Idasam

Gentlemen, I acquired a plane and the previous owner said that he used 5 min. epoxy to join the wing. I need people that have experience with this. Is this wing going to be sound? Can I rely on 5 min. epoxy to hold my wing together? This is a Phoenix Dolphin plane.

shd3920

I would never use 5-minute epoxy, cure time is way too fast. Before you can spread the epoxy on the joiner, both wing halves, and begin sliding the halves together the epoxy is already beginning to set. You will NOT get the full bond strength. Please use 30-minute epoxy as you WILL NEED the set-up time that the epoxy gives, it will take more than five minutes to slide the wing halves together and get eveything aligned and clamped. Plus the longer curing time will allow the 30-minute epoxy to soak into the wood, giving it even more bond strength.

Bonified Wingnut

It depends on what you mean by join the wing. 5 minutes, when you are building, goes by very fast. One misalignment and you have a mess. I use 30 min for anything I cant put together in about 5 seconds. The longer curing time also allows for the epoxy to "soak" into the balsa or ply.-BW

Yeah, what he said...

bigedmustafa

My Feedback: (2)

If the wing was joined with sufficient amounts of epoxy, the 5 minute epoxy should be fine. The front dowls and rear wing bolts will keep the center wing joint from taking too much strain during spirited aerobatics.

Gray Beard

My Feedback: (-1)

It's just a shorter working time, you gotta be quick. People used to think that 30 min. had more time to soak into the wood, that turned out to be wishful thinking. Strength wise they are all about the same. During the winter when it's cold you do get a bit more time. I keep both 5 and 30 in my shop, if it's a small part that I can set and clamp I will use the 5, for things like the fire wall where I need some time I use the 30. Your wing should be OK if the builder was quick and it was mixed correctly.

RCKen

My Feedback: (9)

If I read correctly you have a plane that has the wing already joined and 5-minute epoxy was used to join the wing. If this is the case then you will be just fine with it. While it's not how I would have built the plane (I would use 30+ minute epoxy), but the wing is more than likely going to be just fine the way is. And I can assure you it's not going to be worth the hassle of trying to cut the wing apart to re-do it with 30 minute epoxy. If the wing is already joined the give it a good tug to ensure that it's well bonded and then fly it.

Now if the wing halves haven't been joined yet, then yes you want to use 30+ minute epoxy to join them with.

Ken

Idasam

Yes the wing/plane is already built. The seam of the wing is very clean, the whole plane is very clean for that matter. This guy built the plane, flew it a few times and decided that he didn't like it. He designs and builds his own planes. I was surprised to hear that he used 5 min. epoxy, but I trust what you guys are saying. I looked up 5 min. epoxy and it has a strenght of 1500 psi.

Campgems

I've got to share my Suhkoi SU-31 wing story. It was a used plane when I got it. My first flight with it resulted in a stall and crunched muffler. I rebuilt that and had antother go and it ended up with some damage, I had pinched a hole in the fuel line that became a problem about 2 seconds after lift off. Trying to avoid the barbed wire fence at the end of our field, I stalled again and crunched the cowl and ripped off the landing gear. Last week, I finally got it all back to gether and the third time wasa charm. Ihad my buddy test it out and it was a good flight . I followed up with two good flights and easy landings. Life was good.

I 'm cleaning things up to go home and I discover what looks like a loose joint between the wings. Closer inspection proved it was bad. Epoxy joint broke loose. Used the wrong epoxy, Bad assembley on the other guys part. Well, when I finally dismantled it to see what was wrong, the root ribs which were 3/16 or 1/4" balsa were joined in OKat the glue joint. THe balsa was all broken up. The "hardwood" joiner was snapped in half at the center. The only thing holding the halfs together was the shreaded balsa in the two root ribs.

Guys, 5 minute epoxy, 30 minute epoxy 48 hour epoxy and it doesn't make one bit of difference, the wood is the soft spot in the joint. It doesn't matter if it is the strongest epoxy know to man or hardware store 5 minute, the epoxy is stronger than the balsa and stronger than the glue in the lite ply. The main reasion to use the 30 minute as Grey Beard and Ken stated, is it gives you more time to get things buttered up and clamped and taped together before the epoxy kicks off.

I expect the damage to my wing was when I tried to miss the fence and stalled and clipped a wing tip on the way to crunching the cowl and landing gear. The epoxy had absolutely nothing to do with the joint coming apart.

Don

nitro wing

My Feedback: (1)

5 minute is likely fine on 40- 60 size aircraft. I believe 5 minute is also a bit more brittle, making it less ideal for wing joints and landing gear areas.
On my old joined paneled 40 size airplanes, I never had one fail, even on severe crash days...
Also brand types and proper mix ratios play a key role here.

bigtim

My Feedback: (13)

other than working time, why would you recomend 30 min epoxy for wing joining,relative strength is vurtually the same for both epoxies, as much as there is alot of myth making on RCU about penetration and strength etc.. its just not true.
cured epoxy is cured, wheather or not its the quick hardening or long, the amount of strength difference is negligible, and would make no difference in models of the size generally flown, including giant scale planes.
that being said of course I would use 30 min epoxy for joining wings or any area where minor adjustment might be necessary,but saying its because its stronger is not correct in so much that it would make no real difference the wood in a wing joint would fail before the adhesive did.

RCKen

My Feedback: (9)

This is actually not entirely true. Epoxy gets its strength from polymer chains formed when the epoxy cures. With longer setting epoxy the polymer chains have more time to form longer chains.So the 30+ minute epoxy can form strong chains in the structure of the epoxy and does make it stronger. Yes, in many cases it is as you say that the wood is stronger than the epoxy. But saying that 30 minute epoxy isn't any stronger than the 5 minute epoxy isn't entirely correct. Also it does have more time to penetrate the material it is bonding as well.

Ken

bigtim

My Feedback: (13)

yes a actual sheer strength is between the 2 adhesives is aprox 25%-30% but in real life situations 1900psi http://www.devcon.com/prodfiles/pdfs/fam_tds_175.pdf Vs. 2500psi makes no difference since the load it would take to get to those pressures would destroy a model before the adhesive would fail, which was really my point.

having used both speeds to work with gluing tail feathers, critical surfaces in modeling and in const. you better be a assembly ninja to pull wing joining off with it,
but some of these areas where I have used it have yet to fail under high loads, and the quicker glue can actually be a advantage when gluing a properly fitted part over needing to hold a part in the proper position untill its tacked up, there are alot of postings that seem to imply that there is a significant apparent strength difference which there isn't.

bkdavy

My Feedback: (1)

Personally I've been impressed over the years with how LITTLE stress the wing joint has in a properly designed plane. My mid wing planes (60 size Edge 540, self-designed aerobat, and a 30% Yak-54) are held in either by rubber bands or nylon bolts. One day as I was cleaning up, I was taking the wing off my Edge 540. There was only one loop of rubber band holding the wing in place. If you watch the video of Mac Hodges B-29 crash, look at how many spins it takes before the wing finally slides out far enough to come off.

5 minute epoxy has more than enough strength to hold the wing halves together. Heck, I bet packing tape would work.

Brad

Lnewqban

Idasam,

As the model weight is about 5.5 pounds, and a 10G may be the max stress, you could test the joint by placing 40 or 50 pounds over the center, while the wing is supported on the tips only.

If still not sure, cover the bottom along the center with fiberglass and epoxy.

At least for me, 5 minutes (more like 3) is too short time for proper aligment.
If you have an incidence meter, just check that both halves have the same incidence angle.
It may be possible that the seller did not like the way the model flew due to a slightly twisted wing.

Best luck!

Rodney

RCKen gave you the straight skinny on the relative strength of different cure time epoxies. Fortunately for us, even the poorer (faster curring) strength epoxies are usually stronger than the wood they tie together. If strength is truly a requirement, use the slow curring epoxies.

gunneredwards

My Feedback: (4)

If you are worried about the wing joint being substandard, pull the covering off the center of the wing and glass cloth the center section. This would be easy insurance that the joint won't fail. You can use fiberglass cloth or kevlar mesh for this and just regular 30 minute epoxy.
dan

Gray Beard

My Feedback: (-1)

Or the new one hour Gorilla glue!!! I just got to use that stuff for the first time last week. Tough stuff!!!! The debate over epoxy is starting to sound like the debate over 4.8 volt VS 6volt batteries. You can measure the difference in your shop but in the real world you will never notice it. I recall one very long thread about epoxy not too long ago if anyone needs to do a search. Main point is you use the one you like to use because you aren't going to know what one is best at the field. I'm just not fast enough to be using the 5 min. for the main build but I do like it for small things like servo rails or small parts. If you need to do any adjustments to get things in alignment then 5 minute isn't the thing to use. I also use small dental burrs to drill little holes in the two sides/areas getting the epoxy and it squishes into those little holes and adds even more strength to the gluing surfaces. Just a little trick I learned when making false teeth. None of the teeth in the dentures I made ever came out!!

kristj179

yes i would like to say one thing? i used gorrilla glue epoxy on my clipped wing cub. the manufacter recomends the 5 minute epoxy for the joining of the wing halfs together. dont have a problem with this glue. the kit is a arf kit this might be why they say 5 minute epoxy for this don t know? just my input[]

tony0707

HI IF THE wing was joined straight and correctly you will have no problem with it holding together as all epoxy is very strong-if you still have air pockets (no epoxy ) that you can see in the wing seam fill them with thick CA now. Drying time should not be an issue as the parts should have been prepared to fit-several times before you apply any epoxy (lined up and marked before epoxy is applied ) s/b just a matter of holding them together until epoxy sets-i tack glue with thick CA and a kicker to hold the position desired until the epoxie sets5 minutes is a long time if the parts are properly in line as they should be fit twice mark and glue once -should get it rightTHE DIFFERENCE BETWEEN A GOOD BUILDER AND ONE THAT IS NOTIS THE GOOD BUILDER WILL CORRECT WHAT HE DID WRONG BEFORE MOVING FOWARDJUST TAKE IT APART AND REDO just my .02 ENJOY REGARDS TONY

tony0707

HI like to add - when parts are marked and fit twice i use thick CA and 5 minute epoxy to join the wing center without a problem as the fit is carefully planned before any glue is appliedi will change any wing joiner in a 60-120 kit to 1/4 inch 5 plyplywood at the spar and increase the LE joiner to 5 ply also (strong stuff )i then join the wing center and SHEET OVER the center four ribs to increase the center sections strengthso i have no center seamthis is an old U control building technique-i have not used any cloth at the wing center for 20 years of buiding this way i do not like the way film covering hold and looks over epoxy filled cloth-i have not had a wing center fail on me in that same 20 years again my .02TONY