Aeronavics / Droidworx Skyjib X4 Motor alignment question

[RomanB]

Hey folks,

Have a skyjib heavy coaxial for a while now and I love it. Have been flying 1d and 5d on it with good results. They were mainly test cameras though and I have now switched to the proper working camera (F5 with Cooke prime) and the payload went up to 6.5 kg, 14kg total flying weight and now a few small issues I had before became more serious.

Here are the problems I'm having: when flying DSLRs the top motors were getting pretty warm while the bottom ones were completely cool but because the payload was much lighter it didn't really manifest in flight characteristics.

Now however with the heavier payload the top motors are getting REALLY hot. Around 80-90 degrees. Almost too hot to touch while the bottom ones are around 20 degrees. As a result the copter can yaw randomly when hovering and loose altitude. When I yaw in one direction it stops perfectly when I release the sticks but when I do the same in the opposite direction it drifts a bit before stopping.

I was in touch with Matjaz from kopterworx and he recons that some of the motors aren't aligned/leveled perfectly so the top ones are constantly working to stop the heli yawing hens the overheating.

I aligned the top and bottom props on each arm perfectly parallel to each other with an electronic caliper, but my question is how to get each arm perfectly level. Matjez was saying that even 1 degree can cause problems but can't think of a way to level the arms to that accuracy.....does anybody have a good method to do this? Also any other ideas of why I'm having these issues?

Any help would be much appreciated!


Cheers

 

[redridinghood]

It's normal for the upper motors to become hotter. Too hot to touch doesn't mean the motor is running out of spec. If it is under 60C degrees then its a non issue for short flights (10min). Sounds like a custom mix and larger props on the lower side is what you need but more info on hardware is needed.

 

[RomanB]

It's normal for the upper motors to become hotter. Too hot to touch doesn't mean the motor is running out of spec. If it is under 60C degrees then its a non issue for short flights (10min). Sounds like a custom mix and larger props on the lower side is what you need but more info on hardware is needed.

The specs are skyjib x4 heavy lift, cinestar gimbal, hercules 3 esc, KW10s, WKM, xoar 16,5 props and two 6s 10000mah bats.

I need to get the heli working so that I can swap the batteries and keep flying almost non stop without having to wait for the motors to cool down.

Do you have any advice on custom motor mixing in wkm software? I tried this mix:
http://www.rcgroups.com/forums/showatt.php?attachmentid=5028316
and at around 30 percent throtle the heli was responding as you would expect but on takeoff it went out of control and crashed. No idea why so I'm very reluctant to mess with custom motor settings especially considering the waiting times for xoar prop replacements.

 

[redridinghood]

Sorry I took so long to get back to you. I do not recommend any custom mixing on the Wkm. I tried with mine but the results were unpredictable like the MC could not handle the custom mixing.

 

[Droider]

I take off the landing gear and sit her on a flat surface. loosen boom clamps so you have movement in both directions. If your bottom motor mount is the one with the locator pin set the prop tips dead parallel to the worktop by the very slight movement in the arms between the clamps. When it is perfect tighten the boom clamps. with the bottom OR top motor perfectly parallel with the worktop nip motor clamp bolts making sure you tighten them to pull the top/bottom prop parallel with the opposite prop. once you have got it parallel carefully tighten each side quarter turn at a time and keep checking after a turn on each bolt that the props are still parallel. It takes a bit of time but one you are used to it its easy. The most important bit is getting the motor mount with the locator pin perfect with the boom clamps tightened.

Dave