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Good luck! Stay safe, have fun, and learn a lot. I'm sure it'll be a hit at your school.

I know I've mentioned it in the video but please pay attention to the warnings. It's a risk pressurizing PVC as its not intended for it, so while nothing can be fully safe when doing so, err on the side of caution and use lower pressures. As for the build itself, make sure you take your time to fully seal the sprinkler valve as shown, and properly seat the diaphragm when you reassemble it. Air leaks are the most common issue you will see with this, and even more so with the valve as its more complex than simply gluing PVC together.

They legitimately were saying that. I saw my neighbors across the street watching me film the street launches from their front doorway. Their young son was interested in the device, so of course I had to give him a chance to activate it if his parents agreed. They did, I loaded everything up, gave him my the controller and my earmuffs, and he got to launch a full volley. He absolutely loved it and Immediately looked over to his mom with a big smile on. It was easily my favorite day of filming seeing how excited he was after the fact.

You can tell if the solenoid is working by the click it makes when it activates. The honking is likely from some sort of air leak with the diaphragm. Check to make sure it is oriented and seated properly. There will be a brief moment when air escapes as the chamber pressurizes, but once it is full pressurized the diaphragm should seal and this should stop.

@ thank you :) I got a larger solenoid unit and it helped out :)

Glad you got the chance to see it! It was a lot of fun to make. I've always been a fan of ridiculous builds just for the fun of making something, rather than some utilitarian purpose (although I like those too of course).

I've never actually tested this. The biggest factor even for light objects is a proper seal, one that doesn't introduce excess friction, so it will vary widely by the objects shape.

My apologies for the delay. This setup is good for a single shot as there is no means to partition or otherwise partially release the air reliably.

It's a special feeling indeed, glad you can appreciate it too!

So glad you enjoyed the humor! Thanks for watching.

... I have made a critical error. Who knew they could go to 11. I'll have to make another. Enjoy your superior sound, you are the clear winner here.

Love it. Send me the link when you post the final cut!

Of course, it's a great question. Notice that the blow gun is mounted to the sprinkler valve on the side where (internally) the diaphragm contacts the spring. When you pressurize the cannon, you may be able to hear a small amount of air escaping the barrel. This is because it takes time for the air to pass through the small opening in the diaphragm to the spring side of the valve. Eventually, enough air is on the spring side of the valve that the air pressure and spring tension together are able to seal it off since they now overcome atmospheric pressure. When the trigger is first pulled, a small amount of air rushes out through the blow gun as you'd assume. You can feel this by holding your hand in front of the blow gun opening. The thing is, all that tank air pressure wants to equalize as quickly as possible with the atmosphere. When the "flood gates open" from pulling the trigger, all that air tries to rush out at once. Because of the pressure drop from the air exiting the blow gun, the diaphragm opens slightly, providing a second path of exit for the pressurized air. The air then tries to rush out both the blow gun and the barrel simultaneously, but you'll notice that inside the sprinkler valve on the diaphragm itself there is only that small hole for the air to pass through (through the small white plastic piece in the diaphragm). Initially, the only exit for the air was out the blow gun. Now with the diaphragm slightly opened it is easier for the air to pass through the large open barrel than it is to rush through the small opening of the diaphragm and out the blow gun. Pressurized air chooses the path of least resistance and tries to exit as rapidly through the barrel as possible. This causes the diaphragm to be forced open as the air pressure overcomes the spring tension. The air rushes out the barrel in one big burst and the cannon launches. Once the pressure equalizes to atmospheric pressure again, the spring tension resets the diaphragm and the process can repeat. All this is happening in a fraction of a second so it's hard to tell when one "phase" of the action occurs, but that's the order of operations each time you pull the trigger.

@@HardwareUnknown wow! Thanks for your great answer!

They're Ergon GP5s. There are multiple versions, with the lower the number meaning a shorter side handle. 5s are enough for your whole hand whereas 2s and 3s are more for a finger or so. I've got a link in the description to make it easier to find. You can also find them at some REIs.

Thank you! I'm glad you enjoyed, hope it was helpful for performing your own modification

a bit like the stuka (i mean the effect)

Hey, the comment cut off, can you edit it to add what's missing? I want to be able to give you a proper answer.

Is it leaking out the connection between the valve and the adapter? If so, you may need to simply crank it down a bit harder (be careful, you can do this too much, but perhaps it's looser than you think). That, or add some more PTFE tape before tightening.

I used a 1/4" NPT tap for the fittings. Here's the one I bought: amzn.to/2U3NyoO All parts/tools are listed in the description in case you need any others as well.

It certainly could, only question is if they will rub on the inside of the barrel and pop before launch. I haven't tried it so I don't know, but if they do pop early you could lubricate the inside with a light coat of biodegradable soap. Thanks so much for watching! I love TKOR. What video was it? I didn't realize one of TKOR's linked to mine and you have me curious now.

@@HardwareUnknown Okay, that makes sense. Your project is similar to his, he also used lubrication on his version, as well as cut up plastic bottles for wads. (I heard that using paper bags tied to a string might work better.) Both designs are great, but I might go with yours since it looks easier and I am trying to make a portable version, like with the battery you used. I'll probably add handles externally somehow. For the video, he made an AK-47 style rifle that can be modified for water balloons. th-cam.com/video/7Z-L4GliAts/w-d-xo.html th-cam.com/video/_NaQBvfEGMU/w-d-xo.html Check it out and let me know. I might try to do a mixed version, but we'll see.

I'm delighted you made it yourself for your physics class! How'd your build go? This is a fantastic question and one I looked into back when I played paintball. The thing about a projectile in a barrel is that it's not flying absolutely straight in line with the barrel. It rattles around in there to some degree. How well the size is matched to the barrel will influence this. Too small, and the projectile can move a lot (relatively) creating odd spin as it touches the barrel walls (more noticeable on spherical projectiles like paintballs), and also decreasing the potential velocity as air escapes around it. Too large, and the projectile will experience excess drag against the inside of the barrel, slowing it down. The length of the barrel also comes into play like you're suggesting. A longer barrel will tend to be more accurate as the projectile has more time to orient its flight along the barrel's axis. However, the longer the barrel the more collisions/drag it experiences (imagine a 100ft air cannon, the projectile may not even make it out the end). A shorter barrel will tend to be less accurate as there is less time to orient the projectile, and if you go too short, it will actually slow it down too. The reason being is once the projectile exits and is in the air, it's experiencing a lot more drag from air resistance. On top of that, it no longer has the pushing force of the pressured air behind since that disperses once it exits the barrel. In this scenario, the full force is not going into the launch. Rather, some is going in to push the projectile itself, while the rest escapes the cannon and pushes the air around you. Shorter barrels have the benefit of better maneuverability and portability, but they sacrifice in other areas for these. Combine all this together and you can see how there is a "sweet spot" in terms of barrel length for a given pressure/projectile size/projectile weight/etc. Lots of factors go into ballistics, but it boils down to you want a barrel that is long enough to allow the maximum amount of pushing force to be used for the launch, and not so long that undo drag is placed on the projectile. For maximum distance, ideally the projectile would exit the barrel the instant it stops accelerating. Teams of engineers can do all sorts of math and run all kinds of tests to determine the measurements to use for a given projectile/launcher. I ran some tests way back with tennis balls to try different air pressures, barrel lengths, air tank lengths (volume) etc. It was fun. Perhaps you can set up some experiments with your physics teacher for some extra credit demonstrating how you found the ideal barrel size for several projectiles!

Don't forget to make the projectile a vial of nitroglycerin kids!

I'm delighted it was helpful for you, thanks so much for watching. My panel work has been largely prototype or small production quantity products, and due to that we used off the shelf boards/single board computers. This meant we made use of panel mount buttons and switches, with custom cables made for the internal wiring (as opposed to a front panel mounted PCB design). If you have a circuit made up already and have prototyped it with protoboard, wires, etc., you're set to go with trying out a simple PCB for synths. If you have yet to prototype the modules, I would strongly suggest doing so with protoboard and wires to non-pcb mounted components. The reason being is that changes are much easier to make, and you can tinker with the circuit much more quickly rather than spending lots of time making a PCB only to find out you made a mistake, forgot something, or wanted to add a feature. For all practical purposes, once a PCB is made, it's made. You'll have to change the design, order a new set, wait for them to arrive, and test again. Also, consider the end use. Are you making this for yourself as a one off? Protoboard is easier to repair than a PCB (or change later, like I mentioned) if something breaks. Example of my own: my quad cannon's custom electronics from another video were done with protoboard since I just wanted the one unit. Are you making only a handful for friends or small volume sales? While not as sleek as PCBs, in the time you design a PCB you may be able to finish building several modules depending on the complexity of the synth. Now if you are looking at large volumes, or high end premium products that will command larger purchase prices, it could be worth sticking with learning PCB design.

@@HardwareUnknown Thanks so much for the comprehensive reply, brilliant!

I was thinking about that, even the potential for motorizing it. Would be nuts to outfit it with all those.