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Old Jul 11, 2012, 11:44 PM
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Originally Posted by jcdfrd View Post
oh so the blade root is still in the hub? ok I thought you said it was throwing a blade, ok I misunderstood, so their is nothing anyone can do to improve it. the mnfg needs to adjust their mix, unfortunately they probably are adjusting the mix.....IN THE WRONG DIRECTION lol!!! we are starting to see this in the cs 70/10 blade rotors, we have rotors from 9 months ago that run over 46k rpm but the latest batch of rotors are blowing up at 46k
The blade root is coming out of the hub, Same thing happened on my 1100kv on 12S. lol It was only one or 2 that came out completely but that was enough.
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Old Jul 12, 2012, 12:45 AM
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ok well were seeing both problems then if the whole blade is comming out of the hub then the hub design is bad/weak the one's I have seen in person did not look good to me the shape of the key is diff, the top fit looked ok but the bottom of the blade where it fits to the hub was sort of like a round peg in a square hole so the base is pulling out under load. 4stripes was indicating a blade failure from what I can gather this is a completely diff issue
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Old Jul 12, 2012, 01:34 AM
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Originally Posted by MagnusEl View Post
The 3025 Kv 1500 does have 8 poles.

The 3025 Kv 850 have 10 poles. Maybe a good option for a custom wind. I am thinking in the Kv1100-1200 range and 8 cells?
Thank you Magnus.
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Old Jul 12, 2012, 01:38 AM
Extreme CNC Alloy EDF
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The hub is not the problem, the hub is not coming apart, the blades are molded in the wrong material for a design like this. If Dynamax or ramtec or stumax or ejets molded their blades like CS is doing then they would likely have the same problems. All CS needs to do is mold the blades in a high quality GRP, if they get the best plastics and fillers, and get it done right without cutting corners then the blades should be as good as all the other manufacturers listed above.

Doesnt matter what you glue them with, CA or resins or whatever, they will still fail at a certain power/rpm point, the material of the blade is the weak point and the blade notches are not big enough to be made from a carbon plastic like this.
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Old Jul 12, 2012, 01:43 AM
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If a rotor/blades was bonded solidly with a glue, it would do the job. Because it then is a solid "ring" that doesn't care about the hub much (in holding blades terms) anymore anyway.
The problem is that there is unlikely to be ANY glue know that is suitable for the job.
For a start, no glue truly bonds almost anything... more so in plastics and stuff like these.Even if it can to some very good degree, it is likely to be a very solid and brittle glue, which won't cope with incessant high frequency stress - Could a perfect balanced fan even attain that to a degree good enough to not matter to 'glue'? Probably not.

But anyway... if you COULD glue them solidly (and itself not be overly brittle), then that would solve it.

Hmmmm, a thought.... a mechanical join system - that goes beyond what the stock hub fails to do. EG, Another "internal ring" not that it would work but just a direction clue. I can't think of how to implement something, for now... (if at all to be possible strong enough and reliable enough in the space available)
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Old Jul 12, 2012, 04:39 AM
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Jcdfrd
The blade tabs broke holding the front of one blade in (poor plastic for such loading). The whole blade came out and was still in the plane when it landed. The hub is strong as hell but the small tabs at the front of each blade will fail at high RPM.
That being said, I will continue using the CS fans in my planes running 6 and 7S as they have dozens of trouble free flights.
The whole point of my HET 10S exercise was to find one high powered setup for my RCLander 90mm T33. The CS is not an option but I will try the new all alloy 90mm HK fan (which I was lucky enough to get one before it went out of stock).
Cheers
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Old Jul 12, 2012, 04:51 AM
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Originally Posted by 4stripes View Post
Jcdfrd
The blade tabs broke holding the front of one blade in (poor plastic for such loading). The whole blade came out and was still in the plane when it landed. The hub is strong as hell but the small tabs at the front of each blade will fail at high RPM.
Do you have any pics of the rest of the blades or did they all let go also?

Thx in advance for any input
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Old Jul 12, 2012, 04:59 AM
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Originally Posted by 4stripes View Post
...The hub is not failing, it is the blades, so a better plastic or a completely different locking system is necessary to hold at over 40,000 rpm
So did the blade break off the blade root\base or did the blade root]base come out off the hub?

a pic would tell a lot....a whole lot

I literally hammered a thin screwdriver into the 120mm pieces to try and get the blade root apart and it was a no go. The screwdriver started first to go into one of the root bases and then just went into the gap and the blade bases wouldn't come apart

If the blades are coming off the blade root then there's little that can be done about that

thx in advance for any input
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Old Jul 12, 2012, 05:15 AM
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Originally Posted by Bob Reynolds View Post
What is the expected amperage and performance of the CS-12 with the HK Turnigy L3025-1500 on 6s?
105 amps peak around 7.5lbs peak...

Some people have seen 8 lbs peak on it's lighter wound 850kv cousin on 10s...

Motor has a lot of promise...I'm waiting on the first burn report
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Old Jul 12, 2012, 05:25 AM
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Originally Posted by Extreme_RC View Post
The hub is not the problem, the hub is not coming apart,....
I took one fan up to 11\12lbs on a HET 935kv\12s run and the fan became unbalanced ...started to rub and then a whole blade root popped out along with the blade.

I theorize that the blade roots started to move on the hub because the blades that were left could be move around inside the hub with no issues and those blades were fine.

On that run the fan was butter smooth, it was one of the smoothest running fans I'd put together and no amount of clocking would make it run smoother...I think that added to it's ability to take some RPMs.

Here's BillyD taking the blades up to 11lbs of thrust on 4200 watts...which is pretty decent efficient...using a 900kv motor and a redesigned hub which makes me think it's the hubs or the way the bottom of the blades fit in the hubs that are the issue with higher power.

Change Sun 12 Bladed 90mmEDF@4KW 900kv on 12s (5 min 23 sec)


Well the fan is only 35usd slow shipped so gluing the blades in aren't an issue and seem to address a similar hub prob billy d did here...

He has another vid of the fan un modded doing 10lbs iirc.....not bad power
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Old Jul 12, 2012, 06:15 AM
Extreme CNC Alloy EDF
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Yes and my 8s tests were doing 9.68lb thrust without issue, I exploded one at 11-12lb thrust.

But the issue still stands, the hub is a copy of the stumax, so why are their fans not exploding now at 5kg+?? SM had a bad 2nd batch of blades that were letting go and many SM fans exploded around the world, SM recalled all the rotors and replaced the blades, I could bend the faulty blades over 90 degrees with my thumb. The hub hasnt changed though, only the blade composition and materials used. Ejets changed the composition of their blades as they were too flexy and were losing power, now they are stiff as a board, they are also fitted in a similar way to the hub, The quality of their GRP is very evident when you look at the blade.
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Old Jul 12, 2012, 07:11 AM
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Originally Posted by erh7771 View Post
Do you have any pics of the rest of the blades or did they all let go also?

Thx in advance for any input
No only one came out and it damaged a couple beside it.
The rest may be usable as spares but I haven't looked at them too closely yet.
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Old Jul 12, 2012, 07:14 AM
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Originally Posted by erh7771 View Post
So did the blade break off the blade root\base or did the blade root]base come out off the hub?

a pic would tell a lot....a whole lot

I literally hammered a thin screwdriver into the 120mm pieces to try and get the blade root apart and it was a no go. The screwdriver started first to go into one of the root bases and then just went into the gap and the blade bases wouldn't come apart

If the blades are coming off the blade root then there's little that can be done about that

thx in advance for any input
The entire blade including root pulled out. The PU glue did not hold and sheared from the surrounding two blades. Surprising but who knows how much shear force is happening at +40K.
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Old Jul 12, 2012, 07:18 AM
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Plenty of post about testing and measured thrust but mine was installed in a plane running for an extended period. WOT for the takeoff and climb to 150' before failing. The installed thrust was over 4kg but it failed with all my efforts of gluing and dynamic balancing. It was very well balanced but the blade tabs just can't take the pull force at very high RPM.
Cheers
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Old Jul 12, 2012, 07:32 AM
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Originally Posted by 4stripes View Post
The entire blade including root pulled out. The PU glue did not hold and sheared from the surrounding two blades. Surprising but who knows how much shear force is happening at +40K.
I take it not only did it shear from two blades but the bottom tab broke too?

You're correct about shear forces, who know what they can be at that RPM....to rip out GG and the tab is putting some pull on it.

Did the Gorilla glue come off of either of the four sides of the blade or was their some still in the keying?

thx in advance
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