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Old Apr 02, 2007, 11:49 AM
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vtdiy's Avatar
Southern Vermont
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Jameco is out of the J250 (3611976)s. The order page is still there, and you can still order them, but they are actually discontinued.

Order the motor and caps, and they'll send you the caps and charge our credit card $6.50 for shipping
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Last edited by vtdiy; Apr 03, 2007 at 11:54 AM.
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Old Apr 02, 2007, 12:10 PM
gpw
“There’s no place like Foam”
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Always best choice to have a "flight plan" in mind (I'm going to fly in a large left circle/etc.) ...That way you're ready mentally for the unexpected...
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Old Apr 02, 2007, 05:30 PM
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Metairie, LA
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vt - ask in the for sale section, electric power systems... LF (looking for) some J250s... I see them sell every so often, 5 or 10 for $10-15.

Good deal in my book... I absolutely love my j250 planes... Can't wait for this weekend coming up... I need to get some flying done :P

-ms
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Old Apr 02, 2007, 08:39 PM
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vtdiy's Avatar
Southern Vermont
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Thanks GPW and Mssmith

will do.

Guess what I found after research. There are two different J250s with very different characteristics -- thus explaining the Motocalc results, and things like GPW saying you'll burn one up with a 4x4 prop, and another person saying they use it with one fine every day.

You got two different motors! Both J250s. One will draw 18 amps on a 4x4. The oher will do fine.
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Old Apr 03, 2007, 06:20 AM
gpw
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VT, we use the DCM-189 version of the J250 ... we bought a bunch long ago ... 3x3,4x2 are fine , any bigger is almost too much if you don't stay off the throttle .... it's the Amps that burn/wear quickly the brushes ... Gene showed us how to wire twin j250s in series , runs at half the current with a larger more efficient prop and seems to last Forever...and you only need one esc ... I'm sure someone will do a T-1 twin sooner or later...
MS , I guess you're "jonesing"to fly lately ... Everybody asked for you Sunday past...Get Well !!!!
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Old Apr 03, 2007, 08:47 AM
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Southern Vermont
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There are two versions, the G4046 (20500) , and the DCM-189 (20519).

The Jameco is the same as the DCM-189. It's the 20519. So it ought to run the same.
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Old Apr 03, 2007, 09:26 AM
gpw
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Thanks VTD ... good to know this stuff... I use the flux ring too for more torque, less amps ...schmaybe' a 4X4 then eh???
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Old Apr 03, 2007, 09:59 AM
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we have the dcm-189... can't get them for the same prices we used to, but they're still worth buying...
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Old Apr 03, 2007, 12:20 PM
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vtdiy's Avatar
Southern Vermont
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I think the 4 x 2 sounds good. The 4x4 will draw more amps, and I kinda remember something about using a 7 amp ESC?

The higher pitches are mainly for increasing speed or wattage (power). Since the plane doesn't need much power or speed, doesn't seem to need a 4x4.



I'm still going to go with the 3x3, like you suggested. I'm totally curious about that. I did order some 4x2s too just to see what the difference is.

From what I read the other motor (G4046) is a higher Kv motor -- meaning the rpm per volt is higher, and is suitable mainly if you want a gear drive, not direct drive. So for this plane direct drive you want the DCM 189 aka Jameco 311976 aka 20519.

Take the following with a grain of gumbo file powder:

Motocalc says a 3x3 will draw under 4 amps with a 7 cell Nimh and 4.3 or so with 8 cells on this plane. It says the prop is stalled but will fly (wastefully).

It says a 4x2 prop will not be stalled, and will draw a little less than 7 amps on 7 cells and a little more on 8.

It says a 4x4 will be stalled and drawing around 9 amps. So it doesn't look like a really great combo, though all of them are apparently flying the plane.


Notes: The wattage goes up for each of the choices above in order. So the power delivered does as well.

I don't know whether the motor will heat up on the 4x4 -- this seems to vary according to the flyer.

The above is based on a 9-1/2 ounce AUW finished plane. I don't actually know what mine will be yet. It's a little over 3 ounces, bare airframe.
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Old Apr 03, 2007, 12:50 PM
gpw
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Vtd , we've flown a number of planes on the 3x4 and 4x2 /J250...The Blue Albacorde, SR-71, Mini Horten ,Pond racer(twin 3x3's),the Trainer One , and many others ...As always , lighter is BETTER !!!! Plenty of power for sport flying, lots of noise.. just for effect ... You need to try both props as some planes respond better to a particular size.. Viz. smaller ,faster planes seem to favor the 3x3...Bigger planes , the 4x2 seems to give more push ...
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Old Apr 03, 2007, 05:00 PM
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Southern Vermont
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I got some color on the Trainer One, waiting for the motors and batt to arrive. Hadn't tried magic marker before -- a lot lighter than paint.

I misread the kitchen scale before -- it's 2-1/2 ounces, not 3-1/2, at this point.

I used a 3/16" square strip of white pine for the keel piece, rather than a hardwood dowel -- just what I had on hand. The weight should be the same, and the stiffness the same or a little better. Easier to glue to the bottom of the foam. But you need a saw to rip it out, so not as convenient.

Checking the mailbox every day.
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Old Apr 03, 2007, 08:05 PM
Good glue is evil
melbourne australia
Joined Sep 2003
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gpw said
"Gene showed us how to wire twin j250s in series , runs at half the current with a larger more efficient prop and seems to last Forever...and you only need one esc "

interesting, what size prop are you turning with twin motor setup
thanks
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Old Apr 04, 2007, 06:40 AM
gpw
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5x4, 6x3, 6x4 seems lots better than the smaller props.. We fly GeneBonds Constellation with 4 j250's (5x4props) wired as described..one esc and one battery... Flys and looks like the real one ... Cool !!!
Vtd ... Looks Great !!!
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Old Apr 04, 2007, 11:19 AM
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Southern Vermont
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Thanks GPW,

Any suggestions for a prop adapter or prop attachment for the 3x3 or 4x2?

The props are GWS DD types. I don't know what size holes they have -- they haven't arrived.

Just curious how they attach to the motor. I think that's a 2mm plain shaft...

Is there any way to attach without purchasing something by mail?

This is taking forever and shipping costs more than parts...No LHS here .
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Old Apr 04, 2007, 11:35 AM
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Southern Vermont
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GPW did you put a reflex in the tips to reduce tip stalling?

I could do that at this point pretty easily if it's what you suggest.
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