How we launched a weather balloon in the Urals. Part 1

    Launching a weather balloon into the sky is an ancient pastime of scientists and enthusiasts since the incident in Roswell (New Mexico). Meteorologists launch probes to monitor processes in the upper atmosphere. Someone launches probes in a tornado to find out its structure. Enthusiasts, in the main, do it for a beautiful picture of our home planet from the height of the flight of Francis Gary Powers.

    Our hackspace is full of enthusiasts, and it was only a matter of time before we held such a grand event. This time has come in the spring of this year. On a cool morning on April 11, 2015, the MakeItLab hackspace, together with a chain of optics stores “Four Eyes” and several other organizations, launched a weather balloon into the “Ural” stratosphere!

    I must say, we decided to make a good show out of the launch, and organized a direct video link from the probe to the large TV. A bunch of schoolchildren were able to observe themselves from above, from a flight altitude of a rapidly receding air apparatus. It was very cool! Of course, there was an ordinary action camera on board that captured the beauty of near-space. Finally, we filmed our march to throw 200 km behind the fallen probe. Read / watch about all this under a cat.

    How it all started


    Almost a year ago, Alexander Izgagin, the head of the local planetarium, visited our hackspace and proposed to launch a weather balloon together. He brought a bunch of already purchased equipment, including two cylinders. It remains only to collect everything together, determine the payload, get helium, and launch the device into the sky.

    Then the main goal of the launch was formulated - the popularization of science. To do this, it was supposed to collect many students for the launch itself. Arrange among the guys a contest for the best research that can be carried out on board the probe. Send something memorable to the stratosphere.

    But, unfortunately, while we were slowly preparing for the launch, the cold and snow quietly crept up. So the event was decided to be postponed to the spring of 2015. In addition, in the spring there is also a wonderful holiday - Cosmonautics Day. It was to this date that we planned a solemn launch. It remains only to finish the job!

    What the weather balloon consists of


    Before embarking on the design, we carefully studied the "Internet", and in particular the experience of our colleagues from St. Petersburg. They learned how and from what to create a weather balloon, as they say, with their own hands. So we found out that the classic scheme of an amateur weather balloon consists of three main parts:

    • helium cylinder;
    • parachute;
    • payload.

    All these parts are connected by a halyard - a rope made of light but durable material. We made a section from the cargo to the parachute about 10 meters long. The section from the parachute to the ball is 5 meters.

    Cylinder and harness

    Weather balloons rise into the air due to the Archimedean force, pushing a ball of light gas into the upper discharged layers of the atmosphere. Hydrogen or helium is usually used as the light gas. The first gives a lot of traction, but when mixed with air it is very explosive (remember Hindenburg). The second is an inert gas, therefore it does not burn, but it also gives less thrust. Since we were about to launch a probe among a bunch of children, the choice fell on helium.

    We used a chloroprene ball, widely used for promotional purposes. Actually, we bought it in the appropriate organization. Judging by the specification, the maximum volume of an 8-foot ball was 7.5 cubic meters. meters. The maximum recommended load weight is 4.5 kg. This is how it looked in its original state. Like a giant balloon.



    Parachute

    There are two common schemes for securing a parachute. In the first, the halyard is continuous from the load to the ball, and the parachute with the balancing ring branches off from the halyard, and hangs freely. In the second, the halyard is divided into two segments, the first of which clings to the center of the balancing ring, and the second to the top of the parachute. We chose the second option.

    The balancing ring was drawn in SketchUp, and printed with PLA plastic on a 3D printer. The parachute was cut from a piece of tarpaulin 1x1m. Eight lines were sewn to him, and a hole was made in the center. All edges, of course, processed. This is how a folded parachute and a ring look:



    The idea of ​​such a scheme is simple. While the device takes off, the parachute is in a tense state, and serves as part of the halyard. As soon as the ball bursts, the parachute loses tension and begins to straighten.

    Instrument compartment

    Based on world experience and our Wishlist, we decided to place the following equipment in a flying cube:

    1) GPS GSM tracker of the domestic company X-Keeper. A GPS tracker is a device that sends GPS coordinates of its location via the GSM network every N minutes. In this particular device were the SIM cards of our two largest operators. In order for the tracker to help, ash stump, the descent vehicle should fall in the network coverage area of ​​one of the operators.

    2) A self-powered light and sound beacon . A few hours after the start, this device starts to howl alarmingly and blink with bright LEDs. This was supposed to simplify the search a bit, especially in the dark. In fact, a simple scarf on the energy-efficient microcontroller MSP430.

    3) SJ4000 HD cameraon the side of the module was destined to take off the beauty of our planet from sky-high.

    4) A camera in the module floor and a 500mW 1.2GHz radio transmitter were designed for online broadcasting during take-off.

    5) The unit for collecting sensor readings - a sort of logger - we installed to measure flight altitude, temperature, humidity. In addition, a small solar battery was glued on board the device, which was also connected to the logger.

    6) LiPO battery with a capacity of 2200 mAh and a voltage of 3S (11.1V) - to power all this disgrace.

    7) A special cargo - 12 anniversary coins with the image of Yuri Gagarin, and a handful of all sorts of important things, including a children's toy and a toffee.

    We will write more details about the equipment of the probe in the next article, but for now this is a diagram of what is connected with what.



    The module itself was assembled from a 30 mm thick insulating material. Extruded polystyrene foam, which is sold in every hardware store. The box was carefully glued with Uhu Por glue and wrapped in reinforced tape. This box turned out like this: The



    weight of the weather balloon, including the balloon itself, the halyard, a parachute and the instrument compartment was about 2 kg. Given that we planned to fill the ball with 5 cubes of helium, the probe was supposed to take off at a decent speed of 5 m / s.

    Probe equipment photo
    GPS tracker:



    FPV Camera:



    Transmitter for camera:



    SJ4000 HD camera:



    Light and sound beacon assembled in haste: The



    bottom online camera was placed in a 3D-printed case. They did not put bulletproof glass, so as not to provoke the appearance of dew.




    Ground equipment

    To ensure the broadcast of video from the probe, we used such a receiver and a directional antenna to it. By the way, thanks to this antenna, it was possible to shoot video from a distance of several kilometers.





    A helium cylinder was purchased from a local supplier of industrial gases. In a similar office, the gearbox for the cylinder was also mined. I must say, pumping a ball without a gearbox will not be easy. When unscrewing the valve on the cylinder, the gas will trample very cheerfully, and it will be easy to break the ball. At the same time, all observers will be filled with cheerful gnomeish laughter.



    Launch permission


    Of course, you can try to launch a weather balloon somewhere outside the city without any permission. But once you think about what this probe can do in the tense airspace over modern cities, it immediately becomes uneasy. To do everything right, we were preoccupied with getting permission from the competent services in advance. It didn’t start very well. The police, the FSB, the Ministry of Emergencies, the administration - all denied our request, and redirected to each other.

    As it turned out later, the long-named service deals with the launch of weather balloons: the zonal center of the unified air traffic management service(abbreviated as LC EC ATM). There we were asked to write an official request to launch a weather balloon, indicating the flight characteristics, as well as the exact date and time of launch. Further, on day X, we had to notify the service of our readiness, and inform the estimated coordinates of the probe’s fall. Which we did using the forecast service predict.habhub.org . Finally, after the fall of the apparatus, it was necessary to call again and inform about the completion of the mission.

    1 hour before the start


    So, everything is ready to launch the weather balloon. We take out the equipment to the launch pad, and begin preparation.



    We turn on the onboard power, and thereby launch the HD-camera for recording, and the online camera for broadcasting. Alexander Kormiltsev cuts the foam rubber with which we scored the empty space of the instrument compartment.



    An image from the online camera appears on the TV. So the weather balloon is now "seeing."



    We launch helium into the ball. The gearbox was weak, we had to unscrew it to the fullest.



    Even at the maximum gearbox throughput, I had to wait about half an hour until the ball was filled to the desired volume. After the ball became rampant, we rewound the neck with a band-aid and tied a ring with a halyard to it.



    The last step is to close the probe cover. In fact, we glue it all with the same reinforced tape.



    More launch preparation photos
    Solemn moment - loading of coins:



    Start of helium injection into the cylinder:



    Video broadcasting works (bottom left corner):



    Start


    A few seconds before the start, we begin to slowly push the halyard up. The children around us are counting down in chorus, and it is no longer possible to stop them. The onboard HD camera was working hard, so this exciting moment is well captured on it.





    A little bit more!



    Swift take-off!



    Children rejoice:



    Live broadcast from the board


    And these are a few screenshots of the live broadcast.







    After the ball rose a kilometer up (offhand), the antenna of the video receiver had to be aimed manually:



    Entire video broadcasting from the moment of tearing off the ground is on YouTube: youtu.be/N5ZAYWiAtB0?t=3600

    One more photo






    Search


    The ball flew away, and we could only wait for the first GPS coordinates from the tracker. In general, the probability that the probe will fall in the coverage area of ​​mobile operators was very low. Still, we live in the Urals: the forest around.



    But what happened happened. After one hour and 15 minutes, the long-awaited SMS with coordinates came to my phone! It felt like we got the first signal from the rover. From this moment, everyone began to mentally prepare for the journey. After all, the coordinates pointed to a point 200 km from the city, the loaf is vigorous!



    We opened the tracker web interface and began to wait for the following coordinates. Every 10 minutes, updated information arrived. The probe slowly descended by parachute to the area of ​​the city of Irbit. Finally, the coordinates stopped changing, and we moved forward. There were three cars and 11 people in total.

    The landing party is pretending. In fact, they tried to find the video signal from the transmitting camera all the way.



    Navigator:



    In general, it was already visible on the map that the probe was lying somewhere in the field. For some reason, I was sure that the field was just a pile of land, the maximum - dug up. Well, still planted / dug potatoes. But it was not there! It turns out I never saw a spring fertilized field. The world will not be the same as before ...



    Here we are still funny, immediately after unloading. Looking forward to the search. Guess who was the only one who brought rubber boots with him?



    And ahead is a peppy run through an endless field:



    Following the coveted coordinates, we still found it! In the very, very thin, but found!



    A short video from the place of the fall:



    Collective photo:



    More photos of searches






    Debriefing


    The long journey home took another three hours or more. Finally, reaching our hackspace by night, we opened the instrument compartment.



    We got a bag of coins and a strategic container with a toffee.



    Telemetry SD card. It just stores information about the flight altitude! Everyone was very worried how high our weather balloon could rise.



    Judging by the schedule, the probe rose by almost 19 kilometers. Of course, according to the cheap BMP180 barometer.



    And, probably, the most expected information is video from an HD camera.



    The 32GB flash drive was completely clogged. Moreover, the first 2 hours is a video directly of takeoff and landing. The rest is lying on the field.



    Video and photo of the flight


    The guys from Teleport quickly compiled a film about our adventures:



    And we recorded the full broadcast from the online camera: www.youtube.com/watch?t=10&v=N5ZAYWiAtB0

    Acknowledgments


    The event was extremely successful thanks to the coordinated work of all the organizers and assistants. So I want to say a big thank you to all the organizations involved:

    • Networks of optics stores “Four Eyes” and flight initiator Alexander Izgagin;
    • Television Broadcast Studios Teleport;
    • Atomic Energy Information Center.

    Special thanks to the search team! It turned out a wonderful trip.

    Future plans


    Already in late May - early June, we are planning another launch. And for this event we already have some ideas for modernization:

    1. The launch will most likely be at night. In order to remove the night city and dawn.
    2. We will work on cargo stabilization. Put the swivel on the halyard, and, possibly, the azimuth stabilizing propeller.
    3. Let's try to get a satellite tracker. We also put in the probe an improved GPS tracker, which the guys from X-Keeper promised to us (in order to conduct a more accurate track with altitude data).
    4. We strengthen the light and sound alarm. In particular, we duplicate sirens. Add more bright objects to the probe.

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