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Old Dec 12, 2011, 12:54 PM
1.21 Gigawatts!
Steph280's Avatar
Irvine, CA, USA
Joined Oct 2000
7,531 Posts
Can't blame the fan for motor burning when it's ran past the max spec. Remember you need to find a lower KV motor. Just because the motor worked in Wemo/HET/EFlite fan doesn't mean it will work here. The load is higher so you need to select motor/battery accordingly.
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Old Dec 12, 2011, 01:00 PM
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Thomas Nelson's Avatar
Calgary, Alberta, Canada
Joined Sep 2002
2,906 Posts
Hey erh7771

Is this the motor you are using? HK advertises it as 2800kv in one place and 3800kv in another! I'm wondering if you've tested it and found that it's actually 3000kv?

I'm thinking it might be a good replacement for my uberlight Twister on 3S, with a Mega 16-15-2 and Minifan combo; aiming for 45 amps or so on the CS 10 fan.

Thoughts?

tn

Quote:
Originally Posted by erh7771 View Post
...
I get 52oz of thrust at 67 amps on 4s with this fan using a 2839 3000kv HK motor.
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Old Dec 12, 2011, 01:12 PM
JUNK RADIO
Flazo's Avatar
USA, NY, Queens
Joined Dec 2006
3,136 Posts
alexman

Quote:
Originally Posted by alexandermh View Post
[Im starting to wonder is this fan worth it???? Sounds great, but smoke, and poor performance???]

That's probably too much of a generalization. I think guys are just trying to find the "sweet" spot for a 4S, 5S, etc. set-up. We've never had to deal with a 10 blade 70mm before. Extreme RC is getting some good results with their modified version.
This is wonderful we are all working to get the best performance and some are using this blades already...
Js-1400, is about 4000kv...

Fred
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Old Dec 12, 2011, 01:15 PM
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United States, TX, Grand Prairie
Joined Nov 2005
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Quote:
Originally Posted by Thomas Nelson View Post
Hey erh7771

Is this the motor you are using? HK advertises it as 2800kv in one place and 3800kv in another! I'm wondering if you've tested it and found that it's actually 3000kv?

I'm thinking it might be a good replacement for my uberlight Twister on 3S, with a Mega 16-15-2 and Minifan combo; aiming for 45 amps or so on the CS 10 fan.

Thoughts?

tn
Here's the motor I'm using (link), great middle of the road motor IMHO.

For > 4.5lbs of thrust on this rotor you have to spin it around 47000 calculated rpms (KV x volts). For 5s the KV should be 2700kv (2700kv x 18volts) with a stronger battery for the uptick in amps but I wouldn't do anything less than a long can motor.

HK has a 2900kv 2858 motor (here) that is 18usd and worth trying out if they every get it back in stock.

Hobby Partz sells a 2618kv motor that is 58mm long also for 21usd

Any shorter than 58mm (the can length of an ARC) might just be wasted WANTED energy in the form of heat and lower thrust
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Old Dec 12, 2011, 02:10 PM
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Thomas Nelson's Avatar
Calgary, Alberta, Canada
Joined Sep 2002
2,906 Posts
Thanks!

Is there any chance you have a 3S pack you could use on your 3000kv motor to determine amps drawn at WOT? To keep my Twister light I'm flying 3S ...

Sorry to be a pest, and no harm, no foul if it's not convenient to run another test.

tn
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Old Dec 12, 2011, 02:13 PM
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Thomas Nelson's Avatar
Calgary, Alberta, Canada
Joined Sep 2002
2,906 Posts
Kevin!

Nice F4 and nice skillz!

tn

Quote:
Originally Posted by Kevin Cox View Post
I just test flew my old scratch-built F-4E on the CS 70mm 10. I used the HobbyKing/Turnigy XK-2860-B (2200kV) on 6S 3000mAh packs. The bench test yielded about 73 amps on a 6S 3700mAh pack. I wanted to try 5S but I don't have a pack in that configuration that would fit in my F-4.

The model had the whoosh sound and flew very well the airframe is noisy anyway but it sounded much better. I could not get a camera man on this trip and the weather was perfect, for this time of year, so I just flew it. I will post installed amp readings tomorrow.

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Old Dec 12, 2011, 04:49 PM
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Joined Feb 2006
496 Posts
Quote:
Originally Posted by MagnusEl View Post
They use thread lock on the spinner/nut. If you have a soldering iron on 100W or more, just use it a short time on the spinner and you should be able to unscrew it. I did ruin a perfectly good screwdriver on my first try, (without heat..) used a CDrom rail shaft grinded to perfect fit on second try and that worked.
Thanks, MagnusEl. It works perfectly.
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Old Dec 13, 2011, 01:34 PM
Mile High EDF
420flyboy's Avatar
United States, CO, Denver
Joined Jul 2011
940 Posts
Just got the HK Turnigy L2855-2800 EDF Outrunner (630w)
Just ran it in a sapac 70mm shroud with a 4s 3000 mah, sounded great and made a lot of thrust, now I'll have to hook it up to the watt meter to really see what it does. Then maybe it's into a foam habu to see and hear it in flight.

This is the motor I'm using
http://www.hobbyking.com/hobbyking/s...dProduct=18543
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Old Dec 13, 2011, 02:20 PM
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alexandermh's Avatar
Fairborn, OH
Joined Nov 2009
544 Posts
I'll be interested to see what the watts and amps are. It seems a number of guys are pushing their motors beyond their rate with this fan (with the expected shortened life).
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Old Dec 13, 2011, 02:21 PM
Hey Ya'll!! Watch THIS!!
Michael Paxton's Avatar
Nashville TN.
Joined Mar 2006
2,555 Posts
Not me!! I'm pushing my batteries! LOL
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Old Dec 13, 2011, 02:33 PM
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hommel's Avatar
Netherlands, Zwolle
Joined Jul 2005
312 Posts
Well, not all of us...

I'd be quite happy ending up with a sub 1kW set up pushing 1.5 kg :-)
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Old Dec 13, 2011, 03:18 PM
Hey Ya'll!! Watch THIS!!
Michael Paxton's Avatar
Nashville TN.
Joined Mar 2006
2,555 Posts
Surely someone has an ARC 28-48-1.5!! That would probably be the ticket.
(Altho....for some reason...My Eflite 3600K and 25C GensAce 2500's are seeming to be very happy! And I can't ask for a nicer, faster setup)
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Old Dec 13, 2011, 03:45 PM
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Dave Grife's Avatar
Coldwater, Mi. USA
Joined Jul 2000
830 Posts
Hey Guys,

I have a few of these fans being shipped to me now.

I'm running an Arc 28-58-1, on a 5 cell 3300mah 40 C lipos now.

It's in a wemotec 480 fan pro driving my retract equip. foam habu.

This combo gives me about 1200 watts.

I'd like to keep using my 5 cell packs and just change the motor for the new Change-Sun 70mm fan.

I'd like to keep the max current below 80 amps.

Any suggestions for a motor that will not drop performance ???

Thanks,

-DG

p.s. I have a habu32 stock motor that I plan on trying first.
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Old Dec 13, 2011, 04:04 PM
Hey Ya'll!! Watch THIS!!
Michael Paxton's Avatar
Nashville TN.
Joined Mar 2006
2,555 Posts
The Habu motor will be between 55 to 65 amps and around 1k watts if you have better batteries than what I tested with. (Cheap 3300 30C from Hobby Lobby)
On 6S I got 68 amps and 1400 watts. No thrust measuring equipment.

The problem is that this fan will almost certainly take more watts to make the same power (Thrust/speed) as your Minifan. This fan is about the sound. There is not enough design to the blades to be a mini Stu fan. But it will sound good.
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Old Dec 13, 2011, 06:58 PM
EDF rules... :)
AirX's Avatar
Joined Nov 1999
13,639 Posts
Quote:
Originally Posted by hommel View Post
Well, not all of us...

I'd be quite happy ending up with a sub 1kW set up pushing 1.5 kg :-)
Hommel,

Go with a 2500 kv motor of your choice on 4s, just make sure that the motor mass is ~140-150gr to handle heat issues.

Et al the byproduct of heavier motor is that it is either larger diameter or it is longer providing a stinger magnetic field to handle the fans load making it more efficient. There is no getting more from a motor that is too small even if the kv is right.
I really wonder how many people here in this thread measure the rpm the fan turns or just calculating it because they do themselves and others a disservice by giving misleading information. Basically there is no way the average short can 28mm motor could turn this fan 40000 rpm much less 35000rpm without smoking. I think this is what ERH7771 is trying to say in some of his posts.

Cheers,
Eric B.
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