So I tested 2 things today: Reed valve function and minimal mixer assembly. First I 3D printed a white tube where I fitted the propane nozzle. Plain and simple construction. See pictures. Then I fired the sound cannon indoors (with hearing protection) and turned off the lights. Now I could clearly s...

going off on a tangent a bit it would be cool if you could turn the whole plane into a speaker with one of those amplifier magidgets and just play mp3 audio files of anything you wanted, don't know if you would get the volume though :? That is already possible using this: https://www.mrrcsound.com/...

I tested my quick and dirty reed valve yesterday and it did not give any noticeable difference in sound performance. I guess the radial fan is powerful enough alone to overcome most or all of the back pressure from firing the cannon. I also confirmed this by comparing fan temperature with and withou...

jrrdw wrote:Will yours be as loud as these I wonder?

Check out the video description:

Brrrttt sound effects added in post-production just for a bit of fun

It sounds spectacular !! I like how this project progresses. :) Thanks! Yes, the sound is getting really close to my end goal with the radial fan at the intake. This also opens up a lot of possibilities like the intake mixer can be redesigned to be way simpler as it no longer has the job of sucking...

This project is still moving forward. The test plane can fire in the air but with a low rate of fire and sometimes not very loud, it depends a lot on the propane/air mix. If I add a radial fan at the air intake of the cannon, I can turn all the way up for the propane and also the rate of fire, and I...

hectmarr, thanks. The propane pressure is 8bar and this would blow more than a pump. I would need the pump to blow into the nozzle in reverse direction with the propane feed hose detached so the dirt gets out of the system. But during all my extensive testing, this is the first time I have had a noz...

I went testing again last night where a lot of my club buddies came to see and hear the cannon in the air. At first, I couldn't get any ignition from the cannon, it turns out the propane nozzle was blocked off by a tiny piece of dirt. I managed to remove it, but would like to avoid something similar...

Sound cannon has now been mounted on the test plane. During only 1 evening of testing, I found the sweet spot that generates loud bangs. More testing is planned to optimize rate of fire and testing shapes that better resembles the bigger plane installation. Meanwhile, I'll need to order some alumini...

Oh, for those interested in the actual workings of DDT (Deflagration to Detonation Transition), here is a video I found which shows the flame burning in a tube with obstacles:

[youtube][/youtube]

It has been quite some time since I last updated this thread, sorry about that. But there is not much to tell. I'm still trying to make the sound cannon work on the plane in the air. I'm sure it's an aerodynamic issue regarding air intake and the forward pointing barrel. The plane keeps setting me b...

Thanks, I'll keep this in mind.

I went testing tonight, and my sound cannon is very sensitive to air blown into either the output or input. I have a few ideas to check out to fix this, but now I need to concentrate on fixing my exhaust and hope for good weather for more in-flight testing.

Is this the way the air moves, some of it into the holes for the intake and some moves past the holes? I have ordered some barometric air pressure sensors on ebay, with those I can log the pressure in different locations, and I plan on using them with a WiFi module, then I can see the pressure in re...

hectmarr, can you post a bigger picture and maybe a link to some reading of this "static air bell" because Google does not seem to find anything relevant.

With you level of expertise... Thanks! :D Great idea with the servo controlled carburetor type valve! I'll start by testing on the ground and use a blower to blow air into the intake and barrel and see what that gets me. Remember, when the plane is in the air, the barrel on the wing is pointing for...