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View Poll Results: Have you experienced Stress related damage in your PA Extra MX ARF from normal use
Yes! I had serious Stress related cracks or damage! 5 16.67%
Yes, but they were minor and easly repaired. 3 10.00%
NO! Never happened to me. 22 73.33%
Voters: 30. You may not vote on this poll

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Old May 04, 2011, 10:48 AM
Crash Avoidance Specialist
TracM99's Avatar
Seattle WA
Joined Aug 2007
24 Posts
Poll
Precision Aerobatics Extra MX Owners Poll

This poll is for current or former owners of the PA Extra MX.

I have been very impressed with the PA products I own, and am thinking of purchasing their Extra MX ARF. However, a couple of guys in my club have warned me that they have experienced stress fractures in their Extra MX air frame just aft of the cockpit. These cracks appear after normal 3d flight usage, and are not crash related in origin. After searching the web, I have found a small number of others reporting the same.

In order to judge how common this problem I am hoping all you Extra MX owners out there can help me find out by responding to this poll.

Thanks
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Old May 04, 2011, 01:25 PM
Shore Huckin'
KE Spin's Avatar
Ohio
Joined Aug 2010
2,692 Posts
Seems to be a very capable but very light plane. A friend was flying one the other day in a fair amount of wind when a furious wing flutter occurred that shook the plane so violently that both aileron servos were stripped out. He did a fantastic job of getting the plane back down...with both ailerons just dropping down loose after landing.

Similar planes of this size weight about 10 ounces more. Even though PA uses a generous amount of carbon fiber, I really think that there isn't quite enough rigidity in the fuselage around the wing area. The plane withstood the flutter but was not ridgid enough to stop the flutter to begin with.
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Old May 04, 2011, 04:19 PM
Registered User
aerofundan's Avatar
Panama
Joined Jul 2005
3,452 Posts
Super strong airplane... mine is over 2 years old and has received all type of full throttle blenders.. knife edge spins, harrier roll landings.... never had a single problem with mine!

Extra MX new vid by Aerofundan (6 min 13 sec)
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Old May 05, 2011, 06:59 PM
Registered User
United States, OH, Massillon
Joined Apr 2011
8 Posts
That was my MX that Ke Spin referred to as to flutter. I believe that the flutter was caused by not using strong enough servos. It was very turbulent nasty air that day and i feel that the bouncing started the flutter. I only got a dozen or so flights on the plane before receiver failure put it in but I doubt anyone could stress it any harder than I did before the thump happened. One blender in particular was very violent and the plane stayed together. I liked it enough that I bought another.
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Old May 05, 2011, 08:31 PM
Shore Huckin'
KE Spin's Avatar
Ohio
Joined Aug 2010
2,692 Posts
Quote:
Originally Posted by ircfly View Post
That was my MX that Ke Spin referred to as to flutter. I believe that the flutter was caused by not using strong enough servos. ...I liked it enough that I bought another.
Tim,

Hope thats what it was. Can't wait for you to get the next one together and wring it out a little. We'll see what happens
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Old May 06, 2011, 09:03 PM
Registered User
United States, OH, Massillon
Joined Apr 2011
8 Posts
New mx is ready right now
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Old May 06, 2011, 10:32 PM
Shore Huckin'
KE Spin's Avatar
Ohio
Joined Aug 2010
2,692 Posts
Flying after the meeting tomorrow..weather permitting?? You are coming aren't you??

Mike and I went out tonight locally...just before the HAIL. The VFO needs more authority and I flew your favorite plane of mine.
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Old May 07, 2011, 06:21 AM
Registered User
United States, IN, Indianapolis
Joined Dec 2006
2,257 Posts
The MX is a very strong airplane and I proved it last weekend. While trying to make a couple of trim adjustments while flying, I managed to somehow move the on/off switch to the off position on my DX7 . My MX hit the ground (field with unplowed corn stalks from last year) nose-in very hard from an altitude of 70 feet. The damage...broken prop, canopy cracked in several places, three small broken pieces of balsa in the fuse and a couple of other small cracks in the fuse balsa. The repairs took about an hour. I'm telling you guys, the damage was very minimal. My RC buddies who witnessed the crash couldn't believe the crash didn't result in a "rekit." One of my buddies was so sold on the durability of the PA airplanes, ordered the Addiction X that evening . Anyway, the FiberFusion technology really works. Oh, and I have flown the MX since my repairs and it flies just like it did prior to the crash .
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Old May 07, 2011, 07:29 AM
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Bridgeton, NJ
Joined Mar 2009
2,083 Posts
I typically "upsize" servos on planes including my MX. I fly mine with HS-225 servos. While not the best they have plenty of torque for this size plane. Getting any type of flutter is a killer so always try and avoid that. IMHO trying to keep a plane light using marginal servos is not a good idea.

With that said I have an Extra MX, AdditionX and Ultimate AMR. I just looked over these planes yesterday as the weather was fowl and couldn't find any problems with any of them. I do a lot of high stress maneuvers with these planes too. So while I have my own set of beefs with the AMR (hard to get battery in with the cross spar in the way) and the AX (fuse so narrow, it's hard to get to the wing nuts), build quality isn't one of them.

In my experience, stress fractures and similar problems are usually caused by less then ideal landing or transport issues. These planes aren't ply built like GP or Hanger 9 planes. When on the ground they need to be treated with "kid gloves" so to speak.

Or in other words they are a bit more fragile then other manufactures planes on the ground but are very light AND strong in the air. I buy my planes for their performance in the air, not on the ground...
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Old May 10, 2011, 01:04 PM
Crash Avoidance Specialist
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Seattle WA
Joined Aug 2007
24 Posts
Thanks to all for their input so far. Great information!

For those of you with damage, how about a description of it's location? And how you believe it came about?
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Old May 10, 2011, 02:15 PM
Registered User
Joined Apr 2010
15 Posts
Checked my MX over last night and it is fine, no cracks and I am pretty rough on my birds.
JC
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Old Aug 11, 2011, 08:04 PM
Flying Full Size & Fun Size :)
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United States, CA, Calabasas
Joined Apr 2010
1,896 Posts
+1 to what Cayars mentioned. My only damage was from a few rather hard landings that knocked the landing gear mounting plate out of whack. Some epoxy and strategically placed carbon strips have it as good as new. The only other damage came the other day when I was picking it up. I grabbed the fuse by the wing opening and heard the balsa go "crack". I guess that part's fragile. That said, my son (65lbs) halfway stepped on one of the wings while it was in a wingbag (he got half ground and half aileron), and it was a-okay. Overall, it has its tough and weak spots, but is a fantastic plane. If I could only have two planes, they'd be this one and my E-Flite Beaver. If you haven't gotten one yet Trac, you should!
Josh
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