lmckee1065

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I bought a Goldberg Edge 540 67" ARF. I wanted to know if anyone who has this plane has experienced flutter or structural problems. I had a 120 OS AX on it and was flying down a straight away and it started to flutter. The left wing flew off. (The wingbolts were still securely in place, so it wasn't that.)

Dave

bbellfly

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I am building one right now. And, yes there have been others. There is another link about Goldberg Edge 540 67". It has 10 pages. In the last few pages there are a couple of post about flutter and structural failure. It seems this has happened with to a hand full recently that have been on RC Universe. I have been doing lots of precationary things to mine. I'd like to hear more about your incident. Can you discribe what happened and what you found that was suspect in your plane.

Thanks in advance for your help....

lmckee1065

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The left wing aileron started to flutter and within 2 seconds the wing blew off. We think what happened is that the left wing started to flutter due to the aileron hardware failure. Then the rib where you bolt it on the fuselage pulled out of the wing. So the combination of the cheap aileron hardware and the weak wing, and it was over.

It flew beautifully up until that point. So I took my chances on another. I've just taken my first flights on it and took it easy but it flies beautifully too.

I reinforced the wing in all the places I could reach, especially the rib area. I also replaced all the hardware that came with the kit. It was so cheap, I could snap it with no effort.


I hope this helps.

bbellfly

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Had you counter bored your hinges to allow your control surfaces to meet with very little gap? Did you cover the hinge line between the surfaces? I soaked the balsa in the leading and tailing edge (through the hinge holes) to strengthen them. I counter bored to allow the surfaces to come within an eight of an inch. Then I covered both top and bottom of the hinge line except for the hinge knuckles themselves. I used all Dubro heavy duty hardware. It is not complete yet. But, I am within a week or two of having it ready.

I hope what has happened in all cases is a combination of things. To much space between the hinge line. With that causeing the flutter initially. With the combination of cheap hardware and maybe weak struture design causing the flutter to worsen. This leading to catistrafic structureal failure. I hope this is the problem. I sure have put alot of time into this airplane trying to correct this problem.

Thanks for your input....

PropSpinner

My Feedback: (15)

Has anyone else found the motor mount to be too small? I'm pushing my OS 120 AX right to the end of the mount and I might have the 6 inches + described in the instructions.

I counter sunk the hinges. If you read the instructions carefully it tells you to. When I got into larger planes I was told to always seal the hinge gap to prevent flutter.

Fast Guy

I counter bored the hinges and had the hinge line down to 1/32 of an inch. My plane came with updated hardware which I used. Three min. into the first flight flutter developed in the right wing during a left turn, the tip broke off the right wing and down she came.[X(] Good luck with yours

PropSpinner

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Fast Guy,

Did you seal the gap with covering or tape?

lmckee1065

My Feedback: (1)

"Has anyone else found the motor mount to be too small? I'm pushing my OS 120 AX right to the end of the mount and I might have the 6 inches + described in the instructions."

Propspinner,
I had that trouble but was able to squeak it through by getting a nylon spinner with an aluminum backplate. The backplate was flat so I was able to get about an 1/8th gap. Mine has flown great with it.

"Had you counter bored your hinges to allow your control surfaces to meet with very little gap?"

bbellfly,
Yes, mine were as tight as could be. I really think it was more the rib breaking away. You should probably make sure you reinforce the wing ribs.

lmckee1065

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Oops. I tried making the font a little bigger. Don't know what happened...

Fast Guy

No I didn't. I wonder if it would have helped.

PropSpinner

My Feedback: (15)

Well, I built a 74" Yak and was told by the large scale pilots at our club to always seal the control surfaces. ARF's are nice but they are far from perfect. The gaps and bevels on the control surfaces of my CG Edge are not consistent. There are lots of places where air can pass through and cause problems. These planes aren't made to fly like rockets either. Throttle management is important. Of course, I haven't finished mine yet and plan to take the things you guys are mentioning into consideration as I assemble the CG edge. I already wicked some CA into the root rib on my wings. I have some Dubro control horns that I might put on the ailerons.

As far as the motor mount goes, I guess I could always put some ply behind the mount to get the clearance I need.

Also, the wire broke on my tail wheel when I went to bend it per the instructions. I figure I will replace it with a Sullivan.

PropSpinner

My Feedback: (15)

I'm going to put Hitec 5645MG in the wings, seal the hinges, upgrade to Dubro Horns and make 4-40 linkages and if it blows up after that then it's a poor design.

The manual for the QQ 69" Yak states this:

Servo Selection
The servos used for the control surfaces of this Yak-54 must have a minimum of 130 ounce-inch of servo torque. In the prototype Yak-54 , we used JR8411 on all control surfaces and on throttle we used one standard JR servo. Best results can be obtained by using digital servos. Please do not risk your plane by using low torque servos. This Yak-54 has large control surfaces and fully capable of any maneuvers that a pilot is able to perform, therefore using weak servos will increase chance of flutter and can cause you crash.

The Yak is about the same size plane and I imagine under about the same kind of stesses.

Fast Guy

I don't know if better servos would have made a difference in my case. The kit servo horn bolt broke off flush with the nylon cone nut. To me that means the servo was strong enough to hold it's position while the aileron fluttered and snaped the bolt off. I was using Futaba S3004 servos. Good luck with yours.

PropSpinner

My Feedback: (15)

I am definitely going to replace the hardware then. I have replacement hardware in my ARF and even those screws are too soft. They are not hardened machine screws, like the Dubro, but soft metal that can easily be bent.

bbellfly

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I used the Dubro aluminum w/elastimer bushings. Again this is to try and reduce structural vibrations. Maybe, this will also help. They weren't cheap though. But, I have also gone to the extent to put a True-turn spinner on it.

I am having a little trouble with the elevator setup. Long story short My 7C radio will not setup the elevator (elevons) like the ailerons (flapperon), you can't activate both in the same model. That leaves me with y-harness or (per Bax in Futaba forum) a P-Mix. The P-Mix isn't behaving well, more movement in one side up in one servo, and more movement down in the other servo. Trying to correct this with RT % seems to make this worse. And the y-harnes will require lots of changes to location and pushrod length.

How did you (all) handle the elevator set-up?????????

bbellfly

My Feedback: (2)

Have made a half dozen flights with my Edge. Have been nervous of the possiblity of flutter. But, so far no evidents of it. Got my fingers crossed though. You know....its hard to operate the radio with them crossed. Maybe my toes.... Yeah that's it.....

I stregthened the leading and tailing edges as I fitted the hinges. I through away the hardware (even the replacement kit) and installed all Du-bro HD hardware. That took me from 2/56" junk hardware to 6/32" alloy (Socket Head Cap Srews) and much better clevises. Fitting the hinges is very important. I also used the Du-bro HD pull/pull system. I think this next step is very very important. I covered the gaps between the control surfaces, on both sides. Using Ultracoat white, matched perfect. The only area not covered is the hinge knuckel itself. And, I mean the covering (on both sides) is right up against the edge of the knuckel on both sides. After fitting the hinges properly you shouldn't have more than a 1/16 to 1/8 inch gap. If you work hard enough (and keep checking to assure you don't go to far) you can get the gap down to almost nothing. I also added more epoxy and CA to almost every joint in the fuselage and motor box I could reach without removing covering. Not globbing!!! But, evenly coated. I also thought about vibration, if there were any bad glue joints. I used Du-bro vibration reduction motor mounts. There almost wasn't enough room on the motor box. The top and bottom edges of the mount were 1/16" (maybe less) past the top and bottom edge of the box.

If anyone (who is still working on there plane) would like to know in more detail what I did. Feel free to contact me. I just keep hoping each flight that the flutter doesn't happen. Although, I did some tumbles and even a snap-roll and everything came out ok. It was the quickest most violent I've ever seen. I think it made 3 rotations before I could get off the sticks. But the throws were at 120%.


bbell

PropSpinner

My Feedback: (15)

I maidened my CG Edge Saturday and it flew like a dream. No signs of flutter. I upgraded everything to Dubro except for the rudder arm. I sealed both sides of the hinge gaps and made sure I trottled back on the down legs. I am very happy with this plane. Too bad they stopped making it. If it were a kit I would build one. I think it flys better than my EF Yak. I was doing inverted harriers which I've never done before. Once I get it properly trimmed I think it will do even more aerobatics.

PropSpinner

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What a great plane!!!!!!!

ABELL

I know this is opening an old thread but I have a question. I had one of these planes that died an untimely death a couple of years ago. I think it was dumb thumbs but I'm not sure. I bougth another but have not built it until now. During the down time I discovered this thread or another like it. After reading this I went to great efforts to prevent flutter. Used heayv hardwear 70 oz servos sealed all hinge gaps and glued every thing I could reach without ripping all of the covering off. That said about 2 minutes into the second flight I heard the dreaded flutter. I got it on the ground in one peice and after a good going over I discovered the line up pin at the trailing edge on the left wing had wallowed out about 1/16th of an inch mabey. The wood surrounding it was very soft. I made some new washers out of 3/8 lite ply. Maybe I'll get to try it this weekend and see how it does. I think this plane was destined to flutter. Thats probley why they were discontinued. Any thoughts?

PropSpinner

My Feedback: (15)

I haven't flown mine much cause of engine problems but I haven't had any trouble with flutter. I replaced a lot of the hardware with Dubro so that might have something to do with it. The few times I've flown it I really liked it. Only complaint I have is that piece of fence pipe they call a wing tube.

ABELL

I replaced everything in mine as well,even the pull-pull rudder system. I cut some wooden washers and epoxied them inside the fuse for the line-up pins on the trailing edge last night . I hope that corrects that problem. That Edge I believe is by far the best flying plane I have had to date. I almost shed a tear when my other one went in a couple of years ago. I think I did shed one when I found that they had been discontinued. Mabey I'll get all of the bugs worked out of this one soon and can go to enjoing it. Right now what we need in AL is some dry weather. I believe it has rained 30 of the last 40 days.[&o]. That wing tube is a nice sized one ain't it ?

PropSpinner

My Feedback: (15)

I got mine out and flew it last weekend and it does great. I keep looking for one like it but to put on the shelf but haven't had any luck. I know someone with the Yak that might sell but I like the CG Edge.