Wednesday, June 13, 2012

CineStar 6: First Outdoor Test

After some indoor test hops and flight controller tuning, I was ready to take the CineStar 6 outside to fly for the first time on custom motor controllers. Flying outside is a little more risky: while there are fewer things to hit, there's also the chance for it to fly away (and never come back). And then there's the wind. In this video, the wind wasn't too bad, about 5-10mph. But it definitely changes the way everything performs and I had to turn the gains down a whole arbitrary-notch-of-controlledness from what they were set to inside.

Flying outside also revealed another difficulty: taking off from the grass. You can see at the end of the video that for every successful take-off I had, there were several bloopers. The problem is the landing legs getting stuck, not allowing the frame to rotate as the flight controller attempts to stabilize it. As a result, motors spin up or spin down drastically trying to compensate, but they instead just make things worse and it tips over or stalls a motor. The solution is probably to take off faster, but I'm not up to that level of confidence yet. So, I patiently tried a few times and eventually stuck something flat under one of the legs to help it out. Once it was in the air, though, it flew very nicely.

As flown, it was about 10.3lb (4.67kg). The shear mass makes it much less twitchy than the Talon quad I have, and more able to fight the wind. I didn't collect much data this time - just checking to make sure I can fly it. Other than somewhat unreliable startup exaggerated by the take-off problems, the motor controllers seemed okay. Next time out I will probably load it down with a camera, a Watt Meter, and maybe some supplementary landing gear that aren't like lawn darts. The rated maximum gross weight is 5.8kg. I won't be going very high, just because I'm not very experienced with flying it and it's a lot of weight to fall out of the sky. And all the load testing I need to do can be done below 20ft.

On the other hand, I would like to get some nice video from high up. After testing one at the 2.007 final contest, I decided that the GoPro was an order of magnitude better than the cheaper camera I had and lighter than trying to lift my Panasonic HDC-SD60. So, I got myself a GoPro.

For starters, I mounted it directly to the bottom of Kranmnikopter. (This is about two days after Kramnikopter had an unfortunate looping failure and was completely rebuilt.) The bottom mount will give a much better view than the top mount I tried previously, where you look through the spinning propellers. But, it meant moving the battery up top. It also means that the camera is lower than the stock Talon landing gear.

I'll have to deal with the landing gear problem later. For now, it just makes take-offs and landings more interesting:

The video came out okay. I especially like the 720p/60fps option (the clips with no sound). It makes the twitchy quad seem a lot smoother. There's definitely a noticeable waviness in this video that I didn't see in the indoor 2.007 video. It could be that the mount is different, or that the wind excites more vibrations at frequencies that bother the camera. (In the video, there's about a 10mph steady wind. Can you tell which direction?) I'll have to play with different types of foam mount to fix this. I also might look into a DIY lens change for the GoPro, since its narrow FOV options are not very useful.

This weekend, I'll be taking the Talon + GoPro with me to North Carolina where there are actual trees and open spaces. Hopefully I can get some nice video.

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