Can someone help me figure this out? - RC Groups
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Feb 08, 2005, 02:47 AM
Registered User

Can someone help me figure this out?

HiMaxx HB 3630-800 direct drive
Kv (RPM/volt)= 813
Rm (milliOhms) = 85
max amps = 55

HiMaxx HA 2825-5543 4.3-1 geared
Kv (RPM/volt)=5500
max amps 25-30
Rm (milliOhms) = 11

How can I maximize performance with these motors?
I have 2- 3 cell 2,600ma lipos and a 60 amp esc,
How big of a plane will these motors push?

thanks for the help

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Feb 08, 2005, 07:01 AM
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vintage1's Avatar
I had to guess at idle current,and power dissipation capavbility, but its a hunky motor so 100W is possible as far as heat goes... but here is the direct drive estimations of best voltage cuurent and RPM, and a quick check on what 14 cells would do for you.

I keyed in 10v as well to simulate 3s LIPO on the DD one, and it looks like about 32A is best for it, and a shade under 6000 RPM. Its not terribly efficient at that voltage though. Only 70% or so. Does better at higher volts, RPM and less current as you can see.

300W out makes it a nice sort .25 to .40 glow equiavlent.

Motocalc predcst from the numbers a 12x10 prop on 3s LIPO will pull the right current, and do 43oz of thrust and a pitch speed ofabout 50mph.

Ideal for a 40 style trainer I'd say.
Feb 08, 2005, 07:23 AM
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vintage1's Avatar
And now for the smaller high KV motor.

Well, according to data I could find. its actually more powerful!
I downrated its heat capability to 50W, and that gives best power at 12v and a staggering 45A and 65,000 RPM!!! over 510W out and 560W in.

I find this somewhat hard to believe.

On 3s LIPO the calcs reckon 50A is possible, although I'd feel safer with 35-40A. That's still 350-400W input.

On 2s LIPO I'd say 45A or so. is the limit.

Going over to Motocalc. on 3s LIPO a 9x5 prop gves the right sort of draw on a 4.3 box, or an 8x8 if you want real 100mph speed

On 2s LIPO 10x10, 11x7, to 12x5 seems about right. For a 300W sort of input power.

All these results prediacted on the assumption that the idle current figures I could find are correct, and that I am guessing right about heating, and the motors are in fact as good as the published specs.

In prcatice, I'd say try these sorts of props and packs, and use a tacho and whattmeter, and carefully check the motor temps on the bench, before committng the air.

I hope that someone who owns these motors will confim or refute this with real world data.

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