Originally Posted by rodair

Jack, I am glad you post these results Thanks.
Not too bad prop worth considering on DAT motors especially when you said 4S
It's good for my motor and type of flying / plane ioo bad they don't have 11" dia.

The Great Planes 11 x 4.5 and 11 x 7 would be my choices for bigger props for this motor. They are stronger than the GWS SF props and can be easily used as either tractor or pusher props. You can find them on eBay and they are pretty cheap too. No more than the HZ props for sure.

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

Nice and neat wires terminaison using tie wrap that's a great idea!
Are you going to try DLRK? or keep this one as is?

These motor all came to me as as dLRK winds, I've re-wound one to dLRK and three to Half Parallel dLRK and those are all good winds. I'll keep the LRK motor as it is for now. I want to get it in the air and see what I think. Regardless of the low efficiency, I think this is a good useful motor.

I'm wondering if the efficiency thing is important. Or important to me as far as how I use the motor. I can play with wire size (fewer turns bigger wire, more turns smaller wire, etc.) and get the Kv up or down as needed if I want. And I think this motor will be useful.

I've had a couple of guys who use it on tri and quad omnicopters PM about the wind. They are interested because they are using 4S system to support the cameras and all the FPV stuff and seem to think that a 6,000 RPM DAT-750 that only pulls about 10-12A will let them make major reductions in battery mass requirements and/or extend the flight duration.

I just got it's brother motor here the "AIR L3010C" 1300 Kv rated 420W that I want to test the thing here it's the same motor mount for a lot more heavier bell housing motor with only 2 small grub screw to hold it, same threaded shaft to hold the prop etc..I don't know about the sator I didn't dismantle this one yet.

Roger

How to you think you'll use that one? The 1300 kV is a little high for anything I do. They say it is a 3S motor, with that kV and on 3S that puts props on it that are turning up around 11,000 RPM or so and the continuous power rating. So you're talking props down around 7 or 8 inches in diameter I think.

Jack

Originally Posted by The Tellurian

The L3010C I had needed the mount torched before it would come off. I thought it was epoxied but no its a force fit. Maybe just manufacturing tolerances but it really irritated me to go to that extreme since the mount had to be removed to attach to the firewall then the motor reinserted. Going to buy the 'B' version next time.

Richard

That sounds like a QC issue in manufacture, and there is no excuse for any seller to put it in your hands that way.

When I first saw the 3010 motors I think they were branded TurBORIX and sold by R2 Hobbies. Now R2 no longer has them and they are sold as Turnigy motors. I wonder if they came from the same maker? Trying to keep up with how makes what is getting harder all the time.

Jack

In a posting on another thread, Ron van Sommeren, (a resident power systems genius) said to user jackerbes:

"..I think you have made a mistake in the efficiency calculation somewhere Jack. 50% is dreadful, even the worst of the worst motors do better. Of that number were correct, your motor would get veryvery hot, if not burn up instantly..."

User jackerbes replied to him as follows:

"..Well, then I must have made a mistake. Do you want to take the numbers from the testing I reported on the DAT-750 thread (no load tests and various prop tests) and see if you can get better numbers? These are the numbers I used at http://www.peakeff.com/

DAT750LRK800
Io 1.81
V1 10.85
I1 9.97
RPM1 5540
V2 10.52
I2 12.20
RPM2 4495
Weight 78

Graphed results:
Kv: 828.5375
Io: 1.81
Rm: 0.4176048
Voltage: 10.5
Weight: 78
Motor: DAT750LRK800

I am new to efficiency and the calculator. That I made a mistake in using it would not surprise me at all. ..."

So maybe the abysmally low efficiency I reported earlier is wrong and this really is an OK motor? That would be good news!

So maybe Ron will reply here and we can get this sorted out a little better.

We'll wait and see what happens now...

Jack

Jack,
I got new O rings here with the special tool to hook these!
The Turnigy AIR L3010C was sold as an EDF L3010C in France so the video link I post from "remotly competent" was using that motor and the PKZ1005 so this is what I'll try on my next "new" bipe being CF's reinforced wings and X stings and getting new larger tail surfaces.
I took a good note about your suggested props from GP..and will also try smaller one ( 9"-9-1.2" at 1300 KV), looking at these GPSF the main thing is the 11" dia one have the inner hole too big for 4mm shaft I would have to try to see of the cone of the prop saver works with them (O is 5mm on 11" GP SF prop).
I should rewing one DAT also with 21 AWG this winter.
note: still planning to use my 3S lipo here.
Roger

Originally Posted by rodair

Jack,
I got new O rings here with the special tool to hook these!

Post your impression of them on the prop saver thread after you have had a chance to try them. Like them or not. It is good to wake that thread up every once in a while.

The Turnigy AIR L3010C was sold as an EDF L3010C in France so the video link I post from "remotly competent" was using that motor and the PKZ1005 so this is what I'll try on my next "new" bipe being CF's reinforced wings and X stings and getting new larger tail surfaces.

OK, that prop might work OK with it, you just have to check for heat before you put it in the air much. If it will stand some full throttle duration in a static test will will do fine in the air too. But watch the RPM thing, it will be getting up around 10,000 to 11,000 or so and I don't know if that 10 x 8 will handle that for very long.

I took a good note about your suggested props from GP..and will also try smaller one ( 9"-9-1.2" at 1300 KV), looking at these GPSF the main thing is the 11" dia one have the inner hole too big for 4mm shaft I would have to try to see of the cone of the prop saver works with them (O is 5mm on 11" GP SF prop).

for you up there in Canada, if you don't have a LHS that can and will order them, is probably eBay. But I have not found the GP 11 x 7 prop on eBay yet, only the 11 x 4.5 and smaller. The GP 11 x 4.5 prop has a 5mm or so through hole in it but it comes with four small sizing adapters that will get it do to a 4mm hole. And that will put it right on the middle of the tapered cone. Without the adapter there may be a littler lateral play on the tapered cone.

An ebay search for "great plane prop" will surface them and they sell for like $US4.50 to $US5.50 a pair. Don't know how it will work for you up there but the philshobbyshop guy I usually buy from will give me a combined shipping cost on a multiple item purchase and that makes the shipping pretty reasonable for me.

Did the postal service nail you for a customs fee on that stuff I sent to you? I filled out a customs for because my post office guy said that the Canadian postal service seems to be very aggressive about customs charges, And they nmight do that even when I send something of little value and as a gift.

I should rewing one DAT also with 21 AWG this winter.
Roger

Of course you do, you have to have one of every kind to get any respect here!

This motor is running so cool that I think winding it to a higher Kv to get the RPM up is very feasible. So it you were going to drop down from 19 turns to 17 turns you could go with 20 or maybe even 19 AWG wire and get the current carrying capacity up a little more.

Jack

Originally Posted by jackerbes

In a posting on another thread, Ron van Sommeren, (a resident power systems genius) said to user jackerbes:

"..I think you have made a mistake in the efficiency calculation somewhere Jack. 50% is dreadful, even the worst of the worst motors do better. Of that number were correct, your motor would get veryvery hot, if not burn up instantly..."

User jackerbes replied to him as follows:

"..Well, then I must have made a mistake. Do you want to take the numbers from the testing I reported on the DAT-750 thread (no load tests and various prop tests) and see if you can get better numbers? These are the numbers I used at http://www.peakeff.com/

DAT750LRK800
Io 1.81
V1 10.85
I1 9.97
RPM1 5540
V2 10.52
I2 12.20
RPM2 4495
Weight 78

Graphed results:
Kv: 828.5375
Io: 1.81
Rm: 0.4176048
Voltage: 10.5
Weight: 78
Motor: DAT750LRK800

I am new to efficiency and the calculator. That I made a mistake in using it would not surprise me at all. ..."

So maybe the abysmally low efficiency I reported earlier is wrong and this really is an OK motor? That would be good news!

So maybe Ron will reply here and we can get this sorted out a little better.

We'll wait and see what happens now...

Jack

Jack.

What is the Kv

Your reading., not for specification.

I use Drive calculator. is best for graphic motor.

Manuel V.

Originally Posted by manuel v

Jack.

What is the Kv

Your reading., not for specification.

I use Drive calculator. is best for graphic motor.

Manuel V.

I did two and they both came about about the same.

no load = 7498 @ 9.29 = 807 Kv
noload = 9499 @ 11.92 = 797 Kv

The raw kV on the motor with the factory wind was 780 and I was tying to get about the same kV, the TC6 prediction was very close.

Jack

Jack, your numbers suggest a serious over-load.. taking the 10.52v and 4495rpm... at best (using 800Kv rather than your graphed 828Kv) you are getting "RPM as % of Kv x V" of only just over 53%.. as you well know, target is around 75%.

What size prop is going to get you 75%....an 8x4???... that seems ridiculously small for an 800Kv motor.

I agree with Dr Kiwi... there must be something wrong with your motor or with your data.

I've tried some math with your data and it don't look like the way a motor should go.

Maybe I can ask you a series of runs with 3 different props with 3S and 4S (3x2=6), but no part throttle before, just WOT and a cool motor. Could you also tell the amps for your no-load runs ?

With good data, I'm pretty good at finding output power, so efficiency. I may also compare your motor's "profile" with similar motors.

Guillaume

Thanks for the inputs on this guys.

OK, I'm going to run some tests and get some new data, I probably have this all screwed up for now.

@yomgui,

I'll get those numbers for you and post them tomorrow, I have them in the eLogger data files. And I can do the rest of the runs that you asked too. I'll do the three props test runs too.

I'm looking forward to learning something here. And it will pro bably help others too.

Jack

Originally Posted by Dr Kiwi

Jack, your numbers suggest a serious over-load.. taking the 10.52v and 4495rpm... at best (using 800Kv rather than your graphed 828Kv) you are getting "RPM as % of Kv x V" of only just over 53%.. as you well know, target is around 75%.

What size prop is going to get you 75%....an 8x4???... that seems ridiculously small for an 800Kv motor.

with this numbers, this motor is only good for around 180 watts.
around only 90-95 watts out in the propeller, the rest is heat.


Manuel V.

Originally Posted by manuel v

with this numbers, this motor is only good for around 180 watts.
around only 90-95 watts out in the propeller, the rest is heat.


Manuel V.

And if the rest is heat, would that mean the motor should be getting hot?

One of the reasons I was testing with that APC 10 x 14 was because the motor was not even getting warm. That is with the eLogger temp sensor in direct contact with the windings and checking with my fingers too. There is no doubt or confusion at all that the motor was not getting hot.

At any rate, tomorrow I'm going to go through three props in the size range I think I want to use on the motor and get new data just make sure I have nothing mixed up.

@ yomgui,

The numbers on the no loads tests are as follows, I did those several times, the numbers are the averages for 8 to 15 seconds at continuous full throttle, taken with the eLogger:

no load = 10,014 RPM 12.47V, 1.92A = 803.05 kV

no load = 9,922 RPM, 12.36V, 1.86A = 802.8 kV

Jack

OK, new data for figuring out the efficiency thing:

Full throttle tests runs of approx 20 seconds duration, temps are at start and end of run, post run peak temp is the highest temp seen after stopping and before it started dropping again.

Props used are APC Thin Electric, APC Slow Fly, and Great Planes Slow Fly

Thrust estimates are from flybrushless.com thrust calculator (I am not set up to measure thrust).

DAT-750 motor, 19 turn LRK wind terminated Wye

No load = 10,014 RPM, 12.47V, 1.92A = 803.05 kV

APC TE 13 X 8
3S = 4473 RPM, 10.42V, 11.90A, 124W, temp 66F 73F
4S = 5022 RPM, 14.95V, 14.75A, 221W, temp 74F to 86F

3S thrust estimate = 769g
4S thrust estimate = 979g

GP SF 11 X 4.5
3S = 5245 RPM, 10.53V, 10.38A, 109W, temp 72F to 78F (115F post run peak)
4S = 5958 RPM, 15.19V, 12.44A, 189W, temp 76F to 92F (105F post run peak)

3S thrust estimate = 707g
4S thrust estimate = 933g

GP SF 10 X 7
3S = 4543 RPM, 10.22V, 12.07A, 123W, temp 69F to 80F (89F post run peak)
4S = 5251 RPM, 14.99V, 14.16A, 212W, temp 73F to 95F (111F post run peak)

3S thrust estimate = 472g
4S thrust estimate = 635g

APC SF 10 X 4.7
3S = 5724 RPM, 10.56V, 8.77A, 93W, temp 71F to 73F (83F post run peak)
4S = 6563 RPM, 15.37V, 10.69A, 164W, temp 71F to 77F (89F post run peak)

3S thrust estimate = 584g
4S thrust estimate = 787g

I really appreciate the help, guys!

Jack

Well, I don't know what to say to you Jack !

First, I can't find the Kv with my method, which is quite the same as Drivecalc's. Usually, with such data you can find the value of the kv by searching for which kv the calculated R increases proportionally with rpm (that's what drivecalc is looking for), using :

rpm / kv = U - RI,

R should be = a.rpm + Rm, "a" being a coefficient and "Rm" being some kind of resistance that is not influenced by rpm.

I can't find this relation with your data, the 3S and 4S values looks like being from different motors.

Then, we can guess the torque of an APC 10x4.7SF :

0.097 N.m at 5724 rpm, power out = 58 W (20°C - 30 m elevation - standard atmosphere)
0.128 N.m at 6563 rpm, power out = 88 W

estimating Io = 1.5 around 6000 rpm

( 8.77 - 1.5 ) / 0.097 = 74.6 ---> 74.6 * 30/pi = 712, this should be the kv !!,

same with 4S :

(10.69 - 1.5) / 0.128 = 71.7 ----> 71.7 * 30/pi = 685 !!

BTW, 1.9 A for no-load current at 10000 rpm is a lot IMO, I have a similar motor drawing less than the half of this.

It looks really strange ...

Maybe others have an idea...

My kv is what we call here a "raw kV", simply the RPM divided by the voltage. I've read that while it is not a "true" kv but it would be close to it. Just a little higher?

I'm sorry to be the source of so much frustration for you!

The motor is real, the numbers are real. I can post or email you the eLogger data files. They are text based and can be used in a spreadsheet although I have no idea as to how to do it. The eLogger User's Manual explains the data I have and how it can be used if you want to look at that:

http://www.eagletreesystems.com/Supp...n%20Manual.pdf

I wonder if I am the first person that ever did an LRK wind on this motor and documented it here? It seems to be like a new discovery or something...

But it is making props go around, those will develop thrust, and I'm going to get this in the air so see if it won't make something fly.

Jack