I thought i would share my hexacopter build with the world, it's not finished as of yet but it is getting there.
This is my second multicopter build; the first being a quadcopter which i may make a build log about as well but basically it was to see if my choice of building materials etc would hold up with the hexacopter project.
Components I am using:
- NTM Prop Drive 35-36A series (1800k/v @ 875W)
- HobbyKing Redbrick 80amp esc
- Ardupilot Mega board
- Megnetometer
- Xbee Pro Telemetry
- GPS Module
- Spektrum DX8 tx/rx
- 10x4.5 props
- Carbon Fibre square tube 6mm
- Carbon Fibre sheets 300x300mm
- M3 nuts,bolts etc
- 3Amps @ 5v Micro UBEC
- Turnigy 5Ah 3cell (11.1V) LiPo (x2) (havent purchased yet)
- Assortment of silicon wire (24awg, 14awg, 10awg, 4awg)
- Assortment of plugs etc
Thought i'd better edit the post and add some of the first pictures i had taken...
Now only if i had access to a laser cutting or CNC machine... one can dream i guess. Main chassis plates:
Motor "mounts". Yes you may say i did a poor job of the mounts (not very well designed) but i wanted a light mount (so i could keep frame weight to a minimum) and something nice looking. I didn't go the modular approach with any of the frame design as i didnt see the point in my circumstance. to change the motor incase one breaks there are 4 phillips head screws i can undo to get it off. The roughly cut x-brace under the motor was to see how well it would work with a brace there. The gap between the 'shafts' on the arms is taller now and the x-brace is nicer to look at ;)
Getting ready for the assembly of the frame :)
Bog roll there was to wipe off excess locktight and i was sick at that stage and we had run out of tissues...
A third of the way there... thinking this thing is going to be huge. Always looks bigger off paper
Mainframe assembly complete. motors attached and escs placed where i think they should go.
Comparison next to my quadcopter:
Power distribution looms:
I will upload more pictures as i make progress. i will receive a new esc next week as well as the rest of the components i'm waiting on.
To do:
- Battery tray (another sheet of carbon fibre (hexagonal in shape) that will be suspended underneath the mainframe centre)
- Landing gear (not sure on how to tackle this yet)
- Connect electronics
- Find a method to mount the Arducopter Mega in between main frame CF sheets (throught the hole in the top sheet)
- Make up some brackets to mount GPS, Xbee Pro, Rx onto
- Probably numerous other small things
I would put down weights and stuff but as i havent finished the build it is a bit hard to say, but weights so far and projected weights are:
- Mainframe with escs, motors and all heavy wiring = 2100 grams
- Mainframe by itself = 600 grams
- Battery weight = 860 grams (10Ah)
So total flying weight im hopeing for is 3000 grams but i've given myself a worst case senario of 3500 grams.
Total lift with 10x4.5 props = 17.4kg (i was hopeing for more but because they are such high rpm motors the best props i wasn't able to find in both puller and pusher)
So worst case senario power:weight is around 5:1 so i could get around a 10kg maximum payload i guess (still gives me a 2:1 power to weight); I would have to wait and see about that though.
I tested power consumption of the motors with around 3.5kg of weight and i calculated i will have around 15 to 20 minutes flight time without a payload and i have made enough room for 20Ah of batteries if i want that bit extra flight time.
So far im happy with the frame and its strength. it takes considerable force to even move the arms and bend it.
If you want any pictures taken of it and uploaded i'm happy to do so and any feedback would be greatly appreciated and if you have any questions i will do my best to answer them as soon as i can.
Regards,
Jamie Good
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UPDATE:
So after a couple days of work and study i have had a part day to work on the hexacopter. Today i had my first flight (didn't go above 1 metre from the ground). There will be a couple hours of PID 'tuning' to do to get it to fly nicely. At the moment hover is at about 35% throttle (thats with a linear throttle curve). My hover power consumption estimations were a bit out as in hover the maximum i recorded was 54 amps (instead of my initial prediction of 40 or so amps) so my flight time with 10Ah of batteries wont be what i predicted.
The main components adding greatly to the weight I still have to make/install are landing gear which i hope to do as lightly as possible and i need to add another CF 'layer' to hold the batteries (unless i figure out another nice,clean way to hold batteries). so im hoping i will only have to add another 300 grams or so... fingers crossed.
I was wanting a video to post now but as my partner wasn't home and i dont have a proper camcoder etc (have to use our phones) i will need to wait for her to get home. Hopefully my batteries will be charged and it will still be light by that time so im hoping i can upload one tonight.
If anyone knows of an easy way to tune the PID values could you please let me know? as of now i am flying, landing, adjusting (up or down as needed) which is very time consuming and annoying.
Thankyou,
Jamie
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UPDATE:
Second ever flight. I changed the PID values a little to make for a 'smoother' flight... but they are a long way off from where they should be. Again if anyone knows an easy way to tune them it would be awesome if you share them.
Hopefully i can get these settings calibrated and frame finished so i can upload a proper flight video for everyone. Can;t wait to get a camera on it!
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UPDATE:
Took the copter out again today to show a couple mates. Still haven't touched the PID values but i plan on doing some tonight after learning that i can adjust each value via channel 6 (the pot) on my Tx, which should make things easier. All components are still sitting ontop of the chassis which isn't ideal as the IMU isn't level with the copter but i can just compensate with the controls :P.
Nice windy day at the beach :).
"Can it land on the table?"
"I Guess..."
Flying in a Garage... dont you just love Prop wash?
Also here are some pictures taken from the day. Please excuse the mess sitting ontop of the chassis :)
After a couple minutes of tidying the electronics i have a couple things where they should be...
Also while i'm thinking about it, i need a way to tell the orientation of the thing while its up in the air... i was thinking maybe some fluro orange tape or paint and make an arrow or line underneath a couple of the arms... any ideas?
Comments
Great design very original. I like the simplicity. This could make it possible also to build a portable flat hexa with removable arms ( tho it will become more complex that it should be). I think adding X cf plate like in th emotor mount about 1/3 the arm length with plastic/polycarbonate screw would even strengthen the arm and reduce the vibration (if there are any) but I think your design is already good. hope to see more vid
The arms are very strong. there is no movement at all in them, however if twisted you can twisted the arms a little, this isn't that bad because if you think about it there are no forces produced or encountered that will want to make the arms twist. There may be some 'vibrational' movement in that direction from unbalanced motors/props, i am unsure of what frequencies the arms are likely to oscillate at; if at all. Watching it flying, the frame is solid; doesn't have anything that vibrates out of control (or differently from the rest of it).
As of power distirbution. All batteries (i can have anywhere between 1 and 6 onboard) are wired in parallel, and all 6 motors are connected to the same batteries. I wouldn't want to connect any batteries in series unless it was to up the 'pack voltage'. ie if i needed 6s (22.2V) i could use two 3 cell packs (of the same capacity) in series and then connect that to the power distro...
Also - it looks like you're powering 3 motors per battery pack rather than wiring the packs in series? If so do you find that works ok?
Thanks for posting the pictures, Jamie. That's a BIG hex! So despite their length the booms can resist twisting?
Hi jpknobel,
Nice work.
I started to build my first quadcopter last month but i didn't finish it yet. I bought a wood frame to start because it cheaper. If everything goes ok, my next step will be a hexa with carbon frame.
Did you already test your last frame with wind? Is it ok? Or should the arms be tubular?
Thank you.
Filipe
Hi jpknobel,
Nice work.
I started to build my first quadcopter last month but i didn't finish it yet. I bought a wood frame to start because it cheaper. If everything goes ok, my next step will be a hexa with carbon frame.
Did you already test your last frame with wind? Is it ok? Or should the arms be tubular?
Thank you.
Filipe
Thanks jpknobel, I'll wait, while I'm trying to adjust mines. I'm trying to use the CH6 option but can't get it to work. At least I don't see the diferences.
Jason, I can't find the info about ch6 tuning using cli (I modified the APM config file, I can test the tune going from 0 to 1 when I move my pot) but can't see a difference in PID values.
Ah okay, thanks Jason, I had never heard of the Ch6 tuning option until now. For my quad i used to use the Xbees and mission planner, landing each time i wanted to change values. i will try the ch6 tuning method as it sounds a hell of a lot easier. Thanks again :)
If you use the ch6 tuning option in the CLI, you will want to do it while in flight. I don't know about using XBees with the mission planner. I've never tried, and the values are not range checked, like in CH6 tuning.
Jason
You may be right Patrick L, but i will wait and see. Yes the website he did share with us did have some very nice video work, good piloting skills in there as well.
John Lee, i'll try get a picture of the mounts up soon, they are nothing special, i'll mention what i would do differently with them as well. The tubes are seperated/secured using M3 bolts and nuts. not the most elegant solution but its strong and seem fairly light weight. Main precautions to cutting/working with CF are the dust it produces whilst cutting as it's so fine when you breath it in it can do permanent damage to your respiratory system. I always wear saftey glasses as well as a dust mask (a good one though with filters). Some people say to run water over the cut (which should stop the dust from becoming airbourne) but as i am able to make straight cuts fast it wasn't good enough.
If i was doing it again (will be doing for a mate) i will use lower k/v motors as props are easier to get, i dont see any MAJOR problems with using higher k/v motors.
nicolas grunbaum i can share with you my PID values when they are fine tuned, as of now it is quite unstable because i changed the PID values once from stock. If you give me a week i should have my hexa adjusted and flying well (hopefully) and i'll share the values with you.
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