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Old Jun 23, 2009, 01:29 AM
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My efforts to reduce motor weight, were very simple, to reduce the stator 3.5mm, cut the bell and magnets *, change the shaft to a carbon fiber and install a prop saver on the two screws the bell and change the 6 holes, only 3 large holes in the bell.


I do not know the amount of light weight, I think that is not much and maybe with a little luck and this weighing 20 grams. (for the moment I have nothing reliable to weigh)

* To be pre-cutting with a Dremel magnetos is dangerous, but not both. take several precautions to make and I put the double-filter mask. this is not something that I recommend and should not do.

16T, 26AWG, 46 inch.

My test.

No load, 15,500, 11.30, .6A, Kv 1460.
No load, 12,200, 8.20V, .6A, Kv 1487.

GWS 8x4, 7300rpm, 7.10V, 4.8A, 10oz, 34.1 Watts, 73%
GWS 8x4, 7600rpm, 7.58V, 5.6A, 10.75oz, 41.7Watts, 66.4%

Estimated with Drive calculator.

GWS 7x3.5, 12438rpm, 11V, 5.8A, 13oz, 64Wtts, 70%.

Manuel V.

Note.

The first test measurements with an a shunt resistance. so we can have a margin of error.

So I made some adapters Micro dean to Dean Ultra. to re-test the Motor with Astro Ammeter.
These were the results.

No load, 11700rpm, 35 A, 7.93V. 1474kv.
No load, 16700rpm, 47 A, 11.33V. 1475 Kv.

With GWS 8x4, 7800, 5.46A, 7.65V.
With GWS 8x4, 7500, 5.12A, 7.53V.
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Old Jun 23, 2009, 02:26 AM
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Nice work

Can we see a picture Manuel ,


with the stator at 3.5mm and carbon shaft I would expect less than 20 grams

thats a motor with a lot of work in it , nice experiment
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Old Jun 23, 2009, 02:30 PM
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Pictures.

The new BW-2203.5-1460

Manuel V.
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Old Jun 24, 2009, 05:26 AM
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Yo

Manuel
I wonder how it compares to the 2204-1400 Justgofly motor., I think its a sterling try , well done,,, but we must know the exact weight, as its most critical in small foam models where every gram counts
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Old Jun 25, 2009, 08:42 PM
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Quote:
Originally Posted by NX-687
Manuel
I wonder how it compares to the 2204-1400 Justgofly motor., I think its a sterling try , well done,,, but we must know the exact weight, as its most critical in small foam models where every gram counts

Ok. 20.4 grames.
With conector and prop saver.

Manuel V.
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Old Jun 30, 2009, 10:18 AM
I can fix that.
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Joined May 2006
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Just got my 1500Kv Blue'n'red from HC. I am glad I am going to rewind it. I unwound it to find the stock number of turns.

10 Teeth had 11 turns
1 tooth had 10 turns
1 tooth had 12 turns

I am going to say that 11 turns is stock for the 1500kv. Can anyone verify?
I thought the stock turns for the 1300Kv, 1500Kv, and 1700Kv versions were 14T, 12T, and 10T respectively.

I am going to try 12T of 23g of 24g tonight as Dave suggested. Plan is to turn a gws 9x5 with a Rhino 2S360 for the EPP Yak 55.

I will post results when completed.

-Ken
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Old Jun 30, 2009, 10:50 AM
Dave North
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Quote:
Originally Posted by solomonx
I am going to say that 11 turns is stock for the 1500kv. Can anyone verify?
That's the most common setup I've seen.
Quote:
I am going to try 12T of 23g of 24g tonight as Dave suggested.
Use the 24. 12/23 is a very advanced wind


Dave
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Old Jul 10, 2009, 11:26 AM
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Quote:
Originally Posted by manuel v
Pictures.

The new BW-2203.5-1460

Manuel V.
Nice work Manual; 20.4gm is worth it. Makes me want to take apart my motors and bring them in to the shop with me.

The thing that's troubling me is the e-ring slot in the carbon rod. It seems like the fibers behind the e-ring would split off very easily, but then I've never flown such a "device". Does that e-ring slot hold up well over time?

Cheers,
Kev
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Old Jul 10, 2009, 07:03 PM
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Kev.

In this case the carbon shaft is no slot or c clip. but if it would be good to install a small pressure sleeve, so that the bell do not move towards the front.

Manuel V.
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Old Jul 12, 2009, 01:53 PM
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Manual, are you running that without any sleeve or clip? I figured efficiency might drop off as thrust pulls the rotor out of alignment with the stator, but then I've never tried it myself to see how it works. To be honest, I'm too scared of the rotor and prop flying off and hurting someone.

Considering the cost of a small piece of carbon rod versus a steel shaft, it would work well enough to glue a piece of tubing on as a retainer. Then when it comes time for repair or rewinding, just snap off the rear of the shaft with some pliers and replace it with a new one. Then you won't have to worry about a press fit retainer wearing loose.

FWIW, I have noticed that the hxt 24gm motors often come with their shaft poorly adjusted, such that the bearings are squeezed tight between the rotor and e-clip. This problem adds friction, and probably in not good for bearing life either. I've seen improvements in efficiency up to 5% just by adjusting the bearing freeplay.

Kev
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Old Jul 30, 2009, 10:54 PM
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13T-24awg-DRLK-Y

I started out on a mission to do 13.5T on my brand new Turnigy 2730-3000kV, but the first pair told me it just wasn't happening on this stator. In fact on an older BW I did 14T with the same wire, and getting 13T on the first 2 layers was cake. This indicates a high degree of variance in the thickness of the green goop stator insulation. Maybe next time I'll win the lotto and find a 14T stator in the box.

Dave, I know you've done this before, but I didn't see your 13T numbers so thought I'd share. It's not as efficient as I would have liked, but from the pic you can see it was torture just getting 13T in there.

Cheers,
Kev
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Old Jul 30, 2009, 11:33 PM
Dave North
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Quote:
Originally Posted by Truglodite
It's not as efficient as I would have liked...
It's fine! Especially when you consider that you're overdriving it hard with that battery. 76.5% efficiency with an 8040 at that power level is hunky-dory. Try a smaller battery (or the same one when it's a bit tired) and the watts are closer to 100 and I'll bet it snicks up a few points.

Yeah, the goop is variable. I think the stators are too. So you have to pick your fight based on what the stator tells you. I've done a couple of fourteens, but neither was particularly hard because the stator was roomy. Your technique looks great!


Dave
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Old Aug 01, 2009, 05:01 PM
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Red & Blue Wonder Spreadsheet

Inspired by Manuel, I scoured RCG for R&B test data and write a spreadsheet for our new favorite 25gm motor. I took liberty to add a few extra gadgets over what we're used to, but file size is still cool. I transferred the data as carefully as I could, but please let me know if there are any errors.

Enjoy,
Kev
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Old Aug 02, 2009, 01:46 AM
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Thanks Truglodite.
I have your chart.
I see my 17 turns motor.

Manuel v.
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Old Aug 02, 2009, 11:24 AM
Dave North
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USA, CA, San Jose
Joined Apr 2004
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Various 13T Winds

Looks like I've done three. Note the dropoff in efficiency when overdriven:

Tgy 2730 13T 24g dLRK Wye
Kv 1434 (17212r/12.08v) Io = 0.49 Rm = 0.168
GWS 8040 HD Hex 620 3S
10426 rpm @ 10.23v/8.83a 533 grams 19.6 oz/thrust 80.3% Efficient
GWS 8040 HD Hex 1050 3S
11419 rpm @ 11.70v/10.68a 672 grams 23.7 oz/thrust 77.1% Efficient
V2
GWS 8040 HD Hex 620 3S
10311 rpm @ 10.31v/8.42a 544 grams 19.2 oz/thrust 80.8% Efficient
GWS 8040 HD Hex 1050 3S
11290 rpm @ 11.76v/10.06a 656 grams 23.1 oz/thrust 78.6% Efficient
V3
GWS 8040 HD Hex 620 3S
10525 rpm @ 10.49v/8.78a
B: 567 grams 20.0 oz/thrust 81.1% Efficient
D: 625 grams 22.0 oz/thrust 83.5% Efficient
GWS 8040 HD Rhino 460 3S
10838 rpm @ 11.00v/9.30a
B: 603 grams 21.3 oz/thrust 80.0% Efficient
D: 665 grams 23.4 oz/thrust 82.1% Efficient

In other news, I'm one of those who is Windows Challenged and cannot open excel files.


Dave
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