The UROC launch on Saturday was well attended and the weather was great, especially considering it's still March. My second launch involved a new scratch design that I worked on over the winter. I like everything about it except for one thing: the placement of the altimeter makes it impossible to use motor ejection as a backup. On top of that, in my rush to get the rocket ready to launch, I ran out of time to paint it or to GROUND TEST the ejection charges. Hoping for the best, I installed one of my 915mHz HopeRF/UP-501 based trackers and a Cesaroni J316 Pink and let it fly. A primer-white rocket against scattered white clouds made the rocket difficult to track after the violet flame ran out. Rocksim predicted an apogee of around 8,000 ft, and I lost sight of it long before then. Someone said that they saw it go over the top, but saw no ejection events. By the time I got back to my vehicle, my base station had quit getting packets from the tracker. Hmmm, not good.
A short hike in the direction I thought the rocket would probably land if it had come down under 'chute turned up nothing. Returning to my vehicle, I decided to study the tracker packets more closely. It looked like the GPS had lost its location data at launch (as usual), the radio had continued to transmit every second for 30 seconds or so, and then there were 7 packets with GPS location data immediately before the radio stopped transmitting. I figured we ought to at least see if there was anything at that location, so I entered the coordinates into my phone and my wife and I started on our 4400 ft. hike through the sage brush.
We got to within +/- a dozen yards of the location and couldn't find anything. The brush was quite thick in the area and I was getting tired of wandering around, and was ready to head back to the launch. My wife insisted that we try to get to the exact coordinates one more time, despite my phone saying that its GPS accuracy was only +/- 30 feet at the time. I got out my phone and wandered in circles for a couple more minutes until I got to as close to 0 as I could. I looked up and saw this:
I don't learn things very easily some times, but maybe the loss of my tracker, altimeter, av bay, and 38mm 6-grain CTI case will help me to remember to ALWAYS GROUND TEST NEW DESIGNS. It was definitely more satisfying to find SOMETHING rather than just never knowing what happened to the rocket, but the only thing I was able to salvage was a couple swivels, even the parachute and Nomex shield were shredded. There is no way of telling if the charge fired but wasn't big enough, or if something else went wrong. As a result, this design is definitely going back to the drawing board so that I can use motor ejection as a back up. Even a VERY late ejection is preferable to this.
Further analysis of the tracker data showed that the GPS started sending location data in those final 7 packets when the rocket was about 1000' AGL. At the time it was travelling 333 mph almost straight down. The final packet was sent 100' before impact.
A short hike in the direction I thought the rocket would probably land if it had come down under 'chute turned up nothing. Returning to my vehicle, I decided to study the tracker packets more closely. It looked like the GPS had lost its location data at launch (as usual), the radio had continued to transmit every second for 30 seconds or so, and then there were 7 packets with GPS location data immediately before the radio stopped transmitting. I figured we ought to at least see if there was anything at that location, so I entered the coordinates into my phone and my wife and I started on our 4400 ft. hike through the sage brush.
We got to within +/- a dozen yards of the location and couldn't find anything. The brush was quite thick in the area and I was getting tired of wandering around, and was ready to head back to the launch. My wife insisted that we try to get to the exact coordinates one more time, despite my phone saying that its GPS accuracy was only +/- 30 feet at the time. I got out my phone and wandered in circles for a couple more minutes until I got to as close to 0 as I could. I looked up and saw this:
I don't learn things very easily some times, but maybe the loss of my tracker, altimeter, av bay, and 38mm 6-grain CTI case will help me to remember to ALWAYS GROUND TEST NEW DESIGNS. It was definitely more satisfying to find SOMETHING rather than just never knowing what happened to the rocket, but the only thing I was able to salvage was a couple swivels, even the parachute and Nomex shield were shredded. There is no way of telling if the charge fired but wasn't big enough, or if something else went wrong. As a result, this design is definitely going back to the drawing board so that I can use motor ejection as a back up. Even a VERY late ejection is preferable to this.
Further analysis of the tracker data showed that the GPS started sending location data in those final 7 packets when the rocket was about 1000' AGL. At the time it was travelling 333 mph almost straight down. The final packet was sent 100' before impact.