This was flight 3 of the NOEXC Balloon Project program. NBP3 launched 2016/03/26 at 12:37:23 EDT. The balloon burst at 14:16:53 EDT after 01 hour 39 minutes 30 seconds of flight time. The NBP3 payload is unrecovered and predicted to be a few kilometers south east of Akron, Ohio. The electronics worked well through the ascent phase of the launch but failed during descent. The suspected cause is buffeting caused by falling with out a parachute and a delicate antenna.
Our objectives for this flight were:
- [x] Telemetry with no bad packets (CRC16 added).
- [x] Altitude above 15 km.
- [-] SD Card Logging of GPS.
- [-] Temperature logging (inside payload and outside payload).
- [-] Barometric logging.
- [-] Inertial Measurement Unit logging.
- [ ] Make and follow checklists.
- [-] HD camera recording
Key: [x] Accomplished [-] Attempted, no data to make conclusion [ ] Not accomplished.
|Downlink:||145.700 MHz FM||RTTY 45 (170Hz Shift)||70mW|
There were two payloads for this flight. The first and highest on the tether was a telemetry payload relaying the position of the balloon to the chase car. The second and lowest on the payload was a video and data logging payload that did not have a transmitter.
The telemetry payload was be very similar to our previously successful telemetry payload on the NBP1 flight.
Data logging payload
Our data logging payload consisted of several sensors which loged data to an SD card. Attached to the outside of this payload was be an HD camera. This payload was 3 meters away from the telemetry payload to avoid RFI problems that have plagued us in the past.
Summary of Launch
A few of the team members assembled payloads the night before and finalized some of the code that would be flying on the payloads the next day. We have ourselves warned against even planning a launch day without having completely assembled and flight ready equipment.
The launch group met near Akron to stage equipment and make last preparations before heading to the launch site. After getting both chase cars ready we headed down to our launch site at the State Park in Delaware Ohio. During our setup we were greeted by an officer who told us we needed a permit to launch any flying apparatus. We were unsure if the rule actually applied to our situation, even so he graciously allowed us to launch with the understanding that we would apply for a permit the next time we launch from the location.
After final preparation of the payloads we tested the telemetry of the balloon and confirmed it to me reading good packets with good location data. We then turned on the data logging payload and the video recording of the same, that was located over 3 meters away from the telemetry payload. We filled the balloon and secured the tether to the neck of the balloon with some simple knots and a zip tie as back up.
We readied the balloon in the upright position, took a few photos, and again confirmed the telemetry was still operational. After this confirmation Andrew released the balloon and it quickly started to climb at a rate of 6m/s. The balloon climbed straight up for several minutes before entering higher level winds at over a kilometer altitude. We watched for a few minutes and then headed out to chase the balloon and attempt to retrieve it.
Both chase vehicles had the proper equipment to track the payload and did so. One of the chase cars stopped for gas while the other went ahead. As we neared being under the balloon both chase vehicles noticed a decline in the received signal strength of the balloon. We attributed this to being in the null of the jpole antenna used for the telemetry. The balloon was tracked until the balloon presumably ruptured over the city of Akron at 31.438 km (103,143 ft).
With out a parachute and with very little air at 31km the balloon attained a descent rate of 78 meters per second (275km/h or 174mph). At 30km the speed of sound is around 300m/s indicating the payload attained about Mach 0.26 . We are assuming that as the payloads descended into the thicker lower atmosphere either the antenna or the payloads were buffeted violently enough to damage the telemetry system whence it stopped working. With a loss of telemetry there was very little hope of recovery that day. We decided to group up and head to Jason's house to clean up, talk, and then head home.
We all agreed this was a very successful launch, even without recovery of the payloads. We had many successes and learned good lessons for the upcoming launches.
Mapview Commit SHAs
- (tracking) Have some external device/screen in the middle of the front of the chase van always showing mapview. A tablet would work well for this, we already have a wifi network in the van.
- (tracking) gpsd integration to show where the chase cars are live on mapview
- (tracking) Store ALL metric history in a machine readable form, separate from the websocket coordinate history. This prevents having to re-parse the raw-log for post-flight statistics gathering.
- (payloads) Parachutes should be used. We obtained 78 meter per second descent rate (~170mph, Mach 0.26) without one.
- (payloads) Harden payloads to withstand being buffeted by 170mph winds.
- (antennas) Use an antenna without a null directly below the balloon.
- (procedure) Use check lists!
- (equipment) Bring massing equipment and mass payloads before launch
- (payloads) Mark payloads with contact information for hopes of future recovery.