215 Hopper – GoPro Mounted

Just like that I have mounted the GoPro Session to my 215 Hopper. Having a 3D printer on hand is really cool!

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There was some delay between coming up with the design and printing it as I managed to break the printers glass build plate, my parts were sticking too well. Previously I was using the glue stick approach for 1st layer adhesion but I suspect I may have been a bit heavy handed with the application.
After replacing the glass I decided to try acetone/ABS slurry applied to the bed and have been very pleased with the results. Applying it is simply a matter of squirting a couple of milliliters of acetone on to the bed and then swirling a failed print (preferably of the same colour) around in it until it starts to become tacky. I’ve noticed a couple of advantages to this process. Firstly the surface quality of the bottom is as smooth and polished as the glass. Secondly, and more importantly, as the bed cools the part almost completely separates itself.  Only the slightest twist or push is required to remove it. Further cleanup of the bed is not required unless you intend to change colour as the next application of acetone will simply absorb anything left behind.

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The concern I had about prop. clearance to the straps on the side has proven not to be an issue.
I’ve not had a chance to fly with it in place yet so I’m not really sure what sort of result I am going to get with hard mounting and the 20° angle but when I do the footage will be here.

215 Hopper – Build 2

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I have been a bit slow in getting this report together but I am pleased to say the as of late last sunday evening my second build of the 215 hopper design is airborne. For anyone keeping track that is just a 6 day turnaround from lost to flying again. There are a couple of things that worked in my favour to achieve this.

  1. Firstly the 3D printer from the workshop of SteelCity Electronics is currently on holiday to my workbench, as such I was able to start printing replacement parts immediately (more on this topic in the near future, I’ve got a big build cooking).
  2. The guys over at NextFPV actually had stock of every replacement part I needed. I expected I would need to order various bits from multiple sources internationally but discovering everything was stocked locally was a pleasant surprise. On top of that the service they offer is exceptionally fast. I am a very happy repeat customer of theirs. I the future I will gladly purchase through them whenever possible (hopefully there is an FPV setup in my future).
  3. When ordering parts for the first build I doubled (or more) quantities of the various bits of hardware so all of that was on hand. The PCBs were taken care of as DirtyPCB’s supply 10 per order by default.

With the rebuild I got the chance to address a few of the shortfalls of the first build. Changes included:

  • Shortening ESC signal/ground wires so that there was less wire bulk in the body. it was a bit challenging squeezing everything in to the first build.
  • Direct connection of motors to ESC’s. On the first build I needed to join the motor wires with the ESC wires as the motor wires were cut to short from the Spidex 220 build. In reality this is still not a very practical solution as the wires first need to be passed through the side plates. However for the sake of minimalism I stuck with it.
  • Externally accessible USB. This is the most valuable change from the first build and is thanks mostly to the change in location of the port on the Naze32 Rev. 6 board. I also printed a unique side plate with an opening to suit.215H2-3
  • The upgrade to the Nae32 Rev. 6 also allowed for very tidy connections all around (no more soldering wires directly to the board). Seen in the photo below is the way I have installed the pin headers on the Naze32. 90° headers are used on all connections. The ESC outputs are installed in a fairly typical configuration. The RC input connections are under and towards the centre of the board and the extra features (Vbatt, buzz etc.) are directed back across the board.215H2-4
  • SmartPort telemetry. Rather than trying to fit a buzzer inside (which becomes surprisingly large in such a small space) I connected the SmartPort on the X4R-SB to a soft serial port on the Naze32. A buzzer will fit inside but for now I am relying on the telemetry to know the status of my battery. The photo below shows how tidy this setup is. Also note that for clearance to the ESC connections on the Naze32 I have to trim the top row of headers from the X4R-SB.215H2-1

The only quirk with this build, and I find it strange given that it is newer hardware, is that LuxFloat can’t run reliably ( I had no problems with it on Rev. 5 hardware). It may in fact be the extra processing load from the soft serial so I will have to check into that further.

Next on my agenda for this copter is to get the GoPro mount(s) sorted. Then put together a more thorough look at the design and build process with a full bill of materials and files if you would like to build you own.

Given that the design of the 215 Hopper was inspired by the FliteTest VersaCopter I thought a family photo was a fitting way to end this post.

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215 Hopper Sneak Peak

It has been a while since my last update. Primarily due to the holiday season followed closely by an international getaway which spanned several weeks (some photos from my adventure will appear here in the near future). Since my return I have started to put together the 215 Hopper. It is not quite complete yet, there are still some wiring details to complete/tidy up however it is close as can be seen below. After the maiden flight I will put together a full write up on the parts, build, what I’ve learnt and how it has worked out.

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This progress also means that the Spidex 220 has officially been decommissioned.

VersaCopter Motor Mounts

Through the cumulative effect of multiple crashes and initially over tightening I managed to snap one of the G4 plates that make up the motor mount tube clamps on the Flite Test VersaCopter. Unfortunately at the time I ordered the crash kit for the VersaCopter it didn’t twig that these plates were sold separately. As such I was faced with either making a very small order with Flite Test for replacements or coming up with my own solution.

I took this as an opportunity to test my tube clamp motor mounting method and the folks over at 3dprint-au.com both of which are critical elements of the MultiChase project. I knocked up a very quick model of a direct replacement part for the Flite Test designed tube clamps and sent it off for printing. 3Dprint-AU use an SLS printer which I hope will provide better dimensional accuracy and a more homogeneous structure than a FDM style printer.

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The results are not as spot on as I expected but I generally found the parts are oversize rather than undersized. For example the bottom edge of the clamp, as shown above on the right, is raised rather than rounded as designed. A quick touch up with sandpaper (applied only to the motor side) brought the overall measured height down to the designed number. Also interesting to note here is that the ‘black’ material offered is actually just the white material dyed black on the outside. I’m not sure of the specifics of this process, if it is done by the print head or if it is done as a post process but it is something to bear in mind.

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To ensure a nice clean holes for the mounting bolts I actually printed the hole under size and drilled them out as appropriate, they are shown here as printed.

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The installation process was simpler than the flight test motor mounts as there are less pieces to hold together. I also think it looks cleaner than the original pieces.

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Strength wise I have no doubt that this well be less susceptible to the same style of failure as the original design. Everything is nice and snug with no visible deflection when tightening. That does however raise some concerns about the next failure. My mounts fit much more tightly around the tube and seem much less inclined to rotate as the originals would in a crash. This could make the frame itself or the arm tubes more vulnerable. Despite the much bulkier appearance these mounts only add 1.7g per corner. Each printed half weighs 4g for a total of 8g per corner whereas the Flit Test design weighs in at 6.3g per corner.

Now it’s time to get this rig back in the air, it has been several weeks since I broke flew it last.

Spidex 220

After coming across a great deal on most of the flight hardware for a Spidex 220 and realising I already had all the other required pieces to get it in the air I now have another mini quadcopter. For $130aud I got my hands on:

  • Spidex 220 frame kit
  • 4 Emax 12 amp speed controls
  • 4 DYS 1806 brushless motors
  • CC3D mini flight controller

To get it in the air I already had:

  • 1300mAh batteries (unfortunately of the 25C variety I have since discovered)
  • FrSky X4R receiver
  • 5040 propellers
  • Misc. bits and pieces (heat shrink tube, wire, connectors etc.)

As with the VersaCopter, at this stage i have built this up without any FPV or camera equipment, that’s an expense for the future.

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How to tackle power distribution and connection proved to be the biggest question of this build. Seen above is the solution I came up with which I think is really quite tidy. The rear two motors are joined together with another wire which travels forward to the power distribution board. In previous builds I have always been frustrated by the process of trying to solder multiple wires together, even two can be a frustrating experience. This time around I made a point of seeing how others tackled this problem and very quickly came across a wire wrapping method. The Flite Test crew illustrate it succinctly in the video below.

Using this method, and even splitting it  into two stages, I found the process much more agreeable. The +ve and -ve runs are mirrored with one up each side of the frame. A couple of holes were drilled into the base plate to hold zip ties in critical locations.

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The wires from the rear motors meet the battery wires and front motors at this small power distribution board made from a piece of strip board. The copper strips aren’t really carrying much of the power it simply provides an easy foundation onto which each wire can be joined. Also hinted at in the photo above is the fact that I have routed the battery wires through the base plate. This seemed the only tidy way I could route them whilst providing enough tension that the battery leads be pulled out of range of the propellers.

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The battery connector flies freely out the bottom of the craft but is pulled taught when a battery is connected.

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To fit the FrSky X4R receiver between the flight controller and the battery I striped it of its carboard housing and replaced it with heat shrink, using double sided tape it is then attached directly to the housing for the CC3D mini. For a tidy install I also shortened the wires from each ESC. On all but one connector the +5v wire is also removed and held back with a small loop of heat shrink. I have changed the software on the CC3D mini over to CleanFlight due to my familiarity with that. Installing it was quite simple using the OpenPilot bootloader and flashing software. In the future I would also change over to a CleanFlight bootloader as my experience with that on NAZE32 hardware is a little smoother.

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To fit the ESC’s in to the designated spots on the arms the outer corners of the ECS’s need to be trimmed slightly. A cut out in the cross member on the frame was also required to pass the signal wire from the bottom of the board. The motor wires are soldered directly to the ESC and by paying attention to which wire was going where I was able to get a pair of CCW rotating motors and a pair of CW rotating motors without having to rework the soldering.

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Initial flight impressions are a bit limited so far due to windy days but from what I have experienced it is a very punchy little rig. I am seeing some vibration induced instability/oscillation at hover which will need some work and the tuning could also do with a touch up. All in all though, a very fun little platform that I’ve picked up for minimal outlay.

Flite Test VersaCopter

I’ve been on the lookout for a small quadcopter kit to put together for some time with an ultimate interest in getting in to FPV flying and racing. The high entry cost for a good quality full FPV setup has put me off a number of appealing options over the last 12-18 months such as the ImmersionRC Vortex. I have however finally pulled the trigger on the VersaCopter created by the crew over at Flite Test. This will allow me to put together a rig piece by piece and offers a compelling value proposition. A couple of days ago my kit arrived so over the weekend I have assembled and flow my VersaCopter.

Shopping

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Delivered from the Flite Test store (as shown above) was:

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Delivered from the HobbyKing strore (as shown above) was:

The only missing piece from this shopping list to get off the ground is a radio receiver to suit, in my case, a Taranis X9D. I already had a couple of FrSky X4RSB‘s on hand from a previous order.

Assembly

One of the reasons I was so eager to jump on this kit was the design style used. The slot together laser cut plates really appeals to my sensibilities and I was curious for a close up look at what laser cut Delrin looked like and offered structurally. I have used similar construction methods in the past for other projects but have always used acrylic (unfortunately Ponoko NZ, whom I usually use, do not offer a Derlin option).

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Assembling the VersaCopter from the kit as shown above followed almost exactly as demonstrated in the Flite Test construction videos (both the main video and the NAZE 32 video) with the exclusion of any cameras or FPV equipment and the observations as follows:

  • When installing the motor mounts on to the arm I found it easiest to start only the bolt on the side opposite the slot. This allowed full freedom for the Delrin part to stretch over the tube before adding the 2nd bolt.
  • Aligning the motors on opposite ends of each arm proved more challenging than ensuring the front and rear motors were aligned. I didn’t come up with any clever solution to this beyond align, tighten, check, repeat.
  • The supplied ESC’s seemed to include a much larger input smoothing capacitor which made their length significantly longer. This provided two problems for the installation of the NAZE 32:
    • The wires and capacitor interfere with access to the USB port through the side window.
    • The length meant it was particularly tight trying to fit the ESC between the NAZE and the rear arm, consequently the ESC is in constant contact with the edge of the NAZE board somewhat nullifying the foam isolation mounting of the flight controller.

    Ultimately the compromise was to push the ESC as far back as possible and hold the input wires down as best as possible with an extra cable tie.

  • With about 4-5mm of foam under the NAZE 32 there is not sufficient vertical space within the frame for vertical connectors. This impacts the telemetry, vBatt, buzz and serial ports. Directly wiring JST tails to those I wish to use will be required.
  • As I am using the SBus output from the receiver I had to set serial port 2 on the NAZE 32 to serialRX. I overlooked this detail and spent some time trying to figure out why I was not receiving a signal.
  • I was not happy with how secure the battery felt with just the velcro strap as such I added some Velcro dots to the top of the frame and bottom of the batteries for extra security.

Ultimately the kit went together very well and they have certainly delivered on their aim of putting together a DIY kit that looks professional and tidy when completed.

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Flying

After running through 6 batteries I can say that I am very happy with the VersaCopter and it delivers all that I had hoped. Specifically a no nonsense quad with decent flying performance, i.e. something that will allow me to practice flying with minimum fuss.

The VersaCopter was stable without making any changes to the PID tuning however for better performance I have made a few initial tweaks. The following settings have changed:

PID Controller: 2 – LuxFloat (all default PID values)
Roll rate: 0.05
Pitch rate: 0.05
Yaw rate: 0.17

On the transmitter I have set:

Roll +25 exponential (faster closer to centre)
Yaw -35 exponential (slower closer to centre)

With this setup flight times of between 7.5 – 8 minutes are easily possible with relatively energetic flying (constantly on the move, regularly at full throttle, flying square or figure 8 circuits) and approximately 10-15% left in the battery.

So far I can not report on the durability of the frame, I haven’t crashed it yet.

MultiChase Project

As a foot note there are a couple of lessons to be taken from this build for my MultiChase project.
Wiring, routing and position of electronics needs to be very serious consideration, wires are not as flexible as imagined in close quarters and all connectors and wire volume needs to be accounted for. I already knew this but this project served to reinforce that knowledge
With a 6″ propellor the difference between a 250mm and 280mm motor centre is probably fairly minor.
The laser cut plates method of construction proved very simple to put together and supported by the fibreglass plates provides a very strong frame, it is probably worth reconsidering for as an option.
Delrin looks to be a great material in this laser cut form, tough but still somewhat flexible. I will however continue with my 3D printing approach for now as that is easily available to me.