Donut 3" - Build a Cinewhoop for under $200

By Whiffles on Jul 30, 2019

55  12,529  43

You've probably heard the term "Cinewhoop". Traditionally it's a 3" ducted quad capable of carrying a GoPro Hero7 Black at a low 10 degree angle. More recently the term "Cine" has been applied to a number of RTF quads ranging from 85mm to 3". They all focus on their HD capability, but none compare to the stabilization of Hypersmooth (only available on the Hero7 Black). This is what really offers that cinematic style footage. Now there's also ReelSteady Go which applies a similar stabilization algorithm to previous GoPro models, but Hypersmooth is what popularized this style of build.

Now a traditional Cinewhoop isn't cheap. The most popular frame, the Squirt 2 commands a high price. This build is my attempt to build a Cinewhoop at a budget price, yet still offer the same cinematic style footage. It weighs in at 217g dry and 443g AUW with an 850mah 4S battery with a GoPro Hero7. I'm running the 3500kv motors.

Top down view

Tools

This is a moderately challenging build and does require a lot of fine soldering. With the proper tools and a lot of patience you can pull through. I highly recommend a flux pen, good 63/37 leaded solder and a quality soldering iron. Here are the tools and supplies you'll need. I've included direct links to my gear below.

  • Soldering iron
  • 1.5mm and 2.0mm hex drivers
  • Industrial Tweezers
  • 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

The frame kit comes with everything you need except for enough 6mm M2 screws to mount your stack. In fact, it's only one screw short. The stack doesn't come with hardware so I recommend buying an M2 screw kit. I linked my kit below. Other than that you don't need to purchase any additional hardware.

Frame Assembly

This frame is really easy to assemble. You don't need the ducts or any of the TPU parts just yet, so save those for the end. To start you only need the base plate and the arms. Use the included gold screws to mount the arms on top of the base plate. Screw the black standoffs above to hold everything in place.

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Motors

Now this is where things start to get a little tricky. Mount the motors onto the arms using the included screws. It's helpful to use blue Loctite to ensure the screws don't vibrate out. Once you've done that it's prudent to do a little wire management. I used zip ties to direct the wires across the bottom plate. You want the wires to follow the arms, but not all the way to the standoffs. They need to drop down off to the side so the ducts don't pinch them later. The zip ties help hold them in place so you can solder them to the ESCs.

Once you're ready to solder you need to remove the flight controller from the stack. Do this by unscrewing the nylon nuts on top and unplug the FC from the 4-in-1 ESC. Now you can mount the 4-in-1 ESC to the frame using the aforementioned M2 screws. Make sure the battery tabs point toward the rear of the frame. The front has the camera mount tabs.

Before soldering it's a good idea to flux all the motor tabs then apply a ball of solder to each tab. The pads are really close together, so you may accidentally bridge them. To fix that just apply some flux and slice through the middle with your iron. Now if you're right-handed start with the rightmost pad and solder your motor wires to the pads one at a time. Cut each to length as you go and be sure to give yourself a little slack. Again, if you accidentally bridge the pads just apply some flux and be patient. This can be a tedious process.

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Power Connector

Congratulations! You've just completed the most difficult part of the build. Now you can solder the power leads. Everything you need is at the bottom of the Mamba container.

  1. Solder the wires to the XT30 connector first and make sure you've got the polarity correct. Add shrink tube to cover the joints.
  2. We want the battery lead to come up to the side of the battery between the ducts, so measure the wire and cut it to length. Keep in mind that one wire should be cut a little shorter than the other to allow the wires to run to the side.
  3. Flux and add solder to the battery pads on the 4-in-1 ESC and solder the wires to the pads.
    • Use a steady hand and be very careful not to accidentally bump the components on the board with your iron.
  4. Solder the capacitor on top of the battery leads.
    • The striped side is negative.

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Wiring Diagram

The flight controller doesn't come with instructions, nor are there labels on the pads, so it's crucial to reference the wiring diagram. For this build you'll need to use just about every pad on the left side of the board. Refer to the diagram below. These pads are really tiny, so don't apply too much solder and use plenty of flux. I found it easiest to solder the wires to the little grooves on the sides of the pads.

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Binding the Receiver

Now that you've got power you can add the receiver and bind it. I used the FrSky XM+, but you'll need to choose a receiver that matches your radio.

  1. Solder 3 wires to the 5v, GND and SBUS pads on the receiver.
    • I borrowed some wire from the camera. It's got enough to spare.
  2. Solder these wires to the 5v, GND and SBUS pads on the flight controller.
  3. Add your flight controller to the stack and re-connect it to the 4-in-1 ESC. Don't secure it with the nuts just yet.
  4. Bind your receiver
    • Be sure to double check that you don't have continuity between your main battery leads and use a smoke stopper if you have one.
    • Hold the bind button on the receiver while you plug the main battery in. (It's helpful to clamp this button down with tweezers to free your hand)
    • Put your radio into bind mode and make sure you're bound.
  5. Now that you're bound you can add some shrink tube to your receiver and tuck it under the flight controller. Now secure it with the nylon nuts.

I had a hard time finding a place to mount the antennas. The arms are parallel to each other. Ideally we want the antennas to be at a 90 degree angle from one another, so I found a nice solution. The 30.5mm stack mount holes are perfect for a couple small zip ties. Just tighten them at a 45 degree angle toward the rear of the quad and you're all set! Secure the antennas to the zip ties with shrink tube.

Camera

Next we can add the camera. First you'll want to screw the side plates to the camera and mount it onto the frame to measure the wire. Remove the purple wire and connect the wire harness to the back of the camera. Cut the wire giving yourself a little slack to adjust the camera angle. Refer to the wiring diagram for wire placement. You'll use the first three pads.

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Video Transmitter

Now for the VTX! De-solder the 5v out and GND wires from the board because we won't be using those. Give yourself enough slack to mount the VTX just behind the camera on the top plate. You'll want the antenna to point toward the rear of the quad. Again, refer to the wiring diagram to solder the wires to the flight controller. These will be the 4 remaining pads between the receiver and camera wires.

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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 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

Once you've added the ducts it'll be difficult to reach the USB port, so I recommend a USB extension to avoid removing the ducts later on. If you don't have one you should skip ahead to the Betaflight Configuration section below and configure your quad before the final assembly. You may also want to put the props on before adding the ducts. The motors can be tricky to grip with the ducts in place.

  1. To finish up slide the ducts over the standoffs being careful not to squish the motor wires. You may need to adjust the wires to get a good fit.
    • Make sure the ducts are right-side up so you can screw them onto the tips of the arms.
  2. Remove nuts and washers from the SMA pigtail and fit it through the TPU antenna mount. Put them back to secure it to the mount.
  3. I recommend getting some very wide shrink tube (~26mm) to cover the VTX. That way you don't need to tape it to the frame and it can float above the flight controller. That'll give you more flexibility with your battery strap.
  4. Screw the top plate into place with the TPU components for mounting the antenna and camera.
  5. Screw your SMA antenna onto the pigtail.
  6. Add a battery pad to the top to prevent battery ejections and slide a battery strap under the top plate.

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Betaflight Configuration

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

  1. First go to the Firmware Flasher and choose "FURYF4OSD" as well as the latest stable release of Betaflight.
  2. Click "Load Firmware [Online]" and then "Flash Firmware" to update your flight controller. Once complete, click "Connect"
  3. On the Ports tab
    • On UART1 click Serial RX for your receiver.
    • Set the UART3 Peripherals to "VTX (SmartAudio)".
    • Click Save and Reboot
  4. On the Configuration tab
    • Under ESC/Motor Features select DSHOT600
    • 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
  5. Go to Power & Battery and choose Onboard ADC for the Current Meter Source
    • Click Save and Reboot

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

  1. On the Receiver tab ensure your pitch, roll, throttle and yaw are being applied correctly. Adjust your transmitter and Channel Map as needed.
  2. 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.
  3. 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.
  4. Disconnect from the Betaflight Configurator and open BLHeli Configurator
    • Connect and Read Settings
    • Flash all ESCs to the latest firmware available.
    • Reverse the motor direction of any motors that need it. (The numbers correspond to the same numbers in Betaflight)
    • Save and reconnect to Betaflight Configurator to test the motor direction.
  5. 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 a short moment.

Challenges

The biggest challenge was soldering the tiny pads. I found it worked best to rest my wrist on a flat surface to steady my hand. The more steady you are the better. You just want to avoid bumping adjacent solders causing them to flow together. Other than that I spent a fair bit of time finding a place to mount the receiver antennas. It wasn't the most difficult build, but it did require some patience.

In terms of motor heat, between the HQProps and the Gemfans I found the Gemfans to run cooler. The motors do tend to get hot on these ducted builds, but with very low d-term values on the Gemfans they're coming back reasonably warm, but not burning hot.

Photos

Part List

Frame

Donut" 3 Inch 140mm H-type Frame Kit 3D Printed + Carbon Fiber for RC Drone FPV Racing 75.5g (4 builds)
Banggood.com
$29.99

Flight Controller

MAMBA F405 Mini MK2 Betaflight Flight Controller & F25 20A 3-4S DSHOT600 FPV Racing Brushless ESC (14 builds)
Banggood.com
$39.99

Motors

4 x GEPRC SPEEDX GR1408 3500KV 3750KV 4100KV Brushless Motor for RC Drone FPV Racing (7 builds)
Banggood.com
$51.96

Propellers

2Pairs HQ Prop Duct 3 Tri-Blade 3" Cinewhoop Propeller For FPV Racing
Banggood.com
$2.99

Propellers

2Pairs Gemfan 75mm Ducted Props PC 3-Blade Propeller CW CCW 5mm Hole for 1408-1808 Motor Cinewhoop Cinedrone (7 builds)
Banggood.com
$2.69

FPV Camera

Foxeer Arrow Micro Pro 1/3" CCD 1.8mm M8 Lens 4:3 600TVL PAL/NTSC FPV Camera with OSD Black/Blue/Red (11 builds)
Banggood.com
$19.90

FPV Transmitter

AKK Race VTX 25mW/200mW Switched 5.8Ghz 40CH Smart Audio FPV Transmitter Raceband Support Pit Mode For RC Racing Drone (2 builds)
Banggood.com
$8.59

Antenna

Aomway MINI-2.5 5600-5950MHz 5.8GHz 2.5dBi SMA/RP-SMA RHCP Mini FPV Antenna For FPV Racing Drone (2 builds)
Banggood.com
$4.99

Receiver

Frsky XM+ Micro D16 SBUS Full Range Mini Receiver Up to 16CH for RC FPV Racing Drone (1237 builds)
Banggood.com
$11.99

Batteries

4Pcs XF Power 14.8V 850mAh 4S 70C Lipo Battery XT30 Plug (2 builds)
Banggood.com
$38.99

Batteries

TATTU 14.8V 850mAh 75C 12.58Wh 4S XT30U-F Plug Lipo Battery for RC Racing Drone (3 builds)
Banggood.com
$25.59

Batteries

Gaoneng GNB 14.8V 750mAh 80C 4S XT30 Plug Lipo Battery for RC Drone (4 builds)
Banggood.com
$20.99

Radio

FrSky Taranis X-Lite Pro 2.4GHz 24CH ACCESS ACCST D16 Radio Transmitter Longer Telemetry Range for RC Drone
Banggood.com
$199.99

Goggles

FatShark Dominator HDO 4:3 OLED Display FPV Video Goggles 960x720 for RC Drone (92 builds)
Banggood.com
$499.99

HD Camera

GoPro HERO7 Black Action Camera (49 builds)
Getfpv.com
$399.99

Hardware

Suleve™ M2CH2 M2 Carbon Steel Allen Bolt 4-16mm Hex Socket Cap Screw Metric Assortment Kit 180pcs (2 builds)
Banggood.com
$5.99

Misc Parts

1m PVC Heat Shrink Tubing Black 30/40/46/50/60/70/86mm Wide For Lipo Battery
Banggood.com
$1.99

Battery Charger

ISDT Q6 Lite 200W 8A MINI Pocket Battery Balance Charger for 2S-6S Lipo Battery (17 builds)
Banggood.com
$49.99

Soldering Iron

Hakko FX888D-23BY Digital Soldering Station FX-888D FX-888 (blue & yellow) (19 builds)
Amazon.com
$99.42

Tools

Wowstick 1F+ 64 In 1 Electric Screwdriver Cordless Lithium-ion Charge LED Power Screwdriver From XIAOMI ECO-System (2 builds)
Banggood.com
$36.99

Accessories

10Pcs XT30 Male to XT60 Female Adapter Battery Connector for RC Drone FPV Racing
Banggood.com
$8.50

Accessories

GEPRC 90 Degree L Type Right Angle Micro USB Transfer Extension Module Cable Female to Male for RC Drone (2 builds)
Banggood.com
$3.12

Accessories

Dahle Vantage 10682 Self-Healing 5-Layer Cutting Mat Perfect for Crafts and Sewing 18" x 24" Clear Mat
Amazon.com
$20.99

Accessories

XT60 Plug Parallel Charging Board For ISDT D2 Q6 T6 Lite Charger (3 builds)
Banggood.com
$15.99

Misc Supplies

Kester 24-6337-8800 50 Activated Rosin Cored Wire Solder Roll, 245 No-Clean, 63/37 Alloy, 0.031" Diameter (12 builds)
Amazon.com
$19.60
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Discussion

Sign in to comment

SimJen   Aug 13, 2019  

Great writeup, its inspired me to build one.
I've just bought one of these frames, and another Tyro79. Looking to put the Tyro hardware in mine and run 4s 650mah CNHL cells as my other Tyro freestyle rig.
Hopefully will be good enough to fly with a Session 5.

Show 2 more comments
SimJen   Aug 14, 2019 

Yeah, i'll give it a go. If it's not powerful enough to lift the gopro then I'll put a Split 3 in it to make a lightweight cinewhoop.

SimJen   Oct 30, 2019 

It works, although I'm not particularly happy with the way a ducted quad flies, but could be good when I get the Session mounted up properly.

Whiffles   Oct 31, 2019 

Flying it quick or slow?

Thomaat   Oct 19, 2019  

Seems to fly pretty good! What betaflight version are you running?

Whiffles   Oct 20, 2019 

I think I've got 4.0 on this, but I may want to try 4.1 now.

Thomaat   Oct 20, 2019 

Are you using stock pids? I'm not interested in tuning 4.0 haha

Whiffles   Oct 24, 2019 

I reduced the d-term quite a bit and tweaked the p slightly lower. It's very particular to every version of Betaflight though so you'll need to experiment.

Daniel Arts   Oct 10, 2019  

Hello, very nice build! I have planned to build one ultralight Cinewhoop with caddx tarsier under 250 gram including battery. I have ordered the donut frame and some 1306 motors with 3100 kv. With all components the complete weight without battery will be exactly 150 grams, with the planned 2s at around 220 grams. What do you think about this project? I do not need extreme thrust, this should be only for really relaxing cinematic cruising.

SirSparv   Oct 06, 2019  

what's the weight?

Whiffles   Oct 07, 2019 

217g dry and 443g all up with an 850mah 4S pack and the Hero7 Black.

Dirtstyle   Oct 04, 2019  

Heyho!

Thank you very much for the Guide!
Beginner Question: Will this setup be compatible with the new access protocoll?

Thanks in advance!

Whiffles   Oct 04, 2019 

Sure, if you use an ACCESS receiver. I believe you can even flash ACCESS onto the XM+ which is what I used here.

Carbon FPV   Aug 19, 2019  

Is it really necessary to have hypersmooth on your camera, can't you get the same look just by flying smoothely? I just have a gopro hero 5... Also, do you think 1404 6000kv motors would work?

Whiffles   Aug 26, 2019 

Sorry I missed your comment! Hypersmooth looks a lot more "floaty" than normal flight. A lot of people are getting even more floaty footage using Reelsteady Go. I know it's compatible with the Hero5, so you might want to look into it. It might require mounting the camera on looped zip-ties though. Check youtube for Hero5 Reelsteady Go footage.

As for 1404 6000kv motors I don't think those are a good choice for one of these. The sweet spot is 1407 3600kv or 1408 3500kv on 4S. These builds are typically overweight and under-propped so the motors tend to get really hot. I think 6000kv is far too high.

Carbon FPV   Sep 03, 2019 

Okey thanks for the answer! It's just that I have a pair of 1404 6000kv motors already, though they are running on 3s. Might be a bit too heavy for them but I'm thinking of trying anyway!

catSupremacy   Sep 26, 2019 

with the hero 5, you can use reelsteady go. its even better than hypersmooth. unfortunately its pertty expensive

petrovvladimir   Sep 21, 2019  

Hello! Can you share your PIDs and rates settings?

mhr63   Sep 10, 2019  

hi . can use 3.23.2 mm holes Fc and Esc on this frame ?
I have the following pieces . Can I use them?
FC : kiss v 1.3 ( Mounting Holes: 3x3cm pattern, with 3.2mm holes )
ESC : an esc 4
1 with 3.23.2 holes or 22 holes
vtx : ewrf e7082c

Wouldn't it be better to use a ESC 25 amp? as :
https://www.aliexpress.com/i/33015157840.html?spm=2114.12057483.0.0.4320108fv4VlK6

Whiffles   Sep 11, 2019 

You might be able to fit that KISS FC, but it'll be a tight fit. You're best off using a 20mm stack.

Hegy   Sep 05, 2019  

Hi, I'm very happy with the way you provide information and tutorials. Very clear and good. I want to ask. for the BR1407-3500KV motor. Is it still ideal for a cinewhoop class equipped with gopro season? What firmware is recommended? I use betaflight. and prop gemfan 3052? please enlighten me. thank you

Whiffles   Sep 05, 2019 

Sure, 1407 3500kv should be perfect. I prefer Betaflight for the community support and as for the props the Gemfan 75mm ducted props are great.

Hegy   Sep 05, 2019 

ask for advice. firmware suitable for cinewhoop by using duct. 4.0.3 / 4.0.5 / or how much? I use 3inch prop. is gemfan 3052 right? my cinewhoop spec (cinewhoop duct 3inch, prop 3052, gopro season, 4s 1000mah, Br1407-3500kv)

lord-of-candy   Aug 30, 2019  

Really good looking build and thanks for the work on the guide. Curious if we can find those ducts on Thingverse so we can print them in nylon or tpu. I don't quite like the quality of them from BG. Earmarking this one though, top contender for next build.

Whiffles   Aug 31, 2019 
1

Thank you! I believe somebody designed a remix of the ducts but I haven't tried them myself: https://www.thingiverse.com/thing:3802928

catSupremacy   Jul 30, 2019  

flight footage?

Show 1 more comment
rixx   Aug 07, 2019 

sample video please. :)

Whiffles   Aug 08, 2019 
2

I just added a sample video above.

catSupremacy   Aug 08, 2019 

awesome thanks!

joseki   Aug 02, 2019  

Very nice article and clean build. I have quite similar build and it's working ok but I don't know anything about pid configurations and I am pretty sure that my quad would fly a lot better if I know how to tune pids. Do you have any advices what to tweak from stock settings?

Show 3 more comments
joseki   Aug 08, 2019 
1

I am flying in acro mode, I use angle mode only for landings.

I have "build" my quad by just moving all the parts from Diatone R349 to Donut frame. The R349 was flying perfectly and that's why I tought that maybe the issues are related to Betaflight settings but it can be also props which are causing those quirky moves.

One real example of the issue was when I was chasing mountain biker and did some consecutive turns the quad refused to do the next tight turn when at the same time I was lowering the altitude. Quad acted a bit like when trying to turn hard in angle mode and it tries to force to stabilize it. There was also quite a lot of prop wash even in mellow dives.

kwadkenstine   Aug 08, 2019 

take the ducts off , bet it flies better.
the downside of ducts is that they doo try and satibalise (sort of).
Its never going to fly like a craft without ducts. I see cini woops as tools , maby not the right tool for a chase quad.

Whiffles   Aug 08, 2019 

Do you have any footage to demonstrate the problem? It could just be that you're pushing it too hard with the ducts.

juju   Aug 01, 2019  

Any reason why not go with the full 30.5 x 30.5 Mamba F405 stack? I've seen some other guys use that instead for cinewhoops.. Asking because I just want to know what makes more sense... So far all I've purchased was the shendrones squirt v2 frame (carbon and hardware only). Starting to plan out the build now.

Whiffles   Aug 02, 2019 

For such a tight build it's always best to go with a smaller stack. There's no need for the larger one.

thumbtwiddler   Jul 30, 2019  

darn now I'm tempted even though I don't even have money

Power_FPV   Jul 30, 2019  
1

Clean and cheap!
Love it, looks like a very very solid build.

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