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Old Feb 19, 2010, 08:10 PM
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United States, MI, Grand Blanc
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Originally Posted by TROY01 View Post
I just ran the motor until the voltage dropped to 10.5 in order to compare the voltage that Hyperion showed in the test data.. I just got home and checked my notes from the testing this morning and there is another complication the KV is 1134 after all. I guess what I typed 1034 it was just a typo. The readings were 13860rpm @ 12.21v and 12970 rpm @ 11.45 so 1130 kv is correct. Good grief........ I gought an 11-7 APC prop so I will try that out.
Just out of curiosity were these RPM readings no load data? Another question if I may, wouldn't the rpm (regardless of the watts/amps) determine the thrust/pitch speed of any given prop?
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Old Feb 19, 2010, 11:30 PM
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Good question, Theres only 1 manufacture I know of that states KV at max efficiency and thats Lehner, most others state KV at no load, which will be higher than at max efficiency, and usually quite a bit higher than at max power.
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Old Feb 20, 2010, 07:05 AM
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It was tested with no load. Not sure I undersstand your second question... When you say rpm do you mean the kv? On another note with the 11-7 APC at 12v it measured 455w and 42 amps, which is still less than the published test data with an 11-5.5 at 11.2v. I do not see that it could ever turn an 11-5.5 prop or a 10-7 prop at the figures published. Looks like it may shine with a larger prop though.
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Originally Posted by Buzzkill2 View Post
Just out of curiosity were these RPM readings no load data? Another question if I may, wouldn't the rpm (regardless of the watts/amps) determine the thrust/pitch speed of any given prop?
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Old Feb 20, 2010, 09:02 AM
c/f
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Troy,

Your right about publishing useless data, Only info I ever need is weight, watts and KV.

I dont understand why they post cell count cause if you stay within A stated watt rating,
AMP x VOLTS, why would cell count/amps be needed.

I run 6s on 3020/8 HYPES..........

forget about "A" particular volts, charge your battery fully, put it on your cheapo motor with wattmeter connected and after 30 seconds run, document watts, amps, volts.

Do the same test with the Hyperion,

My guess is that the VOLTS will remain higher with the Hyperion indicating to me that it is running more effiecent, given no load KV is same.

Heck one of my speed tricks in a spec motor class club racing is to solder motor leads direct to speed control board minimizing added resistance of extra wire and bullets.

ARE your bullets the same size grade?? Food for thought as to how difficult it is to say with absolute certainty, apples to apples.

I myself like to buy higher range KV motors as I get more flexibilty by changing props and cell counts for differant flying styles, remaining in the WATTS rating.

ie, my 3020 I push a 9X8 on 6s in an Extreme flight outlaw for 170MPH.

Now I change prop to 11X4 and 4s and it now flies liter than the .32 nitro setup and pulls off the 3D flite envelope.

Your line of questioning is pretty consistant with many I encounter who wonder why e-power can't just be as simple as liquid fuel cubic inches. Even those have some variables when porting and tuned exhausts come in to play.

Hopefully your excersize will have netted you food for thought. The real answer lies in that the "CLASS LEADING NO EQUAL" Hyperion lineup is going to allow you to get a better wingloading and thrust to weight ratio than does a cheapo motor "IF" this ends up important to you, If not save the $30 and go HK.........
.02
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Old Feb 20, 2010, 09:24 AM
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Originally Posted by Dylwad View Post
Good question, Theres only 1 manufacture I know of that states KV at max efficiency and thats Lehner, most others state KV at no load, which will be higher than at max efficiency, and usually quite a bit higher than at max power.
Kv by definition is a measured "noload" condition.

Steve Neu
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Old Feb 20, 2010, 09:25 AM
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Originally Posted by Dylwad View Post
Good question, Theres only 1 manufacture I know of that states KV at max efficiency and thats Lehner, most others state KV at no load, which will be higher than at max efficiency, and usually quite a bit higher than at max power.
Kv is a constant......thus it doesn't change with load... certainly the motor rpm you measure under load will vary with that load, but the actual Kv for that motor won't/can't.
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Old Feb 20, 2010, 09:32 AM
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Only info I ever need is weight, watts and KV.

I dont understand why they post cell count cause if you stay within A stated watt rating,
AMP x VOLTS, why would cell count/amps be needed.


You really need weight, amps and Kv... the waste heat generated by the motor is a product of amps... that is the limit one should be most aware of. Yes, I suppose watts must also come into it somewhere since, sticking to an amp limit, one cannot simply keep increasing voltage and thus watts, ad infinitum.

10A/100W limit; the motor should be fine at 10A @ 10v (100W)... but it might still be okay at 10A @ 15v (150W)... or (if the Kv allows it) at 5A @ 30v (150W)


...but it may not be okay at 20A @ 5v (100W).... or 10A @ 30v (300W)
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Old Feb 20, 2010, 09:53 AM
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Phoenix,Arizona, United States
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Originally Posted by sneu View Post
Kv by definition is a measured "noload" condition.

Steve Neu
Interesting, your right, Lehner does say RPM per volt at max efficiency, not Kv

http://www.lehner-motoren.com/ms10.php
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Old Feb 20, 2010, 11:48 AM
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I just find all this odd because all of the Zs motors I have give higher results than those in the Hyperion prop data. Granted, the Hyperion data was on older technology batteries so that probably explains my finding.


My comment earlier regarding RPM was basically this:

If two motors are compared using the same components (ESC,battery,prop etc.) then the motor that has the higher RPM produced at the prop is the more powerful one in terms of thrust and speed. Is this not correct?

Here's my point. Of all the "data" I've seen produced on cheap motors the overwhelming majority of it has been without the rpm produced at the prop. Which to my thinking means nothing as there's no indication of the efficiency or energy wasted. A HK motor that draws 600w at "X"a may sound great to most but, without knowing how fast the prop is turning isn't it meaningless?

I know I have purchased two HK motors (Turnigy) and compared them to the Hyperion Zs motors and while the watts/amps were very similar the rpm at the prop was not. In both cases the HK motors fried in very short order while my Hyperion motors are still happily taking the abuse I throw at them.

More to the recent topic at hand in regards to Troys situation, wouldn't it be better to calculate a thrust/pitch speed your looking for and forget about watts and amps? I'm certainly no expert (obviously) and am more often wrong than right but, I'm of the understanding that watts/amps, while necessary to achieve a certain rpm based on a motors Kv, voltage and efficiency is in and of themselves all together useless without the prop data.

So doesn't this mean that it's better to calculate how much thrust/speed you need or want for a particular model and then configure a power system to meet those needs based on a particular prop at "X" rpm?

Sorry for the long post but, I'm trying to learn all this stuff and while my brain is pulling 1200w only 600w of it is getting me anywhere
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Old Feb 20, 2010, 11:56 AM
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You are correct... without ALL the necessary parameters, performance data are useless....thrust, derived from a particular prop, tells you nothing unless there is a connotation of pitch speed too.....and how many watts you needed to get it..... watts-in tells you nothing, until you know how much of that has been converted to useful "work" (how efficient the motor is, and how much thrust, at what pitch speed).

As you say, choose the correct size prop first... then get a motor which can spin it, to get you the thrust you want, at the pitch speed you need, while still remaining below that motor's amp/watts limits.
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Old Feb 20, 2010, 12:02 PM
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New fresh batteries may give very significantly different results. I went to the field with a Hacker A50 12s 14 x 7 APCe 6s prolite V2. Manufacturer's tables said just under 1200 watts. Wattmeter at field 1520. So I propped down to 13x6.5.
Do your own tests.
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Old Feb 20, 2010, 07:47 PM
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In this case that is what I did. The test data shows that it will turn a 10-7 at 9870 with a 3-cell pack at a fairly low voltage of 10.52 at 38.6a, and that is not going to happen with the motor that I purchased. It would be very exceptional to get in the area of 10,200 rpm with a fully charged 3 cell pack in this size motor with a 10-7 prop. In order to get that much thrust you will have to increase the prop and this motor can take it while others may not. In my case not a big deal really I will prop it up and the motor should develop much more power than the cheapie motor. The Hyperion is still a good buy in my opionion because of the ability to load it up for power on other air frames, and it is not like the motor is "expensive", for $30-40 more I am getting high qaulity and versatility. I will by more Hyperion motors but now I know that a given size motor at the stated kv will produce the typical rpm, watts, and amps with the normal size prop and be a bit more efficient in the process.
Quote:
Originally Posted by Dr Kiwi View Post
You are correct... without ALL the necessary parameters, performance data are useless....thrust, derived from a particular prop, tells you nothing unless there is a connotation of pitch speed too.....and how many watts you needed to get it..... watts-in tells you nothing, until you know how much of that has been converted to useful "work" (how efficient the motor is, and how much thrust, at what pitch speed).

As you say, choose the correct size prop first... then get a motor which can spin it, to get you the thrust you want, at the pitch speed you need, while still remaining below that motor's amp/watts limits.
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Old Feb 20, 2010, 08:58 PM
c/f
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I'll be running my first Nue motor, not bcause of Eff but because power to weight ratio and wing loading. I will be replacing a DA50 gasoline converision to E-power, and the Nue inrunner gearbox combo is the highest watt rating @ a given weight to swing a 22/10 prop. 3500WATTS advertised,

You know that means I can go atleast 4600W........ scares the heck out of me the thought of it being armed, may have to remove prop with battery.........
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Old Feb 20, 2010, 09:01 PM
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Quote:
Originally Posted by c/f View Post
I'll be running my first Nue motor, not bcause of Eff but because power to weight ratio and wing loading. I will be replacing a DA50 and the Nue inrunner gearbox combo is the highest watt rating @ a given weight to swing a 22/10 prop. 3500WATTS advertised,

You know that means I can go atlest 4600W........ scares the heck out of me the thought of it being armed, may have to remove prop with battery.........
If you're replacing the DA with a Neu, the 1521/1.5Y I presume, you will want to run either a 24x12 or a 25x12.5.

Mike
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Old Feb 20, 2010, 09:54 PM
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That is some major power in an electric motor. I have a 90 size glow plane that I installed a saito 125 but have not flown yet. When I found I could get 6 cell 5000mah lipos for $50 I yanked the Saito off the plane, bought a Scorpion 40mm motor, and ordered batteries. Should turn a 15-16 prop better than the Saito. My buddy has the same motor in a 9.5lb plane and it is great! BTW if flew the Hyperion in the Brio with an 11-7 prop today, and the power is way more than enough.
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