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Old Oct 03, 2012, 11:28 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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I'm going to run up a couple of more props on that later today too. I'm curious to see what that will handle. My normal back off point for this motor would be a little before the windings got up around 130F/54C or so in static testing.

I have an 11 x 7 in the Great Planes prop that I can try and then I have APC Thin Electric 13 x 8 and 14 x 10. I think that one of those would get it warmed up a little more.

I can't believe it took me this long to get around to trying this. I got focused on the half parallel winds and have done one dLRK and three Half Parallel dLRK winds but this is my first LRK wind on it.

It almost makes me wonder if I am missing something, it looks like it only has half as much wire on it and just couldn't be that good. But I just hadn't tried it. On another thread Christain Lucas (the "L" in dLRK) said:

"..Best 12 slot and 14 P with LRK winding ,always and yet and in the future. Only if you have a very short stator use dLRK winding..."

It has taken me some time to discover the obvious wisdom there.

Jack
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Old Oct 03, 2012, 11:44 AM
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flydiver's Avatar
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That looks like great wind and a very informative posting-typical of your work. I have one sitting and a plane I've been thinking to put it in. Thanks and looking forward to more data.
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Old Oct 03, 2012, 03:48 PM
What goes up must come down..
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Very interesting..I'll keep a close eye on the results.. will we have a video?
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Old Oct 03, 2012, 04:12 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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Quote:
Originally Posted by rodair View Post
Very interesting..I'll keep a close eye on the results.. will we have a video?
Of what? A motor going around? :>) I still have to find a plane for this one.

You're the guy that reminded me about this, back in the spring when you either did or were going to do a two strand LRK wind for that motor of yours. I made a mental note then that I really wanted to know how the LRK wind was on this motor. Did you ever get that wind on and try it?

Jack
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Old Oct 03, 2012, 04:19 PM
Jack
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Joined May 2008
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OK, a little more prop testing on the 19 turn LRK-Y DAT-750:

GP 10 x 7 SF = 5,313 RPM, 11.45V, 10.86A, 124W
temp rise 72F to 88F in 47 seconds
estimated thrust = 630 grams

GP 11 x 4.5 SF = 5,261 RPM, 11.37V, 10.95A, 125W
temp rise 77F to 92F in 68 seconds
estimated thrust = 725 grams

APC 13 X 8 TE = 4,495 RPM, 10.52V, 12.20A, 128W
temp rise 76F to 99F in 117 seconds
estimated thrust 760 grams

APC 14 X 10 TE = 3,870 RPM, 10.58V, 14.47A, 153W
temp rise 70F to 114F in 79 second full throttle run
thrust unknown (approx 900 grams?)

I thought I had a 11 x 7 on the GP slow fly props but couldn't find it if I do. The APC thin electrics spun up OK and would fly some planes but nothing spectacular there. But you know what? We need to add some more Volts to the equation!

Tomorrow I will dig out something that is 4S LiPO or equivalent to that and see what that does to this. I am suspecting that it will bring those APC props to life a little. We may yet get to a motor that has to be throttled back to keep it from over heating. On 3S this thing just sort of finds a power level and RPM where it flattens out and keeps running. It is getting enough cooling air that it does not overheat so I really have not found a peak power level on it yet.

Jack
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Old Oct 03, 2012, 05:53 PM
What goes up must come down..
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May I suggest a prop here...especially if you're going 4S..
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Old Oct 03, 2012, 06:02 PM
Jack
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Sure, If I have it I'll run it up!

Jack
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Old Oct 03, 2012, 06:15 PM
What goes up must come down..
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Here:
http://www.horizonhobby.com/products...ni-cub-PKZ1005
check on e-bay since you're in state they might come cheap by the dz.
It's a strange twisted prop 10 x 8 bit with a little fit the shaft not too heavy they can absorb ( with all reserve here) they RPM that you're going to infringed to your motor..
Roger
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Old Oct 03, 2012, 07:04 PM
Jack
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Jeez, I don't have that prop.

But I just bought on on eBay for $3 including shipping...

It will take a week or so to get here but I'll let you know.

What motor and voltage are you using that on now?

Jack
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Old Oct 03, 2012, 07:51 PM
What goes up must come down..
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3S 1500 mAh nano-tech for now..
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Old Oct 03, 2012, 07:52 PM
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Wow, that's the stock prop for the old NiMh Super Cub. I would have thought it would blow up at those kind of watts. It's a serious 'slow fly' that should pull lots of watts for the size.
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Old Oct 03, 2012, 09:39 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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Quote:
Originally Posted by flydiver View Post
Wow, that's the stock prop for the old NiMh Super Cub. I would have thought it would blow up at those kind of watts. It's a serious 'slow fly' that should pull lots of watts for the size.
Oh no! Why didn't I think to ask here what other people think of that prop? I have no idea what to expect of that prop.

Jack
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Old Oct 04, 2012, 01:35 AM
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It was also used for the 9-cell NiMh P51. Later and still recommended as the float prop for the brushed Super Cub on 3S. It pulls ~19-20A with that combo. So, it may well be OK at the loads you may put on it. I'd proceed with some reasonable caution though.
For myself I treat ANY motor prop test as a possible disaster and initially fire them up while peering cautiously around the corner from outside the room.
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Old Oct 04, 2012, 04:11 AM
What goes up must come down..
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Well for sure caution is the name here with all props! especially when higher RPM than suggested are involved.
On my plane the last flts were insane with 4S (build from 2 older 3S pack were one cell was TKO) and the (PKZ1005) 10x8 prop, still on the tail-heavy side for aerobat, she fly like nobody's biz with the rewound DAT 700 motor / prop combo spec's are off the charts (upper limits).
She really rips across the sky, the thing here is if I go 4S. I have to go all the way so I'll end up looking for all my ground support equipment i.e. new charger for new cells to buy but with this setup from a mild flying plane to monster ready to attack!
I was using GWS SF 10X8 even 11x4.7 and x8* props on 3S (Biplane weights is 590 gr. no pack) nothing is better to adjust a prop for a plane and motor than FLYING, I understand ppl here, but in the air thing works differently around the prop rpm wing loading, power to weight ratio, type of flying etc..
Temperature of the bell wasn't on the cold side especially if WOT most of the time was used so be aware of this, but I beleive Jack you'll be fine here will the heavier gauge wire and previously posted spec's.
So try this prop on the bench with CAUTION but also FLYING in your plane! ..get out to the field bring all your props lipo's and run some fresh air throughout your motor since the target of the game here is FUN !

Note: with 3S 1500 mAh and GWS 11x8 lots of flutterings at diving and above certain RPM or AIRPLANE SPEED etc..but a real FUN to fly due to the noise she generate when I go into manouvers at WOT sounds like "radial" gaz engine in a semi scale manner..good laughters with this setup although I am fully aware of the situation here...

I didn't use a prop saver with the PK1005 prop but wents with nuts lock washers / spinner so anything unbalanced in the front will translate in airframe vibrations and will run in DT a lot faster.

Jack, I also never found the "gym thingy" for exercising to make the rubber bands yet, I am still with the "O" ring that doen't last or have to be replaced offenly but saved me so many props so far so make SURE on 4S that the prop is as close to the nose end of your cowling on your particular plane to reduce vib.

Happy Flying all.

Roger
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Last edited by rodair; Oct 04, 2012 at 04:30 AM.
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Old Oct 04, 2012, 07:30 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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Did you ever get that HZ prop up to the RPM where you could see a little waviness in blade where the light glints off of it? That is usually a few throttle clicks from where the humming noise starts to be heard.

I consider those two signals to be the initial warning and final warning of impending disaster!

I do pay a lot of attention to RPM limits and safety in testing. I used two bands on the 14 x 10 APC and that went very smooth and quiet. I have had Thera-Bands fail during prop testing and the prop merely lifts a few inches and moves straight away from the loudly screaming suddenly unloaded motor and then falls to the floor. No real danger or drama.

I virtually never put myself in the swing arc of a prop and also retreat some distance away during tests. One of my favorite spots it behind the work bench and the steel pipe floor joist...

Jack
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