|RITCHIE-1 High Altitude Balloon|
|Articles - Non-Technical|
|Written by Bryce Salmi|
|Monday, 09 May 2011 02:52|
The Rochester Institute of Technology Amateur Radio Club, K2GXT, launched a High Altitude Balloon (HAB) during the Imagine RIT Innovation and Creativity Festival on Saturday May 7th, 2011. Club members had worked since the end of November on a custom payload which aimed to approach HAB design very differently. Initial goals of the club were never to just get to near-space but rather to design a custom mechanical and electrical payload that redefined the reliability, quality of construction, and modularity of most payload designs. The following article overviews a brief design description, launch, flight, and recovery.
Starting in late November 2010 the club decided to commit to a high altitude balloon project for the Imagine RIT Innovation and Creativity Festival to be held on May 7th, 2011. We set on a modular design that was both lightweight and strong. Polycarbonate 90 degree plastic was chosen for an internal support frame used to hold sensors and the foam insulation. A Plexiglas base was machined to mount the electronics, antenna, and wire stress relief mounts. Additionally, the entire payload was hung on nylon mason lines to which a custom radar reflector, 4 foot wide "RocketMan" parachute, and then to a Kaymont Consolidated 1500g sounding balloon were also attached.
The electronics were arranged on stackable boards centered around a command and control system based on the TI MPS430 LaunchPad and custom firmware. The launchpad was used for development while a custom PC board was made for the flight circuitry. Circuits were designed to incorporate a DTMF decoder, MOSFET cut-down devices, two optically isolated LiPo batteries, an Inventek Systems ISM300F2-C5-V0004 "High Altitude Build" GPS module on a custom board, and an Argent Data Systems OpenTracker+ SMT. Brent Salmi, KB1LQD largely designed the circuitry and laid out the PC boards. An 1800 maH battery was dedicated to powering a Puxing PX-777 transceiver as well as the command and control system. Bryce Salmi, KB1LQC, and Ben Sheron, KC2OTS, collaborated together to pick out which batteries to purchase and what the power budget would be. Steve Giannotti, KC2URD, helped with the switching (DC-DC) power supply even though in the end we didn't fly it due to switching noise (it worked great, but we didn't want to take the risk and theres more filtering to be done!). The cut-down nichrome wire, LEDs, and audible buzzer were solely run on a smaller 800 maH battery. Built into the firmware by several K2GXT members including Jake Emenheiser, KB3SVQ, Mike Hudak, and Ian Mackenzie, KB3OCF, were several abilities that few payloads I've heard about are capable of which include the ability to change flight modes, remote cut-down, and on-request APRS packet transmission via DTMF commands on a separate receive frequency to mention a few.
Numerous members of K2GXT arrived at the clubroom bright and early hours before the festival started to prepare for launch. The balloon launch was highly publicized on Facebook, Twitter, local news stations, RIT University News, and word of mouth. A special webpage was created and hosted on CollegeARC by two CS majors who did a great job incorporating the data received from the payload into an easy to view website which could be used to view location and a live uStream of the launch in one place. Google Earth was our main display for the location of the balloon as it traveled over New York. The two collaborators on this part of the project included Connor Carey, K2BOT, and Ben Miller-Jacobson, KD8OKR. Much of their handiwork was visible at the display as well as on the live-tracking website
After ensuring that the GPS tracking system was working, the payload was released to a crowd of 50-100 spectators with a ten second countdown at 10:51AM. I'll tell you, that was one nerve-racking moment, now the design had to work or it was gone forever. It rose quickly as the crowd was directed towards the Clark Gymnasium where the the main exhibit was located. Those of us with Yaesu VX-8R radios were glued to the APRS data on the screen. Quickly we saw 1,000 feet then 2,000 feet and at just over 5000 feet in altitude it breached the clouds and went out of sight. It was addicting for many of us to see that number go up! A local TV station, YNN, produced a great segment documenting the launch which shows many of the highlights. Be sure to check out the first and second YNN videos as well as the 13WHAM News Imagine RIT Preview. To clear it up, Brent and I are not Canadian, I don't know what you're talking "aboot"!
The payload rose heading east over one of the dining areas on campus quickly ascending into the clouds. during the flight, almost 3000 images were taken at five second intervals, capturing the entire launch to landing. Great images of campus and the Rochester International Airport were captured. In flight, it became evident that the predictions from the CU Spaceflight Predictor were not as accurate as hoped, likely due to more lift that expected. This turned out for the better and allowed us to stay much closer to the RIT campus than predicted.
RITCHIE-1 rose to a peak altitude of just over 96,305 feet around 1:14 PM EST. At peak altitude, packets were received from the J-Pole antenna on-board using five watts of power over Palmyra, NY in locations such as W1XM in Boston, Quebec, and Virginia. Even a distance of more than 639 km was reported on one of the packets! Shortly after burst the payload reached speeds of more than 150 MPH on descent. As the parachute became effective in the thicker atmosphere below, it slowed RITCHIE-1 down to its landing velocity.
We absolutely lucked out and appear to descend into a storm cell near 8000 feet in altitude. At times the balloon, which was attached by a 30 foot piece of rope, was visibly pushed up and there are times in several of the photos where there was some sort of ice or hail visible. This would support the GPS data showing a gain in 1723 feet in altitude near the end of the descent possibly caused by a strong updraft. This theory was later reinforced by meteorologists at 13 WHAM news in Rochester, NY who I spoke with regarding this incident. RITCHIE-1 landed in Clifton Springs, NY and was recovered by K2GXT members with the help of the landowner from 70 feet in a tree. The GoPro was actually knocked off the payload and fell 60 feet to a tree limb, bounced off, and hit a wooden play set. It survived to film again! The electronics on the inside were completely soaked in water. Likely from the storm, not just the condensation. It had a rough ride down.
The full APRS track of RITCHIE-1 can be viewed on APRS.fi. Be sure to download the KML file and view in Google Earth too. That about sums up the flight of RITCHIE-1. In the next few weeks we want to open source the documentation including design files and the like. You can already view the TI MSP430 source code on the K2GXT Sourceforge website. Please give us a few weeks to upload the most current build, we're about to enter final exams week and it's bit busy for everyone. Lastly, I'd like to mention a few other people who helped with the project including Jeff Hayes, Stephen Cavilia KC2ZGU, Evan Smith, Clayton Wilson KB3MKR, Steve Ladavich, and Dan Corerrio. If I missed anyone let me know. Your help was well appreciated!
Setting the Bar
Here's the challenge I'd like readers to take away from this article. We've seen tons of ARHAB projects from schools, clubs, and individuals. To the best of my knowledge I do not know of any with similar modularity, construction techniques, and adaptability which RITCHIE-1 exhibits. While many different designs work, why not strive for something that works very well? I encourage the reader to inform me (contact 'at' CollegeARC.com) of a high altitude balloon payload that is similar in design. We put our heads into it and came out with a design that possibly raised the bar in HAB payload designs. The documentation for this project will be released in the Summer of 2011 and we hope to see more payloads that follow the RITCHIE-1 (and subsequent payloads) design. Nearly the entire club agrees that most payload designs we've seen would not have survived the descent RITCHIE-1 experienced combined with the amount of water on the circuit boards. We sealed the payload very well with only the holes absolutely needed for ropes and to equalize pressure. Even with that the inside boards were covered in water yet still worked perfectly, coating the boards in clear nail polish likely saved the day. RITCHIE-1 was designed to get back to the ground in working condition, stay in communications for hours after landing, and strives for a 100% retrieval rate. I am very proud to have had a hand in its design, it will be sticking around for quite some time. I hope everyone enjoyed this article and lets see some projects!
|Last Updated on Saturday, 28 May 2011 16:45|