Rambo-RCU

My Feedback: (1)

Well here we go again. My Giles had started developing cracks at rear wing saddle area and low and behold it completely let.s go while cranking the engine.I've sean the thread on where the tristock was added I think I'll need something more drastic.Any ideas or pics of sucessful reienforcement appreciated.

jjamesrb

My Feedback: (39)

I wish i would of took pics of mine when i had to put it back together.I landed it and the plane split right in half behind the wing and after inspecting it there isn't much structually besides the sheeting holding the plane together in that area.I was able to fix it with a lot of epoxy and some 1/4 inch plywood on the sides (inside the sheeting) and now its stronger than ever and a little heavier but i don't have to worry about it splitting apart in the air.

Geistware

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The wing crack has been well documented and I for one have had two and both have had wing cracks. I glassed the crack area and the plane flies great.

rfw1953

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This is the result of exactly what we have been talking about in multiple threads. I hate it that this happened to you. Every Giles that I have seen has shown signs of cracking fore and aft of the wing saddle formers. Sounds like you were able to salvage the model ok. Glad the damage was not more severe, and that it didn't happen while in flight. Could have been much worse. Hope others will avoid the same by adding the very simple modification that I provided pictures of in previous threads on the subject. Here they are again to maybe help others avoid the same.

Thanks for sharing this with us.

Rambo-RCU

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Thanks a bunch guy's I kinda suspected I'd have to remove sheeting as it let go behind the former towards the rear with no way to access a inside repair.Thanks again.[&o]

Dazzler

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rfw1953, what mods did you do, are you just talking about the tri stock in the front with the strip of ply running in between? and the tristock in the back? I cant see any other mod than that.

Thanks!!!

Daz...

rfw1953

My Feedback: (2)

Thats it. It's doesn't take much to add strength in this area of the formers. I used tristock on both sides of the formers ( fore and aft) on mine and my sons's Giles. Apparently the fuse flexes in this area and it's very difficult to get to. Adding a piece of ply would be better if you can get to the entire area, but you really can't without doing a major modification. I found that adding the tristock stopped the cracking and added just enough strength to the area to help stop the flexing. It's worked so far with many flights after the mod without a failure. Used plenty of epoxy around the tristock and the former.

Geistware

My Feedback: (16)

You also have to do the same to the wing itself.
The cracks will start near the front mount and spread back.

Dazzler

My Feedback: (6)

I will add the tri stock to mine. I've been flying mine for over a year with no cracking, but dont mind adding a little tristock. I will only be adding it to the fuse only. I fiberglassed the center section of my wing so I doubt I will have any problems with that!!!

Thanks

Daz...

rfw1953

My Feedback: (2)

Ditto on the wings.

kingdom802

My Feedback: (5)

wow, you guys are scaring me, I've been flying my GP Giles with an OS 1.6 for over a year and I have'nt seen any cracks yet either.
I will add the triangle stock to the formers, I also glassed the center section where exactly should I look for cracks on the wings?
Thanks guys,
Larry

rfw1953

My Feedback: (2)

If you glassed the center section of the wing you should be ok. Unfortunately I had one shear a wing at the tip of the wing joiner so nothing could have prevented without a major overhaul. This airplane has a bit of a history with wing and former problems. I have seen guys fly the stew out of the Giles with what I would call stressful G's and no problems. Then again, you read of things like in these post where guys had serious failures.

I lost a wing on my first Giles doing a hammerhead stall turn in a non-powered dive. The wing just sheared off. Was using a 160 FX so not over powered. I don't fly 3-D so no hard core stuff involved. Just a bad piece of balsa, I guess. G.P. replaced the airplane, motor, servos, spinner, prop and rx. It happened during an AMA sponsored Big Bird event. G.P. treated me very well with this mishap. G.P. was very interested in what engine I was using. They said wing problems had occurred when guys try over powering the airplane with gas engines.

I love the one I fly today. It flies great and no problems. I did this simple modification and haven't had any problems since. The only thing I think you have to be careful about is watching for hairline cracks in the wings and the fuse, near the formers fore and aft of the wing saddle. If you notice cracks in the covering then you are headed for trouble. If for nothing else other then confidence you would be well served in adding the tirstock. I also added tristock to the inside to the fuse where the firewall connects to the sheeting. Just used small pieces to avoid excessive weight.

Volfy

My Feedback: (23)

I just finished putting together mine. The center section looks extraordinarily strong. The two huge blocks of solid balsa, which makes up the wing saddles, imparts a lot of bending and torsional stiffness. I think it's the areas just aft of the wing TE that's the weak point. Because the center section is so strong, it creates a stress riser directly behind it. This is precisely what contributed to the failure shown in the pictures up top.

Since I had to cut the little cross brace on the former at the wing TE to get my hand in behind the cockpit to install an LED for my onboard glow driver, I took the opportunity to glue stiffening braces on the sides and bottom of the fuselage drectly behind the wing TE former.

BTW, I also glassed the wing center section, as I always do regardless of whether the instruction calls out for it or not. 1~2 Oz. of epoxy and fiberglass here adds a ton of strength and is well worth it.

Mine finished up 12 lbs 10 Oz. with a ST 2300 and onboard glow driver and an empty 21 Oz. Sullivan tank, which is very close to the RTF weight quoted by GP of 12.5 lbs with ST 2300.

Geistware

My Feedback: (16)

I had two, one gas and one glow and had to re-enforce the wings in both.

Rambo-RCU

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Well guy's since I started this thread I thought I should show what I ended up doing to resolve the fuse prob.In the first pic the two black marks are the breaks, in the second you can see I added 1/8" ply splints across the nearest ones to the top of pic on both sides and then seeing the bottom member was balsa only I added a diagonal piece (Has black mark arrow on it) of ply and tied it together that way. It seams like it's very strong now as I get absolutely no flexing.P.S. I did,nt have a inside break but am going to reinforce the corners anyway.BTW I used CA'S only so it did'nt add that much weight.

Volfy

My Feedback: (23)

Rambo, I would strongly recommend glassing over the fault line. Ounce for ounce, stressed skin repair is much much stronger than any internal bracing you could do. I've done it many times to repair damages like that. After you FG, lightly sand, then apply balsa filler, and sand to feather-edge. You couldn't tell the repair was there after it's recovered.

Rambo-RCU

My Feedback: (1)

Great tip think I'll do just that and maybe even the forward section also while I'm at it.What weight of cloth do you use and do you use CA'S or Epoxy? Thanks again

Volfy

My Feedback: (23)

On rare occasions where the repair area is very small, I might use CA, but most of the time I use epoxy finish resin. It flows out very well but still has high viscosity and surface tension so that it "sucks" the FG cloth to the surface well. Plus it sands a lot better than CA.

Contrary to how most folks do it, which is to drape the cloth on the surface, lay on the epoxy thick, then spread/scrape off the excess with a card or plastic scraper, I actually brush on the epoxy on the wood surface first. Reasons are many:

1. It's a lot easier to brush on an even coat without the FG cloth in the way.
2. It's easier to control the thickness of the epoxy coat before you lay on the FG.
3. This allows the epoxy to fully soak into the wood for maximum adhesion.
4. Laying on the FG and letting the cloth wick up the epoxy into its fabric allows the FG cloth to maintain its weave pattern. THis is important to maximize the strength of the omnidirectional FG composite. If you try to spread the epoxy after the cloth is already on the surface, you could easy distort the weave pattern, or worst - unwoven or fray the babric particularly at the edges.

The optimum amount of epoxy to use is with the FG cloth weave still uniformly visible, with no bright spots where the eopxy was laid on too thick. Any more epoxy than that is pure dead weight. THe rule of thumb is that you want to fill the voids between the FG threads 2/3 full. I know this is difficult to judge with the naked eye, but after a few trials, you should begin to get a hang of it. The only exception to this rule are inside corners where you may need to form a fillet for best result, and around open holes to be later cut open (e.g. aileron servo wire hole) to avoid delamination of the FG.

Here are a couple of tips:

a. Lay the FG cloth with the weave crossing the fault line at 45deg angle. This gains the max amount of tensile strength from the FG across the fault line.
b. If you use multiple layers of FG (recommended over a single layer of heavy weight cloth), put down the smaller patch first, then successively larger patches. This makes it easier to feather edge, and more importantly, minimizes any stress risers at the edges of the repair area.

Rambo-RCU

My Feedback: (1)

For you to take this much time and explane a process that thoughly just goes to show R/Cer's are indeed the best of people.My thanks to you . I'm printing off your answer to use as a guideline.[&:]

Volfy

My Feedback: (23)

You're very welcome. I learned a lot about composite construction techniques from building and flying sailplanes back when I lived in SoCal.

Oh, I forgot to answer one of your questions. For general repairs, 1-1/2 to 3 Oz FG cloth work well. Lighter than that, strength won't be adequate; heavier, and the coarser weaves take more resin to fill and are harder to hide. I typically use 2 Oz. glass and adjust strength with multiple layers, not heavier glass.

In cases where unidirectional (in one direction) strengh is required, such as fixing broken tail feathers, I like to embed strips of carbon fiber underneath the FG cloth. You need to be judicious with the use of CF, though. Unlike FG, carbon fiber has very high tensile strength but next to no yield. This means it just doesn't want to bend or stretch. Use it only where high strength is required, such as wing spars and sometimes LE and TE sticks, and only towards to wing root.

Shoot, I can just go on and on...

cap10b

Hey Guys,
I have a Wild Hare 35% Giles 202 and I am looking for a practice plane about 1/4 scale. Cant decide between the TT Giles or the GP Giles. How close to the Wild Hare do you think this plane will perform with a Saito 180 ??

Just wondering

JDS

rfw1953

My Feedback: (2)

Volfly,

Very informed suggestions and also very helpful. Thanks. I sure learned a few new ones. I have only used fiberglass a few times. I used it when reinforcing the firewall to the mounting box on my Pitts Special. I used finish epoxy and liked the finish it provides. It added a nice glossy finish. Took forever to cure, but did the trick. I put a thin coat on the wood surface first and then applied the cloth with three additional coats. Firewall is solid.

Cap10b - can't help you with the Wild Hare. Like the G.P.iles though, even with the history.

Dazzler

My Feedback: (6)

Well, I went ahead and added the mod, some pics.

Daz...

Dazzler

My Feedback: (6)

Here it is complete

rfw1953

My Feedback: (2)

Dazzler,

Nice job and great pictures. That should hold.

Moderator, thanks for getting the pictures fixed !