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Old Oct 27, 2003, 07:42 PM
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New Mega 16/25/3 in Kyosho or MiniFan

Anyone tried it yet? Any thoughts or opinions?
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Old Oct 27, 2003, 08:10 PM
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You will need lots of voltage to get the power up. Really a /2 or /1 would be better for more typical voltages, however they don't seem to exist yet.
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Old Oct 27, 2003, 09:05 PM
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yeah the RPM per volt is waaay down there on it.

Barry
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Old Oct 28, 2003, 08:48 AM
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Might be OK for the Kyosho Fan...

This motor might be a good choice for the Kyosho fan, as it loads a motor much more than a Minifan 480.


Also, take the Kv rating with a huge grain of salt. If you look at published prop/RPM/amp tables, this motor is closer to a Mega 16/15/4 (at 2200 Kv).

This motor will have more torque than the 16/15/x series and therefore will turn the Kyosho rotor with more efficiency at higher watt levels.


My guess would be that at power levels exceeding 200W to the motor, this motor will easily outperform the 16/15/x series (same watts to motor will equaly more RPM to the prop/rotor).

But, it's a balancing act since this motor weighs quite a bit more.



Hope this helps.
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Old Oct 28, 2003, 11:40 AM
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The 3-turn mega in the kyosho fan with 10 1950 AUP cells puts out around 300W (~30A). More than enough for a T-33. I would not put too much power into a kyosho fan. I threw a blade once -- scary!

You would need about 12 cells with a minifan to get top performance from the 3-turn. Haven't tried that yet.

The 2-turn works well on the mini fan with 8 cells but draws too much current with the Kyosho. If you use 7 cells with the kyosho you will draw close to the maximum (30 sec) current (35A).

Charlie
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Old Oct 28, 2003, 11:54 AM
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CharlieS - are you referring to the Mega16/15/3 or the Mega16/25/3?

I wasnt aware of a 16/25/x being available at all untill now. Looks like it can be a great motor for <400W due to its higher mass.
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Old Oct 28, 2003, 12:00 PM
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Oops!

I misread the 16/25/3. I was thinking 16/15/3. I actually would like to know about the 16/25/3 as an EDF motor. I was considering getting one.

Charlie
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Old Oct 28, 2003, 12:17 PM
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There is one EZone member flying his T33 with a 16/15/2 and six ... yes six (6) ... cells.

I have also read where there is a 1 wind available, as a special order.
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Old Oct 28, 2003, 12:22 PM
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16/15/2 and Kyo fan...

Charlie, FYI take a look at my T-33 using SIX cells and a 16/15/2...

http://www.rcgroups.com/forums/showt...hreadid=159737


Kind of an eye-opener!


I really think that the T-33 (Kyosho fan) and the 16/25/3 would be a great combo using KAN 950's.

I'm pulling around 180W on six cells to get the performance you see now. I'd hazard a guess that the 16/25/3 and about 10 KAN 950's would turn exactly the same RPM as the 16/15/2 six-cell combo, with quite a few less watts to the motor.



Thanks.
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Old Oct 28, 2003, 12:51 PM
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The Mega ACn 16/25/3 (Kv=1700)

http://www.megamotorusa.com/Brushles...5-3.htm?id=388

wil pull in the Kyosho fan about 16-18 Amps on say 18 FAUP or Kan 1050 cells. If you like assemblying and mantaining large NiMh packs, then it's the way to go . Otherwise the ACn 16/15/3 is a better choice for edf.

In the MiniFan you will need even more cells, you will get barely 18 Amps on something like 24 cells.
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Old Oct 28, 2003, 01:30 PM
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Hi Meteor,

I saw your 6-cell 16/15/2 Kyosho fan T-33. Yes I was impressed.


Re:

"I'd hazard a guess that the 16/25/3 and about 10 KAN 950's would turn exactly the same RPM as the 16/15/2 six-cell combo, with quite a few less watts to the motor."

Don't you mean less AMPS to the motor? Same rpm => same watts. In any case I would think that it's more like what Herb says, around 16 - 18 cells. 10 cells would only give 17 krpm w/ no load. (kV = 1700)

Charlie
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Old Oct 28, 2003, 01:34 PM
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Real data??

Herb, is that info from experience, or from an extrapolation based solely on Kv?


As I mentioned before, that Kv figure for the 16/25/3 is highly suspect. (or the 16/15/x figures are problematic)

If you look at MegaMotor's, and others, real-world test data you will see that when propped similarly, the 16/25/3 acts like a 16/15/4, which is rated at 2200 Kv.


As I've noted before, the low-wind Mega 16/15/x Kv values are completely meaningless when trying to estimate an RPM under load. (it's not even a -proportional- difference. The difference between Kv and actual RPM at max amps gets erratically larger as you drop the number of turns)

Perhaps the Kv figure for the 16/25/3 is more suited to extrapolation, whereas the 16/15/x Kv values are next to useless.


Addition:

Charlie, what I'm observing is that I get around 22,500 RPM with 180 watts going to the 16/15/2 on a Kyosho fan (almost identical to "stock" AP-29L/7-cells)

The 16/25/3 -will- be more efficient, so assuming that my guess at the "loaded" Kv is correct, putting around 170-180W into a 16/25/3 should turn the same RPM (10-12 cells at 18-15A)

The Kv might require the use of 12 cells, but the Megamotor data shows a 6.5x4 pulling 18.6A on 9 cells (170W).

Now, the Kyosho rotor loads quite a bit less than a 6.5x4, but not -that- much!

I'd put money on 11 cells being the 22,000 RPM area for the 16/25/3 and the Kyosho fan. (any takers?)



One last addition!

Look at the figures!!!!

Mega states the 16/25/3 will pull 17,480 RPM on nine (9) cells and 18.6A. Using a conservative 1.05V per cell, that is a Kv UNDER LOAD of 1850!!!

Something stinks here, that "published" figure of a 1700 Kv is obviously wrong!


That's precisely why I completely ignore Kv figures, and look for real-world data! (I had many nay-sayers about the 16/15/2 and the Kyosho fan, simply because they used *Calc programs and came up with nonsense numbers)





FYI, aircraft-world has the 16/25/3 in stock!
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Old Oct 28, 2003, 01:53 PM
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They are based on calculations, which should be accurate - as I did them .
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Old Oct 28, 2003, 02:51 PM
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A 16/15/4 is not effective for a fan either. Takes too many cells and if you got enough cells behind it the motor is well beyond it's limit.


Barry
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Old Oct 28, 2003, 03:42 PM
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ANY 16/15/x motor is "effective"...

Barry, your statement is VERY misleading...


If your have an EDF application for a 16/15/x motor that works, the number of turns is completely irrelevant to the ability of that design of motor to reject heat.

Any one series of motors has exactly the same heat rejection characteristics amongst winds, the only difference is at what point (in amps) that maximum torque is arrived at.

Also, maximum torque will be THE SAME amongst all the winds.

If you put 250W to the low-wind motor, that same 250W will work across all variants of the motor, and you -will- gain efficiency by not having as much wiring loss for that given power input.


Since a higher-wind motor will arrive at maximum torque at a lower amperage, you simply select a more appropriate battery (eg HR-4/5AUP vs. HR-SC, or Li-Poly, etc...), and the weight becomes a non-issue.



To summarize, no single 16/15/x motor is any more, or less, appropriate to a viable EDF application. If a 16/15/2 works, then a 16/15/4 will work equally as well.

(EDF's usually don't have the problem of having a low-wind limit, as might occur with a direct-drive prop situation)
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Last edited by meteor; Oct 28, 2003 at 04:12 PM.
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