This design has been replaced with the improved SkyTrak Lite, found here: http://www.thingiverse.com/thing:1471256
This multirotor design is intended as a framework, rather than a finalized product.
I had the ideal of building an airframe on tracks (like a camera rig) rather than on plates like most designs out there.
Cutting carbon fiber plates for a custom UAV is complicated and laborious. 3D printed multirotor airframes do not scale up well because plastic is too flexible.
The SkyTrak solves both issues by building a UAV on a carbon fiber tube "backbone". The tubes are light weight, common and cheap. The 3D printed plastic parts simply serve as joints. Tubes are 10mm diameter, spaced 60mm from center to center, I chose this format because it is a common rail configuration used on some commercial airframes and gimbals, like Tarot and DYS.
As an added bonus, this design philosophy makes the SkyTrak fully modular and customizable. You can create your own parts and attach them anywhere on the tracks. It's also easy to repair of modify. I have designed the SkyTrak so that any part can be removed without having to do a full tear-down.
Furthermore, I have invented an arm-folding mechanism that works better than most common clips or friction methods found in regular commercial airframes.
I have been shooting aerial video with this aircraft for a week and I am very pleased with it.
That being said, this first prototype has a few flaws. It's too heavy for my taste. At around 550 g, it's heavier than the TBS Discovery (415 g). I also want to reduce the number of plastic parts. I'm currently working on an improved design: the SkyTrak Lite... Coming soon!
ASSEMBLY - I have included pictures that should help you understand how it's put together. Here is a list of the parts you will need to buy. Make sure that your rail tubes have a 1 mm wall thickness. The 0.5 mm ones are too fragile.
PARTS - For the motor mounts, I used iFlight universal motor mounts (http://www.aliexpress.com/item/Free-shipping-Tarot-M16-Flight-Seat-Motor-Mount-Orange-TL68B08-01-multicopter-multirotor-frame-kit-quadcopter/32315808262.html) but anything that clamps to a 16mm diameter tube will work.
*SkyTrak_arm_mount.stl: 4x CF tube 10x8x500mm (cut them to the desired length) | 8x M3 18mm socket screw | 8x M3 lock nuts | 4x M4 35mm socket screw | 4x M4 lock nuts | 8x 8/4mm washer | 4x 9/4.5mm washer
*SkyTrak_arm_clamp_rear.STL and SkyTrak_arm_clamp_front.STL: 4x CF tube 16x14x180mm (or longer) | 4x M3 28mm socket screw | 4x M3 lock nuts
*SkyTrak_leg_mount_bottom.STL: 4x M3 12mm socket screw | 4x M3 nuts
*SkyTrak_GPS_mount_top.STL: 2x M3 12mm socket screw | 2x M3 nuts
SkyTrak_normal_component_plate.STL and SkyTrak_extra_component_plate.STL: 4x 28mm stand-off | 12x M3 8mm socket screw | 4x M3 nuts | 8x 8/4mm washer