Hi there everyone,

Can anyone suggest the best method of utilising some sort of compressed air to launch a cloth up into the air about 8-10ft reasonably quickly? I'm wanting it to be small though, as it needs to be positioned on or under the stage floor without being noticed by spectators. It sortoff needs to be an unexpected happening

Maybe there's an easier way to do this other than compressed air or a fly rig?

Any help would be greatly appreciated,

Mike

Air jets are a science in themselves and very unpredictable. I am sure that you require a "sure fire" method so I would go with monofilament flylines with release weights. Let the weights go and it all pulls up quickly and accurately.

Air jets and parachute cloth (it would have to be that type" would need considerable precision aimed jets and due to the fluidity of fabric have unexpected lift results.

I am a trained special effects technician and in that capacity have used both compressed air and CO2 to fly things and create general havoc. What you would need (in addition to a compressor of course) is a solenoid valve with which you can control the amount of air released from the reservoir. It is, in fact, quite controllable.

However I´d advise against compressed air if you´re not experienced or have no training. These air cannons, or air mortars can pack some serious power and can break things and hurt you.

There are small CO2 mortars available, they´re also referred to as confetti cannons. Basically they´re small mortars using CO2 capsules or in some cases compressed air as well.

Of course a simple catapult system might do the trick. Tell a bit more about the sequence, that might be helpfull.

Also check these little babies:

http://www.seal-fla.com/confetti/confetti.htm

Thanks for the replies everyone.

Mvmagic,

I'm wanting to use this idea in a number of illusions. However all are vanishes are of reasonably large objects i.e a motorcycle, a car and possibly a person.

A cloth is draped over the objects and then, after a short pause, shoots up into the air to show that the object has vanished. I suppose it would be best for the cloth to fly up and towards the audience a little bit, but it's not that important really.

Will the equipment you described be able to achieve this?

Thanks again,

Mike

Well, it certainly would but I see some problems here. A cloth that covers a motorcycle or a car is somewhat large and would require a lot of power. Also when vanishing a person the safety is an issue-you shouldn´t put a person next to an air cannon. Only times I have used compressed air live on stage were for a play. Once a large mortar loaded with balsawood, bits of insulation and dust to simulate an explosion off-stage. The other time was with small mortars to simulate bullet hits. If this was a film set I´d go with compressed air. In addition to safety, sound is an issue-the tell-tale bang/hiss noise these things make can be loud.

I agree with glodmagic about the fly lines. Granted the effect is a bit different from the cloth just shooting up and its not that fast either. However it is silent, more controllable, safe and also repeatable.

Its possible to make a simple system that releases the cloth when it reaches certain height. Its simpler to have two cloths: One that goes up and out of sight and one that is free of lines and is dropped on stage from above. That would keep the system simple.

What would you think about the cloth going on either side or behind instead of upwards?

Mvmagic,

Where the cloth goes is not really that important. I'm just after the effect of a cloth being launched into the air no matter if it's up, backwards or sideways. I thought compressed air would do this well and the noise would sortoff shock the audience.

Thanks,

Mike

It would do it well, but hiding a system with sufficient power might be problematic. Weaker systems then again don't neccessarily propel the cloth high enough.

A powerful wind machine located behind and on lower level could work also, though it wouldn´t be as sudden.

Combining theatrical maroons or flashes with bang effect with wire pulley system would provide the element of sudden noise.

I´ll ask a few fellow fx techs about air cannons as well and let you know.

MvMagic,

Thanks for your help, I really appreciate it.

That would be great if you could ask a few of your fellow FX techs. If you don't come up with anything new then the wire pulley system will do. I'm looking forward to hearing back from you .

Thanks so much for all your help,

Mike Rogers

I talked with a few other technicians today and actually played with an air cannon (we were on a set) and a bit of fabric we had around.

One of the problems-the way we see it at least-is the size of the unit. Its kinda hard to conceal effectively. On film its easy but stage is another deal. Other is the accuracy. Certainly the amount of air released is controllable but that's as far as it goes. On a dozen or so launches we made, the same piece of cloth we used landed in different places. We measured the position of the cloth more or less precily on three launches (cloth resting directly on the mortar) and it ended up acting differently each time. If it was a bit off, air hit it differently and it folded differently when airborne and consequently affected the place it landed a lot. Still it looked neat.

But we all agreed on one thing: if there´s no trained technician who is experienced with air mortars, don't use one as there´s no room for error. These things can really blow someone´s arm off. Everyone felt the wire pulls would suit stage needs much better as they are safe, easy, repeatable and also cheap. Tim, who is my original trainer, felt (he´s always thinking about budgets) that the trouble and the cost considering the effect and its part in whole is not beneficial and wire pull would have more production value.

If you want something visual and shocking, how about this: Have the cloth rip in two. Basically its two cloths that are sewn very lightly together so it can be handled but when greater force is applied, breaks in half. Have very small metal rings (like the ones used in sails, not sure of the proper term in english) or plates where the pullwires are attached. That wouldn´t require overhead rigging at all but a simple stand on both sides of the stage. A standard sandbag will be heavy enough. You need a bit of slack so the bag gets up to speed before it yanks the wire. The weight doesn´t need much travel either but should stop very quickly after release-that way it doesn´t pull the cloths off the stage but just rips them apart and they land on stage. That does look good, extremely visual. I have made this one (I was the FX tech, not magic related) to reveal a car.

MvMagic,

I love it! I'll certainly use it.

Thanks for asking your FX colleagues about this too. I'll let you know how it all goes.

Thanks again,

Mike Rogers

I think I would go with glodmagic's suggestion and use a mono-filament flyline.

Mike,

The effect sounds great. However, for my two cents worth, I would really not recommend compressed air. Besides the noise, and unpredictibility, it can be very dangerous. Temperature is another factor on a real stage that many people do not consider. (Fear is not the only reason we sweat on stage.)

Never over look the simplicity of a window shade roller and transparent line. Even a long metal measuring tape can make a great reel. There is travel and storage to consider too!

Good Luck!

Bob