The Rotor Riot CL1 is a community collaborated design based loosely on the popular ImpulseRC Alien and the Martian II. It's a low-budget freestyle frame with thick 5mm x 20mm arms, so it should take quite a beating. Additionally it provides 20mm mounting in the rear for a VTX which is a nice touch. It's very easy to build and perfect for a first build. The parts I chose for this build are a balance between peformance and price. They offer a lot of modern features yet keep the price reasonable.

Features

Swappable 5mm arms

Press nuts for lower profile

20mm VTX mount in rear

OSD VTX control and tuning

F4 8k/8k flight controller

Current sensor

Powerful 2207 motors

Tools

Be prepared for some very fine soldering work. Some of these pads require a lot of finesse and dexterity. That being said it's a good idea to use quality tools. They'll make a difference. I recommend a good iron like the Hakko FX-888D, but there are cheaper alternatives. Here are a number of required tools:

Soldering iron with broad and fine tips

2.0mm hex driver

Industrial Tweezers

Jewelers Precision Screwdriver

Wire cutter/stripper

Scissors

Heat gun or lighter

Ruler and cutting mat

Multimeter

Additional Supplies

A variety of heat shrink tube sizes

Blue Loctite

Zip ties (small)

63/37 leaded solder

Liquid soldering flux pen

Hardware Considerations

The screws are something you need to keep in mind when planning this build. The frame comes with 16 M3x8mm and 10 M3x10mm screws. These are for securing the top and bottom plates and the arms respectively. Unfortunately the motors only come with M3x6mm screws which aren't long enough. You need to order 16 additional M3x8mm screws. Now you've got a couple options here. I added anodized countersunk washers to the top and bottom plates to add a splash of color. These are entirely optional, but they require M3x8mm screws as well, but they need to be countersunk. So, if you want to add the washers you only need to buy the countersunk screws. Then you can use the 16 included M3x8mm screws to mount the motors. Otherwise you'll just want to buy 16 button top M3x8mm screws.

Also, I opted to swap the standoffs out for 20mm hexagonal standoffs. They're a little shorter than the included standoffs and offer a more low-profile look. Generally the shorter you build these the more rigid they'll be.

And finally there are the M2 screws. The VTX comes with a set of standoffs and nuts, but no screws. Fortunately the camera comes with a couple spare M2 screws, but you need 4. They can be nylon or steel. I've never had to buy M2 screws, but if this is your first build you may need to. If not then any of your other FPV cameras should have spare screws.

Frame Assembly

This has to be one of the easiest frames I've ever assembled! The press nuts save a lot of time and trouble. Typically you need a second tool to hold the nuts while you screw everything together. Here you only need a 2.0mm hex driver and a couple minutes. There's not much to say here except that you mount the arms below the base plate with the smaller plate at the bottom. Use the 10mm screws while the press nuts are pointed up toward the stack.

I used my own 6mm nylon screws and standoffs to mount the flight controller. It comes with some really long nylon screws which will work, but you'll need to cut them down to size.

Update September 12, 2018: After a few test flights I found that the flight controller was a bit twitchy. After adding anti-vibration standoffs it flew great! The only thing is the flight controller M3 holes are too small for these. I used a drill to widen them which should also help reduce vibrations. Alternatively you can purchase some O-Rings and use nylon standoffs, but I still recommend drilling out the holes. Keep in mind that this flight controller powers the M3 holes, so the metal anti-vibration standoffs aren't ideal. I just didn't have the O-Rings on hand.

Motors

While it's entirely optional I like to sleeve my motor wires with Paracord, but you'll need either a 7/32" cord like BattleCord or a 1/4" cord like Paracord Para-Max. The smaller 550 cord isn't big enough for all 3 motor wires.

Screw your motors onto the arms using 8mm screws and blue Loctite. Cut 4 pieces of cord to 7 cm lengths, remove the inner core and, with a lighter, melt the ends to prevent frays. Sleeve the motor wires and cover the ends of the cord with two 1cm pieces of 12mm shrink tube. One for both ends. Flux and tin each motor pad ensuring each is completely coated with a nice silver bubble. If you're right-handed start from the rightmost motor pad and solder all 6 wires from right to left. If you're left handed start from the left.

Cut each wire to length as you go, not all at once. Position the shrink tube over the ends of the cord and melt it. You can use a heat gun to make quick work of this, but don't hold it over your FC too long.





Receiver



Now you can add the receiver. It's always a good idea to get this out of the way early so you can bind it and tuck it away. I installed the FrSky XM+, so your wiring may vary depending on the receiver you chose. One thing to keep in mind is I used the inverted SBUS pad on the flight controller. If you're using an un-inverted IBUS recever for a Flysky radio you'll need to do things a little differently. You'll likely want to solder your control wire to the TX6 pad toward the middle of the board.

First solder 3 wires to the receiver. I borrowed the wire from the camera wire harness. Use the black, red and green wire from the end.

Make sure you give yourself enough wire slack to slide the receiver under the flight controller. Solder the wires to the 5v, Gnd and SBUS pads. Slide the receiver under the flight controller so the bind button and antennas pointed forward. Add shrink tube to the receiver to protect it from shorts. You don't need to shrink the tubing or even tape the receiver down. The wire and antennas should hold it in place. Add small zip ties to the front arms and use shrink tube to hold the antennas in place.

Power Connector



Before you bind you need power. This board comes with 16awg wire pre-soldered which is fine, but 14awg is more common. Also, it's a good idea to solder a capacitor to your XT60. This helps filter electrical noise and can help eliminate random twitches during flight. You might also want to remove the pre-soldered wires to make this a little easier. I used my own 14awg wire, soldered the capacitor and XT60 and then attached them to the board.

I used short battery leads, but if you're prone to crash often you may want to add some stress relief. With enough force the battery may eject and break the flight controller tab. To do this use longer battery leads and zip tie them to the frame.

Snip and bend the capacitor so the wires dip into the XT60 wells. Make sure the polarity is correct. Fill the wells with solder. Solder one wire at a time into the wells in addition to the capacitor wires. I used about 4cm of wire for either side. Add hot glue between the XT60 wells to prevent shorts. Cover it up with heat shrink. Solder the wires to the flight controller.

You might notice I added the XT60 without a capacitor at first. I thought I might find a better place for it later, but it turns out this is the ideal location. It needs to be as close as possible to the battery.

Finally, be sure to test your main power leads for continuity with a multimeter before powering up. Once you're sure there aren't any shorts you should bind your receiver. Instructions vary depending on your radio, but generally you want to put your radio into bind mode, hold the receiver bind button, power up, wait for the lock and power down.

FPV Camera

This frame comes with camera brackets, but they're blue so I used a 3D printed variation in black. It's listed below in the part list. I found it easier to screw the brackets onto the camera before attaching them to the frame, but the stock brackets should work fine either way. Once the camera is mounted you need to solder the wires to the flight controller.

Remove the purple wire from the wire harness as the voltage reading is redundant. Plug the wire harness into the camera and cut the wires to length to their respective pads, offering a little slack. You can optionally add some 550 Paracord and shrink tube to cover the wires. Solder the wires to their respective pads.





Update September 12, 2018: I found that the 5v output of the flight controller introduces a little camera noise. I suggest powering the camera via the 5v output of the VTX instead. Then, in-turn, you'll need to power the VTX by piggybacking the power leads onto the main battery leads. This produces a nice, clean picture.

Video Transmitter

I love that this frame includes holes for the VTX mount. Mount the standoffs using the aforementioned M2 screws and attach the VTX. Those tiny M2 nuts can be a bit finicky, but it works well to twist them down with your thumb. Make sure the VTX pads are pointed toward the flight controller so you can wire it up.

Using the spare wire from the camera add wire to the Video, OSD_RX, Gnd_in, and 7-26v pads. Again you can optionally add 550 Paracord to protect the wires. Solder the wires to the flight controller. OSD_RX needs to be soldered to the very tiny TX6 pad in the middle of the board.

I just doubled up on the 5v pad to give power to both the VTX and camera.

While the VTX says it takes 7-26v it works on 5v. I've done this in the past on other builds and it hasn't been a problem.





Camera Configuration

Now that you've wired the camera and VTX you can adjust your camera settings. Plug in your quad and check that the video feed is functioning. Then, using the included joystick you can plug into the wired connector behind the camera. Mainly all you want to do here is disable the camera OSD. We'll be using the OSD provided by the flight controller instead. Press and hold the up button to access the OSD menu. Disable each option and save.

Finishing Up

Finally, you need to attach all the standoffs and the top plate. I used a slightly longer dipole antenna instead of the included one. While this isn't entirely necessary, it's a good idea to stand your antenna as tall as possible to clear the battery. To mount the antenna I used a pair of interlocked zip ties to give it a rigid surface to latch onto. The antenna runs along the zip tie with shrink tube to hold it in place. This helps reduce stress on the U.Fl connector and keeps the antenna away from the props. You might be tempted to use hot glue to hold the U.fl connector in place, but it'll most likely melt under the heat of the VTX. The zip ties should prevent the antenna from pulling away from the board.

To mount the battery it's a good idea to use a battery pad like Ummagrip or Nomojel to prevent it from sliding out. For added protection you can use two battery straps. You don't want a battery ejection!

Betaflight Configuration

If you don't already have them, you'll need to download Betaflight Configurator [Download] and the BLHeli Configurator [Download].

First go to the Firmware Flasher and choose "LUXF4OSD" as well as the latest stable release of Betaflight. Click "Load Firmware [Online]" and then "Flash Firmware" to update your flight controller. Once complete, click "Connect" On the Ports tab On UART1 click Serial RX for your receiver.

Set the UART6 Peripherals to "IRC Tramp".

Click Save and Reboot On the Configuration tab Under ESC/Motor Features select DSHOT600

If want to fly "props out" with reversed motors, select "Motor direction is reversed" below the illustration. (This is optional)

Under Board and Sensor Alignment set Yaw Degrees to 90 to address the rotated flight controller.

Under System configuration set PID loop frequency to 8 kHz.

Under Receiver choose your receiver mode. For the XM+ choose "Serial-based receiver" and "SBUS"

Under Arming set the Max arm angle to 180 (Only if you keep the accelerometer turned on)

Under Other Features enable: Airmode, OSD, Anti Gravity and Dynamic Filter

Under DSHOT Beacon Configuration enable the beacon

Click Save and Reboot Go to the CLI tab and enter the following commands to place the motors in the proper positions:

resource MOTOR 1 B01 resource MOTOR 2 A02 resource MOTOR 3 B00 resource MOTOR 4 A03 save

To complete the remaining steps you'll need to apply lipo power to your build:

On the Receiver tab ensure your pitch, roll, throttle and yaw are being applied correctly. Adjust your transmitter and Channel Map as needed. On the Modes tab Assign an Aux switch to arm and disarm your quad.

Assign another Aux switch to enable Horizon or Angle mode if you need them.

Assign the Beeper and "Flip over after crash" to a 3rd and/or 4th switch. I like to assign them both to a single 3 point toggle switch. On the Motors tab enable the motor test and apply a small amount power to check the rotation of each motor. Take note of any that need to be reversed. Disconnect from Betaflight Configurator and open BLHeli Configurator Flash all ESCs to the latest firmware release.

Reverse the motor direction of any motors that need it.

Save and reconnect to Betaflight Configurator to test the motor direction. On the OSD tab Check all of the features you want and arrange your OSD as desired.

And that's it! The default Failsafe settings are generally fine, but make sure they work by arming your quad, applying a small amount of throttle and turning off your transmitter. It should shut down after 4 seconds.