On the morning of May 20, 2017, we flew a high altitude mission just for fun. Paul L. had an old surplus 1600g cell and a little H2 left over, so he slapped together a simple payload reusing the foam from NSL-51. A 42cm inline chute was used instead of an under-hung one. The 150g payload was just a block of rigid, black foam that was carved-out to fit an AP510 APRS transmitter, a Mate808 narrow angle camera, and a single 4200mAh LiPo battery. Like NSL-51, the chute bridle was connected with some loops and some PVA string. This, along with a spool of dental floss, would allow the payload to slowly descend from a tree after after some rain. Basically NSL-51 with a bigger balloon.  During NSL-51, the payload got pretty cold, even with the Mobius camera running hot. So as a test, this flight had a simple wrap of kitchen plastic wrap put around it and 'shrunk' on with a hair dryer. Would a simple clear layer of thin plastic keep the payload warmer in the upper troposphere? Both the camera and tracker were running off of a single battery. These devices usually draw down the battery a bit before launch as we activate all of the electronics and check them out before filling the balloon. So on this flight, an umbilical USB cable was left plugged into the AP510 and ran to a simple USB phone charger battery pack. This provided 'shore power' to the payload while it was operating during fill. Moments before launch, the cable was pulled out of the bottom of the payload, and a piece of tape was slapped over the hole. Would this be enough to power the camera through the entire flight?  The intention was to fill the 1600g cell until it had about 580g of neck lift. It was accidentally overfilled to about 850g of neck lift. As the balloon was so huge, the small pocket of gas stayed at the top of it. There was no chance to vent any extra gas. It had to be flown with this larger amount. This would lead to a earlier burst that desired -- lower altitude and shorter flight. Sadly, during the final build, the small ribbon cable from the lens to the camera was pulled just enough to cause issues. So we have no video/images from this flight. The flight was predicted to just float back and forth over southern Wake County for four hours (a bit less due to the overfill). This allowed the chase team to take care of chores and have a leisurely breakfast before going to recover. The balloon burst at 136,867ft and did not shred/detach as usual. The majority of the balloon fouled the chute and the entire wad came down together. The scraps of balloon were about as large as the parachute, so we didn't know any better until the payload fell below 5km and the speed was still 10m/s! The chase crew watched it come in, ahead of schedule, still at 10m/s. With the huge while balloon scraps, it was easy to see less than a block away. It landed in a suburban area along the street curb.    Flight visualization. Crazy, lazy ground track over Lake Benson   Paul's notes: I think that the saran wrap helped. This flight was a couple of hours later than NSL-51, but it stayed 10C warmer the entire time. Also considering that the Mate808 doesn't give off heat like the Mobius. I think that the wrap would also help shed water if the payload was stuck in a tree for a while. It was fun to put on and added less than 1g, so I can see doing this in future flights. Adding 'shore power' seemed to be a good idea also. The battery stayed topped off during the whole prep/fill. I didn't feel as rushed to launch. I figured it added 15 minutes to the battery time. The battery held out well. The Mate808 was still operating when we recovered it, so it was a bummer when we found that there was no video. I know what happened and I can add it to the list of things to prevent in the future. |
Missions >