MK FPV Heavy-lift X8 using standard ESC's and Futaba TX/RX

[Mactadpole]

MK FPV Heavy-lift X8 and Futaba TX/RX

I had started a build log on the "other" forum for this copter when it was using the HoverflyPro FC board. Since I am converting to MK I wanted a new build log to document how I set this thing up - primarily for my reference but also to share in hope of helping others just starting out. A lot of the initial info will just be a copy and paste from the initial build but I thought it would be best not to send others somewhere else for the info.

My intended use for this platform is to collect aerial imagery of tropical forest that can then be geo-rectified and used for GIS analyses. I would also like to collect HD video for amateur/scientific and possibly professional presentation of my work. I need a platform that is easily transported because of international travel and in-country transportation such as bus, hiking, canoe, etc. I also desired as small a frame diameter as possible since I will often be launching/landing from trees or canopy towers in forested areas. This is why I have chosen the X8 (coax octo) platform. I also wanted/needed redundancy since I won't have a backup. I am hoping I can get enough flight time out of it so I can shoot several hectares in a flight.

2011-Feb: Finished ordering and receiving everything. I assembled the DW landing gear w/AV130 Pro Mount Mini and the very minimal assembly of the frame.

2011-Mar-01-02: (1.) Laid out and began soldering the power distribution ring. It consists of 10 female deans connectors soldered together using 12 gauge solid copper wire. 8 are for the ESC/motors and the other 2 are auxiliary connections. See pic descriptions below for details. (2.) Cut my first motor shaft using my dremel tool and only doing short timed cuts so as not to heat things up too much. (3.) Wired up first ESC/motor to test power distribution ring before sealing it up with liquid electrical tape.

2011-Mar-03: (1.) Drilled holes in frame to mount DW landing gear. (2.) Finished bench test of power distribution ring. No problems found. First coat of liquid electrical tape applied.

2011-March-05: (1.) All coats of liquid electrical tape on power distribution ring and it was mounted using double-sided tape. (2.) Soldered connections for FPV camera and tx. Bench tested ok. (3.) Did a preliminary mounting of the VTX and antenna. Waiting for comments. (4.) Did a layout for LED navigation lights. (5.) Cut off 4 more motor shafts. Will take some pics of the next ones I do.

2011-March-06: (1.) Finished complete mounting of 1 motor on 1 arm with LED's.

2011-March-13/15: (1.) Finished soldering and dressing all motor/esc combo's. (2.) All top motors mounted. (3.) All LED's mounted and soldered.

2011-March-27/28: (1.) Soldered together harness for 12v power to FC board, LED's, and video transmitter/camera. I used JST connections for everything and added an extra source plug for anything in the future. (2.) Tested FPV setup - works great! (3.) Mounted all motors and screwed frame together. Used loctite all over the place.

2011-March-30/31: (1.) Completed the build! (2.) Not happy with 12V harness for FCB, LEDs, and VTX/Camera. Just too much wiring crammed in there. Going to make a power distribution block from micro-Deans and connect everything that way. (3.) I think I am also going to put a switch between 3s battery and micro-Deans power block so I don't have to be so frantic about getting it plugged in after powering the ESCs and motors with 4s batteries.

2011-April-12: (1.) Added toggle switch for 3s battery which powers board, LED's, and VTX. Makes it easier to power board after plugging in motors. (2.) Worked on ground station.

2011-April-15/16: (1.) Added Eagle Tree (ET) eLogger v4, ET OSD Pro, ET GPS v4, ET altimeter v3. (2.) Installed DPCAV 1.3Ghz v-dipole VTX antenna. (3.) Added two fiberglass rods on read to mount VTX and ET GPS, I also plan to add a few LED's to it for orientation assistance. (6.) Completed ground station which includes: 2x Lawmate 1.2/3Ghz receivers, ET EagleEyes ground station for diversity and telemetry, 15" Craig HD LCD, Asus Eee PC 1005HA, EasyCap for recording, and Fat Shark basic goggles.

2011-April-16: Current specifications->

Frame: RCcarbon X4-8
Landing gear: Droidworx's extended
Camera Gimbal: Photohigher AV130
Motors: Pulso 2814/22
ESC's: RCTimer 30A programmable
Props: APC 12x3.8
Batteries: Turnigy Nano-tech 4s 4500mah (single and parallel), Turnigy Nano-tech 4s 6000mah (single and parallel)
Weight (no batteries or camera): 2761 grams

2011-June: (1.) Been ordering parts for conversion to MK electronics. (2.) Also order custom circular polarized antennas from http://videoaerialsystems.com/

2011-June-25: Began creating build log here!

Here is an example of an image I took this past summer in Amazonian Ecuador flying my QP hexacopter from a canopy tower. Look near the upper center of the pic for a white square, that was my launch pad and I am standing just above it. This tower is 150' up in the tree and required about a 20' navigation between tree branches to get in open airspace.

Components - basic

• Frame: RC Carbon X4-8 foldable frame - $410 shipped (note: Sergey has changed the centerplate format, name, and price a bit but basically the same)
I had it extended to 750mm motor to motor distance so I could run up to 13” props with the Droidworx extended landing gear attached. It will also be fitted with an electronics mount for the HoverflyPro board and another for the Quadpowered board, no extra charge for these. Sergey is the designer and builder of these frames and super easy to work with! He even threw together a layout for me so that we knew it could spin up to 13” props with DWX landing gear. I know this is a lot of money but it was much less than my original plan to go with a Droidworx frame. I was originally going to get a Droidworx AD-8 heavy lift frame along with a set of coax motor mounts and hardware to convert to the ADX-4 frame. This would have cost me ~$930 + shipping (that’s minus the cost of the landing gear for sake of direct comparison and I will be using the DWX extended landing gear anyhow). It would have given me the option of flat or coax octo but I really hope to get away with the X8 form because of size and transportation ease. I believe this frame will also be ~100g lighter than the DWX ADX-4 and the arms fold, more bonuses. If for some reason I don’t like it I will sell it and bite the bullet for the DWX frame.

• Landing gear: Droidworx Landing gear assembly extended - $295 + shipping
I went with these because I want to use the PhotoHigher camera gimbal.

• Electronics Protection cover: Camo Gear Helmet from Hobby Lobby - $3.29
I reinforced from the inside with duct tape and painted it black. I am thinking about using some spray plasti-dip to further reinforce from the inside. I love this thing because it is tall and fits perfect.

• Camera gimbal: Droidworx/PhotoHigher Pro Mount Mini (AV130) - $790 + shipping
I went with the AV130 for now, but I would possibly like to mount two cameras like the Sony Nex-5 or Panasonic GH2 in portrait orientation to get stereo photos. I think they would both fit in the AV200 oriented this way if I built a custom bracket to mount to the plate. I still have several issues to consider, one being weight and the other is camera choice. The AV200 is nearly twice the weight of the AV130 and by the time I add the second camera with custom bracket I have added a lot more weight. Currently, I have a Canon SX200 but its images seem a little soft to me. I just received my Panasonic GH2 but have not flown it yet. Droidworx and PhotoHigher say they are working on a gimbal for mounting two cameras in the future.

• Motors: Pulso 2814/22 - $62/each shipped
I have been happy with these motors on the few flights I have taken. We'll see how they do once I get the X8 flying again. I will probably switch to Avroto or Axi at some point since these are getting very hard to source.

• ESC: RCTimer 30A - $10.99/each shipped

• Batteries: Turnigy Nano-tech 4S 6000mAh - $64.75 + shipping
Turnigy Nano-tech 4S 4500mAh - $52.30 + shipping
I have setup the power system to run these single or in parallel with 2 or 3 of the same batteries.

 

[Mactadpole]

Components - electronics

• Flight Controller: Mikrokopter Flight-Ctrl V2.1 ME - $460.00 + shipping

• Navigation:
Mikrokopter Navi-Ctrl V1.1 - $171.00 + shipping

Mikrokopter MK3Mag - Compass Module with ACC - $112.50 + shipping

Mikrokopter MK GPS V1 - $106.95 + shipping

• Communication:

MK USB - $25.25 + shipping

Xbee Set, plug and play - $189.99 + shipping
Wireless communication between MK and laptop. Don't have this yet but plan to get it.

Precision I2C to PWM Converter for Standard ESC [ST] - ~ $17.00 shipped
Allows for the use of standard ESC's

8 Channel Serializer PWM to PPM Encoder - $49.99 + shipping
I am using this to convert my Futaba PWM signal to the required PPM signal on the Mikrokopter.

 

[Mactadpole]

FPV and Ground Station equipment

 

[Mactadpole]

Here is the board position and motor rotation layout I am using. I created a custom mixer file and it works great.

Mixer text:

[Info]
Name= X8 MK_HFP
Version=1
[Gas]
Motor1=64
Motor2=64
Motor3=64
Motor4=64
Motor5=71
Motor6=71
Motor7=71
Motor8=71
Motor9=0
Motor10=0
Motor11=0
Motor12=0
[Nick]
Motor1=64
Motor2=-64
Motor3=64
Motor4=-64
Motor5=71
Motor6=-71
Motor7=71
Motor8=-71
Motor9=0
Motor10=0
Motor11=0
Motor12=0
[Roll]
Motor1=64
Motor2=-64
Motor3=-64
Motor4=64
Motor5=71
Motor6=-71
Motor7=-71
Motor8=71
Motor9=0
Motor10=0
Motor11=0
Motor12=0
[Yaw]
Motor1=-64
Motor2=-64
Motor3=64
Motor4=64
Motor5=71
Motor6=71
Motor7=-71
Motor8=-71
Motor9=0
Motor10=0
Motor11=0
Motor12=0



Wiring diagram:

Build pics:

Frame and landing gear assembled

Power distribution ring consisting of Deans connectors and 12 gauge solid wire

All positive connections soldered

April 2011

April 2011

 

[Mactadpole]

Setup procedures

 

[Mactadpole]

Flight logs and video

 

[Mactadpole]

Reserved 6

 

[RTRyder]

Components - electronics

• Flight Controller: Mikrokopter Flight-Ctrl V2.1 ME - $460.00 + shipping

• Navigation:
Mikrokopter Navi-Ctrl V2.0 - $290.40 + shipping

Mikrokopter MK3Mag - Compass Module with ACC - $112.50 + shipping

Mikrokopter MK GPS V2.1 - $105.95 + shipping

You won't be needing that compass board with that Navi controller, its functions have been integrated into the 2.0 version of the Navi controller. You would have needed it with the previous version of the Navi board, 2.0 was released a very short time ago ( one or two weeks I think?)

Ken

 

[Mactadpole]

You won't be needing that compass board with that Navi controller, its functions have been integrated into the 2.0 version of the Navi controller. You would have needed it with the previous version of the Navi board, 2.0 was released a very short time ago ( one or two weeks I think?)

Ken

Thanks for pointing that out! I actually already have the electronics which are the previous version. The information has been updated above. Thanks again, Shawn

 

[ovdt]

Mactadpole,

I'll be glad to hear your experience with rc-carbon frame.

About the helmet: I looked at the sizes but it looks like it won't feet directly without a modification, right?

 

[Mactadpole]

Mactadpole,

I'll be glad to hear your experience with rc-carbon frame.

About the helmet: I looked at the sizes but it looks like it won't feet directly without a modification, right?

I did have to cut some notches for the outer arm screws. I actually use the industrial strength velcro to secure it to the centerplate at 4 points. I'll be posting pics so you can see soon.

Shawn

 

[Mactadpole]

Wooohooo!!! Just took maiden flight and it was perfect for night time flight. Only thing I noticed was that after I landed and stopped motors and then restarted motors they did not all start at the same time even though they do fine on the bench. Should I go up 1 or 2 on the min gas? Otherwise, I noticed no slight twitching as I previously had with HFP FC. Still need to do a lot more flights and shoot video to confirm that. Wasn't brave enough to try altitude hold but we'll get there. Super stoked!!!

Thanks to everyone for their help!! I will try to get to more of the build log soon.

Very happy! Time to go home have a brew and hit the hay.

Shawn

 

[Droider]

Brilliant.. well done Shawn.. It seem there are a few maidens to be done this weekend as builds are complete and its now testing time!

Take it easy and happy weekend flying.

Dave

 

[Mactadpole]

Brilliant.. well done Shawn.. It seem there are a few maidens to be done this weekend as builds are complete and its now testing time!

Take it easy and happy weekend flying.

Dave

Thanks Dave! So excited I can't go to sleep. All I can do is think about getting it tuned and slapping the navi and gps on there to start doing some pre-programmed flights for aerial imagery. I know - patients.

Shawn

 

[Droider]

Its like Chrimbo when you were ten... I know I know.. TAKE IT EASY!

 

[Mactadpole]

So I got to do several flights this morning in little to no wind. If you have seen my other post about wind settings then you know I am not happy with how it drifts so much in the wind. I now realize it is the auto-leveling that is allowing this to happen. When I flew the X8 with the HFP board I rarely used auto-level because of the wind drift. Hopefully there is a solution with the MK.

It was still hard for me to work on getting it trimmed well because of the slight to moderate breeze at times. A click here and there had me thinking it was close to perfect and then I guess the wind would completely die and it would start drifting in the direction of the trim input. I actually don't think it needs any trim because it really seemed to stay in one place when it appeared there was no wind. Still more flights needed I guess.

My first couple flights were with a single 4s 6000mah battery and with the stock settings it seems perfect. I was getting about 8.5-9 min flight time. I then did my final flight with two 4s 6000mah in parallel and stability wasn't as good. I moved P and D all over the place and it had a very slight continuous wobble/oscillation. I should mention that the second battery was positioned behind the other so it was further towards the rear and I am pretty sure the COG was off. Could this cause that wobble/oscillation? I did get 16 min flight time and I had the GoPro mounted so I expect about 14-15 when I put the GH2 camera onboard. Pretty happy with that time. I have now removed the LG and am in the process of repositioning the battery holders so there will be one in front then the gimbal and the other battery mount in the rear. This means I always have to fly with two batteries to maintain COG but thats my final flying setup anyways. I am also going to add four vibrations dampers (pictured below) for mounting the LG to the frame. I have been wanting to do this since I got the dampers about 2 months ago but just didn't take the time to do so yet.

I must say that altitude hold is incredible compared to HFP!! I can't believe how well it just sits at that ceiling.

Edit: I remember something else. Still have the different startup times after landing, stopping motors, and then restarting motors. It works perfect after first plugging the battery in but if I land and stop the motors and then restart some of them won't even start up without me giving a little gas. I even upped the min gas from 16 to 18. I was too excited to go flying to mess with recalibrating the ESC's so I still need to do that. What is weird too is that after a battery change it is fine on the first start up but then does the same thing as above if I land. Any other suggestions?

Also, I assume its ok to run a throttle curve via the tx to smooth out around the center?

I thought of plenty to comment on while flying but can't remember now. I really appreciate any comments or suggestions.

Thanks,

Shawn

 

[Droider]

Cant really comment on the motor start up coz I am using the MK BL's but I am sure its got to be something in the ESC's.

Throttle curve in the TX is good.. I have mine with two settings one for camera on and one for camera off. There will probity be a way of doing in the MKtools so you can set different flight characteristics but I aint got that far yet.

I aso use the Expo and have two settings in there as well one for normal flight and one for video

Dave

PS where did you get the dampers and how big are they?

 

[Mactadpole]

Thanks Dave. I have the throttle curve setup but just wanted to make sure before I flipped the switch. I also have 30% expo setup on a switch too.

Here is the link for the dampers, if it doesn't take you directly to the page go to page 1367. http://www.mcmaster.com/#vibration-dampers/=d04h69

They are the smallest size.

Shawn

 

[Mactadpole]

Need help tuning my MK X8 to get rid of oscillation/wobble

Have done several flights now and having trouble tuning my X8 copter when fully loaded. When I fly with one battery and default settings it flies very well and stable. When I add the second battery it then has a slight oscillation/wobble. I have tried adjusting the Gyro P and I all over the place and I only get close to getting rid of the wobble when I turn both way down (v.84a, P=60 and I=61; v.82b, P=95 & I=90; rest of gyro settings are default). It then of course becomes pretty mushy on the sticks. I also notice the base of motors getting pretty darn hot (not the bells) and the esc’s are pretty hot too at the end of a 15-16 minute flight of mostly hovering. I have been flying when it is between 95-100 degrees Fahrenheit outside and wind conditions have been a slight breeze to 10-15mph. My flight weight has been 4.266 kg with the two batteries in parallel and my GoPro. I have tried firmware versions v.84a and v.82b.

Am I asking too much from the 12x3.8 props in coax configuration at this weight? I have APC13x6.5 props to try but I am a little worried with the temp of the motors and esc’s.

What settings should I start to change with the current setup? Or do I just go to the 13x6.5 props? (Remember, it flies fine with just one battery at default settings. weight = 3.661 kg)

Thanks for any assistance provided, Shawn

MK X8 current configuration

Frame: RC-Carbon X8 750mm motor-to-motor
Droidworx extended landing gear
Droidworx/Photohigher AV130 gimbal
ESCs: RCTimer 30A Programmable w/Precision I2C to PWM Converter for Standard ESC [ST] (set on High timing)
Motors: Pulso 2814/22 (770kV) (lower motors set to spin 10% faster than top)
Props: APC12x3.8 Slow-flyer
Batteries: Turnigy Nano-tech 4s 6000mah 25-50c
FC: Mikrokopter V2.1 ME (no Nav or GPS) (firmware v.84a & v.82b)
RX: Futaba R6014FS w/Serializer PPM converter
TX: Futaba T10CAP

Weight:
2912 grams with no batteries
1210 grams for two 4s 6000mah
144 grams GoPro with mount

 

[Bartman]

Shawn
Regarding the hot motors and ESC's.....a coax arrangement should have props with a slightly higher pitch on the lower motors as they are operating in the wash of the upper props. This has the effect of lowering the angle at which they are flying through the air which is basically lowering their pitch. If you're using 12x3.8 on the tops then the bottoms should be at least 12x5 or even 12x6, it's a trial and error thing.
WIth the props you're using you may actually be making the lift equivalent of a 5 or 6 rotor craft instead of a heavy 8.
Are you flying at the high end of the throttle curve just to hover? I've got at least what you're carrying on my standard Okto 2 and it hovers around 65%.