|26th August 2017
|Whalan Reserve, Australia
|Sunny, calm, 16C
|PK, John K, and GK
As we've decommissioned the Polaron G2 rocket, this week we decided to convert one of the full Polaron G2 boosters into a smaller version of the rocket. The G3 rocket consists of only two reinforced spliced quads with the original nosecone and fins. It also fits under the 1.5Kg limit we have at Whalan Reserve. We decided to use the 16mm nozzle with launch tube, though we did have to cut 5 cm off the end of the launch tube to fit in this rocket.
We flew it a total of three times, all at 210psi. Because we used the same sized chute that we normally used on the larger rocket, it meant that it came down nice and gently. The flights averaged around 670 feet.
The rocket used 2.8L of water on each flight. We used foam but did not expect it to add too much to the flight profile due to the larger nozzle and launch tube.
We also flew the Axion G6 a couple of times, though the rocket looked slightly bent when we put it on the pad. On both flights the rocket looked fine under boost but as it approached apogee it got a really bad case of coning. From the video you can see that it actually developed quite a spin rate and I suspect the bend in the rocket helped in achieving that motion. Some residual foam or water also may have provided an offset weight near the bottom of the rocket and with that spin. It's time to re-align those fins and make sure the rocket is straight as it can be.
Overall though we were happy with the rocket's performance as it flew to 725 feet at 230psi.
We also brought the Phantom 3 Pro with us to get some areal views of the launches. We wanted to get a shot of the rocket using the high speed capability of the GoPro and so we 3D printed a frame that was going to mount underneath the drone and hold the GoPro. Initial testing with the frame mounted by itself looked like it was going to work. But as soon as we added the GoPro, the whole drone just started shaking. It looks like it hit a resonant frequency. This would have made it very difficult to control the drone and the footage would have been unusable. We tried several different modifications but always with the same vibration. In the end we opted for suspending the frame on 4 wires hanging about 30cm under the drone. It would mean that the frame platform would be free to swing, but would be isolated from the vibration.
This meant that all takeoffs and landings needed to be done by hand.
The swaying motion, we were hoping, would be less of an issue as the camera was using a high frame rate. We still used the onboard gimballed camera for navigation and framing and to record HD video.
In the end we did get good footage with both cameras and the swinging wasn't too bad.