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Old Apr 20, 2007, 02:08 AM
Fly it like you stole it..
Tram's Avatar
Florence, Al
Joined Oct 2000
29,212 Posts
Is anyone running 3S/4S per side on this thing?
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Old Apr 20, 2007, 02:32 AM
The need for speed
Perth Western Australia
Joined Apr 2005
332 Posts
you mean Mega 16/15/4 on 6s
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Old Apr 20, 2007, 02:36 AM
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FrittsLogic's Avatar
Honolulu, HI
Joined Mar 2007
63 Posts
Well, I guess I'll be lazy and just buy two more 2w-25's and be a good boy and stick to my 5s 3700 packs. 1.7kw is still respectable. The 2w-25's are pretty cheap and the plane seemed happy running on 5s with them, nothing too hot.

I only took 1800mah out of the 6s pack before the last motor flamed out. My guess is one went early, then I had to compensate for observed lack of power by going higher on the throttle, which led to the second one smoking.

I guess I found the edge of my envelope
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Old Apr 20, 2007, 04:00 AM
go fly! no crashes!
Synwpn's Avatar
Honolulu, HI
Joined Jun 2003
2,845 Posts
Quote:
Originally Posted by Brett_Warwick
you mean Mega 16/15/4 on 6s

oops! you're right. got 3 setups that. was thinking of the 5T for a multi-motor seaplane.
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Old Apr 20, 2007, 12:16 PM
See the Fur Fly
FNFAL's Avatar
Dayton, OH
Joined Oct 2006
916 Posts
Quote:
Originally Posted by FrittsLogic
Well, I guess I'll be lazy and just buy two more 2w-25's and be a good boy and stick to my 5s 3700 packs. 1.7kw is still respectable. The 2w-25's are pretty cheap and the plane seemed happy running on 5s with them, nothing too hot.

I only took 1800mah out of the 6s pack before the last motor flamed out. My guess is one went early, then I had to compensate for observed lack of power by going higher on the throttle, which led to the second one smoking.

I guess I found the edge of my envelope

Hi,

I too am selecting the 2W-25 for my F-15, but now have concern. Did you have a chance to see if it was bearing, coil, rotor magnet failure...or something else? I wonder whether it's overspeed or current draw.

Thanks
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Old Apr 20, 2007, 12:16 PM
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Ed Waldrep's Avatar
Las Vegas, NV
Joined Dec 1996
7,921 Posts
My scratchbuilt F-22 setup on twin MF480: Himaxx 2825 2700 kv motors on 5S 5000 TP Extremes, pulls 1250 watts in a 6 lb airplane. Motors run cool, about 70 amps full throttle, battery handles this easily, comes out 115 to 120. Not a super awesome power setup but adequate. It's a draggy airplane but still gets around ok, large 100 foot loops and a vertical roll and a half for the pull down the backside for a turnaround. I did fly it one day on 6S, 89 amps and 1850 watts, loved the power but worried about the motors, didn't remember the temp.

The 5000 is a nice sized cell for this size, lite, but more capacity than the 3700 mah range.
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Old Apr 20, 2007, 12:25 PM
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dusmmdb34's Avatar
Alexandria LA
Joined Oct 2004
1,644 Posts
Quote:
Originally Posted by Tram
Is anyone running 3S/4S per side on this thing?

I am running a 4s 3250 per side. I am using mega 16/20/2s. I get about 750watts per side. With my F15 at 5lbs......it is a sweet power setup.
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Old Apr 20, 2007, 12:32 PM
Fly it like you stole it..
Tram's Avatar
Florence, Al
Joined Oct 2000
29,212 Posts
Yeh, I think if I wind up with one of these things, I'll be putting a 4S 3850 per side..
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Old Apr 20, 2007, 01:18 PM
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FrittsLogic's Avatar
Honolulu, HI
Joined Mar 2007
63 Posts
Quote:
Originally Posted by FNFAL
Hi,

I too am selecting the 2W-25 for my F-15, but now have concern. Did you have a chance to see if it was bearing, coil, rotor magnet failure...or something else? I wonder whether it's overspeed or current draw.

Thanks
Both motors are seized. A chunk of rotor fell out of one, so maybe too much speed. Internal wiring also open ckt'd based on esc non-response. Could be due to mechanical failure. I still think using the 2w-25 on 5s is a great choice, it's what the motors were designed for. I just got too cocky. Consider that on 5s, my max power was just shy of 1.7kw. On 6s I got to 2.4kw. That's a 41% increase in power for just a 20% increase in voltage. When using the 5s pack, my max amp draw was 80A, 40A per motor (their specs are 50A).

The other nice thing is that these HET motors are relatively cheap.
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Old Apr 20, 2007, 01:45 PM
See the Fur Fly
FNFAL's Avatar
Dayton, OH
Joined Oct 2006
916 Posts
Yes, it does sound like the magnets flew off the rotor to cause seizing. Air gap between stator laminates and rotors are kept to a minimum to help with performance, but at these speeds maybe they need to put a cover over the rotor to prevent the glued magnets from launching. I've never taken one apart...perhaps they do...I'm not familiar with their rotor construction. Shaft runout on these long stack motors becomes more difficult from a production standpoint too.

Also, this is what HET HK said about the 2W-25. I don't understand him exactly, but I think he's saying the motor can be run on a 6s, but will overpower the F15.

"...But 2 pcs 2W-25 is too much for the F-15. Also to maximise the 2W-25, you need 6S and get 1,100 watts each....

...Yes, you can use 5s battery for 2W-25 as Markos did. He had good performance with that setup...

Regards
Tony
High-End Technology RC"
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Last edited by FNFAL; Apr 20, 2007 at 02:27 PM.
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Old Apr 21, 2007, 02:24 AM
MultipleCrashSurvivor
drksyd's Avatar
USA, HI, Honolulu
Joined Jan 2003
2,886 Posts
From my testing with the 2W-25, I got 1200watts with 6S at 62amps where the motor is rated at 50amps max. Unlike Fritts, I only got ~700watts with 5S with forty something amps, can't remember exactly what I had. I think the 2W-25 in a mini fan would fare much better without dropping too much watts.
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Old Apr 22, 2007, 04:57 PM
Registered User
Tulsa Jones, Oklahoma, United States
Joined May 2002
308 Posts
Just started my Eagle and was wondering if is better to parallel two PQ 4s 3700's to the fans. I am using 2w-20's with Castle 80's. Would it matter if they were both set up independently? I assume you just slave the second speed control to the throttle.

Also, after flying a Sniper and F20 that both had mounting lugs for the fans, it seems odd these are to be a friction fit. Any issues with this yet such as vibrating free?

Thanks.

Jeff
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Old Apr 22, 2007, 05:38 PM
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Honolulu, HI
Joined Mar 2007
63 Posts
I had the fans come loose a couple of times on landing. I then added extra tape like the instructions direct and they have stayed put. Definitely keep your batteries in parallel feeding both esc's in parallel. It will keep the same voltage going to both esc's, therefore same rpm on both motors throughout the flight.
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Old Apr 23, 2007, 11:37 AM
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Las Vegas, NV
Joined Dec 1996
7,921 Posts
http://www.rcgroups.com/forums/showt...92#post7328159
In what may be a first, a HET F-15 has flown with retracts. They weren't installed in the scale location, that's impossible because they aren't rotating retracts (none are commercially available) and even if there were some you could buy, there's no room in the airplane without the ducting getting in the way. The retract location is like that of the F-14, the wheel and strut retract into the wing root fairing (although it doesn't rotate, there'd be no room anyway). I've got an idea for installing retracts in the bottom fuselage but the inlets really get in the way, if they'd been pinched in the middle (heading towards each other and then back out again) or if the fans had been placed closer together (with the mounting tabs overlapping like the fans in my own design F-22) there'd be more room, but apparently no thought was given to this. Now I remember why I started scratchbuilding, it's the only way to get what you want!

Anyway, the plane flies fine, watts per lb is up there well over 200 on a 5S TPExtreme 3850 setup, about 6 lb rtf. The jet's not mine but I filmed it, unfortunately I drained the battery on my MiniDV camcorder and had to use my digital camera so the clip isn't long and it's in the cursed quicktime format.
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Last edited by Ed Waldrep; Apr 23, 2007 at 09:51 PM.
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Old Apr 23, 2007, 09:01 PM
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Renfrew,Ontario,Canada
Joined Feb 2007
22 Posts
Thats great news Ed!! News I , and others here have been waiting for.Somebody to take the plunge! Any build pics or more info?
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