Current feeling on U7 and equivalent KDE?

crayfellow

crayfellow

Member
Hi guys,

(only really interested in objective findings here, but I know these things get contentious sometimes...)
I've seen a lot of chatter on other forums about various compatibility issues with U7 and I know the T80a is the recommended ESC. How do you guys feel about this setup vs. an equivalent KDE motor/ESC setup (and what would that be, in your mind)?

Also, is anyone running U7 420kv with KDE 18.5" folding props? If so, dual or triple? I know the U7 lists 18" as max prop size, so I'm wondering if 18.5" would be OK.

We will be using Pixhawk BTW.

Cheers.
 

maxwelltub

maxwelltub

Member
Most if not all the issues were with the 490kv and none tmotor ecs, or ones too small. I've run the 420s with triple blade 18" and ran fine with the t80 ecs.
 

crayfellow

crayfellow

Member
maxwelltub said:
Most if not all the issues were with the 490kv and none tmotor ecs, or ones too small. I've run the 420s with triple blade 18" and ran fine with the t80 ecs.
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thanks. Would you feel OK running the extra half inch on the 18.5", or is that in fact what you are using now?
 

maxwelltub

maxwelltub

Member
I've tried it and works fine. Most often I dont need the extra thrust so it's more efficient to run two blades.
 


crayfellow

crayfellow

Member
maxwelltub said:
I've tried it and works fine. Most often I dont need the extra thrust so it's more efficient to run two blades.
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But I'm saying even for the two-blade, are you using the KDE 18.5" blades or some other 18"? Maybe I'm getting too picky worrying about the extra half an inch, but the T-motor specs top out at 18" so I want to be sure. Thanks again.

(I see your followup now, OK.)
 

fltundra

fltundra

Member
crayfellow said:
Hi guys,

(only really interested in objective findings here, but I know these things get contentious sometimes...)
I've seen a lot of chatter on other forums about various compatibility issues with U7 and I know the T80a is the recommended ESC. How do you guys feel about this setup vs. an equivalent KDE motor/ESC setup (and what would that be, in your mind)?

Also, is anyone running U7 420kv with KDE 18.5" folding props? If so, dual or triple? I know the U7 lists 18" as max prop size, so I'm wondering if 18.5" would be OK.

We will be using Pixhawk BTW.

Cheers.
Click to expand...
The only problem I have with 18.5'' props is your already be at the edge of max with the 80 amp esc's at 150 degree operating temp with 18x6'' props. Way to close for me. I wouldn't feel comfortable with anything less then 100-120 amp escs. On a 90 degree day in direct sun they will be scorching.
 


fltundra

fltundra

Member
crayfellow said:
Yeah. That makes sense. Would just upping ESC be sufficient or would you go to a different motor altogether?
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Nothing wrong with the U7s. Not my first choice. I probably look at the HV castle series. The sync issues are the problem when using anything other then the T80's.
 


fltundra

fltundra

Member
crayfellow said:
interesting. And in your opinion, why not an equivalent KDE motor/ESC?
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Yep, I am biased toward KDE. But with the logging feature of the castle esc's. Just make sure you have PLENTY of headroom with what ever esc you choose. My minimum is at least double of max motor current with whatever prop size.
 
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crayfellow

crayfellow

Member
fltundra said:
Yep, I am biased toward KDE. But with the logging feature of the castle esc's. Just make sure you have PLENTY of headroom with what ever esc you choose. My minimum is at least double of max motor current with whatever prop size.
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What in your mind is the KDE equivalent to the U7 that would be happy with the 18.5 prop? I have asked Patrick at KDE as well, just curious what your feeling is.
 

fltundra

fltundra

Member
On a side note. I haven't ever run the U7's. But I would almost bet my a** they will be fine with the Castles. The problem is they are expensive, but so are the KDEs Castle did firmware updates this year just to address the sync issues with different low kv motors.
 


Old Man

Old Man

Active Member
From an outsider to this conversation, if I knew Castle's firmware upgrade sync issues, I'd be all over having Castle ESC's. they have always made the best, or in the group of the best, ESC's you could buy, and their data collection capability is absolutely stellar.



As for motors, both T-Motor and KDE make good stuff but there's some evidence the KDE's are more consistent in quality. Their performance stats may be a bit over rated but the products are top notch.

Although not requested I believe having too much headroom with ESC's is a waste of power. They function best when near or at wide open. Everything below that generates heat shunting available current not being used.
 

crayfellow

crayfellow

Member
thanks fellas. Unfortunately I can't speak publicly about these designs or their applications but rest assured we are able to do what we do because of the amazing resource of expertise that is this community. Cheers.
 

scotth

scotth

Member
Using U7-490 and T-motor 80A, 17.5" props. Seems to be a great running combination, but I'm not smart enough to know why. I rely on the airframe manufacturer that has probably tested every motor made to help me with that choice. Fortunately for me, Andrew at Hexacrafter allowed me access to his years' worth of trials and experience and so I didn't need to look any further. And the forums here are amazing as well.
 
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SleepyC

SleepyC

www.AirHeadMedia.com
I'm using U7-490 and T-motor 80A, with 18" and then 16" props and I can't keep the shrink wrap on the ESC's. I just got some heat sinks to try and bring the ESC temp down.

And I had 4 on an 18 lb quad which should be CAKE for the 490's and it was so hot I burned my hands....
:(
 

Pumpkinguy

Pumpkinguy

Member
fltundra said:
KDE4215XF-465??
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4215's are not the kde equivalent to the U7. Not a chance. I learned this the hard way. If you don't mind running a motor @ 250F to get that 3kg of thrust than fill your boots. Patrick put out a video regarding various temps limits of his motors components. I am not Patrick so I can only offer my opinion as to why he released that video but my opinion is to make his posted numbers for load you gotta be running those motors white hot. That video was to put our minds to ease.

If you want more of an apples to apples comparison id say the U7 vs the 5215.

Not interested in getting into a pissing match here. Just offering my opinion. Cheers
 

econfly

econfly

Member
I think the physics just dominate the results. Well built motors of similar size perform similarly, and even differently sized motors reflect only very marginal differences in power consumption for a given level of RPM. Here is a comparison I did a while back where my primary conclusion was that KDE and T-Motor both make excellent motors that deliver almost identical results when you standardize by RPM and power consumption for a given load.

http://multirotorforums.com/threads/kde-vs-t-motor-picking-a-motor-based-on-spec-sheets.24900/
 

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