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Old 27th October 2016, 11:03 AM   #1
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Default Heavy Lift Hexacopter scratch build

UPDATE 3: The big hex has been converted to a Y6!

Benefits are mostly pretty obvious, although the cool factor is somewhat reduced

See the test flight here:



UPDATE 2: Took it for another fly



UPDATE: 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.





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

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.



Ultimately it was a good learning experience but not what I wanted. Cue this design:



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:





This was the first design 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.



An exploded view shows roughly how the frame fits together:



--

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.



I designed it to take the same motors I used on the HAL:



I just used two bolts instead of four per arm



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



The completed product:

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Old 27th October 2016, 11:05 AM   #2
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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, so with a few revisions to the rest of the frame, I have started building version 2. At this point, I haven't put any hardware on version 1 and don't really intend to.

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

Thicker (3mm) plate for the motors
(optional) two motor plates per arm, with vertical posts for strengthening - looks tough as
Actually useful battery tray
Lighter and simpler Pixhawk tray, with holes for mounting a GPS mast
Lighter bottom plate
Longer, lighter and better looking landing legs
Designed for 20x20mm hollow square tube arms, the first design was intended for 20x40mm which turned out to be too big and cause problems when I built it with 20x20mm.
Optional top plate to hide electronics... I called the frame the "ROKU" (six in japanese) but in hindsight it sounds a little lame so I might change it or just not use the cover plate

The new specs list is looking like this:

MultiStar 4830-420kv motors
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 antennas
6S 8000mAh (~980g)
Tarot gimbal
GoPro

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



These motors are HUGE:


They spin nice and smooth too


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


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 and because I couldn't get the holes drilled accurately I had to drill them bigger so I could position the arms straight. Not ideal. I built a jig but the drill press I have has so much play in it, and the chuck isn't even straight, so it's even more useless than doing it by hand.

Stay tuned
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Old 27th October 2016, 8:06 PM   #3
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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?
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Old 27th October 2016, 8:22 PM   #4
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what the fuuuuuuudge... that is sick - I want one
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Old 28th October 2016, 7:51 AM   #5
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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?

Curious also what you went with the Pixhawk?
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Old 28th October 2016, 12:08 PM   #6
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Quote:
Originally Posted by Amfibius View Post
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?
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 but again not really relevant to copters of this class. isrr.slack.com is our public slack group (http://isrrinvite.herokuapp.com/ to join it)

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what the fuuuuuuudge... that is sick - I want one
Thanks!

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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?

Curious also what you went with the Pixhawk?
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 That Talon looks sweet but if this is your first multirotor i'd order a couple of those frames... they won't survive a crash

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
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Old 28th October 2016, 12:54 PM   #7
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More, mooooore.
This looks sick.
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Old 28th October 2016, 1:46 PM   #8
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Quote:
Originally Posted by ShadowBurger View Post
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 That Talon looks sweet but if this is your first multirotor i'd order a couple of those frames... they won't survive a crash

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
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.
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Old 28th October 2016, 5:02 PM   #9
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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

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?

.

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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.
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
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Old 29th October 2016, 11:12 PM   #10
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Scribing


Centre-punching


Drilling carefully


Bolting things together


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


Kinda looking cool


Big mess in the lounge room...


More to come once I get motors from Hobbyking
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Old 30th October 2016, 9:33 PM   #11
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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.





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


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


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.


Tonight I did the last of the drilling () and bolted it all loosely together. Looks OK Can't really continue with the build until more parts arrive
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Old 31st October 2016, 8:55 AM   #12
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Quote:
Originally Posted by ShadowBurger View Post
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.
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?
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Old 31st October 2016, 9:44 AM   #13
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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!
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Old 31st October 2016, 1:46 PM   #14
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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?
Cheers! No... no it isn't. I find that everything on the Pixhawk "works", but that there are a lot of things you need to know in order to get those features to work. The documentation makes it sound simple but I've had to do a lot of extra googling in addition to basic reading. Patience is definitely key.

I'm expecting to get "enough" range not to have to worry about the stability of the radio link. Dragonlink boasts up to 50km range with stock antennas and an average antenna installation... which seems optimistic. If I got 20km I'd still be thrilled with it though. Will I ever need that much? Not at all likely Batteries will be flat before I can get half that distance. That doesn't apply to the telemetry though - the receiver doesn't transmit at the same power level as the transmitter, so I'd expect less performance on the incoming side. Transmitting MavLink data (the telemetry format used by Pixhawk) is quite bandwidth intensive, relatively speaking, and requires the dragonlink to be configured with fast update rates and high latencies and whatnot. I expect that the data link will become unusable long before the R/C signal drops out (i'll lose telemetry and the ability to update waypoints, but will still have control of the copter).

EDIT:

Quote:
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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!
sounds like fun! if I may suggest: 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
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Last edited by ShadowBurger; 31st October 2016 at 2:01 PM.
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Old 1st November 2016, 4:14 PM   #15
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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.
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