5s or 6s for Z20-1470?

[bearwood]

Ok I have a Z20-1470 motor and I am only getting 4:30 flight times doing hovering and slow ff with no name 2200 25c packs.
I currently am running 16/61/61 with the standard 19 tooth owb which gives a calculated hs of 2266. My TC is 0 50 80 90 100.
Now my packs are getting very warm at the end of flight and I am putting approx 1750ma back into them. I think the motor is too hard on them.
The Zpower website is difficult to read due to the Taiwanese characters but I am trying to figure out what the 8th column is. I am wondering if the S is the number of cells and the A is the current (being standard nomcluture)? http://zpower.tw/ch/php/product.php?page=product/z20series.html
If this is the case then the 1470 motor is better run on 5s packs? Obviously higher mah is going to be better. 5s would allow me to run 13/42/61 and upgrade to 20 tooth owb to give a calculated hs of 2229.

Is my thinking correct?

[michael88997]

you could always lower the headspeed, you dont need 2200 to just hover around

[ukgroucho]

you could always lower the headspeed, you dont need 2200 to just hover around

Too right!
Good grief, I use 2100 - 2200 for agressive aerobatics and learner 3D.

You do need to get your HS checked but, seriously, for hovering and FF you'd be better with 1900 or so. This will make a dramatic difference in your flight times and be a lot kinder to the packs.

[bearwood]

ok that is the 100% hs and I am only around 80 - 85 % of that which is 1760-1870! I do not hover at 100% throttle.

I was advised in another post that my headspeed was too low causing me large altitude fluctuations in a breeze. So I upped it, now you say lower it.

I only changed from a 13tooth (1841 100% hs or 1472 rpm at 80%) to 16 tooth (2266 100%hs or 1812 rpm at 80%).

[dave26985]

Hey Eddy,
Saw your post here, thought I would chime in. I really think that with your set up the way it is know, that 4.5 min on those 2200's is about right. You could back off to a 14 or 15 tooth pinion for now, untill you want the extra HS. That might get you another minute or so, but you have to realize that the 1470 kv motor draws a LOT of power. I am using 2 FP3C-3700's with stock gears, but I am running the Z20- 980kv motor, and I am getting at least 8 min. of FF with a few loops, flips & rolls thrown in. The 980kv does not draw as many mha as fast as the 1470 does though.
Dave.

[bearwood]

Hey Dave & others.

I appreciate the headspeed can come down but what I was trying to get an answer to is whether a 5s setup would be more economical, power wise with this motor. Lower voltage, less current although my knowledge of brushless motors could be written on a postage stamp.

[modelholic]

Lowering the voltage will only increase the current draw for the same power output.

[ukgroucho]

No.. lower voltage = higher current.

Back to Physics 101...
Power = Volts x Amps (current)
or
Amps = Power / Volts

If you need 500 watts of power to hover then...
6S = 3.7 x 6 = 22.2v

500 watts / 22.2 volts = 22.5 amps to hover

For 5S .. 5S = 3.7 x 5 = 18.5v

500 watts / 18.5 volts = 27 amps to hover (that's gonna make your packs warmer)

Plus running higher amps = less efficiency, more losses thru heat (i.e. power taken from the packs that is not making the heli fly, just heating up the planet).
If your z20 is not coming out 'warm' now then the chances are that on 5S it will.

[bearwood]

OK so lower the hs and larger capacity packs are really the only options with this motor. Otherwise change down to the Z20-980.

thanks people

[ukgroucho]

that's a great summary.