Hoverfly XY8 Coaxial Quad build with Hoverfly Pro

[Bartman]

Hi everyone,

This project started a couple of months ago using a Mikrokopter XY8 frame set and an adapter board to mount the ESC's and the Hoverfly Pro flight control system. The nice folks at Hoverfly weren't exactly sure if their flight controller would be happy to find itself on my assymetrical coaxial quadcopter so the only way to find out for sure was to build it and have a go at flying it. It flew very well so the next step was to begin redesigning the frame plates specifically for mounting the Hoverfly Pro system.

It's not such a big challenge to put four holes in the right spots for a board to mount to so the goal of the build has become trying to design the neatest and lightest possible installation of a system that uses conventional ESC's and PWM control. To that end I'm experimenting with a few different power distribution ideas.

The first try at a power layout was with the PhotoShip One power board. All in all it's a neat board and has good size solder pads and an open layout. The problem I had with it though was that the pads are oriented +/- on two sides and -/+ on the other two sides. All of the ESC's have the positive on the left and the negative power wire on the right side. On the two sides where the pads match that layout, the wires fell into place well enough. On the other two sides though, the wires got messy as they had to criss-cross and I needed to leave a lot more wire on the ESC's to be able to maneuver them into place. I emailed DJ about the layout to ask if he had ever considered matching the pad layout to the ESC's on all four sides but I didn't get a reply.

Going back to the internet to see what other boards could be used I decided to try the Voltair power board from MultiWiiCopter.com. The board is very compact, has sufficient solder pads for an oktokopter with dual batteries, and can be wired in a way that allows all four pairs of ESC's to be done uniformly on each of the four sides.

View attachment 4738

While trying to address the power needs of the motors I thought about modifying the Voltair board with 14AWG solid wire by bonding it to the underside of the solder pads to supplement the current carrying ability of the board. This made me think of another way to distribute power which involves winding a length of 10 AWG solid copper wire around posts that each represent the spot where I'd want to have an ESC wire attach to the power system. It was easy enough to make (the positive loop is shown) and I'll have to modify the positions of the loops a little but you can see the eight ESC attach points around the outside and the two positive battery attach points on the inside.

View attachment 4736View attachment 4737

I haven't decided yet which method I'll use but I think the Voltair board or my solid wire wrapped method will be minimal in terms of wire used to distribute the power.

The wires for all eight motors will all come up from in between the frame plates through the triangular cut-outs on each side of the frame. THe motor attach points on the ESC's will be on the outside perimeter of the frame and I'll remove the wires that come soldered to the ESC and will solder the motor wires directly to the ESC's similar to how Mikrokopter attachments are made to the Bl's. The goal here is to make replacing motors or ESC's as simple as possible and I think to do that it helps to have open spots where wires are soldered using the most simple layout possible.

I'll be prepping the four arms tomorrow and will post pics tomorrow night of the arms with the motors and a better description of how the wires will be routed and attached.

THanks for reading,
Bart

 

[DucktileMedia]

Way to go. Looking nice. I am days from getting my XY8 going with the Hoverfly pro, so it will interesting to compare results. I too am having a tough time figuring out how to make a power board. I refuse to buy one as none of them are really perfect. My plan is to CNC out 2 copper rings and put a wafer of G10 in between to isolate them. I cant imagine 16ga copper wouldnt be enough for my (8) 2814's. If it works I may decide to manufacture a few different shapes and sizes and try to sell some. The real test will be seeing if the bonding agent to laminate the copper/G10/copper sandwich will hold up to the heat of soldering.

 

[Bartman]

the copper sandwich should work fine but just keep in mind most epoxies that we're familiar with melt at about 130 degrees F which is pretty low and we're soldering at 700. You've got experience with composites so you're probably familiar but what about epoxy with a higher melting temp?
i think any power ring has to have tabs of some sort that can reach proper temp before the heat has overwhelmed the rest of the board.

 

[Bartman]

After some more tinkering I've decided to go with the modified Voltair board. In the pics you can see that I've soldered a length of 14AWG solid copper wire around the bottom of the positive and negative pads. I've also attached the battery wires which run out the back of the frame and will later get zip tied in place.

View attachment 4745View attachment 4746

 

[DucktileMedia]

good solution to add peace of mind. I'm getting restless deciding how to do this. I am about to just use a wire lug and bolt them all together! But seriously, weight aside, why not just solder/crimp bolt lugs to the ends of all the esc wires and just run a bolt through them all? Easy to replace for sure.

 

[tstrike]

That's what I did Yuri-View attachment 4748View attachment 4749of course my hex is totally ghetto compared to the stuff you and Bart are doing, but I needed to
be able to take the arms off without to much effort and also able to do field repairs without needing soldering gear.

 

[Bartman]

i never really considered using mechanical connections to bring the wires together. it would be fun to try soldering a main power wire into a hole drilled into the head of a copper bolt and then sliding the connectors onto the bolt to bring it all together. it would all have to be wrapped up to keep it insulated but it would certainly make swapping parts easy enough.

anyway, here's the Voltair board all wired up with two sets of motor wires attached as well. I could probably have been a little neater with the wire routing but I tend to rush things along sometimes when I'm trying to do too many things at the same time (where's that contest announcement Bart! Doh!) .

The motor wires come out of the arms through a slot in the side of the arm. Like I said earlier, I'm trying to keep this as neat as possible and as light as possible. Copper is heavy compared to carbon fiber so to reduce weight, wire runs have to be as short as possible.

View attachment 4753

 

[Bartman]

That's what I did Yuri-View attachment 6425View attachment 6426of course my hex is totally ghetto compared to the stuff you and Bart are doing, but I needed to
be able to take the arms off without to much effort and also able to do field repairs without needing soldering gear.

the split bolt connectors at the bottom of the page would be interesting to try. they wouldn't need solder or additional connectors, just stripped wire stuffed into the slot and cranked down. one for positive and one for negative and you're on your way, probably very quickly too.

http://www.mcmaster.com/#copper-bolts/=i0n0rg

 

[DucktileMedia]

Tstrike, I started to use those mechanical connectors as I thought it was the easiest way. then I weighed all the parts on the scale and it was 5 times as heavy. Then again even at 5 times the weight it wasnt much. It would certainly be the easiest way if you needed to swap an esc or take an arm off. I'm still undecided on what the best way is. In a perfect world, I would have the motor leads from the ESC's facing in to the center of the frame and the input power to the ESC's woud solder to a distribution ring that was similar to the F450 where is goes right to the outside of the lower frame plate. Maybe next time around, I will CNC out a 16ga copper ring that follows the perimeter of the frame plates.

 

[Bartman]

the heaviest stuff comes from the power distribution so keeping it in the middle minimizes weight. motor connections around the outside of the frame help shorten the distance from the motors to the ESC's also minimizing weight.

if I had to build this again tomorrow I'd probably try a 2" length of #10 wire for each polarity with a ring terminal on each end and my #14 battery wires folded over and soldered in the middle. At each end of the #10 wire I'd bolt four ESC wires each with their own terminal ends soldered on. The benefit of this is that the terminal ends can be crimped and then soldered for security and the soldering of the terminal ends is way harder to mess up than any PCB pads. The mechanical joints can be opened and new ESC's could be fitted very easily if necessary (even prepared ahead of time to be useable as spares). Motor wires would have to use bullet connectors to make the whole disassembly argument hold water though.

but then again, PCB's haven't shown themselves to be as susceptible to vibration or poor assembly as some would suggest. they're in billions of devices (in the air, underwater, and rolling along every highway) and doing fine. it's sorta like the people that say you can't gas weld chromoly aircraft frames together when it's been done that way for decades with great tolerance for the variations in individual welders' techniques. or the people that say aluminum is antiquated when it was recently the material of choice for Aston Martin's latest supercar. i don't understand the absolutes that people will throw about in conversation.

 

[Benjamin Rowland]

Bartman, thanks for sharing these pics along the way. It's always good to see what other people are trying.

I ended up going the route of soldering several smaller wires to one big wire that would have a connector for the battery. PRC6 connectors for the batteries and XT60 connectors for the ESCs. I hid the harness and all of the XT60 connectors in the center of my Cinestar. I got some tips from the video here: http://vimeo.com/20473095

It took me two attempts before I was happy with it. My first attempt I used a lot of solder, so I tried to use less on the next attempt.

I do wonder how going with a distribution board compares. Any thoughts?

 

[Bartman]

Ben,

Thanks for the comments. I like the boards because they keep things neat and they make repairs very easy. By the time the iron is hot I can have the electronics removed and be ready to pull wires from the board. The board is very well made, able to handle my power requirements, and it makes assembly very easy. I'm not sure what else I could ask for.

I'm going to go buy new motors tomorrow. The ones that are already on there are two new spares I had and now I'm feeling like I should just bite the bullet and get new ones for the other 6 spots. I'll use my older Avroto motors for the FPV quad (XY4, what else?!?) I want to build as I don't usually get to just go to the park and fly multi's for fun.

I may be able to get the Hoverfly Pro board mounted and configured tomorrow night if I can get some time to finish mounting the motors. I've got a little trick for mounting the board that I'm anxious to try. I also intend to try a different method to calibrate the board to level that will allow me to leave the trims centered. I'm really looking forward to getting this flying so hopefully this week it'll be airborne.

Bart

 

[Benjamin Rowland]

I'll definitely try out using a board on subsequent builds. Looking forward to reading about your progress and finding out more about your aircraft.

 

[Bartman]

it didn't look like anything was going to get done tonight as I was called to go into work to replace a crewmember that called in sick. 20 minutes after getting the call I got another call that he was ok and was able to take the flight. so i went back on call and went about my business working on things and being with the family.

here are a couple of more photos, the first is an arm assembly with the wires routed and LED's installed. only the two front arms will get the LED's and yellow heat shrink. i use red LED's as they seem to contrast the best with a blue sky. i've also tried blue LED's but they just about disappeared with the blue sky above them.

the second photo shows the top of the frame with the ESC's and Hoverfly Pro board installed. i may or may not have time to continue tomorrow but all that is left to do is to double check the firmware is the latest version, go through the setup client to make sure everything is indicating correctly, and install a receiver with a satellite or two plugged in.

for props i'll be using a set of carbon fiber 13.25" props that i picked up from a friend. they're made in Europe and a good friend has a connection over there so we both were able to get a prototype set. if they're any good i may stock them if i ever can get around to setting up my web shop.

anyway, i'm done for the night. i'm trying to have this flying by the end of the week, i think i'm close.


View attachment 4786View attachment 4787

 

[hjls3]

Super clean! Look forward to your comments about the carbon fiber props.

 

[Benjamin Rowland]

Wow - "super clean" is right. When I get some time, I need to clean up my wiring, and I'll be using your pics as the standard to meet.

 

[hjls3]

dont mean to change the subject but given the super experienced folks on this thread (benjamin and bart)...why arent carbon fiber props used more? is it cost? thanks for the help there. i am new and ever since i began, i wondered why? now i see them on the s800.

and again Bart super impressed with your builds. dont know too much about building a multi-rotor, but i can certainly tell that you put alot of energy into the details and I certainly appreciate that.

 

[Bartman]

thanks guys. i really appreciate it.

i'm trying carbon fiber props because i had the opportunity to try out a new product. i usually prefer wood as it's better at dissipating (or, not transmitting) vibrations and will absorb impact when my landings aren't so good and keep the motors from getting damaged. the Xoar PJA props are very light and have a generous blade design so they make a lot of lift compared to some of the plastic props out there. the motor mounts i use (designed by IrisAerial) are very simple, very light, and also give when the kopter rolls over keeping motors and arms from getting damaged. i also like the balance of having wood alongside the carbon fiber and electronics, sort of a yin-yang thing.

i appreciate the effort and talent that goes into designing some of the fancy stuff we're seeing these days but simple as a design philosophy is timeless.

 

[Bartman]

fwiw, i'm using G10 for the frame plates because it was readily available. It's 1/10 of the price of carbon fiber and doesn't weigh much more in the context of frame plates but it is definitely more flimsy. with four batteries strapped to the ears of the frame plates it will be interesting to see how it does.

i've started running through the firmware and config steps so i'm hoping to fly it tomorrow and get a camera mount on it in the coming days. i never got to try the GPS on the last one so I'm really looking forward to that.

THanks,
Bart

 

[Bartman]

Had a successful first flight today and it flew really well. After going through the setup steps and individual calibration procedures, the first flight is your chance to work on eliminating drift. I'm still not exactly sure at what step in the flight control's life it is taught what level is but the way to tweak it is with trims on the radio. I don't love this so I used very thin washers under the FC to shim it after I had the chance to see which way it wanted to go during the first flight. I use trims when shooting video to establish slow drifts so too much trim just to stay level takes away some of the trim I can use when shooting. The shims worked fine and it's pretty close to zero drift.

The first inflight adjustment that needs to be made after trimming is to tweak the gains settings for Manual Mode and Autolevel Mode. With low numbers for Autolevel (they recommend you start at -25), the helicopter seems almost defiant in that it wants to immediately seek level even when you're only beginning to ease off the sticks. My ideal idea of Autolevel is that as I return the sticks to center the helicopter eases back to level so as not to appear to be rushing or trying to fight me in controlling things similar to how MK's dynamic GPS position hold works (it doesn't really fight you for control even though a mode is active). With my JR 9503 this appears to happen around -38 and I've gone as high (low?) as -54. I may explore the range beyond that even if it's just to see how mellow I can get the Autolevel feature to be. In manual mode, adjusting the gain just makes the helicopter more or less responsive which could be fun provided I got enough sleep the night before and had ample strong coffee before flying.

All in all, I'm very happy to be back to this point and will get a camera mount in place tonight so it can be tweaked in the coming days. I'm also anxious to get the GPS unit in place so I can finally see how well that performs.

No word on the carbon fiber props today, I ended up using an old set of Graupner 11" e-props as I didn't have much weight on the airframe and didn't want it to be too floaty with the larger props.

Bart