Welcome back to my build log/experiences with this project. 

After playing around with and figuring out where to put the various bits I went on to add the XBee headers, powercable and 3 pin RX header to the PX4IOAR: 

At this point I will skip further as the assembly is well detailed in pictures on the PX4 website. I would add that getting the spacers in between the PX4FMU and IOAR is not entirely simple without 3 or more hands, but just fiddle in the white spacer first, then push down the screw through the FMU, one by one is probably one of the easier ways to do it. 

Here is what you end up with after assembly: (zippo again for size - the quad is tiny!)

Ok, now we need to get this all fitted into the EPP foam body donor of the AR Drone, including the GPS and the FLOW. 

Bottom view (I know the battery is a bit incorrect, I took only one pic of this)

In the above picture you can see both the cutout for the battery as well as that for the flow unit. I am not 100% sure yet that the sonar will not have issues, but I hope not. Would not want to mount it any lower as the lens will poke out then and strike ground if it comes down hard. 

Topside GPS mount closeup, as you can see I cut out a flat plateau first, and then carved a smaller space in the middle for the cable and the chip etc on the bottom of the module:

It's ALIVE!!! Look at the pretty lights! 

Next up at this point is to test everything together, get the startup script correctly set up etc, plus installing the FrSky receiver when my FrSky DR 4-II arrives. 

Sharing some pics etc from my PX4FMU/AR Drone build. 

I got the AR Drone carrier to be able to fly the PX4FMU inside to test small things whenever, plus the AR Drone airframe is very well suited to packed urban environments like where I live. 

I do also plan on using the PX4FMU for other airframes, but it seemed sensible to get all the software bits working the way I want them to before I attempt to put the FC on an airframe I am unfamiliar with that may introduce it's own issues. 

The components of the build: 

AR Drone 1.0 (all control electronics and cameras removed)

PX4FMU

PX4IOAR 

PX4FLOW 

uBlox LEA-6 3DR GPS 

Digi XBee Pro (will be testing different radios)

FrSky DR 4-II PPM (not in pictures, yet to arrive)

The goodies arrived in a small box: (zippo for size)

Here is the patient awaiting transplant next to the battery I will use: 

Whats in the box?! 

Just to detail some of what I did not expect: 5 -> 6 position DF13 cable included with PX4FLOW, also correct GPS cable included with PX4FMU. 

Also included stickers with PX4 logo, plus branded micro SD card and reader: 

At this stage I tested the gear I could, so after toolchain installation, setup, etc I got the latest firmware sources, built it and flashed onto PX4FMU, and then tested the PX4FLOW through QGroundControl. 

Now lets get to work, first we need space for the battery: 

Then figure out where and how to place the components + some more carving done: 

This is continued in next post as I cannot add more pics to this one :-) Co Be Continued...