Racing Quad Build

[Damian Axford]

So...  my first Hobbyking order arrived, with motors, ESCs and Naze32 Acro controller.  Battery and FPV stuff should arrive in a week or so.

I've got as far as mk2 motor brackets, printed and waiting to be tested when I'm back.  Meanwhile, airport + plane gave me time to work on the CAD model for the body layout.  Here's the latest:

Notes:

• The main goal is to make this as streamlined as possible, I'd also like the body to act as an aerofoil, which has entailed:
• Keeping the frontal cross-section as small as possible and wider than it is tall
  
• Keeping motor wires concealed
• Minimising obstructions to the air flow from the props (i.e. skinny arms and streamlined motor brackets)
• Placing the battery inside the main frame
• I've also tried to simplify the tilt mechanism as much as possible, that combined with placing the battery inside the body means has ended up with putting the flight controller (FC) on the front rocker  - now clearly that has some challenges!
• With the FC way off the CG, it will require a custom motor mix and may well be an unstable mess.  The good news is that the Naze supports custom mixes, and they look quite straightforward.
• The good news (theoretically) is that the centre of rotations will still be on the centreline of the FC, which should give this a "rear wheel steer with powerslides" feel.  
• Putting the ESCs down the sides is another side effect of the battery location.  It doesn't affect the wiring too much (power dist will be underneath) and does mean there will be plenty of airflow over the heatsinks.
• Not sure where the FPV stuff is going to go yet...  but I'm sure it'll fit somewhere :)  I've ordered a Mobius camera with a ribbon extension cable, the idea is to separate the camera module from the main mobius body to allow greater freedom in locating it.  Also should allow a very basic tilt servo to drive just the camera module, rather than the whole body.  Also have the option of removing the internal battery and potentially the entire case, just heat-shrink the body.  Although would need to keep the heat-sinks exposed.
• The video TX and clover-leaf can probably sit in the tail (perhaps in the trailing edge of the body shell)

[Damian Axford]

Finished the initial design for the body frame and an approximate profile for the shell - just need to print it all and see if it works :)

[Robert Longbottom]

Looks smart, will be interested to see how it flies :-)

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[Damian Axford]

thanks, and agreed :)

it'll also be interesting to see if the body fits on my print bed - it's a little smaller than a 200x200mm plate when on the diagonal, but not much!

[Damian Axford]

big bit printing.... fingers crossed all goes well and it's waiting on the bed in the morning :)

[Damian Axford]

woo hoo....  it worked :)    Will try and put that together this evening (at least the arms and motors)

[Robert Longbottom]

Neat, looks a bit like a model bridge :-)

On 28/03/2015 10:03, Damian Axford wrote:

woo hoo....  it worked :)    Will try and put that together this evening (at least the arms and motors)

[Damian Axford]

Yeah... Or a tank chassis :)

Going to weigh it later as well... Feels a bit on the heavy side, although shouldn't be more than a hovership

[Damian Axford]

Have loosely assembled the frame, thoughts so far:

• Weight is good; all the plastic and carbon bits together are about 80g, even allowing for motor screws that's pretty damn good - vs 165g for the Hovership MHq2.  There are a few bits where I could trim the weight down a bit, but that can wait for another time.
  
• Frame is very stiff front to back and side to side, not great in torsion, but then torsional forces should be minimal in a quad.
• Servo, Rx, battery, ESCs and the Naze board all fit correctly - phew. 
• Wiring is going to be tight, but doable
• The motor brackets work well - quick to print, easy to fit and seem strong enough
• The tube connectors (the bits the two carbon tubes fit into) are not brilliant.  They're strong enough, but printing stood on one end makes them fiddly to prep (lots of support material) and boring the tube holes accurately has proved difficult - ultimately one end has ended up squiff on both connectors.  Think I'll try changing the print orientation first, otherwise that part will need a major re-design.
• It looks cool - although it's a pity the motors are green... 

Overall pleased so far - now to print some more tube connectors...

[Robert Longbottom]

Looks good.  It will be interesting to compare the all-up weight with the Hovership once you have everything on board.

The proof will be in the "how crashable is it".  So far I think I've only broken props and landing gear on my hovership :-)

[Damian Axford]

Good point... I don't expect this to be anywhere near as crash able! I think the tilt design is much less robust than swing arms.

Having weighed most of the bits, I think it'll be about 300g without battery and then the 2100mah battery I've ordered is just under 200g... So prob 500g all in, excluding fpv stuff

[Robert Longbottom]

Thats pretty good. My Hovership is 444g without battery, but that
includes fpv gear.

[Gyrobot]

"It looks cool - although it's a pity the motors are green..."

 

It does look cool, pity the printed parts are orange, AND with a brim ;-)

 

Keep up the good work.

[jmeosbn .]

I was just thinking the motors would contrast nicely with Gyrobot Green™.

Jamie Osborne

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[Damian Axford]

it would not surprise to find that was a valid trademark ;)

The motor arms, tube connectors (mk2) and servo connection are all done - the servo drives the arm rotation pretty well, initial issues/thoughts:

• the push rod wire is a quite flexible, I've ended up bracing it with a skinny bit of carbon
  
• the holes for the push rod in the tube connectors are a little large and leave room for a bit of slop (<1mm)
• It looks like the rod might foul the edge of the battery - will test fit when it arrives
• the servo seems plenty powerful enough - it's rated for 3.2kg/cm - will be interesting to see how it copes with the props under load

The FPV gear also arrived whilst writing this - looking forward to putting the Quanum goggles together :)

[Robert Longbottom]

I'll be interested to see the goggles, I almost clicked the button on a pair of Skyzone goggles earlier today to find out what the discount voucher I have is worth, but then I thought if they end up in my basket I might buy them.