215 Hopper FPV

Recently I flew with a couple of other pilots for the first time, one of whom had an FPV rig. As soon as he flew off in to the distance I knew that I had to get into FPV as soon as possible. So now I have bitten the bullet and started to put together and FPV kit. I haven’t purchased a set of goggles yet as there is some internal debate about starting at the cheap end with something like the Eachine VR-007 or spending the money upfront and getting the Fatshark Dominator V3’s. I’m currently leaning towards the latter option.

To get the ball rolling I’ve started off with the airborne end:

  • Camera – Foxeer HS1189 XAT1200M (NextFPV) – Primarily chosen for the 16:9 aspect ratio.
  • Transmitter – ImmersionRC Race Band 200mW 5.8GHz A/V Transmitter (Hobby King)
  • Antenna – ImmersionRC 5.8GHz Circular Polarized SpiroNet Antenna V2 (Hobby King)

To start with I will keep things as simple as possible so no OSD or any other extra bits, just this basic video system.

So far I have only received the camera, I am still waiting for my Hobby King order, however I decided I would start roughing out a layout to see how all the parts are going to fit onto the 215 Hopper platform. My progress can be seen below.  Obviously I need to design brackets and housings for the various parts but this shows how it might be laid out. To differentiate the FPV version I thought a colour change was in order (I’ve also just bought red filament, the orange will go go back to Steelcity Electronics before too long).

215H-24

Building the 215 Hopper

As promised supplied here in is everything required to put a 215 Hopper together exactly as I have built it.

Please see the end of this article for an update regrading a mistake with the originally supplied brd file.

The digital assets can be found on YouMagine or Thingiverse.
There is nothing specific about the 3D printing requirements, 15-20% infill will do the job and a typical 0.2mm layer height is ok.
For the PCB’s I typically use Dirty PCB’s from Dangerous Prototypes. The brd file to submit is included with the digital assets. Options you will need to specify are 1.6mm thickness, color black (or your preference) and ’10×10 max’ for the size. Note that I have found some flexibility with this limit as this board is actually larger than 10cm in one direction, I got no questions when ordering my first batch (of which I still have 8 unused). The cost they offer can’t be beaten but do note that they are a bare bones sort of service so support is limited, what you submit is what you get.

Purchased Items

  • Naze32 Rev 6 Flight Controller (NextFPV)
  • FrSky x4r Receiver (NextFPV)
  • DYS BE1806-2300KV BE Series Set of Four CW/CCW Motors (NextFPV)
  • 4x ZTW Spider Series 18A Opto Lite (NextFPV) This could be considered overkill from a power point of view, I chose it for its svelte size and preloaded blheli.
  • MultiStar Racer Series 1400mAh 3S 40-80C LiPo (Hobby King) I usually start with 3 of a particular battery size but the more you get the more you can fly.
  • 5×4 Propellers (NextFPV) I like to use a bright colour (usually orange or green) on the front and black on the rear to help with orientation. 4 propellers are required, 2 CW and 2 CCW, but buy plenty of spares.
  • 500mm x 12mm x 10mm carbon tube (ebay) Cut in to two pieces, both 183mm long, there will be a short piece left over.
  • 5V, 500mA Step-Down Voltage Regulator D24V5F5 (Pololu)
  • 20x M3x8mm hex socket button head screw (ebay)
  • 8x M2x16mm torx socket screws (ebay) A generic M2x16 cap or button head will also work however for anything smaller than an M3 I find that a torx socket is more reliable than a hex.
  • 8x M2 Washers (ebay)
  • 8x M3 nylon nuts (ebay)
  • 8 M3x15mm nylon screws (ebay)
  • 10x 15mm round threaded standoffs (ebay)
  • Battery strap (Hobby King)
  • 16 AWG silicone wire (Black Hobby King, Red Hobby King) This size wire is the largest size that will fit through the wire slot on the power distribution board. It is also the same size as the leads on the battery.
  • XT60 male connector (Hobby King)
  • XT60 female connector (Hobby King) Purchase 1 for every battery. I managed to fuse the XT30 connector together, admittedly whilst running 5 motors on a heavier rig, however I think the upgrade is still a worthwhile precaution.
  • 2x JST-PH pre-wired plugs with sockets (ebay) for Vbatt and 5v connections on power distribution PCB.
  • Self adhesive rubber feet 25mm(L) x 5mm(W) x 3mm(H) (Aliexpress) These seem a very uncommon size but are available if you are prepared to wait for delivery. Alternatively anything that is 3mm thick can be used as a spacer. They are required as the battery wire penetrates the top plate below the battery.
  • 9x 160mm x 2.5mm cable ties (Hobby King)
  • 20mm heat shrink tubing (Hobby King) for the modified receiver
  • 10mm heat shrink tubing (Hobby King) for the modified ESC’s
  • 1x 1 pin crimp connector housing (Pololu) For SBus connector to Naze32
  • 3x 2 pin crimp connector housing (Pololu) For receiver power, SmartPort and Vbatt at Naze32.
  • 2x 3 pin crimp connector housing (Pololu) for receiver connection and 5v connection to Naze32.
  • 13x Female crimp pins (Pololu)

Note that a lot of the links provide, particularly for small parts, direct you to sources that are sold in bulk lots. For example the M3x8mm hex socket button head screw I have linked are sold in a lot of 100. As you only need 20 do not purchase 20 of the linked item, 1 bag will give you enough to build 5 215 Hoppers.

Custom Parts

  • 1x Left side pannel (215H 103)
    215H 103
  • 4x Motor mount bottom (215H 104)
    215H 104
  • 4x Motor mount top (215H 105)
    215H 105
  • 4x Tube clamps (215H 108)
    215H 108
  • 1x Right side pannel (215H 111)
    215H 111
  • PCB

Optional Parts

  • 1x GoPro session mount (215H 113)
    215H 113

Build Notes

This is not an exhaustive step by step for building the 215 Hopper but rather a collection of build notes in the basic order of construction.

  1. 3D printed holes for fasteners should be drilled out to their finished size after printing. This includes the 5mm holes for the frame standoffs (parts 103, 108 and 111) and the 2mm holes in the motor mounts (parts 104 and 105).
  2. Depending on the quality and accuracy of your prints you may also need to clean up the counter bore for the head of the M2 fasteners. This detail can be particularly critical as there is very little thread engagement in the motors and getting the thread started can be challenging. If you are using a hand drill for this process take it very slowly and carefully. It is easy for the drill to bite and get pulled in too far. Grinding a flat point on to a spare drill bit can minimize this biting problem.
  3. The PCB needs to be split in to its two pieces along the tabs. Side cutters and a file will quickly tidy up any leftover material. Also round over any sharp edges where wires, zip ties and the battery strap rest.
  4. Clean up any edges on you 3D prints the prevent the parts fitting together nicely. Likely areas that can cause problems in this regard are the knobs that fit into the slots on the PCB’s and the wedge between the side panels and tube clamps. The holes in the side panels should be a loose fit around the tubes.
  5. Solder the 5v regulator and JST sockets in place on the power distribution board.
  6. Shorten the signal/ground connectors from the ESC’s. I found if left as they are supplied there is simply too much bulk in the tight confines of the 215 Hopper.
  7. Solder the motor wires directly to the ESC’s. This will mean that the wires must first be threaded through the last window in each end of the side plate. As previously mentioned this is a bit awkward and one of the shortcomings of the design. You will want to have a rough layout with arms and motor mounts in place to determine the length of wire required.
  8. Once the two previous adjustments have been made to the ESC’s reseal them with heat shrink tubing before cutting the input connections short and soldering them directly to the pads adjacent to the mounting points. Ensure you have the ESC up the correct way to match +ve and -ve connections. The ECS’s can be secured in place with zip ties. As there is no support for the signal wires a dab of hot glue will prevent them moving and possibly breaking.
  9. Solder 16 AWG wires on to each battery terminal and route the wire out through the rear slot. Trim the wires such that there is about 10-15mm of overhang past the end of the board. Attach the XT60 male connector to the end being careful with polarity. You may wish to position a battery to determine exactly how long you would like the battery connector to be.
  10. Prepare the SBus and SmartPort interconnects. The SBus interconnect should have a 3 pin connector at the receiver end. At the Naze32 end, 5v and GND should be on a 2 pin connector with the signal wire on its own 1 pin connector. The SmartPort interconnect need only connect the signal wire to both pins of a 2 pin connector. Use the breakout wire supplied with the X4r, remove excess wires and add a short loop between the two pins.
  11. Prepare the Vbatt and 5v interconnects. The Vbatt interconnect (pictured at top) should have a JST-PH connector on one end and a 2 pin connector at the other. The 5v interconnect (pictured at bottom) should have a JST-PH connector at one end. At the other end either a 3 pin or a 2 pin connector will work, on the Naze32 I connect it to motor port 5. Double and triple check voltages and polarity are correct before plugging either of these in to the flight controller. I damaged a receiver because on the initial board revision polarity of the 5v was reversed at the JST socket. This has been corrected on the supplied board layout.
  12. Use the nylon fasteners to attach the flight controller to the appropriately marked PCB. Each screw comes through from the outside and is secured to the plate with a nut. The Naze32 is then stacked on top and secured with another screw. Prior to attaching it to the PCB install pins on the Naze32 rev 6 as follows:
    • Motor ports – 90° header on top side and pointing away from centre.
    • Digital ports – 90° header on bottom side and pointing towards centre.
    • Auxiliary ports – 90° header on top side and pointing towards centre. This header will also need to be a little higher than usual to clear components on the board. The easiest way to achieve this is to attach a connector before positioning the header strip.
  13. Positioning of connectors dictates that the x4r must be modified to fit correctly. For me this is not a concern as I only use SBus and usually dedicate a receiver to each model. After removing the cardboard housing trim to remove the top row of servo connectors (i.e. the row which SBus is NOT on). Snip the wires before the plastic so that the plastic can give whilst you are cutting it, this will prevent splitting through the bottom row. The remaining connectors may need to be bent down slightly to dip under the ESC connectors on the flight controller. Once modified seal the receiver with heat shrink, you may need to cut a small window for the Smart Port connector. Zip tie it in place on the same board as the flight controller.
  14. It is easiest to assemble the frame upside down. The power distribution board is the top panel, the receiver and Naze32 are on the inside of the bottom pannel.
    Put the battery strap in place around the power distribution board
    Push the standoffs in to their holes and loosely fasten them to the power distribution board with screws. Put the arms roughly in place, the friction on the standoffs should be enough to keep everything in place.
  15. I found the easiest way to get the motor mounts on to the tube was to first screw the two pieces on to the bottom of the motor (do not tighten but ensure there is a couple of turns of thread engaged) before sliding the clamp on to the end of the tube.
  16. Connect the ESC’s, 5v and Vbatt to the flight controller then roll the bottom board over on to the bottom of the frame, poke the antennae out a couple of the side windows whilst tucking all the wires into the frame.
  17. When closing up the body be careful that no wires are pinched between the side panels and the PCB’s. Before locking everything down ensure that the arms are centered (measure from the side of the PCB to the inside of the motor mount) and that the motors are vertical. Rather than simply eye balling this put your propellers on and ensure the tips meet at the same level. Remove your propellers before connecting any power.
  18. Position 4 sticky feet around the battery wire penetration slot and battery strap to support the battery.

215H2-2

Configuration

My flight control software of choice is CleanFlight. When you first connect to CleanFlight there will be a number of setup changes to make. As a starting point change the following:

  • Enable Serial RX on UART2
  • Receiver Mode RX_SERIAL
  • Serial Receiver Provider SBUS
  • ESC/Motor Features Enable ONESHOT125
  • Minimum Throttle 1040
  • Maximum Throttle 1900
  • Battery Voltage Enable VBAT
  • Other Features Enable SOFTSERIAL and TELEMETRY
  • Enable SmartPort and SOFTSERIAL1.

On the PID Tuning tab:

  • PID Controller MultiWii (I found that the Naze32 was struggling with LuxFloat whilst SoftSerial was enabled)
  • ROLL rate 0.4
  • PITCH rate 0.4
  • YAW rate 0.52

Setup auxiliary switches on the Modes tab as you would like. I typically assign a switch to ARM and a 3 position switch to ANGLE/HORIZON/RATE.

You will then need to connect a battery (no propellers attached!) to ensure everything on the receiver tab is coming through correctly.

From here all the usual maiden flight checks and safety procedures apply.

If you have any questions about the build or would like more images or information about something specific feel free to leave a comment here, visit the contact page or leave a comment on either the YouMagine or Thingiverse pages.

If you build a 215 Hopper I would love to see the results. I have set up a form where you can tell me how it went and let me know where I can find some photos of your work.
Build Form

Update 1:
It has been brought to my attention that the original brd file that I upload had a fault on the vbat connector. The ground trace from said connector did not reach the main ground plane. Now uploaded is revision 2 of the board with this problem corrected.
My apologies to anyone who has already made the board. You will still be able to fly with it but you will need to forgo the connector for vbat and connect wires directly to the same pads as the battery leads (mind the polarity), or leave them off all together (mind you don’t over discharge your batteries). I have ordered a new batch myself so if anyone has already made boards and would like a corrected replacement get in touch.

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!

215H-17

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.

215H-16

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 – GoPro Mount 1

Just a quick update this evening. Shown here is is the first draft of a mount for the GoPro Hero4 Session on my 215 Hopper. I will need to check for propellor clearance on the side of the mount, there is clearance to the plastic but possibly not enough for a strap. If that does turn out to be problematic then I have an idea in mind for a plastic clip over the top.215H-14 215H-15

Also on the cards are two other ideas for less typical mounting positions that should both provide an interesting perspective.

215 Hopper – Build 2

215H2-2

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.

215H2-5

Bitter Sweet 215

This shall be a brief post of 2 parts, the first sweet, the second bitter.

To start with I have completed the build and first flights. The photo below is just after completion and ready to take to the air. I very happy with how it has come together. Admittedly there are a couple of problems and mistakes to address but for a first iteration I am very happy with it.

215H-12

Here the 215 Hopper can be seen airbourne on its first battery. Admittedly, the very first hover attempt was a complete failure as I had the motor connections mixed up side to side. After correcting that issue a successful hover test was completed indoors. I was immediately struck by how much more stable it was that its predecessor, the Spidex 220, and that right there was the main reason for starting this project. Success!

215H-11

I have not yet mounted it but in the future I will fly a GoPro session with this platform looking something like this:

215H-13

Now for the bitter part. On just the 5th battery I lost the 215 Hopper. I am not going to try and make excuses, I got a little too far away, that’s not very far for something this small and fast, orientation became difficult. Before I knew it and before I could regain my composure the 215 Hopper was but a small speck high in the sky and a long way away. The signal began failing so I reduced the throttle to try and bring it down gently, more out of concern for where it might land than to protect the copter itself. Evently the signal was lost. I did a few laps of the neighbourhood but my chances of finding it were slim. Most disappointing was that it likely came down over a residential area. I always like to think that I am responsible with where and how I fly and am aware of my surroundings but today I let the community down. I can only hope that it hasn’t caused any damage or injury.

If you have found the 215 Hopper (this is the only one in the world) in the Fairy Meadow/Wollongong area then please drop me a line via the contact page.

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.

215H-10

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