249g Quads: Summer in Seattle

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This summer I am working at Amazon Prime Air, located in Seattle, WA. I decided to recycle some of my 2.007 cash back into the nerd fund and build a micro quad. To skirt the FAA regulations, it has to be less than 250g, mandating careful weight savings.

I chose to build the quad around the DYS 1306 motors paired with 3.5″ props. I also managed to cruft a bunch of 2.007 batteries from the damaged batteries bin (lol), which are 2s 500mah 35c. These would be run in series to get that 4s kick. I purchased the other bits on Banggood, a recent discovery of mine. The bits included Flycolor 20a escs, a micro Skyline32 flight controller, a 200mw vtx, and questionably carbided carbide 2mm endmills to make the frame.

I whipped up a frame in Solidworks. 1/16″ G10. There was a bit of a question of how to mount the VTX, as the space in between the props is so limited. On this model, the VTX sits underneath the cam on top of the FC.

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Banggood is nice enough to provide tracking numbers for the orders, even though shipping is usually free. I confirmed the order 25 days before my flight left for Seattle, good enough for it to get here right? Long story short, no it isn’t. 5 days before I left, It was clear it wasn’t going to get here, still stuck in China. So I quickly rage-ordered another quad, this time from the magic of the hobbyking U.S. warehouse. 1804 2000kv motors along with 4x4x3 props. Whipped up another frame real quick in Solidworks. To handle the larger props I decided to step the frame thickness up to 1/8″ G10, and add holes wherever possible.

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Here’s the CAD as it stood. The frame is of 1/8″ G10, heavily cut to save weight. The props clear eachother by about 2mm. The camera and VTX are held by a 3d printed mount which sits on top of the FC, using the same bolt pattern. The FC is a BrainFPV gen1, rotated 90 degrees to put the pin headers in front of the camera board.

I decided to go and mill and print everything at MITERS the night before leaving for Seattle. Needless to say I didn’t get a ton of sleep, but the results were great.

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Anna helps with the vacuum!!

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Milled two of each. However after milling three
I realized that the frames were a lot more bendy than I had thought they would be, and decided to try one with the grain going along the arms instead of crisscrossing them at the 45. While this arrangement is less efficient stock-wise, it proved to be a lot less flexible.

I brought one suitcase, one duffel bag, and a backpack of stuff to Seattle. The entire backpack was full of quadrotor parts and tools. Over the first week here I slowly but surely assembled a working quad. I initially used the Banggood $10 micro camera but found it to have a lot of lens distortion. I switched it for the trustworthy PZ0420 cam the frame was designed for. The 3d printed mount fits it perfectly, giving the appearance of a design that was actually thought out! 

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Here’s the initial setup with the 600mw IRC VTX.

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I switched to a 200mw Aomway after the SMA broke off the original VTX. Now it looks really nice..

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Soldered on a skew-planar wheel.

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And flies pretty alright too. I’ve been flying in Ravaenna park in this small group of trees. It’s definitely a challenge but good fun as well.

And that’s where we are. The 3.5″ version has yet to be built as the 4″ is too much fun. It hasn’t even broken yet. Hit the ground pretty hard once and the arm got bent, just bent it back and kept going. Surprisingly none of the props have broken, just bent. Un-bend and keep going!

Whee!!

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