Tuesday, January 12, 2016

ZMR250 Build Log

Updated on March 7, 2016
This is the second installment in my drone building saga.  For those interested, check out my hexcopter build, Blackout Mini Hexcopter.  I wanted to try the ZMR250 quad since it looks like they are lighter and fly more precisely.  At least once the aircraft is configured appropriately.  If you are entirely new to flying I recommend starting with a Hubsan X4 quad since crashing larger drones is costly and requires significant effort to repair.  Make your mistakes on lower cost aircraft.

This is an advanced project.  Anyone uncomfortable with computers, software, and using a soldering iron should probably stay far away from this hobby.

Parts List, ZMR250 Quad Multi-Rotor Aircraft (current build)
ZMR250 Carbon Fiber Airframe:  UBAD Kunai PCB,Tiger T-Motor MN2206 2350kv (x4) (banggood.com frame, motors anywhere you can get them)
ESC: KISS 20A v1.4 (x4) *KISS ESC's are awsome!  No firmware flashing required (or supported).  Support for both PWM@500hz and Oneshot125.  I'm running Oneshot125 it's great!
Battery: RMRC Orange Series1300mah 4S 60C Lipo (readymaderc.com)
Prop: DAL 5x4.5 v2  CWx2/CCWx2, 1 set shipped with each unit, what a concept (rmrc.com)
FC: Abusemark Naze32 Acro Version running Cleanflight v 1.11.0
Receiver: FrSky D4R-11 4-ch 2.4 Ghz/ flashed to 27ms 8-CH (hobbyking.com) [4]
FPV Camera:  600TVL Sony Super HAD CCD D-WDR Color Board Camera with OSD Menu DNR
FPV TX: 5.8 GHz 600mW FPV Race Band from ImmersionRC
DVR Camera: SJCAM SJ4000 (GoPro clone, bh.com)
Standoffs & Misc: Bluetooth Mini LE module (Blackbear Labs) required for Apple BT support, antenna: 5.8Ghz SpiroNet RHCP antenna from ImmersionRC, battery straps: Scorpion Lipoly Lock Strap 205mm (1 ea x 3 Small), 3D printed vented Uni-Spacer, blue 1ea (eBay or Shapeways), 3D printed 10 degree motor mounts (droneplastics.com).

I learned a few things from the first build.  My original 30A ESC where way too big and didn't fit on the aircraft frame properly.  I wanted something smaller so decided to go with smaller and popular KISS ESC's.  I eliminated the OSD.  The OSD is mixes the telemetry with your video signal to provide helpful information throughout your flight.  The flight time on these small aircraft is around 6-10min and they fly far too fast to be watching the daisy's.  I found I was not paying attention to the OSD anyway.  I also improved the video and moved to 5.8Ghz system.  Race drone technology is always improving and since I started about 1 year ago the video systems have improved.  The race band transmitter allows up to 32 aircraft to fly together.  Since I dropped the OSD I downgraded to the Naze32 Acro edition.  An unintended consequence is that the Full Naze32 has extra memory for the Blackbox feature.  So even if you don't care about the extra telemetry you may care about using Blackbox.  An ancillary benefit of the video frequency change is that the antennas are much smaller using 5.8Ghz.  ImmersionRC makes a great transmitter as well with built-in filtering and voltage regulation.  Unfortunately, it's also hugely overpriced just like their OSD.

Photo 1: 1st aircraft build (click to expand)
Photo 1, is the more or less the finished quad in my first build.  I have serval hover tests and tried 5" and 6" propellers, 3s and 4s batteries, etc.  I recommend running this aircraft with 6" props since it hovers around 1/4 throttle with 4s batteries.  The 5" props hover around 3/4 throttle.  To run 5" on my motors I would probably need 3-bladed props.  I didn't realize when I began the project the D4R-II receiver had to be reflashed to support 8-channels.  You will need to grab a cable to do that so do your homework if your purchasing one of these transmitters.  In the first build it was really hard to accommodate all the components in the 250mm frame. I still have improvements to make.  The battery cable comes dangerously close to the large 6" props.  I need to lock these cables down better.  Next I have the RC receiver antenna coming off the rear of the aircraft(wrong polarization angle).  I need to reorient this somewhere else, presumably the front of the aircraft sticking up offset from one another 45 degree angle like the old style rabbit ears.  It looks funny but there's not a lot of choice.
Photo 2: UBAD Kunai PCB board
Configuration of the aircraft involves plugging in a USB cable into the aircraft and running Cleanflight configurator on my Windows 10 computer.  I had an unfortunate incident where the back of my flight camera contacted the carbon fiber frame and exploded in a ball of flame.  Since I needed to reinstall the camera I decided to clean up some other stuff I didn't like.  I decided to return back to the PCB and purchased a UBAD Kunai PCB, Photo 2.  The PCB eliminated tons of wiring and really cleaned up the build.  The UBAD board adds a little bulk to the bottom of the board with a voltage regulator.  Since I needed some space on the bottom I decided to run my wires on the bottom and purchased a vented uni-spacer (shown in photo 4).
Photo 3: Top view
Photo 3 is the same stage of construction as photo 2 except looking at the top.  The small board on the top is the Naze32 flight controller.  Notice there is no wiring to the flight controller, it's all in the PCB.  The blue tape on the legs is to keep the ESC's from touching the frame until I lock down the heatshrink tubing to insulate them.
Photo 4: Bottom view, almost finished
Photo 4 is the bottom view almost finished.  I have added a 5vdc regulator, shown in black heatshrink.  The Bluetooth module is shown just above.   A warning on the bluetooth module.  I made a mistake and did not purchase the Bluetooth LE version.  The mistake means I only have support on my Android tablet.  If you want to use your Apple gear to configure your aircraft in the field you will need to purchase a Bluetooth LE module.
Photo 5: Configuration of flight control software
Photo 5 show the aircraft at configuration time.  The blue tape on the top deck is to hold the camera platform stable while my epoxy dries.  The blue table on the motors is so I can see which way the motors rotate.  Unless I put something on the motor it's tough to see which way they are rotating.
Photo 6: Finished Aircraft

Photo 6 is the finished aircraft with LEDs.  The LEDs are super bright.  I tried a quick hover test just before sunset but my Fatshark goggles ran out of charge.  I don't really need them for hover testing anyway.  The aircraft flew rough with high speed oscillations.  The heavier the thrust the more severe the oscillations.  I'm thinking the PIDs configuration settings, specifically the P values, are too high.  I am pretty optimistic about this aircraft build. A small word about Finished caption on Photo 6.  When you get into this hobby you will find you are never really finished.  There is always some improvement to make.  Perhaps a better description is flight worthy.  I plan to post some updates in the future.  Like my maiden flight.

Video 1 is the maiden flight.  I had a number of configuration issues along the way.  Finally got the major bugs worked out.
Video 1: ZMR250 quad maiden flight
Video 2 is a little more interesting.  I few more flights under my belt.  My PID configuration needs some slight adjustment since I change the props from 6x4.5 to 5x4.5x3, a tri-blade design.  Anytime the power to weight ratio changes it messes with the configuration.
Video 2: ZMR250, a more interesting flight

Share It!