Mikrokopter SkyJib 8 problmes

[DASCO]

Hello everione!

I have some problem with the skyjib.
I have put to geather lots of lots of kopters espacially MKs. I building My own frames fro MK electonics.
But I never had a kopter bigger than 90cm diameter.
I have the AXI 2826/12 with aerodrive 8, 15x5 Xoar. I have a serious motor heat problem! Motors are completly leveled. I have 4x5S 8000mAh on board. payload is not more than 6kg (full flying weight is less than 17kg.) The kopter makes a yaw move when its lifting from the gorund. I have seen Kopterworx test video with the same setup and they did not have that problem. What should I change? Do I have wrong P I D????
If someone can help Me it would be great!!!!

Thank You

Dasco

 

[Vortex]

Hi Dasco,

It looks to me like your props are too big for the motors..........I'm sure someone with a bit more experience with these motors can confirm this and give you a better idea of what size props are better suited.

Regards,

Lance

 

[DASCO]

Hello Vortex.

I used 14x7. It was the recomended prop. At that payload the motors went berserk with RPM and
the JETI box watt meter stoped showing the results... 3000W what it can take. After the prop
change the kopter got better flying skills and the rpm got lower. It howers at 2500W.
So the prop size is OK.

D

 

[ghaynes]

D plugged your numbers into ecalc at 17kg and it says that you will have a motor case problem, max current over the motor rate using the 4 batteries in parallel. Changing to just a single battery it says that you are over current limit. Send a note to Kopterworx and they may be able to give you an answer...

 

[DASCO]

Hello ghaynes:

Im already contacted with Kopterworx. They told Me that the heat problem comes from the temperature out side. Here is exactly the same set up : http://vimeo.com/37483994#at=0
I think everione seen that video! Yes it is 3 kilos less than what We have. But it lifts without a problem.
I think I will try out different PIDs and will see what We have!
Im still waiting for ideas guys!!

Thanks!
D

 

[Vortex]

Hello Vortex.

I used 14x7. It was the recomended prop. At that payload the motors went berserk with RPM and
the JETI box watt meter stoped showing the results... 3000W what it can take. After the prop
change the kopter got better flying skills and the rpm got lower. It howers at 2500W.
So the prop size is OK.

D

Hi Dasco,

A really easy method to work out your propeller load is to multiply the diameter by pitch ....... This will give you the "Load Factor"

14 x 7 = 98
15 x 5 = 75

The load factor for the 15 x 5 is definitely lower but that is the prop recommended for the 4120/20 which is a considerably bigger motor.

Regards,

Lance