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Old Apr 30, 2012, 10:37 AM
AU football owns all!
Auburn, AL
Joined Jan 2007
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Using a low KV motor with "low" cell count

I'm trying to start up a scale build on my stretched to 600 swift 16 with 5 blade head. After doing some reading, I realized I would probably need a more powerful, lower Kv motor to swing those 5 blades. So, because I have thousands of 6 cell batteries laying around, I picked up a 500 kv motor hoping to run a HV setup with 12 cells. After doing further reading it seems that the swift's gearing is way too hot to get an appropriate headspeed (1200-1600) unless I did something wacky and unrealistic like get a 4t pinion. I was really hoping to not have to buy a lot of new batteries . Would I overstress any electronics if i just decided to run a 6 cell with the low Kv motor? I read that it is wrong to use a conventional setup's ~1000Kv motor with 6s for multiblade applications, but does that rule of thumb still apply if I use the upgraded motor?
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Old Apr 30, 2012, 02:14 PM
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Joined Jul 2008
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Quote:
Originally Posted by Aero Lex View Post
I'm trying to start up a scale build on my stretched to 600 swift 16 with 5 blade head. After doing some reading, I realized I would probably need a more powerful, lower Kv motor to swing those 5 blades. So, because I have thousands of 6 cell batteries laying around, I picked up a 500 kv motor hoping to run a HV setup with 12 cells. After doing further reading it seems that the swift's gearing is way too hot to get an appropriate headspeed (1200-1600) unless I did something wacky and unrealistic like get a 4t pinion. I was really hoping to not have to buy a lot of new batteries . Would I overstress any electronics if i just decided to run a 6 cell with the low Kv motor? I read that it is wrong to use a conventional setup's ~1000Kv motor with 6s for multiblade applications, but does that rule of thumb still apply if I use the upgraded motor?
I am assuming that if you are using a 5 blade head on a 600 sized heli that you are not going to be using 5 x 600mm blades. That would represent a 150% increase in power loading at any head speed. That is why the rotor span of the 5 bladed H-500 helis is a lot less then the 2 bladed bell Jet Rangers.

You should at least go to 5 X 550mm blades and maybe even 5 x 530mm blades.

That said, the power requirements of the lower head speeds, for scale (e.g. 1400) flying, are a lot less then that of 3D rotor speeds of say 2100. Consequently, on the 5-blade head with the appropriate blades, you will find that a 6S pack, of adequate C rating and adequate mah capacity, will be have more then enough power to fly the heli.

For example. if you have 6S 3300mah packs, then use two in parallel instead of in series, use a common 11T or 12T pinion, and you will find you can easily get rotor speeds of 1500 to 1700 just bay changing your ESC settings.
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Old Apr 30, 2012, 10:05 PM
AU football owns all!
Auburn, AL
Joined Jan 2007
135 Posts
that's actually quite a relief to see. with being able to use six cells. so you're i dont have to worry about any crazy voltage vs amps formulas? because that was my main concern
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