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Great Planes Reactor in Flight Elevator Failure on First Flight

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Great Planes Reactor in Flight Elevator Failure on First Flight

Old 05-17-2009, 11:54 PM
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ArtW
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Default Great Planes Reactor in Flight Elevator Failure on First Flight

I flew my Great Planes Reactor 3D EP Performance Series today on its first flight. I took off, flew to altiude, turned to low rates, trimed the plane out, and then flew an emmelman at about half power. I heard a crack and the plane was no longer in trim. I slowed down to land and overshot the field as I was stunned to see what had happened. I went around again and gently landed. The elevator had factured in two! This plane has about two to three minutes of flight time. It had a structural failure at slow speed, half throttle, without any sign of flutter prior to the failure. It is very clear that there is either a design or construction flaw. Have other people had this type of failure? Is this plane fundamentally flawed or is there a retrofit to strengthen the elevator?
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Old 05-18-2009, 01:28 AM
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freeair
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

i would love to see a pic of the elevator without covering on.  to me it looks to be either a design flaw or material used flaw,    the leading edge of the elevators are no doubt constructed from balsa where i would say they should be made with something like spruce or such.   thats not good for Great Planes Manufacturing.
Old 05-18-2009, 03:30 AM
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rocket_jim
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

Glad to see at least that your eventful flight had a relatively happy ending!

Jim
Old 05-18-2009, 04:11 AM
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tIANci
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

Potentially it might be weak, flutter and keraaaacccck ...
Old 05-18-2009, 11:49 AM
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ArtW
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

Have other people seen this type of failure in this plane? Should I just replace it with a solid elevator?
Old 05-18-2009, 12:28 PM
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TruBlu02
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

I have the bigger brother .46 size but I have not seen anything like this before. Sounds to me like a flaw in the material. I would contact Great Planes about this problem and discuss it with them. Also I would call whoever you bought it from (Tower?) and talk to them as well. I am sure a fairlue like this is uncommon and it would be in the best interest of GP to replace this component for you.
Old 05-20-2009, 10:56 PM
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

Probably a defect in the balsa, or could have been caused by a defective glue joint, the bad glue joint causing excessive flex which could cause the elevator to buckle. Certainly an unusual problem! Contact the manufacturer, Great Planes, they should be able to do something about that.
Old 05-21-2009, 10:51 AM
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

The balsa broke mid span. It was not a glue joint that failed. I did not hear any flutter. The wind was zero MPH. The airspeed was low. Power settings low. I was in a low speed manuver. I think the elevator is not up to the loads.
Old 05-21-2009, 07:18 PM
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

Sorry to hear about your failure but congrats on your good flying skills on landing it successfully. I had a UCANDO 46 wing fail in flight. It was not pretty!  However, Great Planes made it right. Contact them.  Good luck!
Old 05-22-2009, 03:57 PM
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

Glad you got the bird down in one piece. My UCD .46 had a left horizontal stab failure in level flight at half throttle...and I'm only
using a magnum 52 two cycle. No flutter heard prior to this either......the break was close to the fuselage and appears
to be soft balse leading edge. Contacted GP and they haven't heard of any failures on the UCD. Now I've seen three on the 46
UCD ....one the entire tail came off and the other the covering rippped right off the main wing. I am going to install a solid
balse Horizontal stab on the rebuild. Good luck.
Old 05-22-2009, 05:47 PM
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

Sorry to hear about your ICANDO 46. Mine wing failure came 5 years ago. Second one has been fine. Sorry, they wouldn't help you.
Old 05-23-2009, 08:42 AM
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flhyr
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight



it kinda looks like it broke where the hinge is installed which makes sense since that is where a stress riser would be.  So a hole in an unfortuanely picked piece of balsa and snap, broke at the weak spot.  Probably just bad luck. 



Honestly, I would just re-do that side of thr elevator and not bother calling GP, after all whats the best outcome for that?  They give you a new piece and its actually more work installing the new piece than it is fixing it withou the free piece right?





Good luck (nice job landing it by the way)

Old 05-25-2009, 09:29 AM
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

testing
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Old 07-23-2009, 03:45 AM
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

So, I contacted Tower Hobbies and they shipped a replacement tail. I replaced the elevator. I then tested the servo and found the elevator servo gears had been damaged so I replaced the elevator servo as well. I then went out to test the plane. I flew around on half power just enough to maintain altitude. I did a split S into the wind. The elevator fluttered, broke, and the plane was destroyed on "landing". I think the Reactor EP is sensitive to elevator flutter. The design is defective. I am shipping the carcass of the plane to Tower Hobbies for evaluation but this is absurdly poor design. [img][/img]
Old 07-23-2009, 05:50 AM
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

Unbelievable......Sorry to hear about the Reactor. They cannot be testing these ARF/3D planes...no way!
As I said before on my U CAN DO....I repaired the entire horizontal stab (gaussets and filled in with microbaloons with CA).
I filled the spaces up and let the CA smoke it all together. I am flying the bird again, but still aprehensive about
any speed. Sealed all the edges also....no flutter that I've heard.
Good luck with Tower! Cheers
Old 07-23-2009, 10:49 PM
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

SImple question for you. Was the elevator hinge line tight and sealed? I looked at your original pics and it looks like you have high quality linkages installed so you can rule that out.

Sorry about you plane BTW!
Old 07-24-2009, 09:44 AM
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

The hinge didn't fail until the plane hit the asphalt runway. The hinge line was not sealed. That is an interesting wrinkle to this problem. The instructions do not mention sealing the hinge line. I have done it on some planes but not on all. I think, the issue is the "balance" surfaces on the elevator. The "balanced" elevator tabs must place to high torsional load on the elevator and horizontal stabilizer. The elevator starts to oscillate and has a resonance frequency that is too low. On the first flight the elevator fractured. On the second flight the horizontal stabilizer fractured. The design of the elevator and horizontal stabilizer is too light to prevent flutter, oscillation, and immediate fracture. I was stunned that there was absolutely no warning of flutter. The elevator simply fluttered and immediately failed. The entire failure took less than a second. Moreover, the plane was at extremely low speed. Control surface flutter can be a problem at high speed and is part of the reason for a Vne in full size aircraft. In this aircraft, the Vne is less than 10 mph. I think it just turned into the wind, fluttered, and failed.
Old 07-24-2009, 10:44 AM
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

What was you power system?
Old 07-24-2009, 01:47 PM
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

The recommended system from Tower. I was at 1/2 power both times it fractured.
Old 07-24-2009, 04:26 PM
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

Art, you seem to know what you are talking about, and I am not trying to start a fight. But, if the servo had damage to the gears, don't you feel there was a problem somewhere else? Maybe the linkage had slop or the gap was to big? If this was a no name company I would not think twice about it. But surely Great Planes did some extensive flight test on this plane before release. I would hate to see a plane get a bad name because of a problem elsewhere. Is this your first 3D style plane? Again not trying to insult you but we should all be carefull about blaming the airframe.

David
Old 07-24-2009, 04:52 PM
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

I have flown RC for almost 40 years so I am not a beginner. I fly GA and have extensive engineering and design experience. This is not my first 3D plane, or my first electric. I have a number of planes that have more than 200 flights on them. One with more than 500 flights. I have built gliders, power planes, helicopters, jets, 3D, etc. I have a number of Great Planes Planes. I truly like Great Planes Planes. Most of my planes are Great Planes Planes.

I am stunned by how rapidly this plane developed flutter and was destroyed. I would like to understand the problem. Control system flutter is usually a result of excessive speed or excessive flexibilty in control system. This plane has carbon fiber control rods and light plastic control horns. The combination of a very stiff control arm and a very flexible plastic control horn may allow oscillation. The servos were brand new Futaba servos of the exact make and model in the instructions. I built this plane to the exact specs in the instruction manual.

In GA aircraft loose control linkages, exceeding the Vne, or inadequate balancing or damping of the control systems can lead to control surface flutter and loss of the aircraft. This elevator is extremely light and has extremely light construction. It fluttered at very low speed. Great Planes has strenthened the elevator in the biplane version of this plane. I assume that strengthening was done for a reason.

I am not attempting to criticize this plane. I am trying to get advice on how to avoid this type of problem and see if others have had a similar experience with this aircraft.
Old 07-24-2009, 05:10 PM
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

Thanks for the response Art. I hope yours is not an example of all of them. The aero counterbalance does seem a little out of proportion. I hope you get some responses from other owners so GP can fix this problem if needed. If they have already upgraded the bipe, maybe a upgrade is coming soon for this one. Do you think some flying wires on the short stab would stiffen the structure up enough to stop this?

David
Old 07-24-2009, 05:16 PM
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

I think the elevator is simply not strong enough for the loads. They want it extremely light which makes it delicate. Flying wires might help for the horizontal stabilizer but not the elevator itself. The simple fact that this plane had the same problem with two separate elevators on two first flights implies a design flaw. I could see this happening after some wear and tear or with severe manuevers or high speed. It failed on extremely cautious first flight at very low speeds. I didn't even get a chance to try a 3D maneuver, this was simply a split S at a throttle setting that barely turned on the motor.
Old 07-25-2009, 12:27 PM
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

My 2 cents worth guys: Like I said before, I have a solid stab now on the U CAN DO. If GP flyers are testing
these planes, I sure would like to know who and when & how....because I don't believe it. When you see a plane from
GP that says EP/GP then I won't even look at it twice. They are just toooooooo flimsy. But if someone knows how
GP tests their products, maybe they could let us all know....cause I'm sure this has happened to others. And don't forget
they recommend a certain servo/torque combo....my servos were well in that range BTW.
Old 08-04-2009, 02:39 PM
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Default RE: Great Planes Reactor in Flight Elevator Failure on First Flight

Lost the U Can Do today....first flight....level flight pattern (down leg for landing) and the entire tail section snapped off.
This is the one that I repaired.....no flutter heard and I always tug on surfaces prior to flying. I never liked the plane
and now I will bury it finally. All the electronics came out OK as did the engine. Tumbled down a large tree.
This was the easy way to make room for another plane. HE HE. Good riddens.

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