Blood Cannon

P

Paul Reichelt

Active member
NOTE: This is entirely different from a "Blood Sprayer", I'm talking about a Cannon. Something that can disgorge a around 2 Gallons of Blood/Guts at once.

Hey Guys, I'm shooting an Action/Horror film in Mid-July and we've begun the search to fill our special effects needs. We're alloting around $1,500 of our $3,000 budget towards Special Effects, so that says something about where our priorities lie :P

Basically we're looking for something that's able to "shoot" out around two gallons of blood or more. It needs to have enough pressure built up to shoot the contents around eight feet, so a fairly big "spurt".

There was a website online, that I found either from DVXUser or StickToWhatYouKnow where some guys had created an air cannon of sorts that they were using to shoot everything from flames to wood in the air. It was exactly what I was looking to build for our production, however the webpage is down now.

SO, any suggestions on what route we should take. I've thought about buying an electric air compressor, and creating something similar to our blood sprayers (which we use for Squibs) on a larger scale, but I'm not quite sure how powerful of a machine to purchase or if there is anything else I should be looking at.

Any help is greatly appreciated. I'd like to be able to come up with a feasible solution for under $800.

Thanks again :)
 
Air compressor is exactly what you need. I like this one's design because its not sitting on flimsy wheels and looks firmly planted to the ground. You DEFINITELY want a pressure gauge.

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From the air chamber, you could use a valve like this:

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Or if timing is a must, buy a solenoid valve:

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Solenoids are rated for a max psi. This one is 200 psi.

From the valve get yourself some piping. I'd pick up some straight pieces and some curved pieces at different angles. This will give you flexibility with where the blood cannon can aim. If you need it to shoot straight up, dont turn the compressor on its side - adjust the piping to your needs and make sure everything is rated for the psi you'll be shooting. The compressor shouldnt fly backwards or anything, but you might want to throw some sandbags around its base to keep it aimed right.

If you want a lot of blood and guts you 'll need some sort of funnel. You could work your way up to larger sized PVC pipe or you could simply buy some sort of funnel. Just make sure the solenoid is closed every time you load the funnel / piping or you'll be filling your compressor with guts.

I do not recommend an air cannon unless you know what you're doing. AND only if you plan on babysitting it for the duration of its use. It is not something that you can leave around (especially filled with air and projectiles). If you attach a solenoid, you will be setting off the air cannon with a switch. You need to imagine that this switch is a trigger to a powerful gun... because otherwise you might forget or undestimate this device & someone could get injured or killed.


Here's a solid design someone built for confetti.

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Two barrels is probably overkill for blood & guts however. Googling "confetti cannon" brings up more results than "air cannon" or "blood cannon" & its essentially the same damn thing. I've built a lot of these so if you have any specific questions I'll try to help. Make sure to use plumbers tape on any brass connections.
 
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Hi Knoxworth,

Thanks for the great post. Do you have any specific air compressor models you could reccomend. Hopefully something that is "well-built", under $800, and fairly "compact".

Thanks again :)
 
I'll list off a few, with prices.

Porter Cable $189.00, 43 lbs, 150 max psi, 2.6 SCFM
http://www.homedepot.com/webapp/wcs...langId=-1&catalogId=10053&productId=100497651

Another Porter Cable design, $289.00, 94 lbs, 150 max psi, 6 SCFM
http://www.homedepot.com/webapp/wcs...langId=-1&catalogId=10053&productId=100091240

Hitachi $249.00, 67 lbs, 125 max psi, 4 SCFM
http://www.homedepot.com/webapp/wcs...langId=-1&catalogId=10053&productId=100323157


Rigid & Dewalt make air compressors too but I didn't see anything on the home depot site that fits our needs as filmmakers. Just from those three, I'd say the 43 lb Porter Cable is the most desirable. Its weakness is that it compresses air at half the speed of the other Porter Cable design. SCFM = Standard Cubic Feet per Minute. So if fast reload time is necessary go with SCFM rating over anything else. But for filmmaking you might subsitute weight so you can lug it around easier.
 
Its also worth mentioning that you don't HAVE to use the air compressor as the blood cannon. You could buy one compressor & distribute air to separate tanks. This would make the SCFM rating more important, using this method.

Husky air tank, $36, 125 max psi
http://www.homedepot.com/webapp/wcs...alogId=10053&marketID=401&productId=100000784

If you go this route & set up multiple blood shots for one take, you'll also be buying hardware such as quick connect fittings.
 
do a google search for "air cannon" or "air potato gun." i made an air canon that is portable. it's good for one shot, then you gotta refill it with air... i used a sprinkler valve on it. good luck!
 
Thanks for the help. I'm gonna go ahead and get the first Porter Cable design because weight is definitely a factor. Also we are going to do what you suggested and buy two additional Air Tanks for multiple bloodshots in a single tank.

We will be working on it today, and I will update once we've made some progress.
 
I have to say, I'm not sure how well an air cannon would work with 2 gallons of liquid. I think you would want a piston to push it out instead.
 
I've got a few more questions if you guys could help.

We went to lowes a few days ago and browsed their Air Compressors and found some models similar to the ones above, and some standard air tanks (6 Gallons, 150 PSI). However we got a bit confused when buying the valves. We've decided for now just to have a normal Ball Valve, so we don't misfire, however we're confused about whether the air coming out of the tank through a 1/4" opening through the valve into the "tube" (2") will just jet out or whether it will correctly "fling" most of that liquied into the air. Two gallons is overkill, more like a litre or two.

I went searching for water/air/confetti cannons and found many for sale, but no concise tutorials that show the actual construction of one. Any suggestions as to where to look?

I believe I have the basics down, but I want to be sure that I construct it properly.

Thanks :)
 
UPDATE

I went ahead and bought the Compressor and necessary parts for the actual cannon. I'm not kidding when I say its roughly a two foot long monstosity of plumbing parts (had to get up from a 1/4 Nozzle to 2" lol). However once I verify that the basic design is okay and tighten everythig up, I'll be able to have just a 1/2" into (2" or 3" depending on how well this does) thats only 8" or so before the main tubing.

Its a bit late, and the compressor is very loud so I will need to wait until tommorow to begin testing. If all goes well I'll post back with some pics :)
 
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