BigQuad Steps Down to MiniQuad: Quadrotor Mk2

I was pretty happy with my previous quadrotor build, because it was good for its purpose (to provide aerial shots with the GoPro camera). It was large but stable with its long arms, but those arms also added much additional weight to the frame. Moreover, the entire thing was made out of wood and steel machine screws.

My main goal was to make it light and small enough to work as an aerial surveillance drone that would last for practical lengths of time. Since Spirit MK2 is in fact modular and can thus house a helipad, my thought at the time was to create a larger landing platform (Spirit) with its tank tread drive modules and have it carry the quadrotor to its destination. The quadrotor would then fly vertically, take a 360 panorama of the landscape and maybe fly around any areas of interest, then return to the mother-ship (turning Spirit into an aircraft carrier!).

It would be a wonderful splicing of two of my projects (a drone within a drone). As mentioned in earlier posts, I bought a very cheap video camera transmitter/receiver combination that I have housed on this quadrotor. At 40 or so grams, it certainly weighs less than the 400g weight added by the GoPro and mount. With only 150ft of transmission range, the system would greatly extend the usable distance of the quadrotor if the video receiver was mounted directly onto Spirit and later relayed back. And with that, here’s my progress on the MiniQuad so far:

The arms are now aluminum C beams, but the mounting plates are still particleboard. It seems I’ll never fully upgrade to metal until I’m able to buy a mini-lathe and a mini-mill. Fiberglass and carbon fiber were out of the question of course, since I’m limited to the selection at the Home Depot, and I was not able to find any source of significantly large pieces of styrofoam to cut. As a result you have a (proportionally) lighter and compact quadrotor. Motors are now directly mounted to the beams, and I’ve added some plastic landing gear made of Polymorph/Shapelock/Instamorph material. Those standoffs you see there are in fact wooden dowels.

The landing gear was heavy and failed often since it was a last minute add-on with zip ties on the previous quadrotor, so this new addition is a nice feature. The whole assembly is lighter, I promise! It was worth the hours spent rebuilding a smaller chassis. Here’s the MiniQuad’s frame next to the BigQuad’s frame:

The scale may not be apparent in the picture but the diameter of the Mini is less than half that of the Big. I have no idea on how this will effect its wind stability but this smaller size allows the quadrotor to sit on the central module of Spirit without any problems.

As of now, the MiniQuad is almost complete mechanically. The two standoff totem poles in the first picture will be replaced with a lighter material, and will support the canopy of the quadrotor. I’m hoping for something fitted and nicer than last time (a plate of plexiglass) to protect the electronics from dirt and flips. The rat’s nest wiring is shown in the next picture. I’ll clean it up after everything is sorted out.

Here’s the camera mount. It’s the same Polymorph material molded around the camera. This stuff is getting really useful when I don’t want to machine anything. Great for low strength, custom mounts!

My next step in this process is reconfiguring the software on the Arduino. I’ll probably do that tomorrow, but due to sudden and odd rain (Southern California) I won’t be able to do many outdoor tests. Since my brother’s room is vacant after he moved most of his stuff out to school I’ll fly it around in there. Video transmission does work, but it can only display on screens for now. I’m waiting for a to-USB adapter so I can record/view the video from my laptop.

 

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