One of the glass fibre arms of my quad shattered after repeated hard landings on a hard-wood floor, so I have some carbon fibre replacement arms on order. Meanwhile I thought it would be fun to experiment with foam cutting and trying to build a plane from scratch. With inspiration from MyGeekShow I decided to build a flying wing design using XPS insulating foam. One of the advantages of living in the cold north is that thick foam mats (6 cm) is widely available, so there is no need to glue plates together to get the required wing thickness.

The wings were cut using a 26SWG nichrome wire, with a 7 A 12V ATX power supply. The wire didn't get quite hot enough, so the cutting was very slow and I was worried that the uneven progress from tip to root would ruin the airfoil, but I think it turned out pretty nice. I designed my own airfoil with a flat bottom, quite similar to Clark-Y but I made it much thicker because I was worried about the rigidity of the tips of the wings. Turns out that isn't an issue, and I would probably go for a thinner air foil such as MH32 if I should do this again. I would also make the root chord longer to get more wing area. I have more foam laying around, and I'm waiting for a 32SWG nichrome wire which should cut nicer, so we'll see...

In the centre I added a rectangular piece of XPS which i rounded at the tip. I also cut out compartments for battery, receiver and speed controller, and found a nice way to mount the motor. The motor is pointed straight back, not slanted upwards like I see on many models, and I wonder if that is something I need to change. 

The wing span is 123 cm (about 48 inches), and the take-off weight is 450 grams. The center of gravity is calculated using the flying wing CG calculator, and if I was to expand the battery compartment to accomodate a larger battery, the CG would not be affected very much.

This is my absolute first attempt at foam cutting and plane building, and I'm quite happy with the outcome. Of course I still don't know if it will actually fly... If it does, and has some lift to it, I might install the APM and a camera - but my gut feeling is that it will be too small for that, and I do have a Bixler kit on order for that purpose.

Parts list:

• One 6 cm thick XPS foam mat
• Foam safe glue
• One glass fibre rod 
• Two HS-55 servos for ailerons
• Two aileron control horns and aileron rods
• One Nippy Black 0808/98 motor
• Propeller (haven't decided on the right one yet, pictured is a 8x6 RAM)
• 1300 mAh Lipo
• Turnigy 8 ch receiver
• Skywalker 20A ESC

Bottom side (yes, the antenna is too close to the ESC):

This is an update to my previous post about bulding my first quad copter. Finally the most important packages from China & Hong Kong has arrived, containing the motors and the new Hobbywing Quattro 20A ESC / 3A BEC. 

I have also purchased the Turnigy 9x which was quickly updated to the ER9X firmware using a standard Arduino as the programmer. I followed the instructions from here in case someone needs to do the same. I plan on upgrading the radio to the FrSky ACCT module which spreads over 40 frequencies rather than the Turnigy's 16, so it should be more resilient to interference from other 2.4GHz radios.

After having set up everything, verifying the correct rotation (and propeller placement) on each motor, calibrating the ESC and leveling the quad it was time for a test flight. Indoors of course, and with about 2x2 meters of unobstructed space available :-) I'm happy to report that it hovers like a dream in stabilize mode

Just thought I'd write a post describing my first quad build.

Parts list:

• Hobbywing (or clone?) X-450 glass fiber frame (205 g), x-configuration
• APM 2.5 with U-BLOX GPS
• Electron 6 channel 35 MHz receiver (Hitec Optic 6 transmitter)
• Hobbywing Quattro 4x20A switching ESC (no power distribution necessary!)
• EMAX CF2822 1200 kv motors
• 10x4.7 CW/CCW propellers
• 3DR 433MHz telemetry kit

I have also ordered a camera pan/tilt mount, and consider adding a Gopro HERO2, then connect the video out to a 5.8GHz video transmitter for FPV capability. I'm still waiting for the EMAX motors and the ESC before first flight.

A minor inconvenience was that the 3DR telemetry kit cable does not fit the new mini-JST style radio connector on the APM 2.5 board. I could not find a compatible connector in any local electronics store. However, opening up an old Logitech laser mouse I found the USB cable was attached to the circuit board with the right connector! Problem solved. Unfortunately the optical flow sensor in this mouse was some Logitech undocumented proprietary 20 pin chip, so only the connector was usable for the quad.

I'm unsure if the motors and propellers are a good match for this frame. According to some specs I found, each motor should produce a maximum thrust of around 700 grams with these propellers without exceeding the power of the ESC. I think the minimum recommended total thrust is about 2x the weight of the aircraft - my current setup is about 4x the weight...

The APM 2.5 board is mounted with zip ties on top of some soft non-conducting foam for vibration insulation. I think the zip ties will transfer most of the vibration anyway - the first flight will tell. The U-BLOX GPS is currently mounted on a single nylon standoff. I don't think this will hold during flight (or crash), so I will probably mount it under the CD-R spindle lid which fits nicely over the electronics.

I have ordered some 22 mm hex standoffs so that the space between the top and bottom plate of the frame will have room for the ESC. I added some cut-to-length velcro strips to the bottom plate to mount the battery.

Next update will probably be when the final parts arrive... stay tuned!