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Studio Session-106.jpg

Gimbal 540

I got into multirotors to do aerial photography, specifically to shoot bike races. After a lot of research I chose the FPVManuals tricopter, largely because tricopters were said to fly more gracefully. Unfortunately, it proved to be too delicate for a crash prone noob, so I started looking into designing my own VTail (which is the totally logical noob solution here).

Here's an early failure.

Here's an early failure.

After many iterations (and the advent of brushless gimbals) I ended up here. You can tell by the nice lighting and background that I was super excited to build this puppy up.

That’s a Beholder Lite up front, with arms taken from a Flip FPVbobbins from Lumenier and rear motor mounts from Hobby King. Sadly it was a terrible design – the rear booms would slip ’til the props hit each other, and the battery blocks the rear props’ thrust. Most importantly, the whole thing was an oxymoron. I chose a VTail layout because it flew more gracefully, but the gimbal levels out the video so you can’t tell anyway. All I had was a heavy, badly designed, inefficient flyer.

So I made it a quad.

I had basically reverse engineered a QAV 540g, with much failure and expense along the way. As you can see the Beholder is now firewall mounted. 

I tried a few positions for the fpv cam, not wanting to put it up above for fear it'd be too vulnerable in a crash. I hot glued to the dirty section, put it on studs beneath the clean section, but no matter where I put it I got so much jello in the flight video it was difficult to concentrate on flying. I finally caved and put it up top and that solved everything. I found it really surprising that the camera mounted the same way above and below the clean section yielded such different results. I guess it has to be the prop wash buffeting the camera. Long story short, with the camera up top, it was now REALLY a copy of the QAV 540g.

This thing worked great, first on KK2 then Naze32. One thing I noticed, however, was that it was a tad sluggish to yaw. I made it with a square motor layout, but it seemed to me that if I moved the motors closer fore/aft, then the camera/gimbal and battery could both move closer to the CG, reducing the yaw moment. I jammed the battery up against the FC (which has to be at the CG), and moved the camera and gimbal back to balance. I also decided to move the motors out a touch to get the prop wash away from the gimbal.

The arms are barely rendered ’cause I’m still using those Flip FPV arms and landing gear. I put two vtx’s on it so a second operator can view the GoPro feed and control camera tilt. Here it is with Lumenier 4006’s and 12″ props.

I couldn’t get that last bit of jello out with that setup so I went back to Sunnysky 2216’s and APC 10×5.5 props. At just 1660g with a 3300 4s it’s super light for a quad of its class.

Two years after I got into multirotors I finally shot that bike race. I really love how this thing flies, it just goes where I think, which is great when I’m tracking racers while flying sideways through trees, totally confident that it's going where I want while I focus on the shot.

Side note: After flying for half a year I foolishly thought I was good enough to shoot a race. At the time I was flying that Flip FPV, and the day before the race I took it out for a shakedown and promptly spiked it into the ground and split the LiPo – check out the smoke at the end of the video. In hindsight I’m so glad I didn’t shoot that race as I clearly wasn’t ready to fly near people!