High Altitude Ballooning
Fall 2011 Phys 100
This was the first year of the high altitude ballooning project and was a learning experience on how to launch the balloon. This section gives some important information for starting a ballooning project.
Photos
Successful launch and recovery!
Equipment
Notes (from EXTREMELY HELPFUL discussions with Paul Verhage, check out http://www.nearspacenetwork.com):
NOTAM (Notice to Airmen for HiBall) Phone Number: 877.487.6867
Don't launch if the winds are in excess of 10 mph. When filling the balloon, fill with no regulator. Use cotton or latex gloves to handle the balloon. Fill balloon with a 1" PVC pipe with end-cap adapter to gas line (the PVC has a hook on it so a digital fish scale can be attached). Fill the balloon so that the lift force exceeds the payload weight by about 2.5 - 3 lbs. (If the lift force exceeds the payload weight by only ~1 lb it is possible to achieve neutral buoyancy!) To tie off balloon: twist rubber and then tie string around the balloon's neck where the rubber is thick, then fold the neck up and wrap with duct tape. Put about 20 ft of line between the balloon and parachute.
Trajectory predictions
http://nearspaceventures.com/w3Baltrak/readyget.pl (Hays airport is HYS)
GPS/Radio Tracking (N8VRN)
Totex Weather Balloon ($?), http://kaymontballoons.com/Near_Space_Photography.html
Specifications:
mass = 1.2 kg, 3cm neck diameter (use 1" pvc), 28 ft diameter at burst
(We tried a Project Aether balloon on Dec 4th and it bursts as we were filling it...not a bad idea to have a backup balloon for launches)
Parachute ($55), 6ft, 173 g or 6.1 oz; 8.0 oz with wire frame, http://www.the-rocketman.com
Specifications:
Weight: Descent speed: 6.5 lb (4.77 m/s, 15.65 ft/s) 8 lb (5.39 m/s, 17.67 ft/s) 11.5 lb (6.35 m/s, 20.82 ft/s) 17 lb (7.72 m/s, 25.32 ft/s)
String
We are using 250 lb test polyester line (2.0 g / meter, 500 ft roll) and Eagle Claw size 1/0 barrel swivels (125 lb test?, mass = 1.6 g each).
Payload total mass, 4.62 kg or ~10.2 lbs. Thus balloon needs to be filled so that it lifts with a force of ~13.2 lbs.
Payload container, primary (Jon's box), Ready to launch mass: 1.375 kg.
Payload container, lunchbox tracker (Jon's tracker), Ready to launch mass: 1.143 kg.
Payload container, secondary (PHYS100), Ready to launch mass: 1.93 kg.
Made from 1" thick R-5.0 "pink panther" 'Foamular 150' material, hot glue, silicone, and 2" coarse thread drywall screws (x16, for a total mass of 47.5 g). Payload container mass with no tape or electronics inside: 460 g.
Digital Camera ($270), Canon PowerShot D10, http://usa.canon.com/cusa/consumer/products/cameras/digital_cameras/powershot_d10
Specifications:
Mass: 221 g.
12.1 MP Waterproof Digital Camera with 3x Optical Image Stabilized Zoom and 2.5-Inch LCD
Using a 4 GB SDHC card and CHDK camera firmware... http://chdk.wikia.com/wiki/CHDK
Used Acid to determine that the firmware was 100B, then used CardTricks 144 to flash the firmware (d10-100b-0.9.9-1434-full_BETA.zip) to format (fat16) and flash the 4GB SDHC card (make sure card slider is towards pins for reading, away from camera pins for booting camera). Modified script from sparkfun.com: hab.bas
@title HAB FHSU
@param a Interval (Secs)
@default a 20
@param b Secs until 1st shoot
@default b 20
@param c Turn off display (0=no, 1=yes)
@default c 1
t=get_tick_count
d=a*1000
s=t+((b-(15/10))*1000)
goto "shoot"
- shoot
if get_tick_count<s then goto "shoot"
s=s+d
shoot
goto "shoot"
end
Use the play button to turn camera on and autoload the CHDK firmware, which will start taking pics every 20 seconds... (auto focus, auto exposure). To get the display to shut off (and conserve the battery) just insert a usb cable into the camera that is not terminated.
Tested (freezer in TH226, temp -18 °C):
Camera took 350 images (4000x3000 pixels, jpeg) before the battery died in 2h15m (images take up 386MB).
SPOT Tracker ($320) mass 120 g, http://www.findmespot.com/en/
Tracks... http://share.findmespot.com/shared/faces/viewspots.jsp?glId=0obLunbKoqbsUuEq5OyCLRQX3c3lWMFdo
Vernier LabPro http://www.vernier.com/products/interfaces/labpro/
Mass of LabPro with batteries: 376 g.
