They did one where they went to some special effect studio and did some debris shots. IIRC these commercial silo air cannons were being used. They had a big funnel thing to hold the debris

http://www.martin-eng.com/products/big- ... air-cannon

[starman]

A valve big enough, or even multiple valves to do what you want is going to be big bucks. Maybe you could try to come up with a burst disk solution.

Note that the larger the diameter of disk, the thicker it will need to be hold back the same of a lesser diameter.

[jon_89]

What about a setup like this, http://www.spudfiles.com/forums/viewtop ... tml#188434, just bigger. To get the coupling off you can put a dowel through it to pull it apart. Problem is burst disk material.