Table of Contents
Balloon, Mark 9 - "Operation Oskar"
Overview
This balloon will feature our first ATV (Amateur TV) transmitter to fly with the mission. We will send live video during the flight in addition to capturing video on SD cards. We will attempt to receive the video from our ground station at the W2CXM shack and simulcast it as a live stream on youtube during the flight.
Timeline
- October 2015 - Launch
Mission Summary
TBD.
Mission Objectives
- Launch with (2) 808 #16 cameras. One pointing horizontally, and one toward the balloon.
- Broadcast live video on 70cm during the flight.
- Track the balloon with the 70CM beam using APRS telemetry to aim the antenna.
- Simulcast the video from the balloon onto youtube.
- Max 2 1/2 hour flight time.
Mission Parameters
| Balloon | 1200g Hwoyee |
|---|---|
| Lifting Gas | Helium |
| Payload | (2) Peach3 Trackers, (2)808 #16 Micro camera Videolynx VM-70X ATV transmitter |
| Payload container | Foam box with stabilizing bars extending from it. |
| Max Payoad Weight | TBD |
| Flight Time | Under 180 min |
| Cutdown | Balloon Burst |
| Recovery | 30“ Parachute |
| Tracking | Peach3 HAB trackers |
| Telemetry | GPS and temperature data. |
Balloon and payload Weight Budget
| Item | Weight (grams) |
|---|
| (2) Tracker + Counterpoise | 24 |
| Tracker Batteries - (2) L92 AAA Ultimate Lithium | 18 |
| #16 808 Camera w/SanDisk 16G SDHC I, Class 4 | 10 |
| #16 808 Camera w/SanDisk 16G SDHC I, Class 10 | 10 |
| Camera Battery - (2) L92 AAA Ultimate Lithium | 33 |
| ATV Transmitter & Heat Sink | 120 |
| ATV Batteries (8) L91 AA Ultimate Lithium | 120 |
| ATV Antenna | 50 |
| ATV Wiring | 20 |
| Micro OSD, GPS and power regulator | 30 |
| Payload container | 105 |
| Guylines + Chute | 24 |
| Beeper + Battery | 8 |
| Balloon | 1,200 |
| Balloon attachment (Final string and tape) | 40 |
| Total (goal: 1800) | 1812 |
|---|
Final Package
This is the tracker plus AAA battery weight. Note this was actually from a different launch configuration, but the same idea. For THIS launch, we did not secure the battery to the tracker, and the string was not present.
This is the two cameras (in parallel) together from a pair of AA batteries in series.
This is how the payload looks with both cameras active.
This image is the internals of the payload before we chose to add the second camera. It shows the general placement of the tracker and first camera.
Here is the payload box with stabilizing bars and parachute installed.
Budget
Recoverable
| Item | Estimated Cost |
|---|---|
| (2) Mini camera & SD card | $100 |
| Peach3 Tracker | $60 |
| Packaging | $10 |
| Total | $170 |
Consumables
| Item | Estimated Cost |
|---|---|
| ML-541A/AM military surplus balloon | $40 |
| Helium (80 cu ft cylinder) | $71 |
| Total | $111 |
Balloon Prediction Input
| Predictor | http://predict.habhub.org/ |
| Payload Mass | 261g |
| Balloon Mass | 1200g Kaymont |
| Total Mass | 1461g |
| Target Ascent Rate | 5.0 m/s |
| Descent Rate | 9.8 m/s |
| Gas | Helium |
| Burst Diameter | 5.8m |
| Start Location | Seneca Castle, New York |
Notes:
- The predictor does not have 1220g balloons, so we used a 1200, added 20g to the payload weight, and specified an explicit burst diameter based on estimations from previous launches.
- Descent rate based on Launch 7 with a similar payload box.
Balloon Prediction Output
| Burst Altitude | 27,103m |
| Ascent Rate | 5.52 m/s |
| Neck Lift | 1280 g |
| Launch Volume | 85.3 cu ft |
| Flight Range | 65.2 km |
| Time to burst | 82 min |
| Flight Time | 102 min |
Chase Cars
- Launch: Hojo/KD2EAT
Launch and Recovery
Balloon fill
Using volume of a sphere for 76.3 cu ft
- Volume of a sphere
- v = 85.3 (per predictor)
- v = 4/3 pi r**3
- Solving for r, the radius:
- r = cube root(3v /4pi)
- r = 2.73 feet
- The circumference of the sphere is pi*d
- c = pi * 2 * r
- c = 17.158
We called it 17' 1 7/8” circumference.
Expected pounds of gas to use:
PSI = volume / .0265 PSI = 85.3 / .0265 PSI = 3218 PSI drop in tank.
Launch
The Flight
Actual track vs projected track
| Predicted | Actual | |
| Burst Altitude | 27,103m | 16,707 |
| Ascent Rate | 5.52 m/s | 4.9 m/s |
| Time to burst | 01:22:00 | 00:57:00 |
| Descent Rate | 9.8 m/s | 9.3 m/s |
| Time to descend (predictor) | 00:20:00 | 00:29:54 |
| Time to descend (altitude / descent rate) | 00:50:11 | 00:29:54 |
| Flight Range | 65.2 km | 85.7 km |
| Flight Time | 01:42:00 | 01:27:04 |
Balloon burst early after striking the payload in turbulence.
Payload
Given that the payload bounced and hit the payload, it seems the tether was too short. For this launch we had:
| Balloon to chute top | 7' 10“ |
| Chute top to chute gather | 1' 10” |
| Chute gather to payload gather | 3' 8“ |
| Total: | 13' 4” |
Temperature
Lowest observed temperature was -27.6c on the descent at 9774 meters (32,066 ft).
Temperature at apogee (16,707m = 54,819 ft) was -18.4c.
Camera
The upward facing camera failed shortly before landing. I believe it was a thermal problem that we observed in ground testing. It most likely overheated as the payload got to near normal external temperatures. The horizontal camera worked flawlessly through the launch and landing.
Recovery
Recovery was trivial. It was on the ground beside a driveway. Once getting a beacon from the payload as we drove by it, we were able to drive right to it, and heard the beeper on the payload as we approached.
Lessons Learned
- We need a longer string between payload and balloon to avoid the payload striking it.
- We need to assure there are no pointy bits on the payload, in case it DOES strike the balloon.
- It was a cloudy day on launch. The video wasn't very interesting until we got above the clouds.
- We need to work out the thermal problems with the cameras. Perhaps a heat sink will help.
