Alfa Fan motor and power testing :D - Page 3 - RC Groups
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Nov 01, 2005, 08:34 PM
EDF rules... :)
AirX's Avatar
Hi Justin,

Deformation and return to shape is called (elasticity) not unusual for any material (steel will do the same thing but it is not elastic as ABS is), it is when it deforms and then will not return to shape that damage has occured. Since the gap widened the blade stretched a millimeter, rubbed increasing gap tolerance and then went back to shape. Very common on all fans even the microfan at 130watts.

Eric B.
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Nov 02, 2005, 12:04 AM
SoCal, Year Round Flying!
bmiller's Avatar

I love this stuff!

Really nice work Justin!
Just an observation, I was checking out the euromodels website and noticed the mega16/7/4 is rated at 50,000rpm max recommended rpm
and 55,000rpm maximum-1minute
So I'm starting to think the bearings are going to die rather quickly at these 55,000-60,000+rpms you're reaching...
We're gonna have to find better bearings for our motors!
Last edited by bmiller; Nov 02, 2005 at 01:08 AM.
Nov 02, 2005, 12:21 AM
Pro Hoarder
turbonut's Avatar
Hey Justin, I may just take you up on that! sounds cool.. I went and checked out what i have in the huck. Its a himax 2015-5400 and a 1500 3s lipo. on a week old charge batt I got 37 k rpm and 140 watts. 14 amps..Soo I am charging a freash pack and will retest...I think I need a bigger batt.. The temps have always been pretty low after a flight.Maybe this weekend...
Nov 02, 2005, 12:44 AM
Watts your motivation
roccobro's Avatar
Having seen almost 70K rpm and there "only" being that much gap looks like it has the "better" ABS plastic, no?

Well, I got back to the 2025-4200 on 4s before the house went into "noise lockdown". Without the inlet lip, I recorded about 55k rpm and "only" 350g thrust. With inlet lip, and at the 17.5A/14.4V it spun 53.5k rpm and 500g of thrust. This confirms three things. 1) A proper inlet and outlet ducting can make a huge difference in the fans ability to make thrust, 2) right above 50k rpm is 500g of thrust with proper ducting or inlet and 3) A 4s1320 TP PL (or (2) 2s packs adapted) can be used and alot of weight (and cash!) can be saved over the current popular 5300 on 3s setup.

With the Mega motors ability to do as much (and more) than the Himax, AND save a bit of weight makes it an easy power upgrade. I wil next go back to teh 16/7/4 on 4s and use the inlet lip and outlet cone. It initially spun the same RPM w/out the inlet as the Himax did with the lip. I expect a smart increase in static thrust to go along with the 55K rpm it did on the 4s1p, just as the himax experienced with the lip and 4s2p.

One thing that I "worried' about is the max rpm of the motors. The Himax has some reference to 60K rpm, and Power says there is a 55k max rpm for the Mega. Website catalog says "Kevlar bandaged to retain magnets at 35 000 revs or more." There is nothing in the three pieces of paper that came with each motor about rpm, and the only hidden piece of information on the box is inside the lid; "100% recycled paper" and "The handmade box is specially designed for Mega Motor".

Somebody? help? I wouldn't mind throwing a magnet in the name of science, but I don't always wear glasses during this testing....

Scott- just let me know when. We can do it "while you wait"


EDIT: Bruce just read your information. Thanks! Funny that th himax is rated for the same rpms... Boca bearing here I come?
Nov 02, 2005, 01:05 AM
SoCal, Year Round Flying!
bmiller's Avatar
Hah! maybe somebody can find some sort of space shuttle or dental drill ceramic bearings in the right size! Then the next thread will be on how to install them!LOL
Nov 02, 2005, 01:17 AM
Watts your motivation
roccobro's Avatar
I don't have the bearing size specs but here are some with 3.2mm id and close to outer measured size (and ceramic!).

Nov 02, 2005, 01:35 AM
SoCal, Year Round Flying!
bmiller's Avatar
Looks like 89,000rpm w/grease and 109,000rpm w/oil! sweet!
GASP!!! $29.95 EACH!?
Everybody better hurry up, they only have 390 left in stock!
Nov 02, 2005, 01:53 AM
Watts your motivation
roccobro's Avatar

Nov 02, 2005, 09:15 AM
Begin with end in mind...
power's Avatar
Justin, the rpm specs are on the Mega site for each motor. The specs are listed below the chart.

Nov 02, 2005, 01:20 PM
Permanently Banned
well... congratulation on the initial test.

But I am looking forward to the stress test that will
tell much more than that.
I am eager to see the longevity of that fantastic set up,
which is way beyond the manufacturing specs and to a place that
noone 's ever gone before
Good luck guys.

For illustration, here is
The other famous set up like...for instant:
minifan, mega 16/15/2, 3S 3200 Kokam @ 47 amps which is well
within the manufactures' specs.
According the the manufactures' literature:
480 minifan : power rating 100-800 watts:
mega 16/15/2: max rpm is 55 K
with those in mind, the well known minifan set up
is up to 470 watts, at 46K rpm.. everybody is happy
within the safety zone, even with the Kokam.

Now look at the new great set up, everything seems
passed the red zone, the motor, the fan...
that little brother 16/7/3 at 43 amps, 65K rpm, 560 watts?
and that little alfa fan at 560 watts?
enjoy living dangerously then. None for me please, I
prefer to stay within the limit. I have nothing against
that fantastic set up. Just for my own safety's sake.
Don't enjoy seeing the fan blows up in my hands

BTW, what is the power rating of the alfa fan then?
Anybody is going to use this set up in his plane?
I love to see how it works in real test.

Great work, indeed
Nov 02, 2005, 01:27 PM
Suspended Account
Well I'm excited!!!!
I've got a Mig kit and the MKII fan; I'll get a deal on the Mega 16/7/3 from Dynamo and I'll just have to see what see does.

Dynamo Electrics

Don't hold your breath; I'm a SLOOOW builder
Nov 02, 2005, 03:01 PM
SoCal, Year Round Flying!
bmiller's Avatar
Hi Justin,
Please confirm if possible,
Does the mega 16/7/xx bolt right in the mk2 alfafan unit or do you have to "open er up" like power did in his thread?

The mega 16/7/xx WILL bolt right in the alfafan mk1?

And then you should use a mk2 rotor because the mk1 rotor is junk?
Thanks, Bruce
Nov 02, 2005, 03:56 PM
Wayward Pilot
JREEVES's Avatar
Great to see your results Justin, been waiting to see how things turned out...
Following up on max rpm's, is there any liimit on a given esc's ability to phase-shift (term?) to the motor? If all the Megas are 6 pole, isn't that 6 shifts (or 3?) per revolution? Sounds pretty intense to me!

Nov 02, 2005, 04:46 PM
Model Designer
keven64's Avatar

GREAT tests... !

My my, you HAVE been a busy boy !

you complained
Yes I got the testing done, but my screen capture is caput!
What's kaputt, Justin ?

AirX said
As for telly anyone that they cant to domething becuase a manufacturer only stated that it has to be kept at 150watts...
Heh heh... like the Feigao motors...
Frankie and Benny advised us all that the Feigao motors were not to be used over around 5 amps - see here - first paragraph under the top picture...

Ha ! It didn't stop me throwing caution to the wind ( literally - I FLEW the things ) - and running them at around 9A
( admittedly for only 3˝ to 4 minutes at a time… )

You have to push things a little - if only to make sure that the manufacturers are being straight with us...!

Thatovalguy warned me ( in one of my threads ) that you cannot expect a warranty to be in place in such cases...
Like I'm going to bemoan the loss of a couple of tidgy motors after having had WEEKS of fun with them...
( BTW - the motors are FINE ! )

Thanks for the test results, Justin,

Nov 02, 2005, 05:01 PM
Permanently Banned
My brushless motors last thousands of flight, in years, and keep going strong.
No point if they lasted few flights and went puffed in glory
After all, it is my money on the motors, not for insanity beyond the book

After all, within the specs you can get the manufacture, beyond the specs
is your choice, your own risk. No job for lawyers in this case.

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