The other night I went to bed safe in the knowledge that packing teams in Germany, China and America had sprung into life, hurriedly shipping what will soon be my first real world experience with UAV technology.
Just few days later a small package with Chinese airmail written on the side arrived at my door...
The project overview
After reading, lurking and learning here on DIY Drones for the past year and a half, this is my first foray into the real world of autonomy so I am trying to take all the precautions.
My main goal for starting this blog series is to get feedback from the community about my designs and methods of construction, so please fire away!
The design itself is a carbon fiber folding quadcopter that is able to lift a camera (perhaps more than a GoPro) and get good flight times while being armed with the functionality of the Pixhwak.
Parts list:
- Of course - the Pixhawk Autopilot and GPS!
- X650 Carbon fiber frame from RCTimer
- Four 2814 710kr/V High Performance motors with 12" Carbon Fiber Props
- Hobbywing 25A 4 in 1 ESC
- Turnigy 9XR transmitter with the FrSky DJT module in the back
- D4R-II Receiver
- Turnigy Nanotech 4000mah 4S Battery
- Chargers and other accessories...
Tools:
- Hand drill
- Weller TCP soldering iron and accessories
- Glue gun
- Threadlock
- Superglue
- Heatshrink
- Drivers and Pliers
Of the parts listed above, those in bold I have received.
Issues
The first problem that I encountered was that the motors I had ordered did not fit my motor mounts. (motors had holes of 25 and 19mm, the mount had 16 and 19mm).
My solution was to drill an extra two 25mm holes into the carbon plates and mount the motors on locking washers:
After assembling all of the motor arms I assembled the frame, being careful to make sure everything is in place and thread-locked
Results:
The final result felt sturdy...
Main Concerns:
My main concern so far is regarding my choice of Motor and ESC.
As you can see in the chart below the 2814 HP motors weight in at 100g each and consume 23A to lift 1660g each.
My 4 in 1 ESC can only handle 30A for 10 second bursts and runs at 25 amps for continuous power.
Doing some rough calculations:
1660g x 4 equals 6640. Dividing that in half gives 3320g maximum weight for my quad.
Do you guys think this is cutting it a bit fine (risky)?
The hobby-wing ESC does have some interesting protection features, most notably...
...2.8 Full protection: Low voltage cutoff protection / Over-heat protection / Throttle signal loss protection.
Another minor concern is that I could only find 'purple' threadlock' in my local hardware shop... specified for threads that are 1-5mm. So it should be ok...
Other than that there have been a few anomalies with regard to the frame itself (namely one of the screw holes being a 3mm as opposed to 2.5mm), but they were minor issues and I am very impressed with the quality of the equipment so far!
Well, I'm off to replace the battery connector with some XT60's!
Part two will be posted when "goodluckbuy" parts arrive!
Jethro.
Comments
Hi Jethro,
I'm using the 4 in 1 ESC on my Flip Sport with FPV and big battery.
The big aluminum plate on it really sucks the heat out of it, it barely gets above ambient temperature.
Even flying it like a maniac.
If you are getting above 20 amps continuous, you should do what Quadzi suggested with a glue on heatsink, but I don't know how you can fly a multicopter with a max ESC rating of 25 amps at 20 amps continuous anyway.
You will be drawing less than half that in anything remotely like normal flying and these 4 In 1's do a great job without any mods.
I have a second 4 in 1 I am planning on putting on a quad with 4 of the 380KV T-Motor 3508 motors and 15" props.
I am still torn between a Tarot FY650 and a Turnigy Talon V2 with extended booms, but your RC Timer one looks like a good option too.
I am trying to build one efficient enough to be able to use Panasonic lithiums as an option but current has to be kept below 2C so efficiency and lightness are super important.
And max current has to be greatly limited to less than motor max.
And I don't want it to be just an endurance copter but a practical usable one.
The T-Motors listed have best in class efficiency at 50% throttle with 15" props (17.8 G/W) and even better below that.
It just so happens I have some lying on my desk!
No worries Jethro. If you do go down this route, you might find this stuff useful. Don't use this stuff, it works great, but you don't want it on your copter.
Thank you Quadzimodo! That is a fantastic and very practical idea, the good thing is that the frame that I have has a lot of CF surface area (as compared to the original Xaircraft frame) so that might be a very good option to look into.
Much appreciated!
Jethro - Fantastic build.
With regards to the 4 x 25 ESC. With AUW of around 3.3kg, the ESCs will only be running at a 50% duty cycle most of the time. It is only at maximum throttle that you will be approaching the continuous current limit.
Considering the platform you are building is for photographic work (not sport acrobatics), this is not something that is going to be a big issue.
If you would like to build in some extra cooling, then the top heatsink plate of the 4 x 25 can be sanded, heatsink compound applied, and placed against the carbon fibre frame. This will help such heat out of the devices, minimising your risk of heat soak and thermal limiting.