Introduction: Micro FPV Quad
This is a really neat and tidy micro quad build, with frame designed for FPV.
It only took me a day to do, and uses parts that are readily accessible, either from hobby stores or online.
The main materials needed are:
* 6mm square carbon fiber tubing. (44cm long)
* XPS foam, or similar strong, dense foam. (3cm thick, 24cm x 8cm block).
* carbon fiber sheet, or strong wood sheet (ply or mdf), 15cm x 12cm.
* lots of cable ties
* double-sided foam mounting tape.
* stick-on velcro (hook-n-loop) strips.
There are many types of motors and RC gear that can fit this model, but below are the ones I chose for this build:
* Props: 5030 tri blades
* Motors: Multistar 1704/1900kV
* ESCs: HK blue series 12A
* FC: NanoWii. (with Spektrum sat RX)
* Batt: 3S, 500mAh
Since first publishing, I actually had a major crash (in windy conditions), and have made a few small, but effective changes.
One is to use 6mm square CF tubing for the arms (instead of 4). For this scale, these have a negligible weight increase, but are so much stronger. Plus, they have a lot less twist in them, which I suspect contributed to some yaw problems when at full throttle. (any tilt off the main axis produces significant yaw, with quads)
Also, I have done more carving of the foam cover for a more rounded shape, at the sides. I'm hoping this gives a more slippery shape, and helps when in cross-winds.
A number of people have been puzzled at the acronyms used in this post. If you're not really into radio control hobbies, here are some used:
ESC = Eelectronic Speed Controller
FC = Flight Controller/stabilizer
CF = Carbon Fiber
LiPo = Lithium Polymer (battery type)
RX = receiver
TX = transmitter
FPV = First Person View
XPS (foam) = eXtruded PolyStyrene
Step 1: The Plan
Here's the plan I drew up first. For the scale, the prop circle diameters are 5 inches. You can scale everything else from those.
Step 2: The Base
For thing is to cut out the base frame piece. I used mdf, 3mm thick. Is reasonably strong for its weight. I would have loved to use a CF sheet (prob 1.5mm) and cut out to the pictured shape, but don't have any on hand.
Then cut the four arm pieces from the 4mm sq CF tubing, where the from two are shorter (about 10cm), and rear ones about 12cm. (refer to the plan for measurements, especially if you're scaling this up or down).
The most time consuming part was making the four motor mounts. I had scraps of 1.5mm CF which I dremelled to the given shapes, and drilled holes to match the motors' mounting holes. Also two hole midway for cable ties to go through.
The next step is pretty fiddly, and you have to do it reasonably quickly before the glue dries. I used good old Araldite (Epoxy). THe most important thing with the gluing step is to make sure the motor mount plates are ALL LEVEL! So, work on a flat surface. I put 1.5mm scrap CF pieces underneath the mount plates to equal the 3mm mdf frame piece. That way I could just place the CF tube arms over (as pictured). I made slight corrections to the positions of the arms while the glue was drying (measuring the 4 corners with a ruler, and making sure it was square).
Step 3: Figuring Out the Wiring
Once the glue is dry (usually is within 10 minutes), affix the cable ties to the arms/body and arms/mounts.
When I started, I wasn't sure where all the wires were going to go, so I fitted the motors to the CF mounts to get an idea of ways to arrange everything.
Step 4: Installing the ESCs
Next I laid out how I thought the ESCs could be arranged, and once happy with the layout I stuck them to the frame with the servo mounting tape.
Step 5: Foam Cover
Next I cut out the foam piece for the cover/top, then dug out a cavity to contain the ESCs/wires.
I had to do a number of 'fitting tests' like pictured here until it fit properly.
Step 6: Almost Done
Then I cut a hole in the top of the foam cover for the ESCs cables to go through, to plug into the NanoWii.
Once I could confirm that it all was OK, I then used the servo mounting tape on the four contact points (where the foam cover meets the base piece). Once these are bonded, it makes for quite a solid overall structure.
I considered Epoxying the cover onto the base, but thought I may want to access the wiring or ESCs at some point, so the mounting tape was a good compromise (I think). As long as it's good tape it will hold very securely. But you can hobby-knife the tape later if you want to get the cover off.
Step 7: The Paintjob
Then the mean, black paintjob was next. Prob the most fun step (I think).
Well, the flight tests would be the most fun, I guess, which came next. Everything went perfect. The NanoWii is great bang-for-buck, and am really impressed with the MultiStar motors.
Step 8: FPV Gear
After quite a bit of flying I was confident enough to put some FPV gear in it.
I didn't really have any particular cam or TX in mind at the plan stage, so it was a bit of a retro-fit, although the frame shape itself is especially for FPV.
I decided to slice off the nose (pictured), and make a custom cavity for the camera, then Epoxy'd it back on, with the wires going along the underside of the quad.
And them chose to put the video TX in the tail (as in main picture).
Step 9: Misc.
I put velcro strips on the bottom and also a small strip to the rear of the NanoWii, and experimented with where to place the main LiPo.
The CG can be achieved either way.
For the FPV setup, I use a small 3S, 180mAh Nanotech LiPo velcro'd to the rear of the NanoWii for the camera and TX.
Then velcro a 500mAh, 3S underneath for the motors/radio.