JHAB – Build Notes.
We got the idea for Joshua’s High Altitude Balloon (JHAB) project from the Citibank commercial; the one where they used their points to launch and recovered a balloon. http://www.youtube.com/watch?v=FF1zTb_pbfU
After looking into it more, turns out there are a lot of people also wanting to get to near space; many have published their stories and results in great detail. I have posted the links to some of the best sites at the end of this post.
There are a number of sites now on the web which detail how they built their payloads, from the most basic to the very advanced. You have to do a lot of research and testing, re-testing, test again, oh, and then test. And you’ll still have problems. As it turns out – it’s complicated to send something into space, and more importantly recover it, if you’re not a rocket scientist!
Since our goal was Near Space Imagery, we started out fairly basic as well, learning as we went from other HAB enthusiasts.
We modeled our design similar to the image, with the exception of any second payload in the train which many use for HAM radios and more advanced avionics. We don’t have our HAM license yet, but we’re working on that.
Flight System –
We went with the HAB-1200g – which gave us the following specifications
– Diameter at release = 6ft
– Diameter at burst altitude = 28ft
– Volume at release = 113 cuft
– Free Lift = 2lbs
– Ascent rate = 320meters/min / 1000ft/min
– Burst altitude = 102
For the Parachute, we went with the 4ft – which shows a 3.0lb weight specification, and our goal was to be less than 3 lbs.
The filling apparatus was a challenge, and we’re still working on improving it. We needed to find a way to convert compression threading to brass threads, and find the right tubing. The PVC was easy enough, but still leaks.
Our second version seemed to be working a little better. We used air compression hose and some quick connectors, then found a compression to brass thread fitting, and set that into the pvc fitting.
I found this helium tank regulator on the internet, which we then added a quick connect for the hose.
We got our helium from a local company, http://www.balloonsandhelium.net/
There are a couple of ways to measure the neck lift. For our first two launches we have used a digital scale – but have not had great luck, so for our next one, we’re going with a water jug filled to our neck lift.
Tie an emergency line from a heavy object at your launch site (I can’t stress this enough, since our first launch, we let the balloon go by accident and didn’t have a safety line – oops), to the bottom of the digital scale. Tie another line from the top of the digital fish scale directly to the neck of the balloon. When filling the high-altitude balloon stop filling periodically and check the lift indicated on the digital scale.
The second method of measuring nozzle lift is to fill containers with water to equal the nozzle lift required. 1 gallon of water is 8.35 lbs.
Several used a Styrofoam beer cooler, but we opted to go with a more sturdy and smaller design for ours.
We added a waterproof “Lost and Found” note similar to this http://www.thefintels.com/aer/b32.jpg to the top of the payload.
Chemical hand warmers to keep electronics warm. You can find these at sporting goods stores.
GoPro HD Hero
Awesome camera! Durable, waterproof, shoots full HD. Battery only last for about 2hours though, even with the double battery we used on our second flight it only lasted 3 hours – however most flights should be only 2-3 hours.
Camera: Canon A480 w/ 4GB SD Card
We used CHDK, to program the camera’s to take pictures every 12-15 seconds. This took us awhile, to find the right settings. We spent about a month testing, modifying the scripts, and testing again to get the right mix of settings on the camera and the script to function the way we wanted.
Voltcraft DL 180THP Logger
This was a cool little device we found on the internet to test Temperature, humidity. It’s a USB device which can be configured to record at specific intervals. We put it on the outside of the capsule since we used the camera logs to record internal template.
Balloon Trajectory Forecasts
This was the best site we found http://habhub.org/predict/ to run flight predictions based upon payload and wind patterns. You can run as many predictions are you need, and then save the file as a Google Earth KML format.
There are many, but here are several of the sites we used for inspiration, and information.
Below is a complete parts list for JHAB 1 –