Thrust test of Emax MT2204 vs Tiger Motor Air gear 200

update also comparison with HQprop 6x45 on Tiger motor Mn2205 to check if the difference is mainly due to the prop.

Franken Phantom with APMcopter / Pixhawk

The goal of this build is to have a reliable quadcopter that:

• fits into a backpack
• can fly for >15mins (min >10mins)
• has autonomous waypoint flight
• return to home function
• can carry a mobius or gopro including brushless gimbal

The DJIPhantom is a very popular airframe. It is so successful because it is easy to fly for beginners (thanks to the DJI flightcontroller) and has a reasonable flight endurance (version 2). So for me it ticks all the boxes above. I don't like my copter to fly away when it has a funny moment and I am a fan of open source and ArduCopter. So I decided to essentially take a naked Phantom shell and fill it with my own selection of hardware.

The ingredients are:

• DJI Phantom 2 / Vision replacement shell and landing gear
• original DJI, http://www.buildyourowndrone.co.uk/dji-phantom-2-vision-shell.html
• 4 DJI E300 motors
• these motors are very well made. Perfectly balanced. No vibrations. I run them with below props on 4S. Only slightly warm after >10min flights. A bit warmer but not hot when pushed around at high (75 to 100%) throttle. They are relatively cheap, good quality and easily available.
• set of DJI E300 propellers (or rotors as they like to call them now)
• very nice design, perfectly balanced. I have >10 props and I couldn't detect any imbalance at all. Nice!! The self-tightening is a good feature. No fear that a prop will come loose in flight. It also ticks the backpack requirements. It takes literally 10 seconds to take all 4 props off. These props are very thin at the tips, almost translucent. But surprisingly I couldn't find any negative effects in flights. Very durable. Survive a fair bit of bending and crashing.
• full kit: http://www.buildyourowndrone.co.uk/dji-e300-tuned-propulsion-system-quadcopter.html £87, or 2x CW, 2x CCW, + props = 4*£21+ 2*£11 = £106, no-brainer.
• Shell, motors, and propellers are the only DJI items, the rest is a wild mix:
• 1 Hobbywing quattro ESC 20A
• I like the simplicity of a 4 in 1 ESC. No messy wiring, no power disrtribution board needed. The DJI E300 set includes ESCs with a nice coaxial power cable to minimise magnetic fields, but I don't like the lower fixed PWM range (1120-1920 usec). They would require to change RC transmittor throttle range, I'd rather calibrate the ESCs to match my Taranis.
• I stripped the heatsink off it. At hover the Franken Phantom pulls 13A, so 3.25A per motor, i.e. the 20A ESC is not even getting tickled. only 40g without the metal heatsink and bottom plastic cover.
• 3DR Pixhawk
• I bought the original, not a clone. I'm fed up with clones. Some of my APM clones died or had components fail. One APM behaved erratic in flight. The original Pixhawk is a bit more expensive compared to a clone, but it is 100% tested and has a warranty. I was very positively surprised as it comes with a 3DR power module included!! USB cable, SD card, all other cables etc.... http://www.buildyourowndrone.co.uk/3dr-pixhawk.html
• 3DR GPS+compass module
• same here, no more clones and crap GPS signal. This is a huuuuuuge improvement over cheapo clone GPS modules I used before. It picks up GPS signal indoors (upstairs under roof) and enables rock solid Loiter and waypoint flights. http://www.buildyourowndrone.co.uk/3dr-ublox-gps-with-compass-lea-6h.html
• Walkera G-2D, 2 axis brushless gimbal
• people are raving about the DJI zenmuse. I never used one, but for me it is way too expensive. There are loads of cheapo gopro gimbals around. Or one could build a DIY one with an alexmos board. After a long search I decided to go for the Walkera. It is really light. Only 136 g including the controller! (zenmuse H3-2D is 230g) I got a Walkera G-2D for approx £60 on ebay. After using it a for a bit now, I like it. It has the occasional jolt at large tilt angles, the chinglish manual is hilarious but completely useless, tuning it is a nightmare (no USB/bluetooth, just silly button press sequences and mini screws, I gave up and left the default settings) but for £60!?! It performs very well. Well enough with a Mobius (not exactly balanced), perfectly with a gopro. Not a glitch in 'normal' flight conditions.
• Mobius to GoPro conversion case
• https://www.hobbyking.com/hobbyking/store/__61696__Mobius_To_GoPro_Form_Factor_Conversion_Case_for_Gimbal_Mounting.html
• Sony SuperHAD 600TVL
• The mobius will be on the gimbal, the Sony CCD is for FPV and fixed to the copter shell.
• MinimOSD 1.0
• so I can have APM telemetry displayed on my FPV feed
• FVP 3 channel switch
• to switch between analogue CCD and Mobius/gopro
• http://www.hobbyking.co.uk/hobbyking/store/__29651__Hobbyking_3_Channel_FPV_Video_Switcher.html
• ImmersionRC 600mW 5.8GHz video transmitter
• I used Boscam transmitters before, so I wanted to try this one
• DC stepdown converter to power transmitter, FPV camera, and the gimbal with constant 12V
• http://www.electriflite.co.uk/store17/index.php/sdvr-2.html or ebay
• OpenLRSng miniRX UHF receiver
• http://www.fpvmodel.com//hawkeye-dtf-uhf-minirx-433mhz-long-range-receiver-_g707.html
• Bluetooth module for configuration and pre-flight setup.
• http://www.unmannedtechshop.co.uk/bluetooth-module.html
• I plan to use the serial bridge of OpenLRSng for long range telemetry at some point, but haven't figured it out yet.
• Last not least:
• I have a couple of Zippy compact 4S 4000mAh (weight 370g) lipo batteries
• I recently ordered two hobbyking multistar 10C lipos. Also 4S 4Ah. They are lighter (325g). Only done two flights so far, but I'm happy. Enough power, done 15mins slow flying using ~75% capacity.

Here are some photos of the build:

The ESC settings I use. Note: timing low

ESC and motor instllation. ESC is glued into bottom of shell with a little bit of space below.

FPV camera installed in body shell. I used a soldering iron to make a hole for it.

Gimbal and Battery will hang off the bottom on this piece of stripwood. The stripwood is attached to the phantom shell with double sided 3M soft tape and cable ties. The mounting and weight of the battery will add additional vibration isolation for the camera. The other nice feature is that the camera will not have props in the field of view as it does in the stock Phantom.

Top view with GPS, Pixhawk and OpenLRSng UHF receiver installed. The Bluetooth module sits in the front right arm (left in this photo)

No medals for beauty here. It looks very DIY with the stripwood and external battery, but no props in view even in very fast forward flight! Also very easy to move battery around to shift the COG to the middle / centre of lift.

Mini FPV mobius quadcopter

This is a build log for my new mini FPV quadcopter. Everyone is crazy about these ~250mm mini copters right now, so I wanted to give it a try...


Parts list:

• frame:
• Carbon Fibre QA250 Quadcopter Frame Kit from: http://makeitbuildit.co.uk/
• ESC:
• 4x EMAX 12a ESC speed controller (simon k firmware)
• Normally I like the hobbywing quattro escs as there is no need for a power distribution board or wiring, but even without the case the hobbysing quattro is 55g, 4 of these Emax escs are 32g.
• motors:
• 2x EMAX 1806 2280KV CCW thread motor
• 2x EMAX 1806 2280KV CW thread motor
• propeller:
• HQ Multirotor 5 x 3 Props, and HQ Multirotor 5 x 3 R Props
• flight controller:
• an old APM2.5 I had lying around
• a lot of people use the acro naze, but it is constantly out of stock, and as I am familiar with the APM installation and tweaking I opted for the APM. It is just super convenient to hook up a bluetooth module (see: here) or the 3DR radio (see here: http://plane.ardupilot.com/wiki/common-3dr-radio-version-2/) to configure the copter.
• Power:
• APM power module. http://plane.ardupilot.com/wiki/common-measuring-battery-voltage-and-current-consumption-with-apm/ This powers the APM and also measures battery voltage and current. I cut off the XT60 connector on the copter side and soldered some 16AWG cables to connect to the ESCs. No power distribution board needed.
• RC control:
• Hawkeye openLRSng miniRX UHF receiver (http://www.fpvmodel.com//hawkeye-dtf-uhf-minirx-433mhz-long-range-receiver-_g707.html)
• first time I ordered from FPVmodel. Order arrived within 4 days from China!!
• FPV:
• Sony super had 600TVL
• TS5823 32 Channel 5.8ghz mini video tranmitter here
• LHCP antennas: http://makeitbuildit.co.uk/index.php?route=product/product&path=70&product_id=138
• for recording a Mobius camera will be mounted on the vibration isolation mount
• I have not yet installed an OSD, but might install a minimOSD later. Keeping it simple for now.

Some photos of the complete build:

375g weight without battery

I only had these old nanotech 3S 2.65 Ah batteries lying around. a bit heavy at 212g.

589g AUW with the 3S 2.65Ah nanotech. It draws about 11A at hover. Only a little above 50% throttle. I am surprised how well the EMAX motors work. They are not even warm after flight. I might try 6x3 inch props.

APM 2.5 / 2.6 voltage regulator fix

Two of my APM boards have blown their 3.3V regulators. It is a common problem with APM boards and might be connected to plugging in the USB cable whilst the board is powered by the flight battery. There is a lengthy discussion thread on DIYdrones here: http://diydrones.com/forum/topics/ac3-1-rc5-spi-speed-problem?commentId=705844%3AComment%3A1457284

I got this for a replacement: http://www.coolcomponents.co.uk/voltage-regulator-3-3v.html
A little bit overkill, but it was cheap and available around the corner.

Here is an excellent video showing how it needs to be installed:
https://www.youtube.com/watch?v=5Ur_s2inGHY&list=UUlCZWv9dKygCflwty9_s8Sw
It is in German. A little summary:

• remove the blown regulator. For me a combination of soldering iron and brute force did it.
• add three short (few cm) servo wires to the regulator and wrap in heatshrink
• solder the output to the capacitors on the APM board
• solder ground and +5V to the side of the APM board. Labels on the underwise

Now my dead APMs are alive again! For less then two pounds!

Bluetooth Telemetry for Arducopter

After moving my RC control to UHF I needed a different solution for telemetry. Also being able to connect with a tablet or mobile via droidplanner2 (https://github.com/DroidPlanner/droidplanner, https://play.google.com/store/apps/details?id=org.droidplanner) directly over bluetooth is great. No need to carry around the 3dr radio set anymore.

I followed this great guide to set up the bluetooth module for use with arducopter. APM needs to be set to: 7----57600bps. I also changed the name of the module and the PIN. So nobody can log into my telemetry while I'm flying and redirect my copter ;-)

The wiring is straightforward: I used the cable that came with the 3dr radio and just cut it off and soldered servo cable connector on the ends. Red (+5V) goes to VCC, black to GND, the green to TXD, and the yellow to RXD. No changes are needed on the APM side. All on standard settings (57600bps).

It worked straight away using droidplanner2 on my nexus 5 and 7.

Repair a fried mobius

I have actually managed to supply the mobius with 12V! It worked for not even 1sec and it fried it!
Not a huge drama. Replacement board can be bought here: http://www.minidvcameras.co.uk/viewitem.php?productid=65

Open the case:

Unplug the battery and unscrew the circuit board:

Now the fiddly bit is to unplug the CMOS sensor. The little brown bit on left side of the plug has to be flipped up and then the ribbon cable comes out easily. Do not try to force anything. Install the sensor into the new board and put everything back together. All in all it was a 5 minute job.

Video out cable for Mobius camera

The mobius action camera supports live video out for example to use it as FPV cam or just to be able to see the recording video and check framing.

Live video out can be enabled with the mSetup program (get it here: http://www.mytempfiles.info/mobius/):

I ordered a video out cable for the mobius from here: http://www.minidvcameras.co.uk/viewitem.php?productid=35

Nice,  but a bit clunky to mount all these adapters on a copter. So switching cables into one plug. In order BLACK (ground), RED (5V power), YELLOW (video signal).

Finally I clip the redundant cables and remove the black shield. And we have a nice small video out cable with enough flexibility to use it on a gimbal mount:

Word of warning: NEVER connect 12V to the mobius! It will die!