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Triple-Treat (Quantum Trifecta) Truck
#1
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!

Background:
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".

Objectives:
- 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
#2
I look forward to tracking your progress through this build...
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#3
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 1 user Likes Aaron's post:
  • sloscotty
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