[PROJECT] Heavy Lift Hexacopter scratch build

Discussion in 'Other Toys/Hobbies' started by ShadowBurger, Oct 27, 2016.

  1. ShadowBurger

    ShadowBurger Member

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    UPDATE 5: My favourite photo of the hexa so far

    [​IMG]

    UPDATE 4: The big hex has been converted to a Y6!

    Benefits are mostly pretty obvious, but include improved yaw authority and a clearer angle for the camera to see out front (between the prongs of the Y). Although, the cool factor of having six arms is somewhat reduced :thumbdn:

    See the test flight here:



    UPDATE 3: Took it for another fly :)



    UPDATE 2: had a chance to shoot some more video. Still haven't felt game enough to mount the gimbal, but that will happen soon. I've set up a number of failsafes and am doing some final tuning to sort out the flight characteristics.

    scuse the cheesy dubstep....


    UPDATE: bit of an update for new readers... the big hex flies but is far from finished :) I haven't yet flown the camera and gimbal but it's close! just waiting for a new 12V regulator to power the video transmitter.



    [​IMG]

    -------------

    Hi there!

    I thought I would share my experience designing from scratch and building a "heavy lift" (15kg+ thrust, about 3kg weight, not inc. payload) hexacopter.

    I've only ever touched racing mini-quads, so I started my foray into heavy lift with the "HAL" (heavy aerial lift) Turnigy frame from HobbyKing. The frame is okay, but not amazing, and I always wanted this copter to be a hex for the additional lifting capacity. I got two of the frames for $4 including shipping in a sale, so it was a good place to start learning how to fly the Pixhawk PX4 and my Dragonlink radio.

    [​IMG]

    Ultimately it was a good learning experience but not what I wanted. I ended up putting it up a tree, the retrieval of which caused some major damage. Spot the drone!

    [​IMG]

    Cue this design:

    [​IMG]

    I didn't want to use round arms due to the complexity of mounting them to flat surfaces. I also wanted the ability to easily mount:

    px4
    gimbal
    pdb
    GPS
    antennas
    fpv gear

    There was quite a bit of design evolution but the concept remained the same throughout:

    [​IMG]

    [​IMG]

    This was the first set of designs I sent to get cut from carbon fiber. I got it done by Paul at Bezerk RC (bezerk.com.au). Great service, fast, and he offered me some design advice and fixed up some errors in my sketch.

    [​IMG]

    An exploded view shows roughly how the frame fits together (and looks cool):

    [​IMG]

    --

    I got the carbon fiber parts and was stoked with the quality, but realised a few mistakes I had made, such as too many bolts for the arms, and the battery tray didn't work as well as I'd hoped. Happily though, the carbon fiber cutting was great quality and looked fantastic:

    [​IMG]

    I designed it to take the same motors I used on the HAL. I just used two bolts instead of four per arm and it proved to be plenty strong and rigid enough.

    [​IMG]

    The top plate was designed in two parts so that it can be removed without unbolting the arms:

    [​IMG]

    The completed product:

    [​IMG]
    [​IMG]
     
    Last edited: Feb 8, 2018
  2. OP
    OP
    ShadowBurger

    ShadowBurger Member

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    So that's version 1 of my hexacopter frame. I wasn't happy with the size of the motors I designed the frame for (WAY undersized) so with a few revisions to the rest of the frame, I have jumped straight into building a version 2. At this point, I haven't put any hardware on version 1 and don't really intend to ever use that frame.

    Some of the improvements over version 1 of this frame are:

    • Thicker (3mm) plate for the motors to handle more thrust
    • Two motor plates per arm, with vertical posts for strengthening - looks tough as :)
    • Actually useful battery tray
    • Lighter and simpler Pixhawk tray, with a place for mounting a GPS mast
    • Lighter bottom plate
    • Longer, lighter and better looking landing legs
    • More ventilation for ESCs
    • A cover plate to hide all the electronics.... not sure how it will go, but we'll see :)

    The new specs list is looking like this:

    • MultiStar 4830-420kv motors (bloody HUGE)
    • Carbon Fiber 15x5.5 props
    • Flycolor 30A Opto ESCs
    • Pixhawk PX4
    • 3A 5V BEC
    • 1A 5V / 12V BEC (PDB)
    • Dragonlink V3
    • 1.2Ghz 800mW "FOX800" VTX
    • IBCrazy LHCP antennas
    • 2x 6S 8000mAh (~980g ea)
    • Dragonlink OSD

    Got the new design back from the cutter. Again, this was from Paul at Bezerk RC (http://bezerk.com.au). Excellent quality cutting, material, and service once again:

    [​IMG]

    These 4830 motors are HUGE:

    [​IMG]

    I am using two motor plates per arm joined together with standoffs. Looks much tougher and cooler than the V1 frame:

    [​IMG]

    At the moment I am stuck at building a jig to drill the holes in the aluminium arms. The previous frame was a nightmare to put together because I couldn't get the holes drilled accurately enough. A drill press would be better but I don't own one...

    [​IMG]

    Stay tuned :)
     
    Last edited: Jan 9, 2018
  3. Amfibius

    Amfibius Member

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    I WILL be staying tuned! This looks like an awesome and fun project!

    I see you're in Melbourne. Is there a club that flies these things?
     
  4. Kommandant33

    Kommandant33 Member

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    what the fuuuuuuudge... that is sick - I want one
     
  5. Andres

    Andres Motor Admin

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    Very interesting. I'm just starting a build myself, but based on the Turnigy Talon frames.

    What's the goal for lifting? Just as much as possible, or a specific camera, 6 pack of beer? :lol:

    Curious also what you went with the Pixhawk?
     
  6. OP
    OP
    ShadowBurger

    ShadowBurger Member

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    Cheers! Yep I'm part of a few clubs, but that's mostly just for racing. I think people usually only build copters like this for professional reasons so there isn't much of a club scene around it. That said - Inner Suburbs Rotor Racers, FPV Buddy and Eastside FPV Inc. are the facebook groups I'm a member of. We go out racing most weekends :thumbup: but again not really relevant to copters of this class.

    Thanks! :D

    At the moment I have a Tarot T4-3D camera gimbal for a gopro but if this goes well i'll likely want to carry some more high-end camera gear. Definitely going to try carrying some beer around with it :lol: That Talon looks sweet

    Pixhawk seemed to be the only option really. I wanted to build this just for lols initially, but the more I play with it the more likely it seems I might get some work out of it. The Pixhawk is pretty powerful and Mission Planner has a LOT of features making it useful for things like surveying and performing specialised tasks
     
    Last edited: Jan 9, 2018
  7. Alby1976

    Alby1976 Member

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    Mt Isa, again....
    More, mooooore.
    This looks sick. :thumbup:
     
  8. Andres

    Andres Motor Admin

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    I've got a couple of smaller quads (1x250, 1x180) but this would be first 'big' one. Not planning on crashing (thats whats the little ones are for).

    Didn't consider the Naza flight controllers? Mainly curious as I'm tossing up between a Naza-M Lite and a Naza v2, but never really considered the Pixhawk.
     
  9. OP
    OP
    ShadowBurger

    ShadowBurger Member

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    Cheers Alby :) I'm hoping to have the v2 frame assembled this weekend. It looks like I'm going to have to measure out, scribe, centre-punch, and drill 60 holes though, with no room for error :tired::tired::tired::tired:

    Still waiting for Hobbyking to fix their fuck-up (one of many) and send me the other four correct motors... What's wrong with this picture? :rolleyes:

    [​IMG].

    I have looked at the naza-m but it's not even close to being as flexible as the pixhawk, not to mention pixhawk is open source. I do like the Naza-M V2's ability to handle motor failure like a champ though :D
     
  10. OP
    OP
    ShadowBurger

    ShadowBurger Member

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    Scribing
    [​IMG]

    Centre-punching
    [​IMG]

    Drilling carefully
    [​IMG]

    Bolting things together
    [​IMG]

    Throw in a slice of pool noodle and bolt together until it looks like landing gear. Then promptly realise you put all three arms with landing gear on one side and have to undo it all again :thumbup:
    [​IMG]

    Kinda looking cool
    [​IMG]

    Big mess in the lounge room...
    [​IMG]

    More to come once I get motors from Hobbyking :)
     
    Last edited: Oct 29, 2016
  11. OP
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    ShadowBurger

    ShadowBurger Member

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    Just thought I'd share some info about the flight controller and other hardware that will go onto this multicopter. Going back to some shots of the old HAL here. This video was from the day when I was testing the autonomous capabilities of the Pixhawk. Here, I specified three waypoints; launch, move to a spot nearby, then position-hold. Lastly, I interrupted the position-hold by flicking the RTL switch (return to launch), which took it back over to where I set the home position, then landed. The Pixhawk performed flawlessly, with the exception of some instability on take-off which was related to tuning.



    [​IMG]

    Here you can see the flight controller close-up, with the radio receiver (Dragonlink) beneath it.
    [​IMG]

    The disc on top of the mast is the GPS antenna, the other straight dipole antenna is the UHF antenna for the dragonlink
    [​IMG]

    For those who don't know, the dragonlink is a long-range UHF (433mhz) alternative to 2.4GHz transmitters which also supports bi-directional data, so I can interact with the mission parameters and receive telemetry while in-flight.
    [​IMG]

    Tonight I did the last of the drilling :tired::tired: and bolted it all loosely together. Looks OK :thumbup: Can't really continue with the build until more parts arrive
    [​IMG]
     
    Last edited: Jan 9, 2018
  12. Andres

    Andres Motor Admin

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    Looking really good!

    Is the Pixhawk very user friendly? I always find a lot of open-source projects seem to be more tailored towards the experts.

    What sort of range are you expecting with the UHF connection?
     
  13. Amran

    Amran Member

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    Subbed - this is exactly the kind of thing I want to make, only mine will be quite a low budget effort involving a home-made ardunio based controller. Looking forward to seeing what you stuff up so I don't do the same how it all turns out! :D
     
  14. OP
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    ShadowBurger

    ShadowBurger Member

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    Cheers! No... no it isn't. The documentation makes it sound simple but I've had to do a lot of extra googling in addition to basic reading. Patience is key.

    Dragonlink boasts up to 50km range with stock antennas and an average antenna installation... but if I got 20km I'd still be thrilled with it. Will I ever need that much? Not at all likely :thumbup: Batteries will be flat before I can get half that distance. The point of the dragonlink is its ability to transmit bi-directional data so I can receive telemetry on the ground and do mission planning / control while it's in the air.

    EDIT:

    sounds like fun! you can get a flight controller with much more processing power for less than the cost of most arduinos, such as the naze32. These will control up to six motors and depending on how many degrees-of-freedom (DoF) you select they come with magnetometer (compass) and barometer (altitude) sensors on board. The issue with arduino / atmel based FCs is they lack the processing power to remain responsive while handling all the flight calculations and whatever other tasks you want them to perform
     
    Last edited: Jan 9, 2018
  15. Andres

    Andres Motor Admin

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    Sounds like some crazy range!

    I'm stuck in a bit of a loop playing with eCalc, trying to determine prop size, pitch and motor selection.

    Really keen to try some AP of my wife's crew rowing in the bay over summer.
     
  16. OP
    OP
    ShadowBurger

    ShadowBurger Member

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    I've had a play with eCalc... IMO, if you know the frame size / type you are going to work with and what you want to carry, it's easier to look for motors with sufficient thrust for the load, then select a frame that will accept the motors and the desired prop size (most motors will list suitable propellers), then lastly select batteries to suit the motors.

    Bit of a minor update on the hex while I'm waiting for the remaining motors, which still haven't been shipped:

    The beast at the moment:
    [​IMG]

    Today I covered the arms with cloth tape purely for looks, and to assist with orientation. I guess I'm going with a red and black theme on this build!
    [​IMG]

    Since I had the arms off, I did some further drilling out of the holes to make them easier to slide the bolts through. The frame was distorting a little under the weirdness caused by sorta having to force the bolts through holes that didn't quite line up.

    [​IMG]

    While I was at it, I fitted some extra little plates I made to hold nuts captive. This is to make the top flight controller plate super easy to remove to get at the power distribution and ESCs underneath, which I predict will be needed a lot as I add components and stuff to the hex.

    [​IMG]

    Next I'll start soldering together the ESCs and power distribution while I wait for motors to arrive.

    EDIT:

    I soldered some things. Some reviews of these motors suggested there are issues with the bullet connectors so I cut them off and soldered the wires straight to the ESCs. In future I'll order some bigger bullet connectors which I'll fit if (when) I need to remove a motor

    [​IMG]
     
    Last edited: Jan 9, 2018
  17. Subliminal

    Subliminal Member

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    this is really interesting, cheers for sharing :thumbup:
     
  18. OP
    OP
    ShadowBurger

    ShadowBurger Member

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    I put a single prop on and spun a motor up to full speed to get a feel for the power to weight ratio... needless to say... I'm satisfied the thrust rating is accurate :Paranoid: this thing is terrifying... I have the frame gripped tight, like I'm leaning on it and pressing it into the rug just be safe, and it still lifted off the ground. With a single motor. :wired:

    :leet::leet::leet::leet::leet::leet::leet::leet:

     
    Last edited: Jan 9, 2018
  19. Andres

    Andres Motor Admin

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    Sweet! These big beasts are much scarier than their 250 breatheren.

    How much headroom do you think you have on those ESCs?

    And looking at your original drawing, what size prop diameter does your drawing show? (they're quite close yeah?)

    Apologies if in a earlier post, tried skimming through on my phone.
     
  20. OP
    OP
    ShadowBurger

    ShadowBurger Member

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    Hi Andres

    Should have just enough headroom on the ESCs, which are 30A nominal, 40A max. The motors are about 30A nominal, 46A max on a 15x5.5" prop which is what I'm using, but that's according to the sheet below which doesn't seem to make a lot of sense to me because the 17x5" prop has less thrust than the 15x5.5". It looks like most of the values are guesswork as well... After the brief run in the video I posted, the ESC was cold, so I'm satisfied it'll be okay. They have pretty big heatspreaders on them and I've designed the frame specifically so they get a lot of cooling. It should never be at full punch during flight anyway, unless I get a bit silly and decide to do some acrobatics :tongue::tongue: (totally gonna happen)

    [​IMG]

    The props in the drawing are 15"

    EDIT: nope, the props in ver1 were 12". This is the current drawing with 15" props

    [​IMG]
     
    Last edited: Nov 3, 2016

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