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Old Mar 18, 2013, 04:29 AM
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Habu 32 e-flite stock turbine explosion

Hi,

Owner of a Habu 32, I spent lot of time mounting and setting it with lot of care.

Its first flight was awesome, (I've never flown such an RC EDF jet before, plenty of other gas and electrics aircraft and copters for 15 years, but never a jet)
I love this plane and the e-flite gloss finish is perfect.. The first flight was very cool.

But something terrible happened during the second flight, as the Habu 32 was about 100ft high, on downwind leg, the stock e-flite turbine suddenly changed its sound !
The motor was still responding to my thrust stick but it appeared that even if it was running, it delivered no more thrust at all !
I decided to let the plane "glide" in a 180 turn to land face to the wind…But unfortunately the habu is not a good glider and I didn't managed to join the runway My Habu died 5m before it, in a ridge of earth.


When I picked it up, I discovered that the change in EDF sound was a result of the fan explosion !
Indeed, all the fan blades had blown away, passing through the fan tube and through the fiber-glassed fuselage !


I don't know what to do. The aircraft is totally damaged but it's not my fault at all !
Do anybody experience such a malfunction ?

Thank you for your reading and your advices.

Guillaume (from France.)
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Old Mar 18, 2013, 08:24 AM
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United States, FL, Mt Dora
Joined Feb 2007
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sorry for your loss. but awesome carnage! the fan was prob assembled without thread lock and something came loose causing the rotor to touch the shroud during operation. hence your destruction. eflite rotors dont blow apart for no reason. this is build error.
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Old Mar 18, 2013, 10:14 AM
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Hi Stonenforcer.
Thank you for your reply.
I can assure you the fan was properly mount (I'm also flying real jet aircrafts..)
As you can see on the pics, the fan didn't came loose and stayed well in place while the blades exploded...
I suspect a defect in the blade material...
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Old Mar 18, 2013, 10:38 AM
Carbon fiber is our friend
Steve C's Avatar
United States, CA, Lodi
Joined Feb 2001
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Sorry you lost your plane. It's pretty tough to say what caused this. It could have sucked in a small rock and damaged one of the blades.
I'm surprised the blades went through the shroud. I guess this makes a good case for carbon fiber shrouds. I've blown up one of my own and the blades did not make it through the carbon fiber.
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Old Mar 18, 2013, 10:51 AM
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So do I.
At first I supposed the fan ingested some kind of a small rock or an insect.
But it occured at 100ft high after 2min flight ! Moreover, the take off runway is made of perfectely clean asphalt, no rock at all.

If it was due to an insect ingestion, I should have found traces of blood or 'juice' in the inlet, but it wasn't the case...
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Old Mar 18, 2013, 11:06 AM
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San Diego
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Did you balance the fan? My stock fan needed it.
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Old Mar 18, 2013, 11:10 AM
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United States, TX, Grand Prairie
Joined Nov 2005
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Check the motor mount and make sure screws were tight

Also, if you have the other wing the plane is repairable and will give good fiberglass fixing experiencing..

Start with thin CA to get torn pieces back together

Putting, reglass, sand...putty, reglass, sand...paint

I've fixed worse

The fan hatch and be remade fairly easy
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Old Mar 18, 2013, 11:23 AM
Do it Right, the first time!
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United States, MN, Hermantown
Joined Dec 2008
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When I first read this, I thought this is repairable. As erh7771 said,

"Also, if you have the other wing the plane is repairable and will give good fiberglass fixing experiencing.."

Good time to learn new skills. From the photo, not as bad as it may look.
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Old Mar 18, 2013, 12:15 PM
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Yup tack it together with C A glue , glass cloth and Zpoxy on the inside , Zpoxy or West Systems Epoxy mixed with microballoons on the outside . Then sand fill prime paint etc .what I find works really well is put the glass cloth inside , Epoxy it , and then inflate a balloon inside and tie it off .next day pop the balloon , pull it out and the glass is perfect inside .
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Old Mar 18, 2013, 12:19 PM
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Denver CO
Joined Apr 2008
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may be the blade came loose, the sound change? a slipping Blade?

Was the rotor hub still tight on the motor shaft?
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Old Mar 18, 2013, 12:26 PM
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Hi, Thank you all for your advices.

The right wing is quite damages, I think I'll definitely have to buy another one...

Regarding the fan, I didn't balanced it before using it..
I hoped e-flite controlled its products...
According to me, balancing the fan could have improved the efficiency but I couldn't know it was absolutely necessary to do it to prevent such an explosion!

For the nose fuselage, thank you for your tips. I think I won't put it in the bin !
But as far as I'm living in a small flat, it's difficult for me to do proper glasscoating an sanding job.. But I hope to have soon time and space to give it a second life !

The trick of the balloon inside the fuse is pretty tricky, thanks ;-)
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Old Mar 18, 2013, 12:43 PM
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No charge another tip ; clean the inside with 99% isopropanol alchohol . Mist the inside with a bit of 3m77 contact adhesive spray before glassing then lay in the cloth , thin the epoxy with alchohol (make sure its 95 - 99 % because the weaker types contain water ) then apply the thinned epoxy with a brush and then use the balloon. With the shape of the Habu Fuse I'd use one of those long skinny balloons .PS you can always sand outside ..
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Last edited by pencon; Mar 18, 2013 at 12:59 PM.
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Old Mar 18, 2013, 01:33 PM
Carbon fiber is our friend
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United States, CA, Lodi
Joined Feb 2001
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There are only a few expensive edf's that come balanced. All others should be checked. This fan only cost $35. I don't think there's any fan that comes pre balanced at that price. It's no different than props. Some are perfect, most are not. That doesn't mean it's a bad product.
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Old Mar 18, 2013, 01:46 PM
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San Diego
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Quote:
Originally Posted by Steve C View Post
There are only a few expensive edf's that come balanced. All others should be checked. This fan only cost $35. I don't think there's any fan that comes pre balanced at that price. It's no different than props. Some are perfect, most are not. That doesn't mean it's a bad product.
Exactly,

I would bet for the most part those fans are balanced good enough but at $35 there is going to be some QC issues. It is always smart to run any edf on the ground and check for vibration before flight.
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Old Mar 18, 2013, 05:53 PM
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Miramar, Florida
Joined Jul 2007
8,517 Posts
Anything could have happened, a large bug, vibration, loose screw, these things all happen but sadly this happened on your second flight. I can sympathize with you, I purchased a hopped up Habu 32 (I never buy used!) and after repairing the nose (damaged in shipping), replacing one flap servo (dead on arrival), replacing the nose gear (cycled 3 times every time it went up, broken) and dealing with ESC cutoff issues, the CS 12-blade fan exploded on the third flight destroying the CF shroud and almost crashing, though I was able to dead stick land it OK. Truth is sometimes you have bad luck on the first (or second) flight, it's just part of the hobby that you can only do your best to try and avoid by methodical building and maintenance...

Jack
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