X8 build

[RTRyder]

After buying the Avertical camera mount I came to the conclusion that a stock MK Hexa was just a bit too underpowered to carry the mount along with a camera, well that and the fact that it takes ridiculously long landing gear to fit the mount underneath which I was able to solve with a set of Hexa XL legs. This is what it looked like...

I've toyed with the idea of putting the mount under the Droidworx heavy lifter which can certainly carry the weight, but I have essentially the same height problem only its a lot more pricey to fix that in the Droidworx world as the extended landing leg plates it would require retail for $180 a set and then it would still need some machine work to fab up a suitable mounting system!

Going through boxes of spare parts the other night I came up with the idea that an X8 may be just what I need to get this mount in the air and that's where using a common frame on different multis comes in handy. Currently the Hoverfly quad is setup in an MK frame utilizing a set of Octo frame plates and four standard Hexa arms. I have six of the same motors the HF is using new in the box along with another four Turnigy Plush ESC's, and the Hexa XL landing legs are sitting in the Mk spares box waiting for a multi to hold up off the ground. Here's what the Hoverfly looked like before I swapped the flexlanders for a set of Trex 600 landing gear and put the flexlanders on the stock Hexa along with the HiSight II mount...

It appeared that I had everything necessary to mod the H/F quad into an X8 Octo, that is until I offered up one of the Hexa XL legs to the H/F frame and found the lower prop wouldn't be able to clear the XL leg on the standard Hexa arm, hmmm...

Fortunately MK comes to the rescue once again, the Hexa XL arms are 65mm longer than the standard Hexa arms and that will give me the extra space I need to mount the lower set of motors and have plenty of prop clearance, might even be able to fit set of 11 inch in place of the current 10 inch the H/F is using.

So the only holdup right now is I just ordered the set of XL arms and they probably won't get here until early next week. That's OK as I have some work I need to do on the Avertical mount to get it ready to go, so I'll tackle that while I'm waiting for parts to arrive. Once the arms are here it's a simple matter to drill the arms to hold the motor mount X brackets, swap out the arms, install the XL landing gear, mount up all 8 motors, install 4 more ESC's and reconfigure the H/F board for X8 mode in the software.

Best part is that if I decide I don't like the X8 configuration the way the frame is built I can easily convert it to standard flat Octo 2 style configuration and give that a try.

Pictures to follow as the build gets under way...

Ken

 

[Droider]

Are you a Time Lord ken?

 

[RTRyder]

Are you a Time Lord ken?

I was at one time but then I got married and my wife took away the Tardis

 

[Droider]

I think you have a little one under the work bench that you bend time with.. you must have to do all the building you do..

 

[RTRyder]

I think you have a little one under the work bench that you bend time with.. you must have to do all the building you do..

It's actually much simpler than that, my job is remote from my employer by about 1500 miles, meaning I work from my home via phone and computer. When things are slow I'm already sitting in the same room as the helis and multis so it's no big thing to step across the room and twiddle a screw driver or allen wrench for a few minutes now and then. Then there's all the time I save not having a daily commute...

Ken

 

[RTRyder]

Some of the bits I was waiting for arrived on Friday so this morning I decided to start upgrading the Hoverfly quad into its new incarnation as an X8 A/P ship. Here's what it looked like yesterday morning at the field, its the one front center on the top shelf...

As you can see I had most of the fleet out for some stick time and I did manage to fly a couple packs on all of them, the little Silver Bullet even survived the day to come home intact for once!

So the first issue that had to be taken care of was the new motors having a shaft that was longer than the shaft on the old ones. No difference in the prop adaptors though so they would have been sitting a good 1/4 inch or more up off the top of the bell if I had left them as-is...

Since I found out I'm short two working ESC's and had to order matching ones from Hong Kong there's no rush to get the build done so I decided to disassemble the motors so I could shorten the shafts...

Here's the correct way to shorten a brushless motor shaft, tool post grinder on a lathe...

Job completed, motors reassembled and waiting to be installed...

Before the motors can be installed there needs to be a change made to the frame, with the standard Hexa arms the props wouldn't clear the XL landing legs, so 4 new Hexa XL arms were ordered up.

Using the X adpators that come with the motors requires only 1 hole to be drilled to mount a pair of motors coax on the MK arms...

So once again, here's the Hoverfly quad as it looked yesterday after the outing to the field...

And here's how it looks now with all the correct bits swapped onto the frame. Still need to do all the wiring and machine up a couple mount points for the camera mount, but the basics are done. I have to say its a LOT bigger than the old quad, the motor to motor distance is now 700 mm and its swinging 11 x 5 Graupner props...

One of the things I decided to do on this build was eliminate the rats nest of a wiring harness I was using for the ESC's, this time I'm using one of Minsoo Kims power distribution board which just happens to be drilled with the exact same hole pattern as the MK flight controller board so it's a bolt on to the MK frame, you can see the PDB under the dome in this shot...

So that's where I'm up to in just a few hours, have to spend some time on the mill out in the shop making bits for the camera mount and do a bit of soldering of the ESC's already on hand, then it's wait for the new ESC's to arrive before I can finish it up and test fly.

Ken

 

[Buzzed]

Geezuz Ken! I thought I was bad, dude you make me look like a beginner with all the equipment you have in the back of that van. Very nice build by the way, you really do quality work.

 

[Droider]

Ken.. you ARE a TIME LORD.. you never cease to amaze me with your skill at making something out of nowt... adaptability definatly a TIME LORD quality

 

[RTRyder]

Geezuz Ken! I thought I was bad, dude you make me look like a beginner with all the equipment you have in the back of that van. Very nice build by the way, you really do quality work.

Maybe I shouldn't mention that its a Honda CRV and not really a van

 

[RTRyder]

It flys! By no stretch of the imagination is the beast done yet, but this afternoon I rigged it up with enough ESC's to do some motor testing and camera mount setup so while I had everything connected I figured what the heck, put some props on it and see if it wants to get off the ground. Now normally I would never attempt to fly a multi with mismatched ESC's but when you have a coax octo with sets of 4 split evenly top and bottom there's not too much chance of anything going wildy wrong, some erratic yaw perhaps but even in worst case of a motor failing its good practice for the unlikely event of it actually happening in flight with camera gear.

Honestly I never intended to anything more than get a tiny bit of daylight between the landing gear and the ground but the little bugger surprised me when it jumped about a foot in the air with very little throttle, maybe this thing is a tiny bit overpowered with no real weight on it! Once it was actually flying and [proving to be fairly stable I brought it up to about 5 feet and moved it around a bit before landing and shutting it down. I don't think there's going to be any problem flying the Avertical mount with any camera I care to bolt on with this rig, hover was below 1/2 throttle, so I'm thinking if I don't add enough weight I might have to drop the prop size down to lessen the lift a bit.

And yes, due to varying speeds between the top and bottom sets of motors the yaw was a bit erratic but not to the point of being uncontrollable, it was likley a good approximation of what control would be like with a motor out and if that's the case this multi will be perfectly flyable if it loses a motor in flight which is more or less exactly why I built it...

So its proven itself to be capable, now I just have to sit back and wait for the box of Turnigy Plush ESC's to arrive from Hong Kong, they're on the way and I'll be keeping an eye on tracking, hopefully no later than early next week.

One disappointment is the way the Hoverfly board handles the camera mount, there is a definite overshoot on the roll axis, you can lean the frame and the mount will compensate correctly, but when the lean stops the mount will overshoot level and then come back to where it should be. A known issue in the firmware and supposedly being looked at for a fix in the next release but if it doesn't get fixed this multi may be in line to get an MK flight controller with one of the nice little I2C to PWM convertor boards I just ordered. Part of the reasoning there is that the rumored price to equip the H/F with their GPS will be about as much as the board itself and I'm not going to pony up that kind of $ for something that may or may not ever work as well as MK GPS does, more on all that later...

Ken

 

[matwelli]

excellent, just about to build a couple of X8's so very interesting read.

Are they flycam 925's ? if so, they will handle 4S on 10 by 4.5's , i like the fact you are using 11's so will give that a go on 3S

Have been debating redundancy on a x8 platform here with a good friend of mine here in NZ.

The optimum may be two minsoo kim power boards, one for the top 4 esc's one for the bottom, and dual batteries, that way you have a dual redundant system, she should fly if one motor, one esc, or one faulty solder joint happens, as i am guessing it will fly on 4 motors (controlled decent) if needed ? you must have about 3.6 kg's of thrust on 4 motors ?

anyway, cool build, cant wait to start mine (lacking motors, everyone is out of stock)

 

[RTRyder]

excellent, just about to build a couple of X8's so very interesting read.

Are they flycam 925's ? if so, they will handle 4S on 10 by 4.5's , i like the fact you are using 11's so will give that a go on 3S

Have been debating redundancy on a x8 platform here with a good friend of mine here in NZ.

The optimum may be two minsoo kim power boards, one for the top 4 esc's one for the bottom, and dual batteries, that way you have a dual redundant system, she should fly if one motor, one esc, or one faulty solder joint happens, as i am guessing it will fly on 4 motors (controlled decent) if needed ? you must have about 3.6 kg's of thrust on 4 motors ?

anyway, cool build, cant wait to start mine (lacking motors, everyone is out of stock)

Yes, Flycam 925 motors, they've proved themselves to be sturdy and dependable, I like them a lot more than any of the Hobby King stuff that I was using before. The original 4 that I bought took a lot of abuse on the Jakub frame when I first installed the Hoverfly board last fall. That was back when the H/F board had problems with random flips while in flight and I stuffed those motors into both dirt and snow from altitudes ranging from 20 feet up to almost 200 feet and the worst that happened was one slightly tweaked shaft and some rumbly bearings.

I've been flying the top 4 motors on the H/F quad with Graupner 10 x 5 props and getting flight times of over 12 minutes on two 3S 2650 packs wired in parallel. Plenty of power in all the different configurations I've flown it in, tried a set of Graupner 11 x 5 props and it seemed to be too much lift for the weight of the quad so I went back to the 10 x 5.

With the octo coax loss of one motor should not be a problem at all beyond probably having to add a little yaw to correct for it, depending on which motor it may even maintain controlled flight after losing two motors though if they both spin in the same direction it may not be controllable. Loss of all four top or bottom should still allow it to fly provided there's enough lift being generated for the flying weight and they all fail at the same time like in a battery connection breaking in the case of a dual redundant system. That's one of the secondary reasons I fly packs wired in parallel, you can lose connection to one of them and still fly, short of having two of everything its hard to build enough redundancy into one of these to cover anything that might happen, I think the tri and quad coax setups are the best compromise.

Don't know what the RTF weight of the X8 will wind up being, but I do know that this camera mount on a stock MK Hexa was pushing the limits of what the Hexa could lift and still have a safe reserve of power, it was hovering right around 2/3 throttle on 10 x 5 props and 4S power. I think the X8 would be extremely overpowered on a 4S without adding some weight, it seems to have an abundance of lift on 3S, so I should be able to carry just about any camera that will fit on the mount once I get it all sorted.

Ken

 

[jes1111]

so I'm thinking if I don't add enough weight I might have to drop the prop size down to lessen the lift a bit.

But be careful not to lower the thrust so much that you lose the redundancy. I'd always go for added battery, on the basis that the mass will help keep it more stable.

So its proven itself to be capable, now I just have to sit back and wait for the box of Turnigy Plush ESC's to arrive from Hong Kong, they're on the way and I'll be keeping an eye on tracking, hopefully no later than early next week.

If you get fed up with HobbyKing's delivery and service, "Turnigy Plush" are the same unit as "HobbyWing Pentium" - much easier to find.

One disappointment is the way the Hoverfly board handles the camera mount, there is a definite overshoot on the roll axis, you can lean the frame and the mount will compensate correctly, but when the lean stops the mount will overshoot level and then come back to where it should be. A known issue in the firmware and supposedly being looked at for a fix in the next release but if it doesn't get fixed this multi may be in line to get an MK flight controller with one of the nice little I2C to PWM convertor boards I just ordered. Part of the reasoning there is that the rumored price to equip the H/F with their GPS will be about as much as the board itself and I'm not going to pony up that kind of $ for something that may or may not ever work as well as MK GPS does, more on all that later...

...or maybe try using an MK board as a dedicated mount controller?

 

[Bartman]

it's good to put multiple batteries in parallel.
about two weeks ago i had a pack unplug itself near the beginning of a flight. i was high, over tall old oak trees with a creek near the bottom of their slope and thought the GPS was acting weird. i starting bringing it home and as it got near i could hear the thing beeping a low voltage warning. at about five feet above the ground it finally died and dropped into some weeds and only broke a gear skid. the battery that did the flight was at 4% when i put it on the charger.
having multiple batteries in parallel saved my Okto from certain disaster. i was lucky to notice the odd behavior near the end of the flight and to get it down asap as the one battery died.

 

[RTRyder]

...or maybe try using an MK board as a dedicated mount controller?

A rather expensive solution if all you're after is getting the camera platform level! If I were to go that route the MK board would be replacing the existing flight controller for more than just camera mount stabilization. The linked thread on AP landing says this... "Works just as well as it would if flying on a Mikrokopter.", owning two MK's and still trying to get the roll compensation to work as smoothly as I think it should I wouldn't necessarily consider that a big selling point...

Ken

 

[Droider]

it's good to put multiple batteries in parallel.
about two weeks ago i had a pack unplug itself near the beginning of a flight.

Bart get some pucker connectors PLEASE...

 

[jes1111]

Fair point :-D

Is that a beemer I see in your id image? Long time BM man myself - K's, R's, GS's - then someone offered me a Honda ST1100 and it was all downhill from there :-( Now I have a Honda CRV ;-)

 

[RTRyder]

Fair point :-D

Is that a beemer I see in your id image? Long time BM man myself - K's, R's, GS's - then someone offered me a Honda ST1100 and it was all downhill from there :-( Now I have a Honda CRV ;-)

Yes, it's a desk size model that's a fair copy of the real 2007 R 1200RT sitting out in the garage next to a couple vintage Nortons and the Kawasaki GTR 1000 that was my main ride prior to the arrival of the RT.

Here's a before shot of my favorite ride, a 1957 Norton ES2 500cc...

...and here's what it looks like now, it took me 2 1/2 years to do a bare frame restoration of virtually every piece on the cycle...

Anyway, the Givi trunk on the full size RT will hold my 350mm quad and I can fit the TX and battery packs in one of the side cases, who says you can't mix hobbies...

Ken

 

[jes1111]

Nice Norton! Nowadays I go for aircon and cup-holders My father had a Vincent Black Shadow when he was young - swapped it for a knackered boat-tail Bugatti which he then sold for £25 so he could buy an engagement ring for my mother

 

[Bartman]

is it wrong that i'm looking at the motorcycle and thinking how nice it would look from about fifteen feet in the air and a bit to the right?