308jockey

So your feeling is that a longer tube by itself is not the solution, there is structural work that needs doing. Oh well, better than scrapping the whole thing I guess.

Rick H.

big_G

A longer wing tube, along with correcting the shear webs, should help avoid wing failure. I WOULD NOT fly it if these mods. are not done. Other than that, it does fly good.

pshark101

A longer tube itself may be enough, but I think a little extra reinforcement around it would definitely help. I was getting ready to recover mine after doing just the shear web fix. I had a couple concerns, but if it wasn't for bigG's unfortunate loss I would've just done the web fix and soldiered on... and probably had a failure too. I'm not sure if I'll stick to the stock tube with extra structure, or put in a longer tube and sleeve. I was looking at options online last night, looks like it'll be around $55 - $75 for a new tube/sleeve.
On an up note, I found some really nice condition JR 8311 servos for $25 each at a local swap meet.

pshark101

Ahh, looks like we were typing our responses at the same time

pshark101

Looked at it some more, bigG is right... the tube needs to be longer. The ending point of the stock tube is just too close to the center section, where most of the wing stresses are located. A longer tube and sleeve, with a simple box structure built around it, should do the trick. Maybe even carry the center section sheeting out a bit farther.
I've had the urge to build a kit for awhile, so I guess this project will help me relive the good ol' days.

big_G

This picture shows the reason the wing failed. Insufficient support structure around the wing tube. It simply ripped the ribs right out of the wing. There should have been a spar box built around the wing tube, not in front of it. Simply poor engineering.

RonMcCormick

My Feedback: (4)

Your correct, I looked at every wing I have that use a tube (8 or9) and this is the only one with the tube not built into the spar structure. I don't think the tube is to short for the intended service. Question now is what is the best way to correct this defect. Looks like I will have to strip the bottom covering off and move the tube forward with supporting structure to transfer the load to the spar. Not a huge project but....

Champ-RCU

My Feedback: (132)

I TOTALLY agree with Big_G and RonMcC., after removing the lower covering on my wings and adding shear webbing in the correct direction I took a real close look at the structure. As I looked at the wing tube /spar placement my dear old Grand Dad's voice rang in my ear- Looks like they didn't build the wall over the foundation, no good. After mulling what to do about it, my fix is to build a new wing for this thing. Anyone want a set of wings to hang on the wall?

Mark

308jockey

I've spent a good couple of hours staring at this thing and looking at some of the photos on this thread. It appears to me that the tube is built into a pair of spars that go out to about the fourth rib though the tube only goes to the third rib. I was not impressed with the glue job for the tube so I got out a long brush and some 30 minute epoxy and now it is firmly attached. If this structure fails either the tube will break or the wood will fail. It looks to me as though it was glue joint failure that caused Big G's crash. What bothers me is that throughout this thread the wings that did fail apparently did so because of the incorrect shear webbing. With that fixed these planes seemed to stay together and I know of at least one pattern flier who simply wore his airplane out with an OS 160. I earlier thought that these kits might be new old stock from 6 or 8 years ago but now I wonder if they aren't recently made and that a few shortcuts might have occurred in the building process. I'm waiting for a remote glow driver to get here and plan to fly this weekend. I'll be keeping a close eye on these wings and if something starts to fail maybe I'll catch it before it becomes catastrophic.

Rick H.

pshark101

Here are some shots of mine with some of the sheeting removed from the bottom. You can see that the tie-in from the wing tube to the wing structure is simply a piece of 3/32" soft balsa that is split lengthwise into two pieces. The wing sheeting glues to these two pieces. The tube is secured through the ribs as well, but they're really fragile in this area due to their large lightening cutouts.
When the wing flexes upwards under load, the wing tube essentially stays in place (since it's secured through the fuselage) and the wing structure simply pulls away from it.
My initial plan, subject to change , is to build a box structure using 1/8" sheeting and 1/4" stock around the tube and carry it all the way out to where it intersects with the spar. I'll tie it in really well at that point. I'm also going to extend the lower wing sheeting out to the servo mounting box structure, and reinforce the ribs that the tube goes through. I think I'll also add some fiberglass cloth and epoxy where warranted to strengthen it further. All of this while trying to add only about 2 ozs lol... yeah right.
And of course I'll finish the shear webs on this wing panel, the other panel is done.

pshark101

My thoughts exactly. Seems all of the old wings with the just the shear web fix are holding fine. I just purchased my kit a couple of weeks ago. It was double boxed very nicely with a thick cardboard outer box, not like what others were complaining about years ago. The canopy paint line is different... parallel to bottom of canopy, not angled upwards like most pictures of it show. Seems like some changes were made compared to the old models. I guess the wings could have been changed as well, but not for the better if they were.

Champ-RCU

My Feedback: (132)

Rick H.

Adding some glue may buy you a little, however I don't think so. The structure that attaches the spar in the wing to the wing tube is lacking not only in structure, but also in the use of the grain in the wood. What you end up with is a fairly stiff I beam spar in the wing and the rigid Carbon fiber tube with what turns out to be a fuse between them (Like an electrical fuse.), a weak spot that will fail first. After looking at the wing I'm not sure that all of the failures are failures of the structure that connects the wing spar to the CF wing tube. Thus my decision to pretty much scratch the wings and build a new set. 99% sure it will be a foam core, balsa sheeted wing. Been building those for 40 years so far no failures. OK none in the air anyway. OK only ones that failed in the air were results of mid airs.

To fix the wing in my opinion you need to tie the third rib (Were the tube ends.) into the wing spar. In other words a strong ply rib surrounding the tube then into the D- tube section of the wing. Also a spar top and bottom of the wing tube from the wing root extending out to and attach to the main wing spar. In my opinion to do that type of repair you may as well build a new wing. Just my humble opinion. One thing I know for sure,100%, is the pictures of wings failing makes me sick to my tummy.

Good luck,

Mark

Champ-RCU

My Feedback: (132)

PShark,

Once you reinforce the existing structure around the tube you had better beef the structure to the wing spars. You need to transfer the force from the I beam wood spars to the wing tube. If you leave the simple and weak balsa ribs to do the job you will eventually blow the "fuse" between the two beefed up structures. IMHO

Mark

After rereading your post I see you are going to strengthen that area. Sorry for the ramblings. Some people's kids!

RonMcCormick

My Feedback: (4)

I think I have the best solution, flying wires, ROTFLMAO!

308jockey

Go back to page 17 of this thread, post #404 and look closely at the photos. I'm not sure how much of that is original and how much it may differ from what is being sold now. I think that if I took all the time I spent studying this and fretting over it I could have just re built the structure and tied it in to the spar as recommended. I'm still very tempted on one hand to just fly it and see what happens or pull all the gear out and finish up my Phase One on the other hand and come back to the Evo another day. This is what I can't stand about ARF's.

Rick H.

pshark101

Yep, you're exactly correct... that's what I'm going to do. Will be a bit of work, but I'm determined.

pshark101

Ahh, awesome! That's very similar to what I'm doing with mine. The part that he did extending out from the wing tube is not stock, he added that. Otherwise the structure looks the same as the one I have.

pshark101

Yes! The old quote is true... "Simplicity is the hallmark of genius." I love it

Champ-RCU

My Feedback: (132)

ROTFLMAO

Had to google that one.

308jockey

Well maybe I won't fly it this weekend. Damn%$$&()^)()%(%(*ing YS engine that just got rebuilt won't start. I'm remembering now why I prefer OS.

Rick H.

308jockey

Engine still won't start. Maybe it's a sign. In any case I've removed most of the covering top and bottom from the inboard wing section. I've glassed both wings in this area with 2 oz. glass cloth. That should wrap the whole thing together and keep it in one piece. It's the solution that makes me the most comfortable anyway, suggested by a pattern flying buddy.

Rick H.

pshark101

That stinks. Well, maybe a good thing so that you went ahead and did some reinforcing. Keep us updated!

pshark101

308jockey, did you ever get yours in the air? I haven't made much progress on mine, but hope to have it done in the next month or so. The wing mods are done, I just need to re-sheet the area of removed sheeting. The mods I did added 2.5 ozs to each panel. I'll post some pics when I can.

308jockey

Yeah I did. I went back and glassed the inner section of each wing, all of the inboard section that was sheeted, the re-covered. A friend came to town and we finally got the motor running though not quite tuned. Plane flew very well though not very long thanks to the engine. First landing was just fine but I landed a little short on the second landing and broke both landing gear struts. I have a fix in mind but may just suck it up and buy new CF gear from Central or someone. I like the airplane so far, very smooth and no obvious bad habits. Wings are holding.

Rick H.

Ray Wasson

I filled the first 2 bays in front of the tube socket with expanding foam and added vertical shear web to the rest. What do you guys think?.
Ray