HAB - Weights, Measures, and Costs
A story of the electronics and logistics of launching a high altitude balloon.
High Altitude Balloon Page:
- HAB Intro
- Sensor system, Flight Computer and Radio System
- Still and Video cameras
- The Balloon, Enclosure, Helium, and Cut-Down
- Enclosure and Heater System
- Weights, Measures, and Costs
- Lessons Learned
Weights and Measurement
There are two devices that really saved me here.
A digital pocket scale, capable of measuring up to 500 grams with 0.1 gram increments. For $6?! And it comes with batteries and an LED backlight? Wow. Awesome. I used this scale a lot to measure the weights of individual pieces of the payload. Adding those up gave me a rough idea for system weights (radio, batteries, cut-down, etc). This equated to an overall payload weight.
A hanging digital scale, model SR-5 was the one available on Amazon for $16, comes with batteries and works like a charm. It measures 11lbs max with 0.01lb increments. This scale allows you to measure the lift of the balloon before you attach your payload. This helps during filling. We had to detach the balloon from the filler to measure lift (the balloon looked full but had ~1.5lbs of lift), then re-attach to the filler to add more helium (until we had ~2.5lbs of lift).
I would like to brag that my overall payload weight was a scant 1.45lbs or 657 grams! An entire payload that weighs less then a pound and a half. I could have gone with an even smaller balloon! But then, I never found the payload, so the next one may be heavier as I change out the radio or batteries to something heftier. We shall see.
Here's a rough breakdown of weights that may be useful for your own payload planning:
Batteries
860mAh LiPo : 18.5g
1000mAh LiPo: 22g
2000mAh LiPo: 41g
6000mAh LiPo: 110g
I ended up using four 2000mAh batteries: two for the radio, one for the HD camera, and one for the main sensor board.
Sensors
Main sensor board: 28g
LS20031 GPS module: 13.8g
Radio
Digi XTend 900MHz Radio: 25g
900MHz Antenna: 43.3g
Cameras
SD400 camera and SD card: 134.9g
SD400 battery: 151g
GoPro HD Camera: 98.8g
Balloon
Parachute: 110.3g
Rope (48ft): 65g
Styrofoam enclosure: 99g
Payload total: ~600g (1.5lbs)
The overall payload was surprisingly light. There is room for improvement as well - the antenna and extra RF cable added some. With a proper radio and antenna, I should be able to significantly reduce the radio weight, but if the radio is low power, I then may have to add a heater.
Prices
Here's the skinny on this little adventure. It was not cheap, but it was a lot of fun.
Balloon
KCI Latex Balloon (Kaymont) - $70
Helium (locally) - $83
Parachute (RocketChutes) - $22
Styrofoam (hardware store) - $5
Acrylic plate (hardware store) - $5
Metallic duct tape (hardware store) - $4
Still Camera
SD400 (Ebay) - $40
1GB SD card (SFE) - $10
Battery x 2 (Amazon) - $6
Charger (Amazon) - $6
HD Video Camera
GoPro (GoPro website) - $260
32GB SDHC card (NewEgg) - $80
Sensor Board
Proto PCB and electronics (SFE) - ~$100
LS20031 GPS receiver (SFE) - $60
OpenLog (SFE) - $25
1GB SD card (SFE) - $10
TMP102 Breakout (SFE) - $6
LiPo Battery, 2000mAh (SFE) - $17
Radio
Digi XTend 900MHz x 2 (SFE) - $370
Breakout boards x 2 (SFE) - $4
FTDI USB to Serial (SFE) - $15
SparkFun enclosure (SFE) - $12
900MHz omnidirectional antenna (L-Com) x 2 - $40
SMA to RPSMA adapter x 2 (SFE) - $4
Heater
Proto PCB and electronics (SFE and BatchPCB) - ~$20
Power resistor (Digikey) - $1
LiPo Battery, 2000mAh (SFE) - $17
Cutdown
Proto PCB and electronics (SFE and BatchPCB) - ~$20
Nichrome wire kit (Ebay) - $15
LiPo Battery, 2000mAh (SFE) - $17
Depending on what options you choose it can cost upwards of $1200 to get a balloon into the air! This was so expensive for me because I had to buy many of the parts for the first time. This includes some pricey additions: the HD camera could be removed, and many of the projects online are done by HAM operators that already have the radio equipment to track the balloon. Would I do it again? Absolutely! It was well worth the engineering challenge and fulfilled a dream that I had kept since college.
Next page - Lessons Learned
High Altitude Balloon Page:
The details, especially info on specific materials and tools (the scale info provides good low-cost options) is very helpful as we embark on our own High Altitude Balloon mission. I'm bookmarking your page for future use as we begin documenting our own experiences. SpaceRace2013
instead of the listed radio system, i would use these: http://www.mobilepc.com/Electronics/Motorola-MR350R-22-Channel-FRS-GMRS-Two-Way-Radio
And hook them up to an arduino or something that would transmit GPS/flight data via morse code. Much cheaper.
Being realistic, Morse code would not work.
Does anyone know where I could get a "Proto PCB and electronics (SFE)" for under $150 that is compatible with all the other sensors that were used up top.
You guys think about a way to try and stabilize the payload to prevent it from spinning? maybe some fins, or a more rigid line attached to the balloon maybe?
If you were not interested in the data and just wanted cool pictures or video (all that i want) you would need a lot less.
Could you put solar panels on one?
You could certainly put solar panels on your air vehicle to provide power generation. Here's the questions you should ask yourself from a design standpoint:
Do I get equal or better power generation to weight by going solar?
If not, is there some requrement that mandates the use of solar, i.e. long mission time.
Is there a risk of the solar power begin interrupted (night, clouds, obscuration, etc.)?
If so, will I need a battery anyway? Just to provide supplement power.
Of course, it's away acceptable to install solar panels as an experiment, i.e. monitor power output to determine a power generation profile over the mission, etc.
Just some things to consider.