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Old Oct 01, 2009, 05:16 PM
Dave North
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USA, CA, San Jose
Joined Apr 2004
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Looks fine to me! I just happened to finish up a 9T 23awg "blockhead" just before checking in ... so what the heck, here's how that looks.

Dave
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Old Oct 02, 2009, 09:00 AM
Will work for foam
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United States, WI, Muskego
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Now THAT is a work of ART!


Art who, i dunno - but he is GOOD!

JK Dave, very nice work.
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Old Oct 02, 2009, 01:29 PM
Dave North
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USA, CA, San Jose
Joined Apr 2004
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Hey, thanks! Art thanks you too.


Dave
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Old Oct 03, 2009, 08:25 PM
Heli Bouncer
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At the Discount Clambake
Joined Feb 2001
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Quote:
Originally Posted by Truglodite
You're on the right track. Standard setup for BCP 3D is 4100 RPM/V and an 8 tooth pinion. Some quick and dirty math tells us: 4100*8/3000=11, so 11 tooth would give roughly equivalent headspeed with a 3000kV motor. FWIW, the 3mm ID 0.5M pinions you'll need are somewhat hard to find, but you're in luck with the 11 tooth. The Blade 400 uses 3mm ID 0.5M pinions, and Eflight makes an 11 tooth for it (helihobby has several to choose from). ***OOPS edit*** I just realized the B400 has a 2.3mm stepped 3mm shaft, and Eflight pinions are 2.3mm. I also found that helidirect has the 3mm 0.5M pinions you want:

http://www.helidirect.com/motor-pini...c-1_78_513.hdx

Overheating is a chronic problem with these little CP machines. My Himax 4100 with 8 tooth & 3s730 gets too hot to fly longer than about 4min before I need to land and cool off. I used to have a nice heatsink, but then I noticed how much weight counts with 3D. You're rewound motor should be nice and light compared to the standard setup, and should easily handle the ~80W you'll be asking of it. The only question I would have is how long will those cheap bearings last? I'd get some Boca's (3x7x3mm), since you'll probably need them in the near future.

Cheers,
Kev

[Edited to avoid confusion between turns and teeth when using "T".]
I thought I'd check back in with my heli conversion of this motor, the 6T wye ABC motor.

Since most of my scale models fly on 2S pack I've geared the heli for 2S, I found a 12 tooth pinion in my pinion collection that is 0.5 and it works well, but I had to make new blades for this heli.

So I decided to lengthen the blades to a rotor diameter of about 610mm or nearly 24". Since the motor only spins the rotor at about 1600rpm unloaded, I found this works well on 2S. I get bags of lift, the motor stays cooler and the new 1000 mAh 2S batteries don't heat up like my older ones do. I'm kinda thinking that hot winds on these might be a good conversion for the lighter 200 class model helicopters.

In the mean time I've replaced and coverted the tail rotor, done some shaft straightening and bunch of other things probably best left discussed in Micro Helis.

I've decided to call this 'copter "Compromise", because it doesn't do much of anything well, but it will hover nicely, and since I'm a beginner with helis this fits my needs, for now.. Thanks for this thread.
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Old Oct 14, 2009, 02:24 AM
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Carmichael, CA
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23T 26awg Parallel DLRK Y

I tried for another 24T parallel, but the stator stopped me at 9-8-5-1. This would be the equivalent of 23awg 11.5T, so again my expectations were set high, but again it looks like I have another internal short.

The interesting part: this is the second time I've had a short on a parallel Y wind, and remarkably the Kv stays in line and only Io suffers. With only 2 cases I'd hardly call it scientific evidence, but there is a close correlation to what happened with my 24T blue wonder. I'm still not sure if it has anything to do with using 1 common "y-bun"; perhaps the Kv might run away more if I used 2 buns?

Regardless, the result isn't all that bad, but one has to wonder how much more efficient the 3s 8040hd would have been if it had perfect windings. You can tell I let things get a little too sloppy on this one, so a short is no surprise. I was "experimenting" with keeping the 2nd layer a little loose. Oh well, I'm pretty confident I can get this one right, so I'll have to try and redeem myself on this one soon.

Cheers,
Kev

[edit: The 3cell 8040hd was done with a TP 3s730 PL2. In all tests the batteries were partially charged to simulate "middle of the pack" voltage.]
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Old Oct 14, 2009, 04:27 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
The Netherlands, GE, Nijmegen
Joined Feb 2001
10,937 Posts
Quote:
Originally Posted by Truglodite
I tried for another 24T parallel, but the stator stopped me at 9-8-5-1. This would be the equivalent of 23awg 11.5T, so again my expectations were set high, but again it looks like I have another internal short.

The interesting part: this is the second time I've had a short on a parallel Y wind, and remarkably the Kv stays in line and only Io suffers. ...
If it's a wind-to-wind short, you effectively end up with one wind less in your coil. Hence the lack of difference in Kv. But, now you have one shorted wind, and a changing magnetic field in that wind. This leads to high currents in that single shorted wind. Hence the higher Io. You may get a local hot spot there.

Vriendelijke groeten Ron
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Old Oct 14, 2009, 09:03 AM
Got Thermals???
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United States, UT, Roy
Joined Apr 2008
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I have a 2730-1300 ABC wound with 9T of 24G newbie GB wire. I have not been able to get it to run properly. It has 16 magnets in the can and I have wired it in a Delta configuration.

The issue:
Stutters at low stick, then runs fine around 1/4 up to 1/2 maybe a little more then starts to stutter again.

Any insight you could offer would be great.

Cheers,
Jim
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Old Oct 14, 2009, 12:52 PM
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lance dalton's Avatar
Chino Hills, CA.
Joined Nov 2004
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Another nice looking wind there, Kev. Seems to like the 8x4 APC Electric prop on 2S. Did you get a chance to try the APC-E on 3S?

Jim, I'm no expert but my first rewound motor stuttered on ramp up. Turned out to be a bad pigtail termination. Resoldered it and all was fine.

Lance
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Old Oct 14, 2009, 04:25 PM
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Carmichael, CA
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Ron,
When I have an internal short (not phase to phase or phase to stator) on one of my "standard winds" (non-parallel), there is always an increase in both Kv and Io. In both of my parallel winds with internal shorts, there is apparently 0 change in Kv.

A standard wind that has a single internal short has higher current through all 4 poles in the affected phase. Parallel will have high current in only 2 out of 4 poles; the other 2 poles in the phase operate as normal. Perhaps this means an internal short on a 2xparallel wind has somewhere around 1/2 the effect on Kv compared to a similar short on a standard non-parallel wind? Maybe even no effect?

Thanks Lance,
I was about to tear out the windings and try 17T-25awg-Delta, but I'll throw it on the stand with an apc8x4e and 3s first. The apc8x4e is a very nice prop, but I still prefer the lightweight gws8040hd for 3D. Its much lower inertia (rotational mass) gives it far superior throttle response compared to the apc. The GWS8043sfA very interesting counterpart for a plane that won't crash often; it's an awesome prop IMHO, but unlike the tough hd props, the sf requires replacement if it so much as kisses the ground.

Cheers,
Kev
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Old Oct 14, 2009, 04:29 PM
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Carmichael, CA
Joined Feb 2007
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Quote:
Originally Posted by Fishjunky
I have a 2730-1300 ABC wound with 9T of 24G newbie GB wire. I have not been able to get it to run properly. It has 16 magnets in the can and I have wired it in a Delta configuration.

The issue:
Stutters at low stick, then runs fine around 1/4 up to 1/2 maybe a little more then starts to stutter again.

Any insight you could offer would be great.

Cheers,
Jim
Jim, what prop are you using?

9T-ABC-Delta will have an astronomical Kv of around 3350! Even on 2s most available props will be too much. I think that's why it's having trouble starting. Try a smaller prop, like 4"... or adjust timing... or if you can, reterminate Y... or just bite the bullet and rewind for lower Kv with more turns.

If it were me, I'd rewind or reterminate. The switching rate on a 16pole ABC of 3350Kv is going to be high (demanding on esc timing), which is likely the reason it stutters past 1/2 throttle. That very high Kvtask is better suited to a lower magnet count... say, a 14pole DLRK.

Cheers,
Kev
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Old Oct 14, 2009, 04:35 PM
Got Thermals???
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United States, UT, Roy
Joined Apr 2008
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Quote:
Originally Posted by Truglodite
Jim, what prop are you using?

9T-ABC-Delta will have an astronomical Kv of around 3350! Even on 2s most available props will be too much. I think that's why it's having trouble starting. Try a smaller prop, like 4"... or if you can, reterminate Y... or just bite the bullet and rewind for lower Kv with more turns.

If it were me, I'd rewind or reterminate. The switching rate on a 16pole ABC of 3350Kv is going to be high. That very high Kvtask is better suited to a lower magnet count... say, a 14pole DLRK.

Cheers,
Kev
I haven't put a prop on it yet, That was just bench testing to see if it would even spin. Wow, 3350 Kv, that's double what I was shooting for. How do you figure out what the Kv will be per wind? I have some 26G wire as well that I could put more turns on with.
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Old Oct 14, 2009, 06:29 PM
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Carmichael, CA
Joined Feb 2007
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Quote:
Originally Posted by Fishjunky
.... How do you figure out what the Kv will be per wind? I have some 26G wire as well that I could put more turns on with.
For a given motor, say a 16magnet turnigy 2730 with Y termination, the term Kv times the number of turns (T) is a constant, or a fixed number. We also know that generally a delta wind will give the square root of 3 times more Kv than a Y winding with the same number of turns. Knowing that we get the following math relationships:

Eqn1) Kv1 x T1 = Kv2 x T2 = C
Eqn2) Kvdelta = 3^1/2 x Kvy

So how do we use that math to decide what wind will give us our desired Kv? As an example, say we have a stock 1300Kv motor and want to rewind to get 2200Kv. You strip the stator down and discover it had 14 turns terminated Y, and your testing shows it's indeed 1300Kv (never go by manufacturer specs here). We can now solve for Cy with equation 1:

Cy = 1300 x 14 = 18200

Now that we have C for Y termination, we can use equation 1 to solve for any Kv we want, as long as it's terminated Y. So we solve for the Kv of interest:

2200 x T2y = 18200
T2y = 8.3 turns

So an 8T Y would be a little higher than 2200Kv, 9T a little lower. We also want to consider delta winds in our options. Combining equations 1 & 2 we get:

Kv2delta x T2delta = (3^1/2) x Kv1y x T1y = 31523

We how plug in our numbers to solve for how many turns are required to get 2200Kv from a delta wind:

2200 x T2delta = (3^1/2) x 1300 x 14
T2delta = 14.3 turns

So a 14T delta would be a tad over 2200Kv, and 15T delta a bit lower. Which one comes closest: 8Ty, 9Ty, 14Tdelta, or 15Tdelta? Well, we already know our constants Cy and Cdelta, so we can rearrange equation 1 to find out exact Kv's:

Kv(8Ty) = 18200 / 8 = 2275
Kv(9Ty) = 18200 / 9 = 2022
Kv(14Tdelta) = 31523 / 14 = 2251
Kv(15Tdelta) = 31523 / 15 = 2102

So it looks like 14T delta would come closest to our goal of 2200Kv. Hope this helps.

Cheers,
Kev

[edit: I should have read more carefully. I didn't realize you said 3350 was double what you wanted. I could have used 1675Kv as the target in this example. shortcut-> With 26awg, I'd do an 18T delta. That should be an easy wind since only 1 or 2 turns will be on the 3rd layer. Also FYI, 18T of 25awg is probably not doable... unless you're Dave, but he hasn't even done that yet (I don't think).]
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Old Oct 14, 2009, 08:04 PM
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Mexico, BC, Mexicali
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Fyshjunky.

Very simple use Turn Calculator
Post 12.
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Old Oct 14, 2009, 09:28 PM
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Carmichael, CA
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Lance,
After thinking more about it, the 3s 8x4e test would have been for naught because it would have pulled upwards of a blue wonder smokin' 150W. Plus, my bench esc was loaned to my by my buddy, and I already had to replace his tp 3s1350 PL2 and phx25 esc after an accident that happened while I was tuning his setup in my garage. I just couldn't risk another rc related "incident", so I'm holding off on that test until I can at least rewind it "right".

So I stripped the 23T for a retry, being careful to keep all 6 wires intact. I straightened the wires and noticed 5 were within 1/4" length of each other, and one was 1.5" longer; that extra length measured 6.8mOhm!

The good new is I now know the problem wasn't flakey wire, or pushing the packing too far. The problem was merely a lack of attention; looking at my spreadsheet the per turn length is about 1.3", so I'm guessing that was a "late night" wire and I put on an extra turn. What a shame; I'll have swap my beer out for coffee next time around.

I hope the next one turns out perfect; if it does then I'll put it through the 3s 8x4e gauntlet for you Lance.

Cheers,
Kev
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Old Oct 14, 2009, 10:06 PM
C.H.E.A.P.
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Chino Hills, CA.
Joined Nov 2004
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Quote:
Originally Posted by Truglodite
Thanks Lance,
I was about to tear out the windings and try 17T-25awg-Delta, but I'll throw it on the stand with an apc8x4e and 3s first. The apc8x4e is a very nice prop, but I still prefer the lightweight gws8040hd for 3D. Its much lower inertia (rotational mass) gives it far superior throttle response compared to the apc. The GWS8043sfA very interesting counterpart for a plane that won't crash often; it's an awesome prop IMHO, but unlike the tough hd props, the sf requires replacement if it so much as kisses the ground.

Cheers,
Kev
A friend and I have had different opinions on the mass effect of the prop. Good to see that you agree with me.

Thanks for offering to run up the motor with the 8x4 E. Hopefully you won't run it because it's gona be perfecto!

I noticed that I wind better with lots of light. I wound the 12T on a sunny day in the evening. As the sun went down so did the quality of my winds .

Check out a motor I ordered 24 slot This could be a fun rewind or a nightmare .

Lance
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