Air Cannon Growl?

[TwistedDementia]

I want to start designing a air cannon that has a growl type sound when the blast of air is shot out of it. I have a few ideas but want to get some more input before i start investing in R&D (research and development).

Any idea's anyone?

[Sickie Ickie]

put a doberman in the barrell? :p

[TwistedDementia]

or the barrel in the doberman?

[BCat]

Hmm. You're probably going to need something oscillating within the "throat" at a frequency a few KHz, and a tuned resonant chamber to amplify it. To produce the growl, the stream of air should be constant, in order to maintain constant mix of frequencies.

The blast from an air cannon will generally last around one second (or less), and the air flow will drop off precipitously, so not much time for a growl and the frequency of any sound produced will vary as a function of the air flow.

Perhaps your growling mechanism should be in parallel with the air cannon.

-Brian

[TwistedDementia]

Excellent info BCat. I have a custome air cannon that I can control the length and flow of, I'm thinking a 2 to 3 second burst. As far as the growl, I'm thinking a carbon fiber reed type setup (like a 2-stroke engine) and a tuned resonant chamber immediatly after, also might need som baffeling. It won't be an exact groml but I'll be happy with "close", it's something different from the norm.
Thank's for the input!

[Revenant]

In an animal's throat, the growl is a rapid series of discrete sounds as the tension on the vocal machinery sort of slams shut the airflow every few microseconds... seems to me any rapid series of impacts should do it. Ever drive too close to the shoulder where the pavement's grooved and you get that growly, howly whine sound from the tires?

Think rapid hits on a diaphragm of some sort that the airflow passes across on its way to the resonance chamber. Maybe just a rotary motor with a knobby projection on one side to hit whatever you're using for a drumhead. The size of the diaphragm would vary the pitch, and the speed of the motor would vary the "throatiness" or phlegmminess of the sound.

Just a theory but may be worth looking into. I just give you massive kudos for looking into a non-recorded way of producing sound, I think there should be more of that.

[HibLaGrande]

I imagine a large 6 inch pipe with various sizes of surgical rubber tubing stretched across tin inside. with air blowing though it strumming the rubber cords. kinda like a large woopee cushion ,well sorta :) A sub woofer would be more practical though.

on another note, ever run the edge of a pick down your guitar stings? a large wound bass string strung tight with something scraping down the edge at the right speed might give a growl.

now imagine a a 4 foot section of 4 inch pipe set up like a slide whistle with a piston type thing that runs up and down with a heavy bass string stung through the center. the piston has a spring loaded scraper that rubs the string to give the growl, and air pushes the piston up and down to cause the pitch to change. might sound more like a big frog. :D

just odd thoughts.

[Revenant]

Or corrugated drain pipe with something scraping along the length of it... like a massively oversized version of that guitar string. The air stream passes through the pipe while the "scraper" clicks/bumps along the ribs of the pipe.

[BCat]

So far, I've seen lots of interesting suggestions, but why does the growling need to be part of the air cannon? Why not use an MP3 player and a speaker that is triggered when you fire your air cannon?

-Brian

[TwistedDementia]

All great ideas, keep um coming. I've got to get started on R&D now!

why does the growling need to be part of the air cannon?-Brian

Storage, simplicity, easy setup and take down, won't be as vulnerable in bad weather and so I can put it in a minimal amount of space and get two effect's at once. To get the volume that the air cannon (I hoping) should produce, It would take a large speaker or sub to get where I'm trying to be for sound.

[Campdoc]

Try using a Automotive(Body Shop) Air hammer!
These things are very loud! and very easy to control the sound
they make, The cheap china one's work well.too try Pep-Boys
or AutoZone..

[TwistedDementia]

Try using a Automotive(Body Shop) Air hammer!
These things are very loud! and very easy to control the sound
they make, The cheap china one's work well.too try Pep-Boys
or AutoZone..

Hey Campdoc, does an air hammer it give a big blast of air? Cause that would work great if so.

[Campdoc]

Kinda sounds like a Two stroke motorcycle..pop-pop-pop!
I promise these will scare the Yell' out of you..
" better than a chain saw in the woods.."
it's small,looks like a pistol.

[Revenant]

Only problem is it needs to be pressed against something to get the vibration. Every one of those that I've used, if you pull the trigger and nothing is putting resistance against the chisel, it just goes PFFFFFFFFT.

[Ironman]

Ah.....but mount one on the outside bottom of a 30 gallon, or 55 gallon steel drum and the sound is deafening. Plus if you mount the drum on a gimbal, you can aim the barrel and focus that sound in any direction.

[TwistedDementia]

I noteing all these great ideas so keep them coming. I have a lot of materials to work with and plan on trying as many ways as possible and will post the result's after the completion.

[Revenant]

Deafening yes, but about as far from a growl as you can get. Unless the scare involves being chased by a deranged body shop mechanic.

[TwistedDementia]

Unless the scare involves being chased by a deranged body shop mechanic.

That will be my next adventure for a prop LOL.

[TwistedDementia]

I'm thinking some inertube's from a bike streched out over the start of the cannon tube and some redirection chambers (like a flow master exaust) to deepin the sound further. What's your thought's on that?

[Doomsday Cult Leader]

It looks to me as if you're building an enormous pneumatic whoopee cushion!

Hmmm.... That might work with an air cannon!
In a dark maze... The ToTs hear "I don't feel so good!" then as they round a corner, Brrappp!!! with a blast of air washing over them. "I feel much better now!"
Might be good for a dead-end! pun intended!

[Revenant]

Throw in a blast of fog and a packet of "Flatulence" from Sinister Scents and you're there.

[TwistedDementia]

Might work with my outhouse but I need a growl effect.

[halloweenguy]

how about using some sort of propeller inside to give it a fluttering sound...Then all you just need the right pitch.

[TwistedDementia]

how about using some sort of propeller inside to give it a fluttering sound...Then all you just need the right pitch.


That's a possibility.

[dave the dead]

There HAS to be some sort of relatively simple solution to this! I have been reading the posts and thinking about it....damn this is driving me nuts!

<thinking as I type here....>
When you make a growling noise, some of the air is passing thru the sinus cavity and some thru the mouth. There is a positioning of tissue deep in the roof of the mouth, just at the start of the sinuses that creates a flapping effect, much like the whoopie cushion idea. However, it seems like the tissue is facing forward into the airflow rather than just trailing the airflow like you would get with a bike tube or similar set-up. The airflow is very low velocity compared to normal air props, so the psi passing into the growl would have to be greatly reduced. (try growling with your mouth closed....sounds like a snore, right?) Now, once the positioning is correct in the sinuses, a small amount of air going thru the mouth turns the noise into a growl. (open mouth slightly and make an RRRRR sound) The more air that goes thru the mouth now helps it sound more like an animal growl and less like a snore. (continue to make the same noise, but pinch nose shut) The optimal growling sound happens when there is a combination of air leaving the nose and the mouth.
So, it seems like a rudimentary mouth/sinus/flapping membrane should be able to get the growling sound....

I know this didn't solve the problem, but maybe it will spark a thought out there.....this would be really cool if we (or someone) can make it work!

[TwistedDementia]

I know this didn't solve the problem, but maybe it will spark a thought out there.....this would be really cool if we (or someone) can make it work!


Hey dave... all input is appreciated!

[porsche986]

I’m sorry that I'm late getting into this thread but this is a "must try" for you and it's cheap.

I stumbled on this accidentally last year. I wanted to put an air cannon in my TCT but didn't have a way to bring the air through a straight pipe because of the other mechanics. I found some flexible/corrugated pipe in the irrigation supply area of my local Ace hardware and attached it to the output of my cannon. The corrugation caused an absolutely EVIL sound. It is blue with black, threaded ends. I have seen it at HD or Lowes since. If I find a link I'll update the post.

[porsche986]

Here's a photo of one of the hoses with the part info inset.

http://www.raw-footage.com/dl/hosesm.jpg

I found it at HD in the irrigation section.

[Revenant]

I’m sorry that I'm late getting into this thread but this is a "must try" for you and it's cheap.

I found some flexible/corrugated pipe in the irrigation supply area of my local Ace hardware and attached it to the output of my cannon. The corrugation caused an absolutely EVIL sound.
Describe the evil sound?

Or even post a wav/mp3 of it?

A combination of that and halloweenguy's propeller idea might do it, too... I'd love to find out what would work. I'd love to experiment on it but I don't have an air cannon to play with.

[Severin]

I Love the caption on that flex tag. Fits in here perfectly.
"Ideal for placing heads in hard-to-reach areas"
HEHE... :D

[porsche986]

It's hard to describe the sound. It's like a deep throated vibrating growl followed by a loud "thwap". The air disturbance over the corrugation causes the vibrating sound and material of the pipe is thin enough that it seems to amplify the it.

I'll probably be building a new cannon next weekend. I'll see what I can do to capture the sound once I finish it. The effect is best if the pipe is kept straight. The one in my TCT has a bend in it so I can't record the full effect from it.

[fg4432]

I am only 33 but some of the Gen Y'ers here probably never did this...

Take one Coke (glass) bottle and blow into it. You have to blow into it with the right angle to get the low boat/fog horn sound. Gen Y'ers say, "you mean there weren't always plastic bottles?".

Could the technique be transfered into a lower groan? Maybe. Instead of placing something in the way of the blast, what about just to the side? Make the air cannon blow by the opening of something. However, rubber bands inside the tube was my original thought.

That something could be a swimming pool tube that is similar to the blue tube pic in previous replies with one end taped. It could be a piece of pvc tubing set perpendicular to the air cannon. I don't have an air cannon so someone else will have to report what kind of things they can replicate.

Just a possibility...

[fg4432]

Of those with air cannons, did you really build it for under $30?

How are you setting it off? Automated or manual? And do you use a compressor to shoot it off directly or with an air tank resevoir?

All these pages on how to build one but I haven't found much on how to actually use it.

[TwistedDementia]

Thanks porshe986 for letting me know!

[crazy8svt]

what about stretching a inner tub over the end of the pipe that might give you a growl. If you use a thick tub inside a small metal trash can. just a thought.

[tuck]

Not sure how much of a growl this would produce but maybe some of the people over 30 will remember the crocodile dundee movies. He used a piece of wood attached to a rope and spun it around and it made a low pitched noise.

Instead of spinning it around your head could you attach it to a tube or aluminum trash can at both the the top and bottom using say fishing line and swivels, then running air through the tube. If the wood does not produce a low enough sound perhaps you could use a stretched bike innertube attached the same way. Just a thought, I really have no idea if it would work or not.