Capsule Construction, Testing & Planning

It’s been a couple weeks since our project was funded and we wanted to update you on our progress. We’ve been hard at work ordering equipment, testing equipment, and solving various problems.

The following equipment has been ordered and received:

  • 2 GoPro2 cameras and extended battery packs
  • Sony NEX-5 and 16mm pancake lens
  • IR intervalometer for still photo time lapse
  • Spot GPS and geo location service
  • GPS Tracker via cell texting

GoPro’s are working great and with the extended battery packs will have plenty of power to last the entire 2 1/2 to 3 hour trip.

We’ve tested the SPOT GPS and learned how to track down a payload within 10-20 meters. We will need to run a couple more test recoveries to see how accomplished we can become.

The intervalometer is triggering the NEX-5 perfectly. The file size for a camera RAW file is about 15 megapixels and we have calculated that we should set the interval to about 5-7 seconds to take the maximum number of pictures for the duration of the flight and not fill up the 32 GB SD card. We still need to test the camera battery to ensure it will take pictures all the way up and back (covering a maximum of 3 hours). This may push us closer to the 7 second mark to conserve battery depending on how the tests go. We also know that the colder the battery gets the fewer pictures we can take so we will want to be careful and err on the side of more time between shots.

We did encounter one issue with the IR trigger: it only works from in front of the camera. However, Saturday we planned a work around using a mirror that will allow us to place the trigger above and slightly behind the camera and still keep the majority of the camera (and intervalometer) inside the payload container.

The GPS tracker that uses cell technology has been a little more problematic. The first unit we received worked great with our ATT pre-paid sim card. However, when we texted the unit and requested the GPS, it responded but would not send the coordinates. So, the unit worked great from a messaging and cellular standpoint, but the GPS appeared to be broken. Our second unit had issues with the on and off switch and the seat for the SIM card. It was of very poor construction. These were supposed to be the same product but clearly had differences. We are hoping the third unit will actually work. If it doesn’t, we are going to have to find another option for cell based GPS tracking.

Saturday we worked on measuring the payload weight so we could determine the balloon size, parachute size, ascent rate (in meters per second), descent rate (also in meters per second), burst altitude, and amount of helium for the correct lift rate to place the balloon at its burst altitude in 1 1/2 hours and the descent taking 1 hour. All these things enable us to run computer models using wind speed calculations to predict where the payload will land more accurately. We had to convert a lot of different measurements to the same format which posed several mathematical challenges. Mini’s dad jumped in and helped with a key one. Thanks! 🙂

Now that we can run more accurate simulations, we are going to run them every day for the next two weeks. This will allow us to pick 3-4 different launch sites that, based on the weather pattern, are most likely to leave the payload in farm land. The plan will be to run the simulation the morning of launch and pick the most appropriate location based on the simulation. Then, we can drive to the location, run through our launch check list and go. Currently, we think either the 21st or 28th of July will most likely be the launch date.

We have ordered the appropriate size balloon and parachute today along with the radar reflector. We still don’t have the right size payload container. The one in the picture at the top of the page is just too big so we are working on getting a smaller container.

Tasks ahead over the next few weeks:

  • Receiving additional materials
  • Finding an appropriate payload container
  • Building the capsule with the equipment
  • Testing the capsule with the parachute
  • Running more recovery tests via GPS devices
  • Acquiring helium tank
  • Building a hose and valve to fill the balloon
  • Creating counter weight for appropriate “lift weight”
  • Compiling pre-launch check list
  • Compiling launch check list That’s about it.

We are all very excited to see what we get back!

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