The main objective of this project is to build a dual purpose multirotor, able to fly heavy lift payloads for videography and lightweight cameras for aerial mapping.
We want to be able to fly different missions, with minimal part changes. To achieve this we decided to maintain the center frame (flight controller, power distribution board, battery packs) and change booms (with motor and ESCs at the end) when wanted. Open the case, get the center frame, choose booms and fly. This first part of the build consists of the heavy lift configuration, and parts for the long endurance config still need further research to be purchased. This build will have an A2 controller (because we have a spare one at the shop), but later will be changed for a Pixhawk, which is our preferred controller for aerial mapping).
Objectives:
- Small form factor when disassembled for ease of transport
- Quick-release arms
- One carrying case for both multirotor configurations
- Quick release system for different camera gimbals
- Heavy lift payload around 5kg (Red Epic + Light Lenses)
- Light weight payload: Sony A7R
Parts used for HL configuration:
- Cinestar 8 frame X-8 configuration
- Famoushobby 25mm metal boom clamps
- Catalyst Machineworks 500mm C25 quick release boom system
- Avroto AVL3520/520 motors
- Spyder 60A Opto ESCs
- Foxtech Supreme 1550 props
- DJI A2 Controller (later to be changed to Pixhawk)
- Ronin M Gimbal
- Foxtech FPV D130 dual landing gear
- Powerhungry PHS-10 distribution board
- Tattu 10A 6S battery packs
Parts used for Long Endurance configuration:
- Cinestar 8 frame X-4 configuration
- Catalyst Machineworks C25 quick release boom system
- KDE 7208XF-110 or Tmotor U8 100kv (to be decided)
- KDE Direct XF UAS 75A+ or Foxtech Multi-Pal OPTO 80A HV ESC (to be decided)
- KDE Direct 27.5" x 8.9 or Foxtech Supreme 2880 (to be decided)
- Pixhawk Controller
- Custom built Gimbal (for Sony A7R)
- Tattu 10A 12S battery packs
- Powerhungry PHS-10 distribution board
Replies
I sent an e-mail to the manufacturer of the C25 quick release system, asking about the optimum position for installing the booms at center frame. Below is his response. I thought it would be interesting to share for whom may be following the build. I sent him the following 2 pictures, and after that you can read his replies.
Response:
"The C25 is designed to be mounted up flush to the center hub of the craft (like picture 2). This keeps overall size of the detached hub smaller for travel.
Plus I noticed in your pull tests you had the couple rotated 90 degree from where its optimum orientation is. You want to mount it and pull it at 90 degree to where you had it. In other words the red clamp should not be facing straight up but rather parallel with your work bench. This will most likely stop that little bit of movement you saw where the interior coupling edge mates to the CF tube."
After that I asked about the optimum pressure one would apply to the main tube clamps...
Response:
"This is a little of a gray area to be honest. The reason is every carbon fiber tube manufacturer produces tubes with slightly different OD's. And the same manufacturer will produce two batches with two different OD's! The C25 will compress down to that OD. So the required position of the arm might be different from tube to tube.
BUT, as a general rule set the arm as in the picture. Or maybe even with the top of the arm horizontal for a nice tight fit. You can get a feel for what is correct after a while. Also, with the testing you did it will help you to know where that "sweet spot" is."
What a great customer support, that's all I can say. You should take a look at their instructions manual, amazing quality. Let's hope it works as expected.
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Arm.jpg
Pictures of the build:
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Starting the build. Put main parts on scale to have an idea of total weight before assembly.
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Before starting the assembly of copter I did some further tests with the boom mechanism to be sure (at least try to be sure) it will not fail on flight. This test was focused more on the joint points. Sorry it was a bit long after all.
Joint Test:
https://www.youtube.com/watch?v=Q-TvIpF03tM
I have been researching for quick release systems for a long time, and had quite a few issues with some makes I got at the past. Normally the joints are not deep enough or show some play after a few flights, which can be very scary. I ended up getting this one as it looked really well thought out.
I performed 2 tests yesterday, one for vibration resistance and weight tolerance (they have a similar test on their website but I preferred to make my own test as well). For the vibration test I left the system running for almost half an hour to check possible play on screws and moving parts. It produced some heavy vibration, a lot more then we would expect on brushless motors, and at the end it was totally intact, with no plays at all. Looks promising.
Take a look at the tests I did:
Vibration test:
https://www.youtube.com/watch?v=ckY_Nm227n4
Load test:
https://www.youtube.com/watch?v=6UN2Pvg-f5A