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Triple-Treat (Quantum Trifecta) Truck
I've started the thoughts on building my second multi-rotor as I've struck the packaging limitations with my Cheap250 build.  Not to mention it's getting pretty beat up by my attempts at learning to fly!

Initially I had thought of building a TBS Discovery/Reptile/Alien style 450-550mm design and setting it up for my ultimate use, carting GoPro and GoPro like cameras around as a bit of a slow-moving camera truck type of thing.  With the basic DJI Phantom3 available for under AUD700 at the moment and numerous competent big platforms like the Hubsan X4 Pro and Xiaomi all being in the same price area complete with camera I figure I need to be built and flying for under AUD350 otherwise it's a bit of an "own goal".

- Carry GoPro or Sony Actioncam in a stabilised Gimbal (up to 200g of Camera)
- Control functions/modes including Altitude and Position Holds.  Way-Point Navigation/Missions.  Return to Launch.
- ~20 minutes flight-time with 4000mah battery (3S or 4S)
- Portable design when not in use/Travel friendly.
- App support to manage extended functions via iPhone/Android Phone (i.e. Mission Planning).
- Measurably under 2kg AUW (say 1.8kg MAX)

The path less travelled:
Instead of doing something sensible like building a folding 450 on any one of the dozens of frames I've elected to give myself a different challenge.  A Tricopter.

The Quantum Trifecta sold through Hobbyking is a circa 295mm Tri-copter that folds down pretty small and can run up to 8" propellers.  It's got a pretty robust design and the "regular" price of the frame is under AUD50.  There's a lot of information on RCGoups and Youtube about some of the design pitfalls and tips and techniques for successful construction.  

The built weight of these with an GoPro or Mobius on the nose seems to be around the 600g, and some people have got AUWs well past 1.5kg in the air.  I suspect my build will be about 900g.

This is going to be a slow build and this post basically serves as an anchor for the ideas and research and then ultimately the shopping and the build.
[-] The following 1 user Likes Aaron's post:
  • sloscotty
I look forward to tracking your progress through this build...
The Build Plan:
My biggest challenge is to avoid scope-creep and shaping and changing plans on the fly because somethings "on sale" and then ending up with a hodgepodge of bits that work but don't quite come together (like my 250 build).

So here here's the rough list of bits I'm going to be trying to use.
  • Quanum Trifecta Frame
  • Metal Gear servo (Corona 919 or similar based on RCGroups Trifect thread this is more durable)
  • 2208-1250kv Motors (Probably Racerstar as they're very affordable at AUD8 each)  - These perform well with an 8038 prop on 3S but if my weight goes up too much there's going to be problems, but ecalc is indicating that prop choice will be most critical.
  • Some 18A ESCs I have spare (Multistar Mini V2) - these will limit me to 3S but I already have them.
  • A Matek PDB I have laying about
  • A Flysky ia6B RX using either PPM or SBus (already have it, but may grab another iA6C for size reasons)
For the Flight control I'm a bit torn between going APM/Pixhawk (probably a Micro APM like I've got in my 250) or trying out Cleanflight/iNav with a F3 based board.  10DOF of course.  These have the benefit of being "cheap" and add-ons like Sonar are much cheaper to implement although the APM/Pixhawk Sonar and Optical Flow systems are much more mature if pricey.  It's a bet each way.  

The difference is all about cost, I can have a 10DOF F3 board and Sonar module for less than the typical micro APM price, plus the same style of Sonar for the APM costs about 3x what it does for the F3 (which itself is 1/10th the price of "good APM/Pixhawk Sonar).

Either choice will be coupled with a M8N type GPS because this weak and slow satellite lock of the older M6N thing I have is super annoying on the 250.

I am toying with buying some all-in-one PDB ESC thing, they do exist but don't drop much weight and the 4th ESC will be "wasted".  That said my current ESCs are of unknown quality and probably not "real" BLHeli so will probably find their way off the build...

When I chuck all the parts into a cart and loot at the price it comes to a hair past AUD200 (including buying stuff I already have).  

I reckon I can wait for some sales and discounts and knock another AUD50 from that point.  So lets say the challenge line is to be sub-$200 in a flying state.

The brushless gimbal will be phase 2 and not included in the initial build....
[-] The following 2 users Like Aaron's post:
  • Tom BD Bad, sloscotty
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Blowing out my own expectations by finding all the neat APM/Pixhawk compatible PDB/BEC boards and Telemetry OSD boards that are 35x35 to mount in the frame (PDB/BeC in particular as it gives me the power meter data to the FC. The combined Telemetry/OSD board will stack neatly with a micro APM board.

Shame that's another AUD100!

So now more and more it's looking like a $200 flight electronics package. Around $100 for frame, servo and motors.

Then another $150 for a brushless gimbal setup on the nose.
And like $60 for the ultrasonic sensor for low altitude work.

So my $200 built goal is slipping, but it would be a much more effective build. And naturally expanding the scope could be a good thing (from a fun build perspective)
I was thinking $150 for a brushless gimbal is a bit steep, just saw a 2 axis on BG for $40-ish then went on to brushlessgimbals.com and saw they charge up to $265 for a cable! So you always knew you could completely NUKE your $200 budget, now you know by just how much!
Hobbyking currently have a reasonable 2-axis gimbal for just over AUD100 which I'd be happy with - so it's not all bad, I'm not as keen on playing lottery with the cheaper alloy frame or fibreglass framed ones as inevitably they always seem to be "awesome" right after the review has "tweaked" the setup. While I have no doubt that they work after tweaking I also know that in most cases a few small tweaks is actually 10's of hours trying to get it right.

I really challenged myself to do the build to flying frame for AUD200, leaving the gimbal out and that's still my intention, but obviously now I've got bigger and more integrated goals for flight control setup I really need a good sale to come along when I have spare $$ Smile
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Because I'm shocking at remembering stuff here's the parts list so far with the links to the vendors:

Frame:  https://hobbyking.com/en_us/quanum-trife...e-kit.html  Currently AUD44.31

Spare Servo Mount:  https://hobbyking.com/en_us/rotorbits-se...black.html Currently AUD7.36

Servo:  https://hobbyking.com/en_us/corona-919mg...c-12g.html Currently AUD8.22

Frame Expansion Pack:  https://hobbyking.com/en_us/quanum-trife...-pack.html  Currently AUD3.90

Subtotal for Frame: AUD63.79

Motors:  http://www.banggood.com/Racerstar-Racing...mywishlist (OUT OF STOCK) Currently AUD7.81/each AUD23.43 set of 3

ESCs:  https://hobbyking.com/en_us/mini-blheli-...-opto.html (AUD6.61 each) But I already have them.

ESC Programmer because "Normal" methods haven't worked:  https://hobbyking.com/en_us/turnigy-mult...r-esc.html  AUD9.03

Generic 8" Props 8038 or similar:  AUD10 for a couple sets

Subtotal for Drivetrain:  AUD42.46

Flight Control:  https://hobbyking.com/en_us/micro-hkpilo...2-apm.html Currently AUD53.01

PDB/BEC/PowerSensor:  https://hobbyking.com/en_us/micro-hkpilo...nting.html Currently AUD13.97

Telemetry/OSD:  https://hobbyking.com/en_us/micro-hkpilo...15mhz.html Currently AUD72.74

GPS Module:  https://hobbyking.com/en_us/mini-ublox-n...xhawk.html  Currently AUD59.65

Subtotal for Flight Control:  AUD199.37

Cheap 3-axis Gimbal:  https://hobbyking.com/en_us/gh3-3d-3-axi...black.html Currently AUD106.03

Grand Total:  AUD411.65 + Shipping

Even if a money fairy came and flew around the house I'm a little snookered by the lack of motor availability.  I'd probably try the 1500kv version of those Racerstar 2208s - in reality I'm really only looking at Racerstar because they're cheap.  With one goal being long 3S flight times the ~1250kv range is here I need to be and the frame works with a max 8" prop - otherwise I'd be adding 2212s and some 9045's straight up.   9" props can be made to fit but it's another modification.

All told I know we don't build these to "save money", but without discounts on parts this is not a cheap build considering I've already got ESCs and the Receiver.  My Cheap250 was under AUD180 including radio gear!

If I remove the Telemetry/OSD and the Gimbal I'm much close to the AUD250 area which is more palatable, but still hurts.  If I had to buy everything AND the GoPro to sling on the front I'd be starting to think a Mavic sounds like a far better idea!
It's started!

Ordered Today (25th January) via Hobbyking HongKong Warehouse:
Frame:  https://hobbyking.com/en_us/quanum-trife...e-kit.html  Paid AUD19.82
Spare Servo Mount:  https://hobbyking.com/en_us/rotorbits-se...black.html Paid AUD7.33
Frame Expansion Pack:  https://hobbyking.com/en_us/quanum-trife...-pack.html  Paid AUD3.88
PDB/BEC/PowerSensor:  https://hobbyking.com/en_us/micro-hkpilo...nting.html Paid AUD13.93

Total Order: AUD44.96