Recently I have been asked for my recommendation for a super lightweight pocket rocket. At the time of writing there are no stock lightweight RTF 2S copters I can recommend. You will have to assemble it on your own, luckily you can buy all the needed parts, there is no need to assemble circuit boards on your own. In the end you end up with ~280g thrust on a 27g + 17g (battery) = 45g quadcopter (6.3:1 thrust to weight ratio).
For a decent flying and durable copter I would recommend BR1103 motors. I have used the old racerstar motor design in the past, but unfortunately it looks like it is not in stock anymore… I have updated my frame design to the newer BR1103B motor mounts. The 070x motors I have tested in the bast used brass bushings instead of real ball bearings. In combination with poorly balanced flange you will end up with a short lifetime and maximum vibrations :-\ This is why I recommend 1103 motors.
- pepperFIISH BR1103B frame for (83mm diameter)
- a set of 4 Racerstar BR1103B 8000KV motors
- tinyFISH flightcontroller
- tinyPEPPER 2 2S ESC (FPV-0252-S from furiousFPV)
- a bag of 56mm props such as JJRC1000A (use a 1.45mm drill to widen the hole!)
- VM275 camera/VTX combo
a 3.3V or 5V step down regulator (e.g. Pololu D24V5F3 or Pololu D24V5F5)
- a 5V step-up/down regulator Pololu S7V7F5
- a handful of Turnigy nano 2S 300mAh
- M2 x 12mm nylon screws
- Micro JST PH2 3pin plugs
- some 24AWG and 30AWG silicon wire for wiring
- some 5mm rubber foam for battery protection
UPDATE: changed the regulator to a step-up/down. This way this build can run on 1S and 2S! Thanks for the recommendation nwbb!
3D printed parts
- 1x Camera mount (10, 20, and 30° options)
- 2x Battery mount (2S) (optional now, the new frame comes with rubber band tabs!)
- 4x M2 x 2mm spacer
- 4x M2 x 3mm spacer
Due to changes to the mounting pattern this frame design is only for BR1003B motors!
With this new design you can save some weight by using foam and rubber bands for battery fixation instead of the 3d printed holder. In case you want to use different motors I have a similar design for you: One for 070x motors (with rubber tabs) and one for the older BR1103 motor design.
Start by soldering the power cables to the FC input pads. Next, add power and signal connections between the FC and ESC. Connect the input pads of the stepdown to the Lipo Vout pads of the FC and connect the 3.3V output to the camera/vtx combo. I had to add a 47uF capacitor to the 3.3V pads of the step down in order to get the camera to work. You can use any 47uF capacitor rated for at least 10V for this, I used a SMD multilayer capacitor in the 0805 size.
Use a M2 drill bit and cut the thread into the camera holder. Next, take four screws, the spacers, the FC, the ESC, and the camera holder. The 2mm spacers go between frame and ESC, the 3mm ones belong between ESC and FC. Screw everything together.
Take the motors and mount them to the frame. Make sure to use screws with the right length, they should not touch the motor coils! I used some nice and lightweight titanium screws instead of the ones that came with the motors. Add some low strength threadlocker to the motor screws (I use the purple Loctite 222).
Cut the motor wires to the appropriate length (keep some extra) and solder them to the ESC tabs. Those motor wires are really fragile. The best way to strip the isolation is to cut the wire a bit longer, overstretch/expand the isolation, cut the isolation and apply some heat to it. The isolation is made from heatshrink tubing and will shrink on heat exposure. This exposes the wire you want to solder. Do not use wire stripper/cutter tools as they might leave cut marks on the thin motor wire which cause it to break on vibrations.
Insert the camera into the holder and add a shortened zip tie as protector cage. Now finish up the quad by adding sticky foam on the bottom and mount the battery using some rubber bands.
Start by binding your TX to the receiver by pressing the bind button during powerup. Do the normal bind procedure you are used to. Now it’s time to proceed with the configuration — Fire up the betaflight configurator. Please note that the FC will not run on USB power, you will have to connect the battery as well. Do not let it run on the lipo for long time, the camera will drain a fully charged battery within less than 40 minutes…
The most important thing you will have to do is to set the FC orientation to the right value! Depending on how you mounted the FC, it is +/-45° or +/- 135° rotated (yaw axis)! Set and doublecheck it by viewing the 3d model of your copter, it should follow all your turning motion. If you screw this up the copter will end up in your ceiling on the first arming — been there, done that…
Check your motor ordering and fix it by using resource remapping. Verify the receiver functions properly in the input tab. That’s it. For me the copter flies quite good with the stock PID settings.
Just in case you want to use a buzzer on this FC with bf 3.1.7 make sure to apply the appropriate fix.
You finished your 2S pepperFIISH? I would be happy to see and share a picture on my blog!