A little over a week ago, Cawd 2 successfully launched its first ever near space balloon flight. You may have read about it in the Burlington Free Press on the the 21st of April!
You can read the full article on their site here.
I’m typing this up to give you a little more information about the launch than what was in the newspaper.
Cawd 2 has been working in class and in our robotics / programming class to design, build and test our balloon with our payload over the last month or so. Here are some of the highlights of the design, launch and recovery.
Our first step was to do some research and find out the best design for our balloon. We used nearspaceballooning.com and balloonchallenge.org to find a lot of the information we would then use to build our balloon.
The first project we undertook was designing how we would cut down our payload at 95,000 feet above sea level. We found that if we used a 30ft balloon and kept our payload below 4lbs, we could get the balloon to ascend at 20-30 feet a second. This would allow our balloon to reach a high altitude quicker, and due to that, travel a shorter distance. The 30ft balloon ended up popping at around 140,000 feet. Which was way higher than we wanted to go.
Here is what our predicted flight path would be if we launched in Essex Jct. and flew to an altitude or 95,000 feet based on the weather:
It would fly for about 3 and a half hours and land around Rygate, Vermont.
So we had to design something that could tell what the altitude was and then cut through a parachute cord at a certain height. This is called a Fight Termination Unit (FTU). We found this site that describes how they used the same wire that is found in toasters to cut through a cord. So using this as inspiration we added a barometric sensor to the design that could tell how high up the balloon was.
As a class we all wired up our Arduinos based on my amazing whiteboard drawing skills:
Here is one of the finished Beta Flight Termination Unit:
We ended up using the following in our FTU design:
- Arduino UNO
- 1 10 Volt Relay
- 9 Volt Battery
- 8 AA Litium Ion Batteries
- Nichrome Wire
- 1 BMP085 Adafruit Sensor
Here is what our FTU was able to do to 550lb parachute cord in 20 seconds:
Now that we were sure our FTU could cut through a parachute cord with ease, we wanted to be able to record our temperature and altitude during the flight so we could look at the data later. This meant adding a SD card reader to our Arduino that would have to be soldered on.
This is what our final FTU looked like when everything was said and done:
Here is just a section and description of what the student’s C program that was loaded onto our FTU looked like.
I believe this is Evan’s completed program:
Now that we had a working Flight Computer, we wanted to test if it could detect the difference in height from the ground outside CTE and the roof of CTE. If it could read that difference in height and cut down our payload, it would surely be able to do the same with 95,000ft.
Here are some photos of us testing our FTU:
You can see the students setting up the test in the first photo and then see the flight computer successfully cutting the cord in the second photo after it’s raised 20ft in the air.
After we tested out the Flight Computer, we wanted to test and make sure the parachute would deploy and safely slow down the payload after the balloon was separated. In all reality I really just wanted to chuck more stuff off the roof like Letterman.
Here’s Jenn just hucking things off the roof:
Once we were sure that all the parts of the balloon would work the way they were supposed to, we wanted to test and make sure that they would function properly at the temperatures they would be reaching at 95,000ft. At this altitude our payload could see temperatures around -70 degrees Fahrenheit.
We decided that the best thing to do would be to put our payload, with cameras and all in the Professional Foods freezer. This freezer is much colder than most home freezers and would hover around -10 degrees Fahrenheit.
Here’s the freezer with the payload next to some burgers:
In the image below you can see that all of our equipment lasted well beyond the 1.5 hour flight:
Just to make sure everything would work, even at -70 degrees for however brief it was, we added two hand warmer packets that hikers use.
Now we could be sure everything would survive the flight, we wanted to be sure that no planes would be running into our balloon. Regulations say that you have to have what is called a radar reflector attached to your payload.
This is a radar reflector could be bought for $120+. We just needed our reflector to survive 1 flight and not be marine grade.
We had access to some foam core board and a laser cutter. So all of the students designed a radar reflector in Adobe Illustrator.
We decided upon Dylan’s design, and sent it to the laser cutter.
Here is Dylan’s design being printed:
Here are the three shapes we ended up with:
After some careful folding and scoring, here is our finished reflector shape:
We then headed outside with some spray adhesive and tin foil and ended up with this:
I forgot to snap a photo of the finished reflector before we sent it up. It looked a lot better than this when we first made it. This reflector has seen some stuff…
To keep tabs on where our payload was on it’s journey, we purchased this GPS:
The only problems with this GPS is that it only works up to 20,000 ft and that it only works really well if the logo is facing up. To solve this problem the students designed a gimbal in 3ds Max 2015, which we then we printed on our MakerBot Replicator.
This is Alison’s gimbal design printing:
So no matter what angle the payload is at, the weight of the GPS itself keeps it level.
Here is the finished and assembled gimbal:
Since our altitude and temperature sensor will be outside of the box, we needed to design something to protect it from impact and precipitation. Yet again, the students used 3ds Max to design a shelter for the sensor.
This one is Alex’s and is sloped to shed away water:
The last thing that needed to be designed was something to keep the hot nichrome wires from touching the parachute after it had separated from the balloon. Here is what the students came up with to protect the parachute.
This is John’s design:
Once we had attached everything to the payload box and painted it bright orange so it can easily be spotted. We noticed that the new shelter for the sensor made it look like the box had a face. So the students threw some googly eyes on it and named it GEORGE.
Little did we know that Jade named our balloon payload after a petulant child that is in line for some silly crown in England.
Here is what the final payload looked like on the inside:
- 3d Printed Gimbal
- Spot Gen 3 GPS
- Custom Arduino based Flight Termination Unit
- 8 AA Litium Ion Batteries
- Canon G10 facing starboard
- Canon G9 facing down
- GoPro Hero 3 Black facing port
- 2 Hiking Hand Warmers
On April 15th, 2015 at 8:30 am most of CAWD 2 headed outside to start setting up for the launch. Students helped to fill the balloon as I made sure all of the payload was on and functioning properly.
Here are some shots of us getting it ready:
At 9:40 am the balloon was filled with absolutely all of the helium we had and was ready to launch.
We received word from George’s GPS at around noon that he had landed off some back roads in Bradford, Vermont.
Jen, Seth, Dylan, Elizabeth, Jade, and I all jumped in the CTE van and headed towards George’s location.
After driving for 2 hours, we arrived at the road, which lead to the road that George was on. At this point we realized that none of us had even the slightest cell phone signal and that not a single road here had a sign. So we basically just started driving down random roads that looked familiar to our black and white Google maps print out.
That lead to this:
And then this:
Then this guy joined the party:
And finally this majestic portrait:
I will admit that right before we got stuck, everyone thought we should turn around. I responded by saying that I was driving and I believe I muttered the phrase “I am a professional”.
Once towed out, we continued blindly wandering around the beautiful and quite muddy town of Bradford.
Eventually capturing these shots:
After aimlessly looking in random fields for 2 hours, we decided to call it quits. As we headed back down the back road from which we had come, we noticed an unprotected WIFI signal. We then proceeded to leach off of the free internet, only to realize we just needed to go one field further than the one in which most of us had almost lost our shoes in the primordial mud.
This is where we started our search again…
Just two minutes later, Jade found George just chilling in a completely dry and mud free field; mocking us and our muck covered pants.
After collecting George, we proceeded to drive back to CTE absolutely exhausted. We got back at around 7pm that night, but it was definitely not too late to off load the photos and footage from cameras the George had held.
Now onto what you’ve all been waiting for and probably skipped to.
Here are some of the photos from on-board George:
Burlington International Airport:
Sugarbush and Mad River Glen maybe:
At a final maximum altitude of 107,560 feet, the balloon popped. George was supposed to cut himself down at 95,000 feet, but the sensor mounted on the outside of the box, froze up at 89,000 feet where it was -30 degrees Fahrenheit. This meant that George didn’t know he had crossed the 95,000 foot threshold and continued on his merry way all the way until the balloon popped.
You can view parts of the 2 hour long flight in the video below:
We can’t wait to do this again next year. And we will definitely be bringing boots and something with 4 wheel drive as well.