After a wait the weather finally cooperated, albeit with a healthy dose of wind. Which was good in that the conditions were ideal for testing our newly made balloon containment system. BCS. There were a couple of new things this year which worked out well. First, we launched on a Friday which meant that it was a class trip as opposed to being optional. This means there were all hands on deck for the launch activities. A big plus. Secondly, we took a group of 4th graders to launch pongsats. They had a lot of fun and enjoyed the launch. Them accompanying us had an alternative motive. It was a pilot for conducting a district wide 4th grade launch. The 4th grade teacher, Kathryn Bonzo, and I are sorting out details of what worked and what didn't to make a future launch even more successful. Thirdly, we conducted a proof of concept for the BCS. Winds over 5 or 6 miles per hour made wrangling the balloon difficult. The idea is simple. A large piece of fabric to place over the balloon while being inflated and while waiting for the count down. Muslin was used to make a 5 by 7 yard fabric tarp. This material was chosen to reduce the chance of a static charge developing on the balloon. Eyelets were made at each corner and the midway points between the corners. These were tied to milk jugs filled with water. Some eyelets tore out and the jugs were not massive enough. Lessons learned. BUT the idea worked perfect. So a redesign is due for next year. The launch went perfectly and the balloon reached around 64k ft and was cut down by the timer cut down system. Future launches will have a longer time. >90 mins. Recovery happened in about 30 minutes after the module landed. Mostly due to stopping for a bathroom break.
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Launch conditions were far less than optimal. The ground wind was out of the west south-west at a steady 20 mph with gust up to 30 mph. Inflation was hampered by the balloon oscillating from the gusts. Therefore ascertaining an accurate lift proved impossible and our ascent speed hovered around 2.5 ft/s. An hour into the flight the balloon altitude had only reached 49k feet.
The technical aspects of the flight were almost flawless.We sent aloft 1 still camera, an upward and sideward pointing video camera, a live video transmitter, and a LabQuest recording alpha, beta, and gamma radiation levels. In addition a new and improved cut down system was on board. The cut down system work perfectly. A couple of minutes prior to launch the timer was set to 60 minutes and executed on time. The only hiccup occurred with the radiation meter. A switch was not moved prior to launch so no data was recorded. The live video feet exceeded our performance metrics and maintained contact until 30 kft. Once the command module was cut from the balloon we did not regain the live video feed. We're not sure why as we expected the link to reestablish once the module fell below the cut out altitude. The agreed upon most likely culprit was that the antenna was spinning to fast. Overall a good flight considering the bad launch conditions. It's a good thing the launch was canceled because Mikaela's LCD for the cut down system stopped working after she transferred the circuit from the bread board to the proto board. She diagnosed the problem this week. I've been in Denver for the NCTM conference so I haven't talked to her yet. Hopefully she got it figured out.
Mikaela is completing her revision of the cut down system. She is adding an LCD interface and a keypad. These improvements will allow us to input exact times for the cut-down, perform cut test, monitor wire usage, and battery status. A big improvement from the previous version. Also a three position key switch will be used to control power on/off, and keypad lock.
Helen's project will be to create a live video feed from the balloon to the bus. We have ordered the materials and are excited about the project. The video camera is about an inch cube in size and is connected to a transmitter that is about 2 inches by 1 inch by 1/4 inch. The frequency is 2.3 GHz. The receiver will be hooked up to a screen on board the bus. The signal will also be routed to a video recorder. Kenny will be testing electronic equipment in near space conditions. He'll be sending up a cell phone. His hypothosis is the LCD screen will break due to pressur Over the Xmas break I designed and built the cut down module. To be clear the module is the housing for the NICR wire that actually cuts the balloon tether. I went through 4 designs to get to the final version. The final version uses a cardboard fiberglassed frame w/ a molded insulation around the frame. I used an 10 foot stereo speaker cable as the link between the module and the controller. I'll get a picture of the module soon. I performed several weighted test and it worked flawlessly. Next is moving the controller from a breadboard to a protoboard. I'm waiting for the protoboard to arrive.
The cut down system circuit design is complete. I have a breadboard version that works consistently. The controller is a Basic Stamp 2. A flashing yellow led indicates the unit is powered. A flashing green led indicates the NICR wire is in place. A pot is then used to adjust the countdown timing with an 7 segment led to indicate countdown time. Once a button is pushed the unit is armed and both leds stop blinking and a red led starts blinking. The controller sends a signal to a NPN transistor which then uses a high current source to trigger a mechanical relay. The relay turns on the circuit that has the NICR wire. The wire heats up and cuts through the nylon rope.
The next step is to design the circuit on Eagle so that a PCB can be ordered. Since I'm not very familiar with Eagle that will take some practice. I'm almost thinking of ordering a project board from Parallax and just using that for the circuit. If I'm having too much trouble with Eagle then I'll use the project board. After that testing in the cold chamber |
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