Balloon, Mark 9 - "Operation Oskar"


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.


  • October 2015 - Launch

Mission Summary


Mission Objectives

  1. Launch with (2) 808 #16 cameras. One pointing horizontally, and one toward the balloon.
  2. Broadcast live video on 70cm during the flight.
  3. Track the balloon with the 70CM beam using APRS telemetry to aim the antenna.
  4. Simulcast the video from the balloon onto youtube.
  5. 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.



Item Estimated Cost
(2) Mini camera & SD card $100
Peach3 Tracker $60
Packaging $10
Total $170


Item Estimated Cost
ML-541A/AM military surplus balloon $40
Helium (80 cu ft cylinder) $71
Total $111

Balloon Prediction Input

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


  1. 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.
  2. 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

  1. 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.


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.


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”


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.


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 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

  1. We need a longer string between payload and balloon to avoid the payload striking it.
  2. We need to assure there are no pointy bits on the payload, in case it DOES strike the balloon.
  3. It was a cloudy day on launch. The video wasn't very interesting until we got above the clouds.
  4. We need to work out the thermal problems with the cameras. Perhaps a heat sink will help.
Last modified:: 2015/09/19 20:45