RICRAC

I had a CAP 222 ARF from topmodels cz that crashed 1month ago, on its maiden flight 10 seconds after takoff the right wing collapsed.
It was alutub, but the internals in the wing was not glued right and the alutub was nor long enough.
It only reach past the 2nd spar, it ended between 2nd and 3d spar. The glassfibertube in the wing went thru the 3rd spar.

So i guess its common on different planes, and some planes of same make works great and some % of them fails.
Maybe because some bad material/craftmanship or a combination of it.

So i dont say That cap model is bad, i will buy a new because i liked that model so much. And the ultimate is a great plane to, but some % of the pruduktion sems to have some issue of the
thing mention above.

I will have my ultimate up again( if i get a new set on warranty), because i like this plane to.

Mylons

Hello. I was one of the persons here that had a wing joiner failure. I did let GP know. I used all recommended epoxys as well as engine (Fuji 43 at the time). I explained to them that I am a licensed aircraft mechanic as well as mechanical engineer (I think that helped.....maybe). They promptly replaced my entire plane after I sent them the pieces of the original plane. The whole process took only a week. What I do think is going on is, as I have read many times, some guys (most) are using larger/heaviermore powerful engines as well as WAY more control surface throw than recommended on 3D rates. This, coupled with the already questionable design of the joiner, is causing the failures. On my second build, I wrapped the joiner in CF and cured in vacuum bag to strengthen it. Seems to be fine now. I now am using a BGX-1(35cc) Glow engine, which is a lighter package than the gasser. This lowers the wing loading alot. I think if you calculate the wing loading with some of the total weights mentioned here, it will scare you...well maybe not scare you, but it is up there. I dont think anyone has come in at GP's weight, which is what their recommended wing loading is based on. I dont think you can, for whatever reason. At any rate, we all know how crazy this thing rolls, etc.-even at the recommended throws. The guy above who calculated wing loads, has hit the nail on the head, I believe. I dont know of any RC plane outside of full composite 40% that will let a 180 pound person stand on the wings!! Anyway, that is my take on it. BTW, my 3D rates are way more than they are supposed to be- but....can you blame me? This baby is wicked!! Hope this helps.

iflywhenican

My Feedback: (1)

I am guilty as can be on the more powerful engine and 3-D rate controls charges. Let me say this though...when I do the 3-D stuff, I use throttle management like a drag racer would in bracket racing. I set up my controls "by the book" when I built my Ultimate and I remember the first time that I rolled it...ON LOW RATE...it scared the heck outta me. I promptly brought it in and lowered the control throws on low rate.
I have mine setup on a 3 position switch:
1. Low and docile [:-]
2. Medium: get your attention and heart rate up [X(]
3. High: WHOAAAA NELLLLLLLLLLLIE!!!!!!!!!!!!!!!!!!!!, but again with throttle management. [sm=tongue_smile.gif]

jzinckgra

My Feedback: (11)

Well, I hope my moki won't tear the plane apart

bluestratos

I have a good 50 flights on mine and I did install the DA 50. I did not do any mods to the wing joiner so I guess any failures, and I have only heard of a few, were more of the exception than the rule. I do practice throttle management as a matter of habit on large models since the real aircraft would not likely be able to survive the kind of forces our models encounter. That being said, if I was building the arf now I would put more attention into the critical part. Just a note, the only serious failure I have experienced is the fabric hinges and I would definately recommend using a good pinned hinge or at least the a higher quality fabric.

I also had a problem with the wheel pants cracking from vibration so I ordered new ones and lined them with extra fiberglass around the wheel opening.. no more problems.

I did have a bit of a problem with vibration losening the cowl screws but I bought some small rubber backed washers and that elimated the problem.

This has been the best plane I have flown in a long time, it makes even an old guy like me look good in the air and especially when landing. Never have I had the pleasure to fly a plane that I can throttle on to the start of the run way, drop the throttle to idle and float in like it is on rails. Landings are so pretty I have to do 5- or more every flight for the shear pleasure of it, lol.

Regards,
Randy

fishdeth

My Feedback: (2)

Got the Graph Tech gear all drilled and mounted.
I'm gonna put the axle all the way through the outside of the pant with a small block of wood glued inside the outboard side of the pant.
I'll post up some pics when done.

Jim

fishdeth

My Feedback: (2)

Here's the pics......

jzinckgra

My Feedback: (11)

REgarding my idea of now putting fiberglass on the bottom of the bottom wing. Well, since I already glued the belly pan on, I am not about to cut it back off to get at the seam. Would putting the tape on the top of the bottom wing help at all? In the past, on some kits I have always taped top and bottom and I would think the bottom would endure the most stress, so if putting tape on only the top isn't going to do much, I won't bother. As far as the top wing, I was only going to tape the bottom.

RICRAC

You can just cut the covering from the bottom cover, then you can put glassfiber att the bottom to.
Then cover it again, the exact blue can you get from oracover i think it was,

If you only will put it on bottom of top wing it will increase the trength in negative Gs an in forward flight, the same for top wing wrapt on bottom but it will increase in negative Gs.
So they will probably work together and increase the total + and - Gs compared to the standard joint.

But i recomend that you wrap both wing around, then you will have a lot more strenght in + and -Gs

fishdeth

My Feedback: (2)

Absolutely cut off the belly pan !
This is your best area for good reinforcement and easy to hide.
Just lay somthing 1/4" thick along the sides of the belly pan and cut it off at that height from the wing with a sharp razor blade.
Glass your wing joint then add a thin strip of balsa to the back of the 1/4"of bellypan that is still attached to the wing, but make it stick up higher than the 1/4" so that portion goes inside the remaining belly pan when put back in place.
Wick in some thin CA and if held tight while gluing, the seam shoul be pretty good.
Touch up where needed with a blue Sharpie .
So now, you can wrap the whole bottom wing and if you are good at recovering, you could also wrap the whole seam on the top as well.
Me.... I would, just for the piece of mind while knockin the sticks around......

Jim

chuck l

My Feedback: (17)

Anyone know how to download this entire thread so it can be read on an airplane over the Atlantic?

DLEVETT

My Feedback: (13)

Now thats a great idea! for those long flights. I to would like to now if its possible.

thx Dave
p.s. I,m a computer caveman

jzinckgra

My Feedback: (11)

Well I added the glass cloth to top and bottom of the bottom wing. I didn't bother with the top wing. I'll take my chances. Now for the somewhat dissappointing part-my all up weight with moki 2.10 is 15.3 lbs.[&o] Quite a bit heavier than I thought it would be. I was thinking it would be around 13 or so. Not even close. Should still fly fine I imagine. Hoping to maiden tomorrow.

iflywhenican

My Feedback: (1)

Good luck with your maiden...we are waiting for a detailed report.
Your all-up weight is not unreasonable and I think the Moki will give you very pleasing results.

Heavy Metal Flyer

A funny thing happened to me on the way home from the field yesterday. I've had the GP Ultimate flying for about a month. Approximately 20 flights with the usual aerobatic maneuvers. While packing up for the day, I removed the top wing and was walking to my car when it simply folded in half in my hands. The joiner had obviously failed. The glue joint was fine as the balsa root rib tore apart leaving material on the metal rib. From my recent experience and all the posts at this thread, it's obvious GP has a design flaw in this kit. Has anyone contacted them and if so, what were the results? I figure if the a plane is advertised as an aerobatic flyer as well as 3-D, it should be able to handle it.

One photo shows both wings intact, so it did not happen from a crash. The other photo shows a closup of the failed joint.

John

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iflywhenican

My Feedback: (1)

HMF...Send GP the wings and photos that you have posted. I cannot tell from the pics, but did you have a dowel rod in the leading edge?

Heavy Metal Flyer

iflywhenican

Yup!
Dowel rods front and rear which are still in the right wing half (upper in pic). You can see them in the close up photo as well as the 'now' enlarged holes in the left wing (lower in pic) where they pulled out and took some balsa stock with them.

Also, I was very disappointed with the quality of the covering when it arrived. The Monokote was wrinkled the worst I've ever seen on a new kit. It was to the point that after spending an hour to straighten out one wing halve, it had that vinyl car seat finish look to it. So I stripped the entire model and re-covered it in Ultracote. Superior material, easier to work with and lasts longer in the Florida sun.

I also scrapped the original landing gear and went with the TNT metal setup. The original gear had cracks at the axle holes area on one of them after about 5 flights. I fly off of grass and I didn't like how the gear wobbled on take off.

The plane is a great flyer and good looker. It has been a lot of time, energy and money to get it right. So it's even more upsetting to have something like this happen. Although I'm lucky it happened on the ground

John

iflywhenican

My Feedback: (1)

I'm thinking that I may try to order a top wing kit for my Ulti and do some mods to it and replace my current one. I will give GP a call tomorrow and see if they have a top wing replacement as it seems to be that it is the one that is letting go first.

John...your kit probably was stored in the western warehouse is the reason for all the wrinkles.

jzinckgra

My Feedback: (11)

Well, after reading the above post, I may reconsider glasssing the top wing afterall[:@]. No maiden today. Lousy weather.

Heavy Metal Flyer

When I do put the top wing back together, I will intall a carbon fiber tibe in the joiner area as well as fiberglass top and bottom of both wings.

More covering work, but it doesn't matter how good it looked on the bench as it spirals to ground in pieces.

John

Charlie P.

Heavy Metal Flier,

I'm looking at the images of your upper wing sections and I'm not seeing the torn up remains of the plywood & balsa wing joiner insert! Did it shear prefectly evenly (I can't believe plywood would do that??) or did you miss a step?

Heavy Metal Flyer

Charlie,
It sheared almost even with the wing root.

Those square looking things on each wing root are what is left of the ply/balsa laminated joiner.

John

Charlie P.

I apologize. I looked back through (Some Thread!) and see that yours is not the only case. And thank you a1pcfixer for the summarized links to modifications. I just ordered my G.P. Ult two days ago and I see I'll be milling out the blocks and adding a reenforcement in the upper and lower blocks and glassing a bit of the wing joint. Did they use lite-ply for the "wing tube" insert?!? I have some odd lengths of fiberglass battens (from sailboat sails) that will do it up proper when laminated in.

I always research a model AFTER I drop the coin on it. Makes life more interesting.

Gave me a chuckle - the landing gear cross-wires idea I had done with musky leaders on an Big Stik that I added a heavier 4-stroke engine to and converted to a tail-dragger. Worked great. I may have to upscale to bluefish leaders for this bird.

iflywhenican

My Feedback: (1)

I would be interested to see someone that is building a new Ulti re-cut a joiner out of hardwood and use it.
I did the "strapping tape" mod on mine yesterday. I put the tape, a strip about 6 inches long x two inches wide, under the top wing joint at the leading edge and let it overlap about a half inch of the top part of the wing. I then covered the strapping tape with a piece of matching trim tape that I had. Looks great and even at that I think it would be better than doing nothing, but again, I have been flying mine for almost 2 years with no problems in that area what-so-ever. (knocking on wood)

Heavy Metal Flyer

After I rejoin the wing halves, I will carefully slice through the sheeting just in front of and along the ply part of the joiner, for the entire length of the joiner. I'll channel down to the bottom. Then I will insert a carbon fiber rod (or rods) with epoxy to fill in the new channel I just made. After the installation of the removed balsa sheeting, and sanding smooth, I will wrap a 4 to 5 inch wide piece of 2 oz fiberglass cloth with epoxy around the top and bottom of the wing center.

With the new reinforced carbon fiber wing joiner and the reinforcing with the fiberglass on the outside, I don't think I'll have any more problems. This is also the only method I can think of to get at, and then reinforce the bottom wing joiner that is already installed and still in one piece.

Of course this means removing the Ultracote and re-covering the wing 'again' with Ultracote, but hey, that's supposed to be the fun part; right?

However, with all the hassles of covering this "ARF" with Ultracote and now having to reinstall a proper wing joiner system and recover again with Ultrocate, I have to say that for the 20 or so flights I've had with it already, it is a fantastic flyer. Properly balanced it will handle all the maneuvers I can think of with ease. It takes off smooth without any bad habits. Stalls are very stable with the nose dropping a little without any violent wing drops. Very stable in windy conditions.

It does sink faster on final than the mono wing planes, but that's expected with a bipe. When you’re a couple feet off the ground with the nose level or slightly flared, just crack the throttle a little and it will slowly grease in nice and easy. Same procedure for landing full scale planes on grass strips.

It's all it's advertised to be, minus a couple of wing breaks, weak landing gear, and poor covering. [8D]

Oh ya! I installed the Fuji 43. Awesome motor. However the stock muffler is junk, as two of the three exhaust tubes fell off in the first few flights. Buy the Bisson or similar pitts-style muffler. Worth the money


(jzinckgra - Finished weight without fuel is just over 15 lbs. No flying problems.)

John