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Old Nov 12, 2012, 02:10 PM
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United States, NY, New York
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V8,
Is there anything I need when using the freewing shroud? I have the spare shroud from my ef. Do you have pictures by any chance?? All this talk about exploding CS 12 os freaking me out....
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Old Nov 12, 2012, 02:14 PM
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United States, NM, Clovis
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Originally Posted by EDForever View Post
If you try to tighten up the screws on those shrouds Freewing etc. they will crack..
on the CS shroud it will just go deeper.. so you can clearly see the plastic IS soft there
I think you are on to something. The more I think about it the more it makes sense. I remember noticing something "soft" about the first mount screw I tightened and remember thinking to be careful with the rest of them.
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Old Nov 12, 2012, 02:19 PM
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United States, CA
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Originally Posted by EDForever View Post
If you try to tighten up the screws on those shrouds Freewing etc. they will crack..
on the CS shroud it will just go deeper.. so you can clearly see the plastic IS soft there
Ya I hear ya. The key is to not over tighter and use CA on the edge of the screw just before you make your final tightening turns. I do inspect the outside of my shroud every so often for evidence of cracking. I think the DPS alloy shroud is the best bet.
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Old Nov 12, 2012, 02:24 PM
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Originally Posted by Torchy View Post
V8,
Is there anything I need when using the freewing shroud? I have the spare shroud from my ef. Do you have pictures by any chance?? All this talk about exploding CS 12 os freaking me out....
Nope, I just used the stock shroud and screws with my cs12 & motor of choice. However if you do use it like EDForever said, don't over tighten. Read my last post about how I tightens it down. I do not encourage using it on high powered setups above 1500kv, im using it on my 1600kv HTG and so far it's doing good. Still checking it after every day flying so I would say it's probably good at 1600kv max, but still use with discretion.
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Old Nov 12, 2012, 03:00 PM
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Originally Posted by 4stripes View Post
If you have the stronger fan, the chance of it failing is very low unless you are pushing above 2500watts. The fan fails and destroys the shroud using up all the energy before it can penetrate the fuselage very far. Hand launching a 90mm EDF isn't something I would do due to the weight and energy needed to get some airspeed. Perhaps on a windy day it would be safer, but I still think there is a high risk of a crash. Look into landing gear or a strong bungee setup.
Cheers
Thank you for the heads up. I fly all my six foam jets only with hand launching over 3 years.

LX MiG-29, LX F-22, LX F/A-18F SUPERHORNET, FW F/A-18E, FW Eurofighter
and the last FW Su-35.
All planes life and have over 30 flights.
Now wants I improve the sound.
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Old Nov 12, 2012, 03:29 PM
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I would be inclined to agree with the 'Something is not done right' explantion to fan exploding.
Whether not perfectly balanced, or runout on a shaft, or motor mount flex etc.
This is very high rpm and any issues will produce very high frequency shock waves, that would severely test any materials, or any flaws.
And once it begins it snowballs too......

I have not seen anyone post of a CS12 rotor exploding in an alloy housing yet, so until that happens the above list of reasons liklihood is high.
And even then, if one fails in an alloy housing, it will still come down to WHAT did they do exactly? They can still not balance it well enough, or have a dodgy shaft adaptor.... alloy only fixes the motor mount possibility.

CS could very well have upped the strength of the blades, in response to "Oh oh, something is wrong.... so we better make it a bit stronger, to offset returns and potential dangers"... when it wasn't even truyly the blades at fault. They probably have low in-house technology, so just opt for the 'make it stonger' blanket fix.
Which won't actually fix it IF it is truly the motor mount! Unless they did the housing strength too (did they?).

It could be a good idea to make a motor mount plate, that goes on the front side of their housing mount, so you get just metal through to metal for the mounting. But I can see that would need some creative "complex shape filling" to do a proper job. Possibly a 1mm steel plate and standoffs into the screw 'posts'. The mounting pressure needs to be distributed across its face, not on the screw post/lugs.
And then the rotor clearances - to the housing lip. So it could be a fine line to get to work.
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Old Nov 12, 2012, 03:34 PM
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Originally Posted by Thomas Nelson View Post
I fly the very scale Exceed 90mm Superhornet and have had two CS12 failures while airborne. In neither case did any blades penetrate the foam fuselage. Some blades were embedded, but most ejected out the back since I was vertical when it happened. And this was good news for me since .....

Well ... since I exclusively hand launch this bird. 121 successfull HL's to date. With a decent T/W (at or above 1:1) and good javelin throw I think many could confidentily launch this jet with zero wind on the flat. YMMV of course, but a successful HL with a 90mm EDF need not be a hit or miss thing.

The launch in this video was into a 15kph headwind from a hill so quite easy. From the flat and with no headwind, just aim higher.

Still - if the fan exploded just as I released it I'm sure I'd be more than a little freaked out. But having carefully examined the damage from my failed units, I would also expect to be completely uninjured.

And keep in mind we are talking worst case scenario here.

http://youtu.be/EBynaCRRQY0
Very nice hand launching. You are making me courage.

Thanks for your ecxellent flight report.

Cheers.
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Old Nov 12, 2012, 05:27 PM
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The shroud failing caused only one fan failure for me and it was the 1600kv outrunner supplied with the X flight combo. My half dozen other failures still had the motor securely fastened with no damage to the mount. The failures normally start with one blade coming right out of the hub causing total destruction of the fan and surrounding shroud. Having built up more than a dozen of these fans with excellent results except for the bad batch purchased from HK this summer....
Glad the quality of plastic has improved because it is an excellent fan for most 90mm planes.
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Old Nov 12, 2012, 06:18 PM
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United States, TX, Grand Prairie
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Originally Posted by DamonH View Post
Now this I would believe. I noticed after mine exploded that the area where the motor mount screws go was a little wore out like the screws dug into the plastic..
I've been an advocate for months now of using slow start on ESC's or the radio when it comes to EDF these days.

I've seen reports of all types of plastic can holders either splitting or cracking under 45 - 65c packs and the burst of power that is given with a good controller and a good motor.

It's be great if we all could go to metal rotors and shrouds with stators designed for the rotors but the pricing of those units these days is a little ...
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Old Nov 12, 2012, 06:19 PM
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Originally Posted by 4stripes View Post
The shroud failing caused only one fan failure for me and it was the 1600kv outrunner supplied with the X flight combo. My half dozen other failures still had the motor securely fastened with no damage to the mount. The failures normally start with one blade coming right out of the hub causing total destruction of the fan and surrounding shroud. Having built up more than a dozen of these fans with excellent results except for the bad batch purchased from HK this summer....
Glad the quality of plastic has improved because it is an excellent fan for most 90mm planes.
4S, you've had 7 failures total?

regards
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Old Nov 12, 2012, 06:26 PM
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Originally Posted by erh7771 View Post
4S, you've had 7 failures total?

regards
Yes.
Thankfully I've had many more successes!
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Old Nov 13, 2012, 12:04 AM
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South Africa, GP, Pretoria
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Originally Posted by Thomas Nelson View Post
I have a theory regarding the CS12 failures. Well at least my failures.

I think mine were related to the adaptor shifting on the motor shaft.

The resulting runout introduces vibes that can be heard (barely with the quiet CS12). In both my failures I am convinced I heard excessive vibes for 1-2 seconds before things went pear-shaped.

I am leaning toward using 30 min epoxy to permanently mount the adaptor on the shaft, with special attention paid to the very end of the shaft. If the end is secured, then there should be zero chance of the adaptor shifting, introducing runout and soon thereafter fragging the blades and shroud.

I say this because as we know (those of us that have measured runout) we can "play" with the grub screws - tightening and loosening in various sequences - and "correct" the runout problem. Suggests a loose adaptor, no?

After thinking a bunch about my own experience with this fan, I believe both failures occurred after rough landings. Meaning the heavy CS12 rotor could have pulled the adaptor off center ever so slightly.

Hey ... it's a theory ... any thoughts from others? I mean, in my case how does a fan rack up many dozens of flights and then go 'bzzzzzzzzz' and fail? Tying the failure only to blade strength doesn't totally seem to fit from my own experience.

I'm thinking we need a better adaptor, or we need to use the existing ones with epoxy. But as I mentioned, I'm all ears to other ideas ......
Thomas,

I agree with you on this.
I think hand launches are more at risk as the landings are normally a lot harder on the frame with more deceleration forces.
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Old Nov 13, 2012, 06:19 AM
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Canada, ON, Newmarket
Joined Nov 2006
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Quote:
Originally Posted by Torchy View Post
V8,
Is there anything I need when using the freewing shroud? I have the spare shroud from my ef. Do you have pictures by any chance?? All this talk about exploding CS 12 os freaking me out....
The stock shroud is quite solid and in most cases has held the damage to the shroud. They have also improved the quality of the fans material so these failures should deminish . Most other failures would be unbalanced or exceeding the rpm limits. i still have one of the older fans running very well.
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Old Nov 14, 2012, 07:41 AM
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Germany, SH, Neumünster
Joined Dec 2011
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Glue the rotor blades?

Hi Guys.
I will use the FW stock shroud and screws with the new cs12 replacement rotor and the 1500kv setup for 6S, the same as V8 it have used.
It is necessary to glue the rotor blades?

Thanks.
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Old Nov 14, 2012, 09:13 AM
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United States, CA
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Viper,

Are you using the 1500kv motor on the Euro?
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