Wright State University High Altitude Balloon Team - Our lab is at 100,000 feet
2007-2008
From HABTWiki
Contents |
Summary
Team Goals
To design a three dimensional, unfolding truss using a shape memory polymer (SMP) composite material for the hinges. The truss will be launched to a near space environment, via a high altitude balloon (HAB). It will be launched in a folded state, of approximately 2 feet in length, to approximately 70,000 feet where it will be deployed by providing power to heating elements attached to each hinge. The heating of the hinges will cause them to revert to their original shape thereby extending the truss to approximately 10 feet.
Launches
Launch 5
Launch 6
Pictures from launch, July 2008
On Sunday, July 27, 2008 we launched for the first time from WSU Lake Campus. After adding additional helium to the balloon 3 times, we finally had enough lift to launch the balloon. The balloon traveled from WSU Lake Campus in Celina to approximately 5 miles west of Urbana, reaching approximately 87,000 ft in altitude.
During the last launch in the spring the balloon ruptured prematurely, and it was presumed this was because it was over-inflated. However, it is likely that this theory is not true because the balloon for this launch was inflated with more helium than the previous launch (300 additional psi from the tank). A flow meter has been purchased to aid in future launches in order to make the inflation process more precise.
Upon locating the payload post-launch, it was found that the parachute had broken free from the payload. This means the payload likely returned to the ground at terminal velocity from 87,000 ft. The payload survived and the beacon was still active which allowed us to locate the payload approximately 15 minutes after entering the surrounding area (of course this was easy since fortuitously it landed in the middle of the only harvested field around).
The experiment during this launch was the deployable truss. Due to the belief that the over-inflated balloon caused the premature rupture during the last launch, and the fact that we put more helium in this balloon, the truss deployment initiation altitude was changed from 70,000 ft to 35,000 ft. Unfortunately, the truss did not deploy and we were unable to get pictures, above approximately 5,000 ft, of the “non-deployment”. This was not a total loss however as there were some valuable lessons learned.
Firstly, the truss actually entered its deployment sequence prematurely prior to launch. This we found was due to the beacon activating the basic stamp telling it to initiate sequence. We restored the truss to its stowed state and turned the beacon down to low power. This actually helped during recovery also, limiting the search area to a much smaller vicinity once the beacon was heard.
Our belief is that the reason the truss did not deploy during the launch was the timing of the launch sequence. The timing of the truss deployment was changed a week in advance of the launch due to a lack of communication between the team members. This sequence had all of the truss hinges deploying simultaneously within 30 seconds of the deployment initiation. The battery was not powerful enough to deploy all 10 sections of the truss at once in the low temperature environments experienced at these altitudes.
The camera, taking pictures of the truss at 30 second intervals during the launch, failed at approximately 5,000 ft. This is believed to be due to low temperatures. Handwarmers placed in the payload box with the camera should help with this problem.
Other successes include that electronic confirmation was sent to the ground of deployment initiation and the truss payload materials (other than the camera) survived the extreme conditions of near space. The structural integrity of the truss was much better than expected as well considering an impact at terminal velocity from 87,000 ft and experiencing up to 120 mph winds during ascent and descent.
The following are recommendations for future launches/experiments:
• launch a smaller (2-3) section truss (probably salvageable from this truss) prior to a large scale reattempt
• keep the beacon at low power to help narrow down the payload recovery area
• test the camera in the vacuum and extreme low temperatures to focus the cause of failure
• an improved connection of the parachute to the payload
The following are design recommendations for possible future deployable trusses:
• add diagonal members for structural support
• improve the carbon fiber to vertex connections (currently weakest part of the truss)
Prediction and actual flight path
Viewing the graphic, it's easy to observe that the prediction and actual flight path for this launch were very similar.
Experiments
Major Developments
Team Members Josh Hartman (Mechanical Engineering) and Chip Mallett (Mechanical Engineering) are testing a mechanical/electrical release designed by Steve Mascarella. This device will allow the balloons cargo to be released at any instance the ground crew desires.
Team Members
Senior Design Students
Josh Hartman- Mechanical Engineering 2010, (Chip) Clyde R Mallett III- Mechanical Engineering 2010, Brooks Snyder- Mechanical Engineering 2008, Joe Bozeman- Mechanical Engineering 2008, Oluwaseun Ilenbiluan- Mechanical Engineering 2008, Michal Andras- Electrical Engineering 2008, Daniel Rahn- Electrical Engineering 2008.
Advisors
Stephen Mascarella- BSME - 1989, MSME - 1995, BSEE - 2007, Ruby Mawasha- Mechanical and Materials Engineering, Joseph C. Slater- Mechanical and Materials Engineering, J. Mitch Wolff- Mechanical and Materials Engineering, John Wu- Electrical Engineering
Graduate Student Support
Kumar Yelamarthi- Electrical Engineering, Ruolin Zhou- Electrical Engineering
