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FPV Knuckles H-Quad Build Log

#1
I have my FT Knuckles H-Quad since 6 months now. I flew a lot with it, had couple of crashes, nothing really bad though but now I want to it take to the next level. I always wanted to try FPV so I decided to tear down my Knuckles H-Quad and transform it to a FPV quad. Why tear it down you might ask? Because I already tried to attached a GoPro on it. Videos are not too bad but more importantly, it felt heavy on the sticks and not really responsive. I know I can shave the weight down, it's just a matter of choosing the right wires / components, avoid connectors when possible and be smart sometimes ;) As I had to change the layout of components to make room for the FPV gear, it was a good occasion to review everything.

Here is from where I start:

2014-01-12 19.27.02 (1).PNG

The AUW is 785gr with the GoPro and a 2200 mAh LiPo. The blueWonder motors can support that but as I said, too heavy and not responsive. This little beast should be faster and agile. So I aim for a target AUW of 650gr. I know that a lot of weight to save but I think I can do it :)

So, To achieve my goal, I went on HobbyKing and bought some stuff: Boscam vTx and vRx, clover leaf antennas, board camera, multimeter and other stuff form ebay like LCD screen, Pololu voltage regulator (those things work very well and so small, less than 1gr! I really recommend them) and foam boards because yes, I will build my own FPV googles and it will be the subject of another thread :D Good thing about it is that If I don't succeed it, I still have a classic LCD screen ;) For those who wonder how much I spent, the shopping list amount is about 100$.

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First, I tried to connect the FPV gear all together. At first I didn't get an image from the camera. I checked, double checked all connectors, FPV channel, the wiring and it turned out that HobbyKing sold me a camera with a reversed connector so the polarity was wrong... Spent 2h on that but hopefully, I didn't fried my camera. Then, I removed all electronic components to leave only the frame and the motors.

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I mocked the new places for the ESCs

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I cut out all connectors leaving only what I needed

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I soldered the motors directly to the ESCs with 18awg wires and started my own power distribution with 16awg wires. Before soldering everything, I also need to add another extension to power up my vTx but this will be for another day! :)

Finally, here is what I managed to shave so far: 80gr!. It really surprises me how heavy these little things are.

2014-07-13 12.43.25 (1).PNG
 

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jhitesma

Some guy in the desert
Mentor
#2
I'd strongly suggest considering swapping those multi-stars for some SimonK ESC's. The difference it makes in handling of the quad is flat out amazing. I had the same setup on my knuckle with the 15a multi-stars and the 24g motors, I switched to the 20a blue series flashed with SimonK and couldn't believe how much better the quad was. Night and day difference in performance!

Shedding weight helps and is always good, but ditching those multistars for some ESC's that really are designed for multirotors and not just marketed for multirotors would probably give you the performance and feel you're looking for. You could try flasing them with SimonK but the 15a multistars are almost impossible to flash as they don't have programming pads and they use a leadless package on the AVR chip so it's extremely difficult to get a programming harness on them.
 
#3
Thank for the advice! I have the multistar because this was what FT recommended. I was a newbie by the time I started to build my Knuckle and if I had to do it again know, I would probably choose something else for all components.

Anyway, I will think about it, I don't want to put another order on HK just yet. But maybe next time :)
 

jhitesma

Some guy in the desert
Mentor
#4
Yeah, I used the multistars when I built mine as well because they were cheap and I saw FT used them on some of their knuckle builds. I put off changing to simonK for a couple of months thinking it couldn't make that big of a difference. But once I sprung for some blue series 20a's and flashed them I couldn't believe the difference it made.

When I first built my quad I used the actual wii sensors in my homemade multiwii. It flew but was quite a handful. A few weeks later I upgraded it with a MPU-6050 acc/gyro that most boards are now using and the difference was night and day. With the wii sensors I had to turn my PID's down from stock to get it to fly at all, with the new sensors I was able to turn the P gain up considerably high and the performance blew me away.

When I upgraded from the Multistars to the BS with SimonK it was just as big of a change again and again I was able to push the P gains considerably higher giving it a much more locked in and responsive feel.

The 24g motors were kind of the same story. I went with them because I was familiar with them from my planes, they were cheap, I had a few spares on hand and I saw on the FT knuckle vid that they would work - so I went with them. But I went through them fairly fast, they were easily damaged in crashes (epoxying the wires like David does on the DT750's helps a LOT, but the shafts still bend easily) and as my skills with the quad grew I wanted more power. I recently upgraded to some 2212 1400kv Angel motors by sunnysky that were only $11 each on ebay - the difference isn't as major as the upgrades to the sensors and the ESC's were...but the extra power is great and the design of them is far better at resisting damage in crashes. And now I have a pile of 24g motors I can toss on some planes (I'm kind of thinking about using the multistar ESC's and the old 24g motors to make a four engine FT cruiser just because I have the bits laying around...)

Other than the wires and easily bent shafts the other thing to watch out for on the 24g's is the bearings. They're tiny and not very high quality. I never worried about oiling mine since I tended to bend shafts/break wires so often...but after 6-7 months of flying my quad I had several motors develop issues due to the bearings failing. A little bit of motor oil (or even sewing machine oil) will go a long way towards keeping them going!
 
#5
Your story sounds familiar, probably because I followed with a lot of attention your thread :)

I know my components are not the best nor the most efficient. In fact, I see my Knuckle H-Quad as a learning platform so I don't really care. I prefer spending time on my build technics, tips and tricks with basic components. If I build something efficient, that works well, great! It means I learned everything I needed to know to take my knowledge to another level by building other quads properly with great motors, ESCs, flight controller, etc.

Actually, I'm planning my "perfect flying" platforms with some Tiger motors, BS or Afro ESCs, MultiWii controller and FPV gear:
- A small one, 250 like to bring it everywhere, like a plug&play quad I can put into a backpack really easily.
- A bigger one with a 2 axis gimbal to video footage.
To getting there, I also need few extra stuff like another Tx (like a 9XR with a FrShy module) GPS capable board and so on.

For now, I'll focus on implement properly my FPV gear... and improve my soldering joins as well! :p
 

jhitesma

Some guy in the desert
Mentor
#6
Fully understood as I'm much the same. Like I said the 24g and multistar certainly work and I'll take a less than perfect quad that flies over a perfect one that doesn't any day :D And the journey and knowledge gained is just as rewarding as the time in the air!
 
#7
Most definitely true! I'm so exciting to finish the build, get in the air and have my first FPV experience! :D
It reminds me that I need to buy some cheap ski goggle and few cables, I'll do it right now!
 

jhitesma

Some guy in the desert
Mentor
#8
One other thing...Another thread just jogged my memory. I had the 10a and 15a multistars mixed up. The 15a ARE flashable as they do have the larger chip on them. It's easiest with the overpriced flashing socket but if you're handy with a soldering iron you could just tack wires right to the pins to flash. It's only the 10a multistars that are practically impossible to flash. The 15a are just kind of a pain :D
 
#10
Ok so, I have been weak yesterday and went to hobbyking to buy a crimping tool as well as a flashing tool :D So I will follow your suggestion jhitesma and flash my ESCs.

Anyway, today I continued my journey into building a FPV platform and more specifically, I created my FPV camera mount. I plan to attach it in a front boom of my quad so I needed something in a L shape. I bought few month ago a jar of TermoMorph, that was the perfect occasion to pull that out of my drawer!

Note: there are few technics you need to know to achieve something that looks not too terrible. This website helped me a lot for this particular piece.

Ok, let's start! I made a sheet from my TermoMorph and drawn the shape I wanted

2014-07-16 17.43.32.jpg

Then I cut it with scissors

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I bended the bottom part to a right angle

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Drilled few holes to attach the camera as well a passing the cable

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A couple nylon screws and dampener balls after, here is the result

2014-07-16 18.37.57.jpg

2014-07-16 18.38.08.jpg

For my first attempt to shape a ball of TermoMorph, it's not too bad! It's not as clean as I would either but it will do for now :)
 

jhitesma

Some guy in the desert
Mentor
#11
Ok so, I have been weak yesterday and went to hobbyking to buy a crimping tool as well as a flashing tool So I will follow your suggestion jhitesma and flash my ESCs.
As long as it all goes well I suspect you'll love the change it will make. For the multistar 15a's you'll want the kda.hex version and the "lazyzero" flash tool makes it pretty easy: http://lazyzero.de/en/modellbau/kkmulticopterflashtool

After flashing it's a really good idea to test them first so you don't let the magic smoke out if something went wrong:
http://wiki.openpilot.org/display/Doc/Flashing+Instructions#FlashingInstructions-TestingyourESC.

There are two fairly minor drawbacks to the multistars once flashed. 1) Don't bother with the bootloader version because even with the custom bootloader you can't reflash through the servo wire on them because they invert the signal. Not a huge deal but a little annoying if you want to reflash with a newer version or change some options down the road. And since you'll have the flash tool now re-flashing isn't that hard anyway. 2) They're a P/N fet design instead of an all N fet design so they're slightly less efficient. But honestly you'll probably never notice the difference and since you're not switching from one design to another you shouldn't notice ANY difference.
 
#12
As long as it all goes well I suspect you'll love the change it will make. For the multistar 15a's you'll want the kda.hex version and the "lazyzero" flash tool makes it pretty easy: http://lazyzero.de/en/modellbau/kkmulticopterflashtool

After flashing it's a really good idea to test them first so you don't let the magic smoke out if something went wrong:
http://wiki.openpilot.org/display/Doc/Flashing+Instructions#FlashingInstructions-TestingyourESC.

There are two fairly minor drawbacks to the multistars once flashed. 1) Don't bother with the bootloader version because even with the custom bootloader you can't reflash through the servo wire on them because they invert the signal. Not a huge deal but a little annoying if you want to reflash with a newer version or change some options down the road. And since you'll have the flash tool now re-flashing isn't that hard anyway. 2) They're a P/N fet design instead of an all N fet design so they're slightly less efficient. But honestly you'll probably never notice the difference and since you're not switching from one design to another you shouldn't notice ANY difference.
Thanks for the information. I already have the kkmulticopterflashtools as I used it for my kk2.0 board. But I'll most definitely check out the instruction about how to test my ESCs after a flash.
 
#13
Nice build.
But I wonder if the damperner balls work this way. I think the only contact between cam and copter must be the dampeners. Mounted this way the vibrations will travel trough the screws. I think you're supposed to make bigger holes and put the dampeners directly trough them without the srews
Succes with the build
marc
 
#14
Thanks!

But I wonder if the damperner balls work this way. I think the only contact between cam and copter must be the dampeners. Mounted this way the vibrations will travel trough the screws. I think you're supposed to make bigger holes and put the dampeners directly trough them without the srews
Succes with the build
marc
This is the way Blackout mounted his camera on his mini H-quad, I just tried to replicate it not as good as he did unfortunately. Although, I cannot have only the dampener balls because from the camera side, there is no way to attach them directly... unless you have a solution. I'm more than opened to suggestions :D
 
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#15
Hello Guys!

Bad news, I wanted to moving forward yesterday as I had a bit of spare time. I pulled all components, quad and tools out of the drawer, plugged my soldering iron and waited for it to get hot enough.... I'm still waiting, my soldering iron is dead :(

I bought another one from hobbyking with control of temperature + really good tips (from Hakko) This combo seems to be a good solution for someone on budget. I'll resume the build as soon as I receive the parcel (hopefully Saturday)
 

cranialrectosis

Faster than a speeding face plant!
Mentor
#16
I have heard good things about the Hakko. I use a Weller and adjustable temp and fine tip make all the difference when soldering to ESCs or flight controllers.

'Cmon postman!!!
 
#17
Yeah, it's what I got form my different researches: the tip makes all the difference. I went for a Hakko one as they have a very good reputation and seem to be compatible with the soldering iron I bought.

However, I received the dispatch email from HK today so I will never get it for this week end, too bad.
 
#18
Hello guys, time for updates.

I finally had some free time (and received all the part I needed) and what a pleasure to have a good soldering iron. Well, to be honest, any soldering iron would have been better than the one I used to use. Anyway, I resumed my build, finished the power harness and tied up cables for the ESCs and receiver (yes I crimped my own lead wires :)).

Then I moved to the FPV gear. I was doing the camera cable by putting a 12v regulator between the camera and the FPV Tx. I powered up everything to test the output voltage and... I did something wrong and created a short resulting by a magic smoke coming from the FPV Tx...

I was really angry at myself but this is how we learn right? I ordered another one right way from ebay (comes directly from the UK rather than HongKong or China) which should arrive next week. In a meantime, I can go forward on my own FPV googles build :)