DIY Matchhead Cannon Brings the Heat

If your local surplus store is fresh out of supercapacitors but you’re just really in the mood to fire stuff at other stuff, check out [austiwawa]’s step-by-step guide to building a thermal cannon. It shoots whatever will fit into a 1/2″ copper pipe, propelled by cut-up matchheads and lit by a propane torch. [austiwawa] demonstrates it by firing an AA battery at an unsuspecting pumpkin. For what it’s worth, we don’t necessarily condone applying this much heat to alkaline cells.

[austiwawa] used a copper pipe for the barrel because it provides the fastest heat transfer. One end of it is flattened and folded over to form the propellant chamber. A couple of packs worth of match heads are tamped down into the folded end with a paper towel serving as wadding. [austiwawa] tosses in his battery, lights the torch, and then runs away.

This whole dangerous contraption is secured to a wooden base with a u-bolt and a couple of pipe straps, and suspended between more pieces of wood with a length of threaded rod for stability and aiming.

We’ll let the safety-conscious readers do our work for us in the comments, but in the meantime, note that this thing is not safe. As [austiwawa] demonstrates, the copper gets brittle and will split open along the folded edge.

But kudos anyway to [austiwawa] for showing shot after shot of the cannon in action at the end of his video. You know where to find it.

If it’s a stronger, more beautiful barrel you’re after, just machine one by hand.

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Coke-Propane Rocket Blasts Off Without Ignition

Everyone’s seen the Diet Coke and Mentos “experiment” that ends in a brown eruption. But have you seen the Coke and Propane experiment insanity that results in a rocket launch? As [Itay] pointed out when he sent us the tip, this doesn’t need to be lit. The simple act of turning the bottle upside down starts a powerful reaction without any ignition.

coke-propane-rocket-thumbOf course it’s the how of this that tickles our brains, but let’s finish the setup. This starts with a bottle of Coke which is about 3/4 full. The head space is displaced by spraying propane into the bottle; propane is heavier than air. All that’s left is to turn the bottle upside down and pray it doesn’t smack anyone in the noggin as it takes off.

In trying to find an explanation for this phenomenon we came across a plausible answer on the Chemistry StackExchange. It points to the Mentos phenomenon combined with the temperature differential caused by the very cold propane. The answering user theorizes that tiny ice crystals form and when the bottle is turned upside down the cold propane and micro crystals rise through the warmer soda acting as a much more rapid catalyst than Mentos alone. Of course this is just a theory so please share your own ideas below.

We thought the folks who microwave stuff outside of a microwave enclosure had their fill of danger but this videos is also one of theirs. It should be no surprise that they also tried the experiment with an ignition source. That video is found after the break and should immediately convince you to never try any of this yourself.

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Hackaday Prize Entry: Gas Grenade Helps Instead of Exploding

If someone lobs a grenade, it’s fair to expect that something unpleasant is going to happen. Tear gas grenades are often used by riot police to disperse an unruly crowd, and the military might use a smoke grenade as cover to advance on an armed position, or to mark a location in need of an airstrike. But some gas grenades are meant to help, not hurt, like this talking gas-sensing grenade that’s a 2015 Hackaday Prize entry.

Confined space entry is a particularly dangerous aspect of rescue work, especially in the mining industry. A cave in or other accident can trap not only people, but also dangerous gasses, endangering victims and rescuers alike. Plenty of fancy robots have been developed that can take gas sensors deep into confined spaces ahead of rescuers, but [Eric William] figured out a cheaper way to sniff the air before entering. An MQ2 combination CO, LPG and smoke sensor is interfaced to an Arduino Nano, and a 433MHz transmitter is attached to an output. A little code measures the data from the sensors and synthesizes human voice readings which are fed to the transmitter. The whole package is stuffed into a tough, easily deployed package – a Nerf dog toy! Lobbed into a confined space, the grenade begins squawking its readings out in spoken English, which can be received by any UHF handy-talkie in range. [Eric] reports in the after-break video that he’s received signals over a block away – good standoff distance for a potentially explosive situation.

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Add CNC to your…Propane Tank??!?

It’s starting to be that time of year again; the Halloween-themed hacks are rolling in.

[John Lauer] needed a propane-powered flame effect for his backyard ICBM “crash site”. Rather than pony up for an expensive, electronically-controlled propane
valve, he made a custom bracket to connect a stepper motor to the propane burner’s existing valve.

With the stepper motor connected up, a TinyG stepper motor controller and [John’s] own graphical interface, ChiliPeppr, take care of the rest.

The hack is almost certainly a case of “everything looks like a nail when you have a hammer” but you have to admit that it works well and probably didn’t take [John] all that much time to whip up. Maybe everyone should have a couple spare stepper motors with driver circuitry just lying around ready to go? You know, just in case.

All the details of the build are in the video. If you’re done watching the flames, skip to around 2:50 where we see the adapter in action and then [John] steps us through its construction.

You may have seen coverage of the TinyG motor controller here before.

Additional thanks to [Alden Hart] for the tip.

Hacklet #9 Bugs and Fire

9 This week on the Hacklet, we’re spending some time looking at bugs and fire! honeybeeFirst up we have [Noel] who is saving the bees with Bee-O-Neo-Tweet-O. Bees are incredibly important, both to Earth’s ecosystem and the food chain we humans need to survive. Unfortunately bees are also sensitive to some of the chemicals humans dump into the atmosphere. Sometimes it results in colored honey, but more often than not it’s detrimental to the bees.

Neonicotinoids are a class of insecticide that has been causing problems to hives near where they are used. [Noel] is banking on sensors created with bismuth electrodes to detect the chemical near the entrance to hives. The data can be collected by beekeepers all over the world and sent to a central server. He’s using an Arduino Yun as a WiFi connected base station. Each individual hive has an Adafriut Trinket and a 433MHz radio link to send data to the base. [Noel] is even hoping to detect individual bees by the sound of their wings beating.


[Ken] is keeping his own bees, and wants to monitor more than just chemicals. His honeybee hive monitoring system keeps track of the temperature and weight (and thus the honey produced) by his hives. Rather than buy an expensive load cell setup, [Ken] modified a standard digital bathroom scale to suit his needs. The insects connect to the IOB (Internet of Bees) with a bit of help from the Apitronics platform and a BeagleBone Black. Ken even added a solar-powered weather station with the Apitronics system.

bug-killa[Mike] is taking a slightly different approach. He doesn’t want to save the bugs, he wants to kill the ones that bug him! [Mike] doesn’t want to get his hands dirty, so he’s created Lazy Killer 9000 for easy bug killing. Lazy Killer uses the business end of an electrified fly swatter to do its work. This project wouldn’t be complete without an Arduino, so [Mike] is adding one, as well as a WiFi shield. The entire system will have a friendly interface to turn the juice on. One of the best features of Lazy Killer is the internet connected kill count. [Mike] knows that there aren’t any bugs in the vacuum of space, so he’s entered Lazy Killer in The Hackaday Prize.


From bugs, we move on to Fire! [mr.jb.swe] needed a reliable portable power source. He found it in LiFePO4 batteries, but still needed a way to charge them. Toward that end he’s created The Multicharger, a watt meter and charger which can be powered from solar, wind, or thermometric power. A Powerpot X provides the fire and the power to charge the batteries. [mr.jb.swe’s] charger converts that into the standard constant current->constant voltage charging system needed by lithium chemistry batteries. The Multicharger isn’t a complete battery management system yet, but it’s well on its way.

Unitycandle candles have become a staple at wedding ceremonies.[Quinn] has taken things to the next level and beyond with this take on the classic unity candle. This candle throws fireballs 30 feet into the sky! We covered the candle back in June, but [Quinn] has been busy since then. With over 20 updates, [Quinn] has created one of the most well documented projects on Of course, being that this project is dealing with propane and monstrous fires, [Quinn] mentions you shouldn’t try unless you really know what you’re doing. Don’t set any brides on fire! That’s it for this week’s Hacklet! Tune in next week, same hack time, same hack channel, for more of the best of!

The Party was Bumping, then the Fire Dragon Showed Up

Epic Party.

I don’t use that label lightly. After the Red Bull Creation’s day of show and tell was over — winners having been presented with trophies and stuffed with barbecue over at Bert’s — people started to trickle into OmniCorp Detroit for the party.

Like all of the best parties we didn’t really see it coming. I grabbed a folding chair on the street out front with a beer in my hand and enjoyed a rotating variety of interesting people to talk with. Brian Benchoff trys out the team choice trophy -- a modified toddler's tricycle [Brian] rolled up riding one of the trophies, a modified toddler’s tricycle that proves his future with a travelling circuit is still viable. They roped off the area and set up huge speakers for the DJ. Then two guys game lumbering down the street sharing the work of hauling a tub full of ice and 12-ounce clear glass bottles with colored liquid inside. Turns out they just opened a distillery down the street and decided to donate some vodka infusions for the festivities. Yum!

Upstairs, a couple hundred square feet of area was ringed by a bar (with wide variety of kegs, slushy drinks, and one of those hot dog rollers), couches, a few work benches, a second DJ booth, and a photobooth. We only got one picture before the smoke machine reduced visibility.

Unlike a lot of ragers I’ve been at, it was easy to start up a conversation with just about anyone. Living expenses are so low in Detroit and artists are flocking to the area. This is who made up most of the group. Fascinating people who are working on a multitude of different projects and have stories of building community on their streets while rehabbing houses that cost $1-2.5k to purchase but didn’t come with most of what you’d assume a house should.

Then the fire dragon showed up

Inside was packed and outside was starting to get crowded. Then the fire dragon showed up. Named Gon KiRin, it’s the collaboration between [Teddy Lo] and [Ryan C. Doyle] who was on Team Detroitus and is artist in residence at Recycle Here!, the build venue for the Red Bull Creation. Couch on the back above the propane tankThe beast is built on the frame of a 1960’s dump truck and most of the building materials were found on the sides of the highway. The huge propane tank on the back allows it to breathe fire. I love that three daisy-chained 9-volts and two bare wires are the control mechanism for this. One thing became readily apparent; you don’t stand in front of Gon KiRin while it’s breathing fire.

The crowd piled onto the couches on top of the tail and at either rear hip. The dragons back also bore a continually rotating set of people. After midnight the guests really started to flood in. [Caleb] and I tried to close down the party but a few hours after midnight it didn’t seem to be getting any slower.

Capping off the weekend like this really proves that you need to get your team into next year’s Red Bull Creation. I got in the easy way — judges don’t have to stay up for 72 hours building stuff. Despite the sleep deprivation for contestants I didn’t come across anyone who wasn’t having a blast during the build, while goofing off, or trying to stay awake as this party got moving.

Bravo Detroit, you’re now on my short list of best party towns. Who else wants to be added to that list? Hackaday’s going to be in Las Vegas for DEFCON in a few weeks. Anyone know of parties planned that weekend and how we can get in?

[Furze] Sets Fire to Everything with Pyro Gloves

Pyro Build

Crazyman [Colin Furze] is back, and this time he’s setting everything on fire with his Pyro gloves. Though Hackaday readers are already a discerning bunch, this is a build we get submissions for all the time and feature fairly often. It would take an exceedingly impressive build to outshine the other fire hazards. But, as with his pneumatic Wolverine claws and his electromagnetic boots, [Furze] knows how to build the insane and then put on a good show.

The Pyro build is part of [Furze’s] 3-part celebratory X-Men extravaganza, a nod to the realm of superheroes coinciding with the release of the new X-Men film. [Furze] began with a custom reservoir cylinder that fitted with two solenoid valves: one for a pilot light and another for the big blasts. He’s also affixed a Piezo element and a AA battery, which sits in a cozy little container. The bulkier bits of the assembly sit in a backpack, hooking up, as expected, to the wrist-mounted devices. This flame cannon, however, is unique among the ones we’ve encountered here.

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