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Old Dec 04, 2012, 04:57 AM
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took the angel out on the weekend, very pleased! half throttle cruises easily and when i gave it a blip it had bags of power on hand. very smooth, and on inspection after landing there was no bad smells or loose bits....only more flight time will prove the motor, but for now this power set up has proven itself. 30% batt left after 7 mins flight so not a bad start at all
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Old Dec 04, 2012, 07:44 PM
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papabatman's Avatar
United States, CO, Firestone
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well no really number to give, but i have been running this baby on a 14x10e 6s 5000mah WOT just the way i fly 70 amps 1489 watts holding strong about 45 flights so far
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Old Dec 04, 2012, 07:57 PM
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USA, CO, Dacono
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Quote:
Originally Posted by theheed View Post
took the angel out on the weekend, very pleased! half throttle cruises easily and when i gave it a blip it had bags of power on hand. very smooth, and on inspection after landing there was no bad smells or loose bits....only more flight time will prove the motor, but for now this power set up has proven itself. 30% batt left after 7 mins flight so not a bad start at all
That is good news indeed! I went ahead and picked up some 5 cell's for my 50/50...my next test will be 3 bladed props just as soon as I can round up some of the more elusive ones.
I will also be taking it apart and filling those magnet gap's with epoxy for good measure, just in case.....better safe than sorry...etc....
I like your prop/battery setup so if all else fails I know that one works.
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Old Dec 05, 2012, 03:44 PM
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It's been a painful process, but well worth it. I'm doing a more detailed inspec tomorrow as I'm re positioning the cowl, but fingers crossed I think I have found an economical power set up. I'm also doing a refurb/coversion on an acrowot and I will be putting this power train straight in!
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Old Dec 09, 2012, 09:15 PM
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USA, CO, Dacono
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Heads Up! I have tried a couple of different props on the NTM 5050, This time a couple of master airscrew 3 blader's.
For this test I used one of my newly aquired zippy 5 cell 4000mah Battery's.
Yes, yes this test is in no way scientific...just real world strap her down and give it a go, I really do need to get this thing in an airframe for some quality time...so here's what I got:

Zippy 5 cell 4000mah 40c series...true "C" rating...who knows?(see voltage sag) - Charged to 20.98v.
Castle Ice lite 75
13x8x3 MAS > 880watts @ 52 amps
14x7x3 MAS > 1050watts @ 56 amps

These are not Peak Numbers by no means - I wound it up and let the numbers level out until they seemed to progress at a steady rate of decline, I'd say at about 5 or 6 seconds is where i took the reading.

Voltage sag: at full power the battery voltage would drop 1.77v from the initial "at rest" voltage, the battery was at 20.2v when I measured it.

I had hoped the 13x8x3 would be the prop for me, but by going with the real world feel it didn't seem to have the grunt i was after.
The 14x7x3 on the other hand was a monster..plenty of pull and the motor seemed to "spin up" better whereas the 13x8x3 just felt like it was batting the air( pitch speed...but I'm not after speed).

PS: the 5050 didn't even break a sweat with the13x8x3....and just got warm with the 14x7x3....not hot, of course the total run time was too short to see if it would get hot but i doubt it would.
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Old Dec 09, 2012, 09:18 PM
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nice. great info. thank you for that. 14x7x3 should be fun
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Old Dec 09, 2012, 09:36 PM
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United States, CA, Heber
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I can't wait to see what he VarioProp does. Have a 100 ice CC ESC and a 6s 5000 65c lipo to test with. Just waiting for 4mm connectors.
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Old Dec 09, 2012, 10:02 PM
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United States, WI, Stoughton
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You guys have me kinda worried. I just ordered this motor for the 1/7 scale top flite P-51.

I used ecalc to come up with a good combination, and for an optimistic 160oz flying weight, it came up with a 5s4p 3600mah battery combo, with a 15" prop in the low end ranges (4,5,6).

I did not realize there was a 8000rpm limit. Should I try to cancel this order?
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Old Dec 10, 2012, 07:25 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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Quote:
Originally Posted by Dacono Air View Post
<snip>...so here's what I got:

Zippy 5 cell 4000mah 40c series...true "C" rating...who knows?(see voltage sag) - Charged to 20.98v.
..<snip>...

Voltage sag: at full power the battery voltage would drop 1.77v from the initial "at rest" voltage, the battery was at 20.2v when I measured it.
Not sure your battery numbers are right. A good way to think of it is the cell voltages. A 5S pack charged and rested to 20.98V = 4.196V per cell and that is a good ready to use voltage.

If it dropped 1.77V under load that would give you 19.21V or 3.82V per cell. That this a good high to full throttle under load voltage and if the pack is good it will sustain there dropping slowly as the pack is used up.

When the cells are down to the 3.5-3.7V or so range while under load, 17.5-18.5V on the pack, that is you signal that you've nearing the end of your capacity.

For good battery life don't expect to get more than 80% of the rating or 3200 mAH out of the pack. So when you recharge it, if you are near that value, it was used to it's full capacity.

Another tell on the battery is how hot it is at the end of the flight, it should be no more than warm. And a voltage check immediately after landing will show the cells to be at 3.8-3.9V or so.

Those are the conservative numbers, some of the best and newest batteries will do a little better. But taking cells down much below 3.7V under load is hard on them. And the recharged capacity against the no more than 80% rule is the real tell.

At 56A in your tests you were at 14C (56 / 4000 mAH or 4A) against the rating of the pack and about 18C (56 / 3200 or 3.2A) against the reasonable capacity expectations. Those are reasonable expectations as far as getting the capacity out of the battery. If you fly it a lot harder than you tested it (more throttle and more duration at high throttle) it changes things. But if you are off the throttle a littler after take off and using occasional increases and bursts of full throttle, things will be OK>

So if you want to fly at higher throttle settings and stay at those for longer durations, you have to have larger capacity and better quality (higher "C" rate) batteries. There is no free lunch on power!

Here is some info on LiPO cell voltages and remaining capacity from some old posts over on the battery forum:

LIPO Capacity @ Voltage per cell (cell voltages, multiply by cell count for pack voltage, i.e. for 3S pack multiply x 3)

4.20v = 100%
4.03v = 76%
3.86v = 52%
3.83v = 42%
3.79v = 30%
3.70v = 11%
3.6?v = 0%

Capacity below 3.7V "resting" is not usable for flying, it's where the battery voltage dumps and damage begins.

Avg Resting V % Remaining Capacity (for 3S pack, divide by 3 for cell voltages)

11.0V-- 17% (3.67V per cell)
11.1 --- 26 (3.70V per cell)
11.2 --- 30 (3.73V per cell)
11.3 --- 37 (3.77V per cell)
11.4 --- 46 (3.80v per cell)
11.5 --- 50 (3.83V per cell)
11.6 --- 57 (3.87V per cell)
11.7 --- 63 (3.90V per cell)
11.8 --- 69 (3.93V per cell)
11.9 --- 77 (3.97V per cell)
12.0 --- 83 (4.00V per cell)

These values are the average of many discharges of different size/age/brand packs. As you can see, the values are not absolute. A new pack gives different results from a well used pack but the chart is still useful for the broad picture.

Jack
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Old Dec 10, 2012, 09:53 AM
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United States, WI, Stoughton
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Well now, thinking about it, why would there be a 8K rpm limit if it's rated for 6S? Doesn't make sense.
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Old Dec 10, 2012, 10:07 AM
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papabatman's Avatar
United States, CO, Firestone
Joined Jun 2008
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Specs:
Model: NTM Prop Drive Series 50-50 580kv
Kv: 580rpm/v
Max current: 90A
Max Power: 2000W @ 22.2v (6S)
Shaft: 8mm

i not sure what you mean
on 6s with no load rpm is 12760 rpms

this is the tool i use

http://2bfly.com/tools/
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Old Dec 10, 2012, 10:21 AM
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Someone earlier in this thread mentioned a 8K rpm limit? Like I said, it doesn't make sense now.
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Old Dec 10, 2012, 10:22 AM
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papabatman's Avatar
United States, CO, Firestone
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lol ok thanks for that
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Old Dec 10, 2012, 10:27 AM
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Yeah, I feel better about using this motor now. I just wish they stocked the prop adapter in the US. Kinda silly to pay international shipping on a $3 item.
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Old Dec 10, 2012, 11:14 AM
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Canada, ON, Owen Sound
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Quote:
Originally Posted by catspaw View Post
Someone earlier in this thread mentioned a 8K rpm limit? Like I said, it doesn't make sense now.
The 8000rpm limit applies to the prop, not the motor! Mfg claims you can safely run that particular prop at 8000rpm continuously. That does not mean it will self destruct if you spin it to 8100 once. Most flights are well below full throttle. I can't see these motors being any more than 75% effcient, that brings the max prop speed down to 9000 or so. There is some risk of course, but I believe the mfg have a true rpm limit well above the "safe' limit quoted. Doug B
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