The conditions were challenging but the crew stepped up to the plate and we were able to get most of our experiments off the ground and into the stratosphere. We were able to launch despite wind gusts in the 30mph range. The winds were coming almost straight out of the south which meant the balloon and experiments would be blown directly toward the hanger. This meant we needed to determine a safe distance to preposition the payload chain outside. It was a team effort with each person having a very specific roll. Using some basic physics and geometry Anuja calculated the angle of flight (lift v vs. wind speed) and gave us the safe distance from the building. We used the hanger as a windbreak and with Alan’s guidance, Mike and I quickly hustled the balloon out of the hanger. Michael quickly attached the balloon to the 50ft tether connecting the balloon to the payload chain and cleared out of the flight path. In order to maximize the ascent angle – thus clearing the building – each element of the experiment chain was held up by one of the crew. As soon as the balloon was hit by the first large gust we released. The combination of an excess lift given to the balloon (6lb vs the typical 5) and the high winds, made the launch very fast. It was so fast, in fact, that the 50lb connections to the second tracker and the ballast system gave. They never left the ground. The balloon, parachute and payload box did make it. The payload contained a tracker, the GoPro Hero2 and Hero3 cameras and Fred’s battery monitoring experiment.
GoPro Hero 2 vs. Hero 3
The two images above link to full scale comparisons of the two cameras. The GoPro Hero 2 captures 1080i imagery (1920 x 1080 pixels/frame) at 24fps. The GoPro Hero 3 captures 4k video at 12fps. That’s an amazing 4096 x 2160 pixel resolution. In addition, the new Hero 3 allows an un-color corrected “RAW” capture. This saves on processing time and gives freedom of correction in post production. GoPros have two metering modes Spot and Averaged. Both settings are problematic for stratospheric imaging. We are dealing with a very high contrast situation. What may be best is presetting the exposure for the conditions. It appears there is a possibility to hack or write scripts for GoPros. Here’s a link to their open source resources. If anyone wants to look into the options it would be much appreciated.
Another thing we tested this flight was the use of a long tether. We were wondering if the use of this 50ft line from the balloon to the payload chain would reduce the pendulum motion in flight. We’ll run some comparisons from previous flights to see if there was any discernible improvement. A cursory look is inconclusive.
Here’s the initial report from Fred about the battery flight test:
At launch the temperature was 9.6 C (49F) and the batteries are at peak value(3.58V for each lithium thionyl chloride and 1.81V for regular lithium). At about 72 minutes after launch, this would be around burst, a minimum temperature reached was only -8.5C (with voltages of 3.48V for lithium thionyl chloride and 1.63V for regular lithium). The surprise here is that the minimum temperature was only -8.5C. Either the batteries were really well insulated, which is a distinct possibility, or the LM-60 (temperature sensor) did not follow its spec sheet. At 92 minutes after launch, the temperature increases and flattens out around 5.7C for the duration of the flight (during this regime the voltage on the batteries drops only very very slightly- around 5mV for each battery).
My conclusion is that the batteries were insulated so well that a test of extreme temperatures did not occur. The temperature range was a maximum of 9.6C at launch, -8.5C at minimum and then about 5.7C for the duration. The lithium thionyl chloride batteries started the experiment at 3.58V and ended at 3.48V- a loss of 0.1 volts while the regular lithium started at 1.81V and ended at 1.63V- a loss of 0.18V. One could conclude that the lithium thionyl chloride batteries held up better than the regular lithium by the difference in voltage lost- 0.1V vs 0.18V- or a 2.8% vs 9.9% decrease in voltage respectively.
Saturday With An Astro-Pilot, Anyone?
Just a reminder for anyone interested in space exploration and would like to hear about the new generation of commercial astronauts. This Saturday the 22nd the Adler will be hosting a talk from 11-12. Here’s the scoop on the talk:
Brian Binnie is a Test Pilot and Astronaut for Scaled Composites. He flew the first and last flights of the company’s award winning SpaceShipOne and in the process he opened up the vehicle’s envelope to supersonic flight, beating the long standing altitude record of the X-15 and clenched the $10M Ansari X-Prize. He is currently working on SpaceShipTwo, an 8 place vehicle that will provide suborbital space flights for commercial tourism and be operated by Sir Richard Branson’s Virgin Galactic. Brian will talk about some of the challenges of the endeavor, provide video highlights and offer his personal perspective on the rewards of space flight.
I’ll have some tickets reserved for any Horizonites interested in attending.