Bob Morley's Posts (10)

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3D printed tricopter - latest version.


Thought I'd share some pics of my latest tricopter, it'll be the 10th version and the second 'flying prototype' (with any luck).

The design has come a long way, I suspect its still over target weight but I *really* want to get this thing flying.

Its all printed in PLA so it can be made on any printer, even the really basic ones.

There have been quite a few changes, however here are the specs :-

- PixFalcon

- Raspberry Pi 2

- Arduino Teensy

- PiCam

- DYS 850kv motors, 10x4.5 props

- 30A ESC

- Dualsky 2300mAh PiPo (4S)

- Camera gimbal (only 1-axis)

- Bluetooth, Wifi, (3G possible)

- PS2 Controller

- GS9018 servos for gimbal & tail boom, 2:1 gear ratio for tailboom

The Pi2 streams video, telemetry via mavproxy, talks to the PS2 controller directly over bluetooth or via wifi to the groundstation, and streams controller inputs to the Arduino Teensy via I2C.

The Arduino handles all the real time stuff, it generates an SBus signal for the PixFalcon and will (eventually) sample sonar sensors.

Everything else is pretty standard. The camera gimbal is vibration damped with foam ear plugs, the PixFalcon as well by clamping it between foam pads and the front booms fold back for transport.

Here are some more photos :-




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Tricopter update

3689719702?profile=originalThought it about time I posted an update.

Attached are a couple of CAD sketches for the current Tricopter, the last one almost flew but was too fragile.

Changes are :-

  • Folding front booms.
  • Enclosed fuselage.
  • Foam plug anti-vibration mount for PixFalcon.
  • 2-axis gimbal (maybe)
  • M2M is 400mm
  • 3G, Wifi & Bluetooth, all at the same time

The prototype will have a 3D printed fuselage shell but I'm hoping to mould a polycarbonate sheet. Perhaps a coke bottle, a heat gun and a vacuum pump will do the trick. If it works out it'll be super light.


Here's a rear view showing the tail servo mechanism.

The servo is a GS-8901MG & the gearing ratio is 7:12 so there's plenty of torque.

One thing I'm not sure on - initially I put the GPS/compass module at the very front however I was going to try having it stuck to the top of the PixFalcon, for no other reason than it seems to fit and leaves useful free space at the pointy end.

Is it better to have maximum separation between the two compass modules or is that not really an issue ? I was also thinking the extra weight on the PixFalcon may help with vibration damping.

Thats all for now, I'll post an update when the first set of parts are ready for assembly.

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Tricopter tail boom linkage


Here's a better photo showing the tail boom linkage - basically a pair of printed gears.

This design has fewer parts than a conventional linkage, less things to break so hopefully more reliable.

There's a 2:1 gearing ratio between the servo and the tail boom. The servo moves +/- 60 degrees which seemed excessive so I traded motion for torque.

The gears really need to be printed in nylon but for the first prototype PLA is good enough.

There's no slop in the linkage and the tail boom rotates smoothly, so that's a promising start.

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Tricopter assembly

3689717960?profile=originalDry assembly to make sure all parts fit, so far so good.

The distance between motors is 450mm so obviously the arms need to be cut down.

A PixFalcon goes on top, the GPS/Compass module will either go directly on top of the PixFalcon or have its own mount at the front of the drone.

Target weight is 700 grams & its going to be close.

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Printing almost complete 13 hours later.

Not sure about the 'lurid purple' colour, for some reason it was the only filament left at the shop.

This version doesn't have a camera gimbal, I want to see what the all up weight is without any 'extras' and have some fun flying it for a while.

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Getting down to target weight has been challenging.

This version is lighter, stronger, and stiffer than its predecessors. Only airtime and hard landings will show if its good enough.

I'm printing in PLA with 60% infill, 0.2mm layers and slow print speeds which seems to give the strongest parts.

I'll post photos when its assembled.

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The design is almost complete so thought I would share it.

The remaining part is the connection between booms and the chassis, which needs to be strong and provide vibration resistance. 

All I've come up with so far is a 'rubber grommet sandwich' with M4 bolts/washers etc, seems simple but somehow inadequate.

The PixFalcon will have its own foam/gel damper but extra isolation seems worth the effort.

Ideas & inspiration welcome :-)

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Frame design.


I've been experimenting with frame design, an essential component to keep all the parts flying in formation.

I printed some interlocking plastic parts in 2mm PLA & super glued them together to see how rigid/strong the end result.

The attached pic shows about half the fuselage section, it weighs 23 grams and seems more than strong enough. 

So far so good.

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More progress...


Most of the parts have arrived so I've been able to get accurate measurements and start on the airframe, a small tricopter. Materials are carbon tubes & 3D printed PLA.

The laws here in Chile are restrictive. You need a license, drone registration, insurance and the drone has to pass inspection - apparently *very* hard to get.

If the drone weighs less than 700 grams its classed as a toy, which means no restrictions other than common sense and being responsible for any damage. So that's the plan - a 'PichiCopter', as 'pichi' means 'small' in Mapudungun.

Here's a screenshot from CAD, lots to do yet but with luck I'll start building at the weekend.

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PixFalcon, Mega2560, Pi2 & S-Bus


Hi all,

Thought it about time I posted something about my new project, which is all about getting way too many sensors airborne on something interesting. I've flown fixed wing models before (many years ago), multirotors look like more fun.

So far I have a PixFalcon, a Pi2 and Mega 2560. The Pi2 provides redundant connectivity (WiFi & 3G dongle), streams video from a camera module & mavproxy telemetry to a laptop running QGC. All good stuff thats been done before.

The Pi2 receives control inputs over Bluetooth from a PS3 controller (if directly connected) or 3G/WiFi from the groundstation laptop if thats where the controller is. This goes over USB to the Arduino Mega, which converts to S-Bus and streams to the PixFalcon - giving 18 channels to play with. Right now its set up to give 6 flight modes, remote kill, primary flight controls, RTL & I can set/clear trims & works quite nicely. I'll have to think of something for all the extra channels to do.

All this is running on a 12v power supply (on the kitchen table). Missing parts are motors, ESC's, battery and frame so there's plently more to do. I'm considering a T-6 with a 5500mAh 4S. The range of available parts is limited here in Chile but I found some D2830 Motors and 30A ESCs that may work - opinions welcome.

Above is a pic of what I've got going so far - next step is the frame.

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