When we think about hydrogen and flying machines, it’s quite common to imagine Zeppelins, weather balloons and similar uses of hydrogen in lighter-than-air craft to lift stuff of the ground. But with smaller and more efficient fuel cells, hydrogen is gaining its place in the drone field. Project RACHEL is a hydrogen powered drone project that involves multiple companies and has now surpassed the 60 minutes of flight milestone.
The initial target of the project was to achieve 60 minutes of continuous flight while carrying a 5 kg payload. The Lithium Polymer battery-powered UAVs flown by BATCAM allow around 12 minutes of useable flight. The recent test of the purpose-built fuel cell powered UAV saw it fly for an uninterrupted 70 minutes carrying a 5 kg payload. This was achieved on a UAV with below 20 kg maximum take-off mass, using a 6-litre cylinder containing hydrogen gas compressed to 300 bar.
While this is not world record for drones and it’s not exactly clear if there will be a commercial product nor the price tag, it is still an impressive feat for a fuel cell powered flying device. You can watch the footage of one of their tests bellow:
There’s something oddly menacing about some vacuum tubes. The glass, the glowing filaments, the strange metal grids and wires suspended within – all those lead to a mysterious sci-fi look and the feeling that strange things are happening in there.
Add in a little high voltage and a tube that makes its own hydrogen, and you’ve got something extra scary. This hydrogen thyratron ended up being just the thing for [Kerry Wong]’s high-voltage, high-current experiments. One would normally turn to the solid-state version of the thyratron, the silicon controlled rectifier (SCR), to switch such voltages. But the devices needed to handle the 30 amps [Kerry] had in mind were exorbitant, and when the IGBTs he used as a substitute proved a little too fragile he turned to the Russian surplus market for help. There he found a TGI1-50/5 hydrogen thyratron, a tube that has a small hydrogen gas generator inside – thyratrons are actually gas-filled rather than vacuum tubes and switch heavy currents through plasma conduction. [Kerry] set up a demo circuit with a small RC network to provide the fast switching pulse preferred by the thyratron, and proceeded to run 3500 volts through a couple of 1/4-W resistors with predictable results. The video below shows the fireworks.
About an hour’s drive from where this is being written there is a car plant, and as you drive past its entrance you may notice an unobtrusive sign and an extra lane with the cryptic road marking “H2”. The factory is the Honda plant at Swindon, it produces some of Europe’s supply of Civics, and the lane on the road leads to one of the UK or indeed the world’s very few public hydrogen filling stations. Honda are one of a select group of manufacturers who have placed a bet on a future for environmentally sustainable motoring that lies with hydrogen fuel cell technologies.
The trouble for Honda and the others is that if you have seen a Honda Clarity FCV or indeed any hydrogen powered car on the road anywhere in the world then you are among a relatively small group of people. Without a comprehensive network of hydrogen filling stations such as the one in Swindon there is little incentive to buy a hydrogen car, and of course without the cars on the road there is little incentive for the fuel companies to invest in hydrogen generating infrastructure such as the ITM Power electrolysis units that seem to drive so many of the existing installations. By comparison an electric car is a much safer bet; while the charging point network doesn’t rival the gasoline filling station network there are enough to service the electric motorist and a slow charge can be found from most domestic supplies. Continue reading “The Hydrogen Economy May Be Coming Through Your Cooker”→
Nerf blasters have been around for decades now, exciting children and concerning parents alike. Most are powered by springs or compressed air, and are the ideal holiday toy for putting delicate family heirlooms at risk. Not content to settle for the usual foam-flinging sidearm, [Peter Sripol] decided to take things up a notch.
The build starts with a MEGA CYCLONESHOCK blaster, which uses the larger red NERF darts as ammunition. Water tanks are rigged to the outside, fitted with stainless steel electrodes. The original spring & plunger firing assembly is then removed, to make room for a firing chamber made out of copper pipe. A small taser-like device is used as an igniter. When the charging switch is pressed, current is passed through the electrodes in the water, which splits the water into hydrogen and oxygen gas. This is then passed to the firing chamber, where it can be ignited by the taser module, activated by the trigger.
Despite some issues with the blaster occasionally destroying darts due to what appears to be overpressure, it is capable of higher shot velocities than the stock blaster. For all its complexity, performance is somewhat hit and miss, but the cool factor of a handheld hydrogen bubbler is hard to ignore. [Peter] does note however that the combination of explosive gases and dangerous catalyst chemicals make this one build that’s probably best left to adults.
Ever since I first learned about radiosondes as a kid, I’ve been fascinated by them. To my young mind, the idea that weather bureaus around the world would routinely loft instrument-laden packages high into the atmosphere to measure temperature, pressure, and winds aloft seemed extravagant. And the idea that this telemetry package, having traveled halfway or more to space, could crash land in a field near my house so that I could recover it and take it apart, was an intoxicating thought.
I’ve spent a lot of time in the woods over the intervening years, but I’ve never seen a radiosonde in the wild. The closest I ever came was finding a balloon with a note saying it had been released by a bunch of schoolkids in Indiana. I was in Connecticut at the time, so that was pretty cool, but those shortsighted kids hadn’t put any electronics on their balloon, and they kind of left me hanging. So here’s a look at what radiosondes are, how they work, and what you can do to increase your chances of finding one.
Because the universe is mostly made of hydrogen, H-line emissions are abundant, and their distribution can tell us a lot about the structure of galaxies. The 21-cm emission line is so characteristic and so prevalent that we used it as a unit of measurement on the plaques aboard the Pioneer probes as well as in the instructions for playing back the Voyager recordings. But listening in on 21-cm here on Earth requires a special setup, which [Adam (9A4QV)] describes in a detailed paper on the subject (PDF). [Adam] analyzes multiple configurations of LNAs and filters, both of which he sells, to determine the optimum front-end for 21-cm work. His analysis is a good primer on LNAs and explains why the front-end gear needs to be as close to the antenna as possible. Using his LNAs and filters and an SDR dongle, a reasonable 21-cm rig can be had for about $200 or so, less the antenna. He promises a follow-up paper on homebrew 21-cm antennas; we’ll be looking forward to that.
Not keen on the music of the spheres and prefer to listen to our own spacecraft instead? Then read up on the Deep Space Network and how you can snoop in.
[Experimental Fun] shows us how you can create a cola power generator that runs on nothing more than cans of cola including the container and a little bit of sodium hydroxide to speed the reaction up.
This might sound a bit crazy, but it seems you can power an engine on little more than your favorite fizzy drink and the cut-up remains of an aluminum can. What happens is that aluminum and water create a chemical reaction when mixed together, which gives off hydrogen. Normally this reaction is very slow and would take years to make any noticeable marking on the aluminum, but with a little help from sodium hydroxide the reaction is sped up to such a rate that hydrogen is produced quite quickly.
The crazy contraption they created has a reaction chamber which then feeds the hydrogen through condenser then to a bubble filter made from a bottle filled with water. After that it is on through a carbon filter to get rid of any impurities, and finally it is fed directly into a two-stroke engine’s fuel line. Then engine still needs an electric start from a battery, but after that it runs directly on the hydrogen created during the reaction from the chamber.
This is quite a cool project, however you could replace the fizzy drink with water and still get the desired effect. Since the drink comes with the aluminum cans it seems like quite a good fuel though. There are other crazy fuels out the for the avid DIY hacker, but just be careful and don’t blow yourself up.