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03-15-2008, 05:10 PM
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#1 |
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Bad-ass Super Contributer!
 
Join Date: Nov 2007
Location: Port Orchard, WA
Age: 61
Posts: 6,864
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Dodged a Bullet on my Aviation Models Extra
So I pull the cowl off of my Aviation Models Extra 260 to do some engine tuning on it's DL-50 and just happen to notice this!! Turns out the POS aluminum angle supplied with the plane wasn't strong enough for the torque of the DL. No doubt that one more flight would have pulled the firewall out. I went to the LHS and got some thicker 3/4" angle and replaced it. Whew!!! That was a close one.
__________________
 http://www.southeastrcengines.com http://www.vessaero.com Remember every second of every day there are thousands of men and women giving of their lives to keep you safe. Never forget them for they never forget you!! |
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03-15-2008, 05:20 PM
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#2 |
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Mother Huckin'
Join Date: Jan 2006
Location: Caguas, Puerto Rico
Age: 25
Posts: 4,304
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Re: Dodged a Bullet on my Aviation Models Extra
Wow Al, that was close! One more flight and disaster. Glad you found out about it before it was too late. Chinaminium is not good.
 (I crashed my 260 today  )
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Pilot RC Aztech Aero/Secraft/EG Aircraft B&E Graphics, Jersey Modeler, TailDragger RC |
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03-15-2008, 05:25 PM
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#3 | ||||||||||||||||||
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Bad-ass Super Contributer!
Join Date: Feb 2006
Location: Durango Colorado
Age: 20
Posts: 1,945
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Re: Dodged a Bullet on my Aviation Models Extra
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03-15-2008, 05:25 PM
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#4 |
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Bad-ass Super Contributer!
Join Date: Jun 2006
Location: Washington
Age: 41
Posts: 427
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Re: Dodged a Bullet on my Aviation Models Extra
Nice Catch Al, that was a close one....it looks like the firewall had no glue to the side frames, is that true ? was the aluminum bracket the only thing holding it together?
__________________
____________________________________________ WWW.FLYRCEXTREME.COM "We are the Extreme in R/C" What am I flying Now ?: Quique Aircraft Company - Python and Yak on Hacker A100 Converting all my Giants to Electric in 2008!!!! 
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03-15-2008, 05:27 PM
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#5 | ||||||||||||||||||
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Bad-ass Super Contributer!
Join Date: Jun 2006
Location: Washington
Age: 41
Posts: 427
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Re: Dodged a Bullet on my Aviation Models Extra
__________________
____________________________________________ WWW.FLYRCEXTREME.COM "We are the Extreme in R/C" What am I flying Now ?: Quique Aircraft Company - Python and Yak on Hacker A100 Converting all my Giants to Electric in 2008!!!!
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03-15-2008, 05:49 PM
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#6 |
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balsa, glue & gas
Join Date: Jun 2006
Posts: 2,972
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Re: Dodged a Bullet on my Aviation Models Extra
Wow !!
I'm pulling my cowling tonight!! Thanks for posing Al ! |
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03-15-2008, 06:24 PM
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#7 |
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Bad-ass Super Contributer!
Join Date: Nov 2007
Location: Port Orchard, WA
Age: 61
Posts: 6,864
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Re: Dodged a Bullet on my Aviation Models Extra
Awwww Vic!!! Sorry to hear that man!!! Is it repairable???
The firewal was originally installed, after cutting the box to length, with the angle and epoxy. The epoxy broke of course as did the angle. Everytime I think about the NEXT flight it scares me as I only have one way to take off...straight up!!! http://www.flyinggiants.com/gallery/...hp?photo=40186
__________________
http://www.southeastrcengines.com http://www.vessaero.com Remember every second of every day there are thousands of men and women giving of their lives to keep you safe. Never forget them for they never forget you!! |
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03-15-2008, 09:28 PM
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#8 |
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Mother Huckin'
Join Date: Jan 2006
Location: Caguas, Puerto Rico
Age: 25
Posts: 4,304
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Re: Dodged a Bullet on my Aviation Models Extra
Thanks for caring guys. All the info and pics are in the dumb thumbd forum. Dont wanna hijack Al's thread. Sorry bud.
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Pilot RC Aztech Aero/Secraft/EG Aircraft B&E Graphics, Jersey Modeler, TailDragger RC |
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03-15-2008, 09:39 PM
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#9 | ||||||||||||||||||
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Bad-ass Super Contributer!
Join Date: Jan 2006
Location: Pennsyvania
Age: 38
Posts: 1,017
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Re: Dodged a Bullet on my Aviation Models Extra
Actually it probably had nothing to do with the torque of the engine. Vibration kills aluminium angle, specially if it is bent alum. Albert
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http://www.banditwallet.com/ |
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03-16-2008, 08:02 PM
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#10 |
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Bad-ass Super Contributer!
  
Join Date: Jan 2006
Location: Chile
Age: 58
Posts: 5,856
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Re: Dodged a Bullet on my Aviation Models Extra
Actually it looks like window framing aluminum and that stuffs about as strong as chewing gum. Seriously if it was decent quality alloy and bent it would still be stronger that that extruded stuff.
The only load that stuffs designed to take is the wind rattling the glass. Good catch AL: Just goes to show that pulling that cowling off every once in a while has value. ARF´s are not fly and forget models. You need to maintain them just like anything else. |
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03-16-2008, 08:47 PM
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#11 |
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Bad-ass Super Contributer!
Join Date: Jan 2006
Location: Austin, TX, USA
Posts: 282
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Re: Dodged a Bullet on my Aviation Models Extra
Where is the top of the engine box?
__________________
Bob S Austin, Tx "You're not drunk if you can lie on the floor without holding on." |
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03-16-2008, 09:01 PM
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#12 |
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Flyin Higher
Join Date: Jan 2006
Location: HARTWELL,GEORGIA
Age: 55
Posts: 253
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Re: Dodged a Bullet on my Aviation Models Extra
Good Catch, I always Gorilla Glue my firewall, install the alluminum, and drill and pin the sides into the firewall. I am running a 30% w/ 55CS, a 35% w/ 106cs, and a 40% w/ 170cs all Aviation Models, never had an issue. I think the metal is weaker (thinner) in later models. Great heads Up for fellow pilots Thanks
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03-17-2008, 02:33 PM
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#13 |
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Gettin' Lower!
 Join Date: Feb 2006
Location: seattle, wa
Age: 49
Posts: 36
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Re: Dodged a Bullet on my Aviation Models Extra
Being from China and being extruded has less to do with the failure than the fact that there appears to be no inside corner radius but, rather, a sharp corner. So, you have a super high Kt combined with high cycle vibration and the resulting fatigue failure shown in Al's photos.
Replace it with angle that has a decent inside corner radius (as well as a radius or chamfer on the outside corner) and the problem should go away. BTW: chop those protruding bolts short, they're just adding weight! |
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03-17-2008, 02:40 PM
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#14 |
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Bad-ass Super Contributer!
Join Date: Nov 2007
Location: Port Orchard, WA
Age: 61
Posts: 6,864
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Re: Dodged a Bullet on my Aviation Models Extra
You're absolutely right. Aluminum extrusions with inside radiused corners are very strong indeed. Any sharp internal corner is a fracture point waiting to happen. I really should have replaced the material when I built the plane but only had what came with it to work with at the time. Next time I'll know better.
__________________
http://www.southeastrcengines.com http://www.vessaero.com Remember every second of every day there are thousands of men and women giving of their lives to keep you safe. Never forget them for they never forget you!! Last edited by Al Lewis; 01-24-2010 at 03:13 PM. |
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03-17-2008, 04:14 PM
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#15 |
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Bad-ass Super Contributer!
Join Date: Jan 2006
Location: Austin, TX, USA
Posts: 282
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Re: Dodged a Bullet on my Aviation Models Extra
Al, Make sure you put the top of the box on there. That box is very flexible with only 3 sides on it. It will twist very easily. I know it makes it nearly impossible to get to stuf in the box but it is needed to make the box stable.
__________________
Bob S Austin, Tx "You're not drunk if you can lie on the floor without holding on." |
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