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Old Apr 24, 2012, 07:40 AM
What goes up must come down..
Canada, QC, Saint-Laurent
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No I wasn't looking at the right place, Thanks Jack!
I have order some already.
All I'll have to do is to open up to 10 mm.
Too bad Don didn't have the right bearing size and brass stopper for the DAT..
I'll keep you post onece I got these install yours looks really good.
Roger
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Old Apr 24, 2012, 01:33 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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Quote:
Originally Posted by rodair View Post
No I wasn't looking at the right place, Thanks Jack!
I have order some already.
All I'll have to do is to open up to 10 mm.
Too bad Don didn't have the right bearing size and brass stopper for the DAT..
I'll keep you post onece I got these install yours looks really good.
Roger
I thought so. To drill them out clamp them flat to a piece of wood, center them under the drill press with a 8mm drill bit, then change to a 10mm bit, spin it at high speed, and use a very light cutting pressure. That will keep you from snagging on the thinner material.

I think I may have actually shifted the the 10mm hole location up towards the top a little to leave a little more material at the bottom. And it two winding wires won't fit through the holes on the terminator, you can drill those out a little too.

On the 8mm tubes the black mount will trap the Terminator between the step where the tube becomes larger. That moves the locking screws down a little and they may not center on the slot or flats as it did originally.

I use 3mm button head hex socket screws to replace the 3mm set screws in the motor mount. Those have 2mm sockets so they will not strip as easily and they provide more clamping force, you can see them here:

http://www.rcgroups.com/forums/showp...postcount=1135

And there is a little more info on the screws a (Traxxas RC car part) here:

http://www.rcgroups.com/forums/showp...&postcount=997

These motors have a lot of torque, the bearing tube is small, keeping them from spinning or loosening in the mounts requires a little extra attention. Remember, we are hot rodding this motor quite a ways beyond it's intended power levels!

Jack
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Old Apr 24, 2012, 06:49 PM
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Looks neat

my motor is usually torn out of the plane and away someplace so Im wondering

I just bring the 3 double wires straight out, from the stator , really they are thick and withstand the abuse ,

will post picture that is better
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Old Apr 24, 2012, 06:59 PM
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Picture

Will have to learn that fancy power wind , this LRK is OK but not as good as the latest

See how the reinforced tape holds the wires and stops them being sort of torn out

Normally 4 legs on the mount , its was torn off in the last crash a straight into the runway from a wild ball in the sky type of power spin with everything added rudder and all,,,,,, its easy to lose it that way
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Old Apr 24, 2012, 07:52 PM
Jack
USA, ME, Ellsworth
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Quote:
Originally Posted by NX-687 View Post
Will have to learn that fancy power wind , this LRK is OK but not as good as the latest

See how the reinforced tape holds the wires and stops them being sort of torn out

Normally 4 legs on the mount , its was torn off in the last crash a straight into the runway from a wild ball in the sky type of power spin with everything added rudder and all,,,,,, its easy to lose it that way
I have not done a LRK rewind on a DAT-750 yet but I have it on my list to do one. I've done a couple of other LRK winds that were perfect for my tastes in prop. I like larger and stronger slow fly prop like the Great Planes 10 x 4.5 and 10 x 7 and the LRK wind's torque really seems to work good on those.

There is a thing called the Winding Factor that sort of rates the torque output on motors. In theory, a perfect motor would have a Winding Factor of 1.0 and the lower that number gets the less effective the motor is. And the LRK wind on a 12 arm 14 magnet motor produces the highest winding factor (WF) of all the winds at 0.96593. A DLRK wind only produces a 0.93301 in comparison.

You can see the WF thing here: http://www.powerditto.de/bewicklungsrechner.html

For the LRK wind go to the advanced mode, enter A-b-C-a-B-c- for the Scheme and 14 for the magnets. If you just enter 12 Slots and 14 Magnetpoles it gives you the DLRK wind.

So we all need to do more LRK winds!

I did a LRK wind on D4023-850 12 turns of 18 AWG terminated Wye for a 901 Kv. It is beautiful to look at! I am still getting it sorted out though. It kept ripping itself out of the mount in static tests and I have not fixed that yet...

This photo shows the D4023-850 wound LRK with 13 turns and the transit runs made on the top of the stator. But I had a short in that one (last turn was really hard to get on) and I had to take one turn off.

It is a lovely motor, I have to finish it up and find a use for it...

Jack
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Old Apr 24, 2012, 09:51 PM
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Jack

That is the big version of the DT I assume ?

Quite powerful

Ive got a DVM and shunt to measure my DT but its quirky , dont know what amps Ive got ,

my batteries are shot , getting new ones, may get a wattmetter , but I had a 13x6 on last flight and a 900 3S and a CC25 , model is less than 14 Oz

so any prop is OK , only had 2.4 bullets on so I changed to 3mm bannana, to suit the new 40A 3S 900s that are on the way,

Well I like the big props too,, the thick laminations on the DT dont suit revs,

Hey 60 A at 8 volts for the A123s that is 480 Watts , that kills the 900 3 S

I will have a look at my A123 , Have not touched it for about a year



I did have a 4 S A123 1100 behind it and that was good ,, not much duration but big power
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Old Apr 25, 2012, 06:04 AM
Jack
USA, ME, Ellsworth
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"..That is the big version of the DT I assume ?..."

Yes, it is rated at 380 Watts and the DT750 was about 135 Watts. Have not run the 4023 at 380 Watts yet though, that would be a peak reading and I would consider it to be more like a 300 to 325 Watt motor until it proves otherwise. There is a thread on it here:

http://www.rcgroups.com/forums/showthread.php?t=1491875

It has a little taller stator, slightly larger bell, bigger bearings, and weighs about 108 grams compared to the DT-750's 79 grams. I think I like it just because it looks like the DT-750...

http://www.hobbyking.com/hobbyking/s...ner_Motor.html

But I do need to get the issues on it's mounting sorted out...

In a couple of recent threads talking about LRK winds, Christian Lucas (he is the "L" in LRK and DLRK) has said that the LRK wind has the most potential in general because of it having the highest winding factor. And the motors with longer stator arms are also the best place to use the LRK wind. The DLRK wind is better suited to motors with shorter stator arms.

So I think these DT series motors need to investigate the LRK wind a little more. Especially so it you are looking for medium RPM power and performance and not a high RPM screamer. And the thicker plates don't seem to as much of an issue on lower Kv motors either.

Jack
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Old Apr 25, 2012, 09:27 AM
What goes up must come down..
Canada, QC, Saint-Laurent
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NX-687,
what was the size of your wire and how many turns on your rewind?...very nice machine motor mount!
Jack,
sort the "short" issue on your nice rewind and post us a video of it running.
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Old Apr 26, 2012, 05:04 AM
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Rodair

the mount is out of a piece of 3inch aluminium bar ,, I have to make another , the wire diameter is 0.7mm , dont know how many turns are on sorry

What sort of model do you fly your DT on ?
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Old Apr 26, 2012, 05:28 AM
Jack
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"..Jack,
sort the "short" issue on your nice rewind and post us a video of it running..."

I'll add that to the list of things I need to do...

Jack
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Old Apr 27, 2012, 03:56 AM
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Jack

Just broke the other 2 legs off the mount in a crash, but got a wattmeter on and its 21 A and over 200 watts , dont know the volts , its a 3S 900 Hyperion,

That is the maximium that can be drawn from the Pak without damage, but the new 900s can draw 40 A , amazing

On a 12.6 Oz model AUW , with battery , the performance is good
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Old Apr 27, 2012, 07:28 AM
Jack
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Pulling 40A on a 3S that will handle the current load that puts that motor up around 400 Watts. And that is about as much as anyone has ever got out of it. And the torque on this is impressive too, that is what is making it hard to keep them in their mounts.

I think I see a GWS Slow Fly prop there and you are probably well beyond the RPM and strength limits of that prop. I moved on to using the Great Planes slow fly props, they are much stronger and will handle the power very nicely:

http://www.electrifly.com/miscproducts/gpmq6610.html

I get mine on eBay from a seller named philshobbyshop, good deals, quick shipping...

Jack
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Old Apr 28, 2012, 02:33 AM
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Jack

I was using a 11x8 slow fly prop at the last crash and it always vibrates at around 200Watts but does not fail

I will use the stronger props for the new battery as it be at least high 200 watts

Thanks for the prop link
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Old Apr 28, 2012, 06:07 AM
Jack
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The Great Planes slow fly props are pretty thin and light but are a lot stronger than the GWS props. The GWS slow fly props are good up to about 45,000 / dia. in inches and will usually start fluttering around that speed. When you get much beyond it you run considerable risk of the blade roots "wrapping the hub". And if a blade comes off the imbalance can rip a motor and mount right out of a plane.

In comparison, the APC slow fly props are good for 65,000 / dia. in inches. The GP props don't have a published RPM limit but I have spun them up to the same speeds as the APC prop and saw no fluttering or problem so I consider them to have the same limit as the APC at least. I have hit 12,000 RPM with a 10" GP slow fly (by accident in static testing) and it did not show any distress.

And they seem to pull like gangbusters, very well suited to this motor.

Dr Kiwi did some testing on the GP slow fly props and you can see it here in the prop database at flybrushless.com, they are the ones listed as "GP SF" props:

http://www.flybrushless.com/prop/search

And the prices on them is not bad, around $2 each in pairs of two from the eBay guy. They are only stocked by Great Planes dealers and they are not easy to find at the LHS. Another well kept secret...

I use those over 200 watts all the time, on a prop saver, with the Thera-Band prop saver bands.

Jack
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Old Apr 30, 2012, 03:22 AM
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Jack

I made a new mount for the DT , will post a picture ,

can you give me a rough steer with a 21dia stator x 6 deep 12 tooth 6 magnets ,

with a 2s 800 and a 5.5 x4.5 prop I have .63 mm wire , Im guessing as many turns

as possible about 8,, maybe less, Im a bit lost never done a rev wind before
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