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12-22-2010 05:58 PM  9 years ago
BobOD

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Here's 4 and 6 minute duration.

12 cells
4400 mah
80% pack usage
4 min
80% eff

45.6 v
201 Whr
3010 Watts Bat Consumption
2408 Watts at motor shaft

3.2 HP at motor shaft

12 cells
4400 mah
80% pack usage
6 min
80% eff

45.6 v
201 Whr
2006 Watts Bat Consumption
1605 Watts at motor shaft

2.2 HP at motor shaft

It looks to me to correlate quite nicely with the videos that have been displayed actually. Of course...that should be no surprize.
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12-22-2010 06:17 PM  9 years ago
BobOD

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Uuuhhgg....This thread,however entertaining at first,is tiresome and boring.
Get yourself some popcorn for the dull times.
Pop Sectret of course....forget that O.B. crud.
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12-22-2010 06:21 PM  9 years ago
g_dmitry

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Average power consumption could be (and most of the time is) way lower. Therefore flight time will be much longer.

BTW, how long flightime you will get if you run nitro engine at full throttle all the time (to get all power as in your calculations)? I am quite sure that even less than on electric heli.

P.S. 80%eff - it is quite bad motor.
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12-22-2010 06:24 PM  9 years ago
BobOD

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And, if that Tareq setup was 2 x 6S2650, here's what that looked like.

Not too shabby for a 425mm bladed setup.

I've made a few assumption changes...just ballparking really....but gets you in the ballpark anyway.

12 cells
2650 mah
90% pack usage
3 min
75% eff

45.6 v
121 Whr
2417 Watts Bat Consumption
1813 Watts at motor shaft

2.4 HP at motor shaft
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12-22-2010 06:27 PM  9 years ago
g_dmitry

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75% eff - ??? Where you get such crappy motors?

For example efficiency of stock Scorpion 4035 drops below 80% at ~ 110 - ~140 Amps peeks. Scorptions SE and Kontroniks Pyros has even higher efficiency.

You should use 85%-90%eff considering power consumptions in your calculations.
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12-22-2010 06:31 PM  9 years ago
BobOD

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I'm making an assumption that in a decent hard flight, the pilot has the motor loaded pretty maxed out. I think a fair assumption but yes...we aren't sure. However, I have looked up some fuel consumption data to see if the assumption had merrit and it seems to be good for the ballpark. Other data is welcome if you have it.

Actually, I thought I was being generous to put 80% (motor and speed control). Also an assumption but you know, when you see a rating on this, it is generally a calculation using the best conditions which are often not what you get in real life. But an assumption it is...what would you like me to put there? Frankly, at 100%, it doesn't change the picture that much.
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12-22-2010 06:33 PM  9 years ago
BobOD

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75% eff - ??? Where you get such crappy motors?
Sorry, I added a little more eff loss as the protos seems to be a little less eff in the gearing versus nitro and other e-helis have similar gearing.

Actually, the gearing on a typical e-heli would be less efficient because it is often a higher ratio. But, I think we're splitting hairs.
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12-22-2010 06:36 PM  9 years ago
g_dmitry

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The green one is 4035-560kv
Frankly, at 100%, it doesn't change the picture that much.
Changes a lot actually, especially in your last calculation.
Actually, the gearing on a typical e-heli would be less efficient because it is often a higher ratio.
Could you explain more? Because I do not see reason for that (i.e. for lower eff.).
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12-22-2010 06:50 PM  9 years ago
BobOD

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Good data. How was it determined. Is that at 100% throttle and they vary RPM and current.

OK, so the max eff is 87%. Add the ESC and it is no more than 85%
Actual in flight is probably less but we'll use that.

It doesn't change a LOT. 7% . That's not a lot compared to how some have gone on about how much more energy there is in the electrics.
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12-22-2010 06:51 PM  9 years ago
BobOD

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Higher gear ratio = lower efficiency. Well known. But, again, it is not too significant.Team POP Secret
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12-22-2010 06:55 PM  9 years ago
g_dmitry

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Electrics has very high torque at whole RMP range. Nitro engine is not even close. Electrics motors can pull way more power in time of need. I have seen 12KW peaks on 90size electrics, this means electric heli goes, nitro bogs. So, there is no comparison in power and response. The only bet for nitro guys is flight time. But even nitro engines goes bigger and bigger -> less flight time.
Higher gear ratio = lower efficiency. Well known. But, again, it is not too significant.
Could you provide real data for 50size nitro (Trex for example) and 50size electric (Logo for example). Otherwise it is assumptions only. BTW, RPM of the motors not that much different (like ~17k vs ~20k).
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12-22-2010 07:02 PM  9 years ago
Aaron29

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..
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12-22-2010 07:05 PM  9 years ago
BobOD

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I know g_dmitry, but this is not what has been being argued here. I haven't seen too many of the nitro guys saying that the nitros have the peak power of the electric. They seem to be saying they have plenty of peak power and typically better duration. And that is their preference. Then the debate either turns to they should have some other preference, or the electric is more than it seems to be. Why, I do not know.

Now, having said that, you know a nitro has a pretty good flywheel for providing peak power impulses well beyond what the nitro is thermally producing. You just have nothing to give you a measure of this. I might run some calcs some day if I don't bet bored first.
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12-22-2010 07:06 PM  9 years ago
g_dmitry

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12KW is 16 horsepower.
Here you go:
http://www.youtube.com/watch?v=wkre...player_embedded

Guys were hitting 256amps peaks here.
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12-22-2010 07:08 PM  9 years ago
Aaron29

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..
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12-22-2010 07:11 PM  9 years ago
g_dmitry

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BTW, I had one flight on Shawn's Logo 600, stock 4035-500kv, 620mm blades. I have hit 5600 Watts peaks. It was logged by EagleTree.
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12-22-2010 07:15 PM  9 years ago
BobOD

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Yes and no Aaron.

OK, the eff. is certainly not sticking to the 85% level under the 12kw peak so yes...that's not all getting to the gears. We also do not know the impulse capability of the gears until it is calculated. So, we don't know for sure what it is. Certainly seems better as evidence of the flight videos...but 12kw...probably not.

Better argument is, what is the impulse power comming from a nitro. We don't have that info.

To put this in perspective of how useful this information is without more detail, I could create 12kw impulse out of a penlight battery and a little dc toy motor....with ease. It needs to have more information to be meaningful.
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12-22-2010 07:17 PM  9 years ago
g_dmitry

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The data was logged by very respectful electric motor builder - PowerCroco. I do not see reason not to believe him.

Go to http://www.powercroco.de if you want to read more.

Some examples (from different flights):

Here heli was pulling > 7000 watts for 10sec.

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12-22-2010 07:30 PM  9 years ago
BobOD

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So, just to be clear, I am not addressing peak power. I am strictly looking at how much energy there is available for a pilot to use however he or she is willing and able to use it. What is preffered is strictly up to personal preference.

My conclusions so far (but still developing) are:
On paper, both have pretty similar average power. Nothing is jumping out at all either way.
In flight, it looks to me like the Nitros win on total display of energy (good hard flight and good duration). As soon as decent duration is attempted with an e-heli, it gets very boring. I do not know why given the above information except that the elec. eff. might be lower than advertized.
When I want to play with peak power, I'll grab my electric.
When I wand a good long and exciting flight with the challenge that I need to manage the peak demand....I grab the Nitro.
And, I like them both as they are very different animals.
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12-22-2010 07:34 PM  9 years ago
BobOD

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Please do not assume I would not beleive the data. Not what intended. I just want to know more about the test. All the information is not there to identify all of the eff loss. That's all. But, no matter...again, we are splitting hairs as far as I'm concerned. I will use 85%. 90% if you prefer.Team POP Secret
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