Building a Mikrokopter a' la carte (from parts, no MK kit purchase)

Bartman

Bartman

Welcome to MultiRotorForums.com!!
With one Mikrokopter Okto flying well and the possibility of work being secured in the future I'm starting to think about what the next multi-rotor in my fleet is going to look like. It's going to be based on the Mikrokopter FC/NAVI/GPS suite of electronics and it's going to be another flat-eight motored craft. THe problem though is that the Mikrokopter kits leave a lot to be desired regarding certain features so I won't be buying a kit MK again.

Here's a list of what I can reasonably surmise I'll buy, feel free to chime in

Mikrokopter FC 2.1
MK Navi board
MK GPS
Diversity board for MK/JR radio
I2c buffer board (the single board, not the individual I2c condoms)
giant box of wires, hardware, connectors, batteries, etc.


As for a frame, I'm thinking the Droidworx frame would be best but I'm not sure. My intention with this frame would be to have a camera mount capable of carrying a Canon 5D MkII but I wouldn't buy the camera myself. I'd probably fly my own T2i and carry the 5D if someone has one (like a wedding videographer) and they want me to use it. Of course this could change as things/opportunities evolve so who knows?

Anyway, the big variable for me is what motors and ESC's to use. I don't want to use a hard framed power distribution board like MK supplies with their kits. If I upgrade motors in the future I want to also be able to upgrade the ESC's. What's motors would be considered professional grade? What ESC's are compatible with the MK electronics?

Between the motors and the frame I'd like to turn at least 11" props although 12" props would be even better.

And then there's the camera mount. I'm not that impressed with any of them to be completely honest so I'll just cross that bridge when I get to it.

I'm not sure when or if I'll pull the trigger on this project but I'd like to have some of these details ironed out. This discussion will also help someone else that may have the same idea so I thought I'd kick it off with a fresh post.

My Son-of-Okto build will still proceed at some point but not before this new XL Okto if I can start getting business commitments in the near future.

Thanks!
Bart
 

FOX222

FOX222

Member
Bartman,
I still think the droidworx is one of the best kit frames available at this time. I may be biased considering I have a AD-8 but after seeing what else is out there their frame is simple and very strong, not cheap but what is if it's worth having.
As for the HL motors you probably can't beat the Axi. I have owned several over the years and they pretty well out preform everything else. I have been talking to Adam at Quadrocopter and they are really happy with them. If you are going to run 11 or 12" or even a 13" props you won't have any problems with the MK Bl 2.0. They are rated at 30 amps continuous but if you really load them to where they are getting warm you can add the heat sink to them. Plus I think the DW frame cools better. I don't know if you have seen the new XL power distribution board but I like them much better then the standard one and it's easier to get the bl off if you need to. they also allow for the extra caps to be fitted very cleanly.

John P.S. They have the octo heavy lift kits in stock now.
 
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R

RTRyder

Merlin of Multirotors
Droidworx are good, expensive, but good. New frames and new designs are appearing almost daily, personally I'd like to have one of these but I have too much $ in high end equipment as it is right now... http://www.1001copters.com/lang-en/frame/2-hexastar-700.html

For motors and heavy lift there are only three to choose from IMO and they're all 2814 series, AXI, Pulso, and and the Avroto. I would fly any one of the three and currently have the Pulso on my HL mainly because Rusty @ AGL had a set he wanted to sell when there were none available so I grabbed them.

Anyway, when I had the opportunity to build another MK Hexa with minimal new parts I did it, they just work, period. Can't go wrong with Mk electronics and I firmly believe it will be a couple years before anyone catches up to what Mk can do right now.

My $.02

Ken
 

Bartman

Bartman

Welcome to MultiRotorForums.com!!
RTRyder said:
For motors and heavy lift there are only three to choose from IMO and they're all 2814 series, AXI, Pulso, and and the Avroto. I would fly any one of the three and currently have the Pulso on my HL mainly because Rusty @ AGL had a set he wanted to sell when there were none available so I grabbed them.
Click to expand...

These are all comfortable with 12" props? I guess when it comes to motors/esc's/props/batteries if one element limits the system then the rest are safe? So regardless of the other components if you have 20C batteries then the ESC's can't get exposed to much more than 20 amps? And the motors can only give what they can with 20 amps of electricity?
 

R

RTRyder

Merlin of Multirotors
Bartman said:
These are all comfortable with 12" props? I guess when it comes to motors/esc's/props/batteries if one element limits the system then the rest are safe? So regardless of the other components if you have 20C batteries then the ESC's can't get exposed to much more than 20 amps? And the motors can only give what they can with 20 amps of electricity?
Click to expand...

All of these motors will work with 12 to 14 inch props though I would not put anything higher than 4.5 pitch on a 14 inch prop. I originally had the Graupner 11 x 5 on the heavy lifter and the big Pulso motors really were not happy, swapped to APC 12 x 3.8 which I thought would be too little pitch but amazingly they seem perfect. I can't go any bigger on the AD-6 frame unless I swap the arms for the longer 355mm HL versions and I'm not keen on spending $150 for new arms to try out bigger props so I'll stick with the 12's for now they seem to work well with the RTF weight of roughly 8 pounds. As for the spped controllers, the BL 2.0 are well within their capacity range with these motors and 12 and 13 inch props. Only thing that remains to be seen is how warm they get under load when the ambient temps get up into the 80 to 90 degree range though where I live that happens for about 6 weeks on the middle of summer so no big deal for me anyway.

Oh and BTW, for anyone that is thinking of adding heatsinks to the BL's, consider this, you MUST epoxy the heatsinks to the FETs with something like Arctic Silver thermal epoxy which is very strong and permanent. If you use this you basically give up hope of ever being able to replace a FET if it goes bad as they will be glued to the bottom of the heatsink.

Ken
 

FOX222

FOX222

Member
Bartman said:
These are all comfortable with 12" props? I guess when it comes to motors/esc's/props/batteries if one element limits the system then the rest are safe? So regardless of the other components if you have 20C batteries then the ESC's can't get exposed to much more than 20 amps? And the motors can only give what they can with 20 amps of electricity?
Click to expand...
Hi Bartman,
I think you are overlooking he fact that have 6 or 8 motors sharing the power. My fully loaded octo with a Canon G12, video tx, mount and everything hovers at around 27 amps total. That is 27 divided by 8 = 3.375 amps per motor. With the data log the highest current draw I have ever seen is less then 68 amp. So I doubt any one esc or motor will ever see 10 amps.

John
A heavy lift with the the 2814 and 12" props may get up to 10 or 12 amp per motor while lifting a a small person.:)
 

C

Crash

Defies Psychics
FOX222 said:
Hi Bartman,
I think you are overlooking he fact that have 6 or 8 motors sharing the power. My fully loaded octo with a Canon G12, video tx, mount and everything hovers at around 27 amps total. That is 27 divided by 8 = 3.375 amps per motor. With the data log the highest current draw I have ever seen is less then 68 amp. So I doubt any one esc or motor will ever see 10 amps.

John
A heavy lift with the the 2814 and 12" props may get up to 10 or 12 amp per motor while lifting a a small person.:)
Click to expand...

Additionally,
A 5ah battery rated at 20C can pull 5*20=100Amps.
 



matwelli

matwelli

Member
prod_MD2510_LE_lg.gif


these are what you want http://www.gobrushless.com/shop/index.php?app=ccp0&ns=prodshow&ref=MD2510-LE talk to Dan, tell him i sent ya (will try to talk him into a deal, i know Dan well, have delt with him for 2 years)

they are machined in the USA, and hand wound by Dan using the best bearings and wire. very tourque responsive ( a mate had to de-tune his gain settings running these) Dan will custom wind to different kv, the motor above will run a 11 by 4.7

I use these (mainly the high rpm stuff in flying wings) the power handling is amazing - i have had over 600 watts on the high kv ones

The reason is the very open bell allows massive amt of cooling air, and very fat wire for low resistance
 
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Bartman

Bartman

Welcome to MultiRotorForums.com!!

C

Crash

Defies Psychics
matwelli said:
prod_MD2510_LE_lg.gif


these are what you want http://www.gobrushless.com/shop/index.php?app=ccp0&ns=prodshow&ref=MD2510-LE talk to Dan, tell him i sent ya (will try to talk him into a deal, i know Dan well, have delt with him for 2 years)

they are machined in the USA, and hand wound by Dan using the best bearings and wire. very tourque responsive ( a mate had to de-tune his gain settings running these) Dan will custom wind to different kv, the motor above will run a 11 by 4.7

I use these (mainly the high rpm stuff in flying wings) the power handling is amazing - i have had over 600 watts on the high kv ones

The reason is the very open bell allows massive amt of cooling air, and very fat wire for low resistance
Click to expand...

I wonder if he would sell these unwound.

After the recent problems I have seen with MK motors, I will NOT be buying any more. I think I'd rather spend the time and wire them myself so I know they are done right. (That's not to say that Dan can't wind motors. I just prefer to use my time rather than cash to wind them.)

the 20C rating is per cell? i thought it was per pack but then again they would probably just call it 20A if it was a fixed amp rating.
Click to expand...
It's per Amp-hour or milliamp-hour rating.
 
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Bartman

Bartman

Welcome to MultiRotorForums.com!!
Crash said:
It's per Amp-hour or milliamp-hour rating.
Click to expand...

for a 5000 mah, 20C, 4S pack
5000 mah is capacity, 5000 milliamp-hour which (I think) is a 5000 milliamp load for one hour
20C is available amperage rating (per cell?) so this pack is 4S (4 cell) which means it can potentially supply 80 amps?
 


FOX222

FOX222

Member
Bartman said:
for a 5000 mah, 20C, 4S pack
5000 mah is capacity, 5000 milliamp-hour which (I think) is a 5000 milliamp load for one hour
Click to expand...
Correct or you could say 5 amp hour (5 ah). The amount of amps used in an hour.
5ah could be 10 amp @ .5 hour or 20 amp @ .25 hour and so on.
So if your load is 20 amp you should get .25 hours (15 minutes) of flight from a 5ah battery (in a perfect world)

Bartman said:
20C is available amperage rating (per cell?) so this pack is 4S (4 cell) which means it can potentially supply 80 amps?
Click to expand...
The "C" rating is the max amp the battery is rated at. If it said to be a 20 c battery this means 20 x the rated capacity of the battery. So a 5ah (or 5000mah) battery rated @ 20c can safely handle up to 100 amp load. Capacity x the "C" rating = max amps.

John
 


C

Crash

Defies Psychics
Bartman said:
what recent problems?
Click to expand...
One motor where the windings were never connected. There's no excuse for that. It's just shoddy work. Another motor in the same set had some mysterious problem that fried a phase and took a BL-Ctrl with it. (I wasn't there when that happened so I can't say with 100% certainty what the cause was but I can assure you it wasn't builder soldering or a solder blob on the board.)

It's quite obvious to me that Mikrokopter is sending out untested parts. Then it's difficult or impossible to get them to stand behind their products when they are defective. They just blame the builder. If the bird is flying, then the crash damage helps to mask the defect. I could go on....and on...

In the future, I am going to do my best to avoid MK motors, ESCs, and distribution rings. I need to look into how well those I2C to PWM convertor boards work.
 

Bartman

Bartman

Welcome to MultiRotorForums.com!!
it is a bit disconcerting isn't it? they have this stupendous flight control but they seem to source everything else from the cheapest places possible. for what i paid for my okot kit i had a major WTF?? moment when i sat down to balance the props they sent me.
i don't understand the motivation behind it. the weakness of the I2c architecture is also a bit of a mystery. maybe they just don't see it?
 



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