High-altitude balloon flights have become somewhat of a known quantity these days. Although it’s still a fun project that’ll bring your hackerspace together on a complex challenge, after the first balloon or two, everyone starts to wonder”what next?”. Higher? Faster? Further? Cheaper? More science? There are a variety of different challenges out there.
A group of Stanford students just bagged a new record, longest time in flight, with their SSI-41 mission. In addition to flying from coast to coast, on a track that went waaaay up into Canadian airspace, they logged 79 hours of flight time.
The secret? Val-Bal. A “valve ballast” gas venting valve and ballast dispenser system that kept the balloon from going too high (and popping) or dropping back down to earth. The balance seems to have worked nearly perfectly — check the altitude profile graph. We’d love to see more details about this system. If anyone out there on the team does a writeup, let us know?
There are as many interesting ways to get into high-altitude ballooning as there are hackers. We love the extreme economy of the Pico Space Balloon project, which has gone around the world (twice!) on a solar-powered party balloon. And we’ll give both the best-name and ridiculous-concept awards to the Tetroon. But for now, most time aloft goes to the Stanford team. Congrats!
At my university, we were all forced to take a class called Engineering 101. Weirdly, we could take it at any point in our careers at the school. So I put it off for more interesting classes until I was forced to take it in one of my final years. It was a mess of a class and never quite seemed to build up to a theme or a message. However, every third class or so they’d dredge up a veritable fossil from their ranks of graduates. These greybeards would sit at the front of the class and tell us about incredible things. It was worth the other two days of nondescript rambling by whichever engineering professor drew the short straw for one of their TAs.
One greybeard in particular had a long career in America’s unending string of, “Build cool stuff to help us make bad guys more deader,” projects. He worked on stealth boats, airplanes with wings that flex, and all sorts of incredibly cool stuff. I forgot about the details of those, but the one that stuck with me was the Cyclocrane. It had a ton of issues, and as the final verdict from a DARPA higher-up with a military rank was that it, “looked dumb as shit” (or so the greybeard informed us).
The Cyclocrane was a hybrid airship. Part aerodynamic and part aerostatic, or more simply put, a big balloon with an airplane glued on. Airships are great because they have a constant static lift, in nearly all cases this is buoyancy from a gas that is lighter than air. The ship doesn’t “weigh” anything, so the only energy that needs to be expended is the energy needed to move it through the air to wherever it needs to go. Airplanes are also great, but need to spend fuel to lift themselves off the ground as well as point in the right direction. Helicopters are cool because they make so much noise that the earth can’t stand to be near them, providing lift. Now, there’s a huge list of pros and cons for each and there’s certainly a reason we use airplanes and not dirigibles for most tasks. The Cyclocrane was designed to fit an interesting use case somewhere in the middle.
In the logging industry they often use helicopters to lift machinery in and out of remote areas. However, lifting two tons with a helicopter is not the most efficient way to go about it. Airplanes are way more efficient but there’s an obvious problem with that. They only reach their peak efficiency at the speed and direction for which their various aerodynamic surfaces have been tuned. Also worth noting that they’re fairly bad at hovering. It’s really hard to lift a basket of chainsaws out of the woods safely when the vehicle doing it is moving at 120mph.
The cyclocrane wanted all the efficiency of a dirigible with the maneuverability of a helicopter. It wanted to be able to use the effective lifting design of an airplane wing too. It wanted to have and eat three cakes. It nearly did.
A Spinning Balloon with Wings
Four wings stick out of a rotating balloon. The balloon provides half of the aerostatic lift needed to hold the plane and the cargo up in the air. The weight is tied to the static ends of the balloon and hang via cables below the construction. The clever part is the four equidistant wings sticking out at right angles from the center of the ship. At the tip of each wing is a construction made up of a propellor and a second wing. Using this array of aerofoils and engines it was possible for the cyclocrane to spin its core at 13 revolutions per minute. This produced an airspeed of 60 mph for the wings. Which resulted in a ton of lift when the wings were angled back and forth in a cyclical pattern. All the while, the ship remaining perfectly stationary.
Now the ship had lots of problems. It was too heavy. It needed bigger engines. It was slow. It looked goofy. It didn’t like strong winds. The biggest problem was a lack of funding. It’s possible that the cyclocrane could have changed a few industries if its designers had been able to keep testing it. In the end it had a mere seven hours of flying time logged with its only commercial contract before the money was gone.
However! There may be some opportunity for hackers here. If you want to make the quadcopter nerds feel a slight sting of jealousy, a cyclocrane is the project for you. A heavy lift robot that’s potentially more efficient than a balloon with fans on it is pretty neat. T2here’s a bit of reverse engineering to be done before a true performance statement can be made. If nothing else. It’s just a cool piece of aerospace history that reminds us of the comforting fact that we haven’t even come close to inventing it all yet.
If you’d like to learn more there’s a ton of information and pictures on one of the engineer’s website. Naturally wikipedia has a bit to say. There’s also decent documentary on youtube, viewable below.
Launching a high altitude balloon requires a wide breadth of knowledge. To do it right, you obviously need to know electronics and programming to get temperature, pressure, and GPS data. You’ll have to research which cameras will take good pictures and are easily programmable. It’s cold up there, and that means you need some insulation to keep the batteries warm. If you ever want to find your payload, you’ll also need an amateur radio license.
This flight data recorder for balloons is based on the ever popular ATMega328, and includes humidity, temperature, pressure, accelerometer, gyroscope, and magnetometer sensors. All of this data is recorded to an SD card. The Real Engineers™ who are wont to criticize design decisions they disagree with might laugh at the use of a 7805 voltage regulator, but in this case it makes a lot of sense. The power wasted by a linear regulator isn’t. It’s turned into heat which keeps the batteries alive a little bit longer.
This balloon data recorder has already flown, and [Jeremy] got some great pictures out of it. It’s a great piece of the puzzle for an exceptionally multidisciplinary project, and a great entry for the Hackaday Prize.
There was a time when you could do what you wanted in your yard and hams could build giant antenna farms. These days, there are usually laws or deed restrictions that stop that from happening. Even if you can build an antenna, you might want to quickly put up something temporary in an emergency.
[Eric’s] solution? Suspend a wire from a weather balloon filled with helium from the local WalMart. The 8 foot balloon took two containers (18 cubic feet) of gas before it would rise sufficiently. Once you have a floating balloon, the rest of the concept is simple: connect a wire (100 feet of 26 gauge), use a tuner to match the load to the transmitter, and you have instant antenna.
The name of the game in rocketry or ballooning is weight. The amount of mass that can be removed from one of these high-altitude devices directly impacts how high and how far it can go. Even NASA, which estimates about $10,000 per pound for low-earth orbit, has huge incentives to make lightweight components. And, while the Santa Barbara Hackerspace won’t be getting quite that much altitude, their APRS-enabled balloon/rocket tracker certainly helps cut down on weight.
Tracksoar is a 2″ x .75″ x .5″ board which weighs in at 45 grams with a pair of AA batteries and boasts an ATmega 328P microcontroller with plenty of processing power for its array of on-board sensors. Not to mention everything else you would need like digital I/O, a GPS module, and, of course, the APRS radio which allows it to send data over amateur radio frequencies. The key to all of this is that the APRS module is integrated with the board itself, which saves weight over the conventional method of having a separate APRS module in addition to the microcontroller and sensors.
As far as we can see, this is one of the smallest APRS modules we’ve ever seen. It could certainly be useful for anyone trying to save weight in any high-altitude project. There are a few other APRS projects out there as well but remember: an amateur radio license will almost certainly be required to use any of these.
Ever been out in a big field and need to tell something to Joe at the other end? If you’re lucky Sally is in between and you can shout to Sally to tell Joe your message. Maybe Joe shouts back to Sally in reply.
The higher radio frequencies, say 50 MHz and above, typically only propagate within line of sight. Add in limited power and antennas from a hand-held, typically under 5 watts and the ubiquitous ‘rubber ducky’ antenna, and you cannot talk very far. Mobile rigs in vehicles with 50 watts and larger antennas do better but in reality they don’t help all that much.
What really makes an improvement is height to improve range. Height provides a longer line of sight with fewer obstructions. Hams created repeaters and put them on towers, buildings or hill tops to expand the radio horizon. The ultimate repeaters are space satellites. Can’t get much higher than that. A close second are balloons going to near space altitudes with repeaters which will provide multi-state coverage.
Besides providing height, a repeater will also have higher output power and much better antennas, especially important for receiving weak signals from distant handhelds. A signal comes in and is repeated back out on a slightly different frequency. All modern ham gear on these frequencies is setup to handle this offsetfrequency operation.
Whether hams came up with the idea is arguable, but they were certainly there during the early days.
Although the distance these balloons have travelled is quite remarkable, the interesting part is how [David] is tracking the balloons. Cell phones obviously won’t work over the Atlantic, and satellite transmitters are expensive, so he used a low-cost transmitter that was programmed to broadcast using a variety of Ham radio signals. The most effective seems to be WSPRnet (the Weak Signal Propagation Network), a system used by Hams to see how far low strength signals will go. This system relies on Hams leaving their receivers on and running software that uploads the received signals to a central server.
By cleverly encoding information such as height and position into this signal, he was able to turn this worldwide network into a tracking network that would report the balloon’s position pretty much anywhere on the globe. [David] is continuing to launch balloons: his latest went up on the 24th of September and travelled over 4300km (2600 miles) before the signal was lost over the Atlantic.