Attention all 150cc Extra 260 and Yak 54 owners

[Sukhoikid]

I did the simple wood fix and here I am down at college. I am very lucky to have a few friends of mine to keep my stuff and I am still able to fly the plane but if this tube snaps I will be very mad with AW cause with my situation if I lose this plane I am out of a 40%er for a while! I am just doing IMAC manuevers with the plane luckily but every now and then I will flip the switches and do some 3D stuff.

I am glad to see there are others out there like I am. My parents and I spent too much money on this ARF and find out two or three weeks later the tube is breaking!!!! Its a design mistake and I believe this company should be able to make a thicker tube and not change the actual size of it. If this tube does break I will probably NEVER buy another ARF in this size again!!!

[BOSSIER_ROB]

	Quote: Originally Posted by 50%plane
	I'm sorry, but how hard is it to get tubing with the same outside diameter and bigger wall thickness? ***? We use all kind of tubing here, not much 1.5", but everything smaller, no matter what the WT, the OD is always the same,,,

I think it is a 40mm carbon tube. If I had just bought one of these and was told not to fly it until I was sent a friggin stick to shove into my CARBON wing tube, I'd be on the phone raising nine kinds of hell until they sent me a new replacement for free. You shouldn't have to spend $150-$200 on a carbon tube that is replacing the carbon tube that came with the plane simply because the original tubes slipped through quality controll. They should buck up, buy some stronger tubes, and be going through their shipping records sending everyone with a bad tube a new replacement. For a company as large as Aeroworks, with the reputation for quality they have, this shouldn't be hard to do nor should it take very long. Come on guys! You should be sending out aftermarket tubes until your supplier gets theirs fixed and not a piece of wooden dowel rod. That is 100% bull!!! I would expect much better service from one of the leading ARF companies. The bottom line is YOU, as the customer, should NOT have to buy a carbon wingtube to replace a stock carbon wingtube because they are breaking.

[Bruce]

The problem is there aren't any aftermarket tubes readily available. Most 40% or larger planes use 50mm tubes at the four foot length. I have talked to PBG and they can make one up at 40mm OD and 2mm WT - cost would be close to $200 plus shipping from New Zealand.

[Jim Martin]

TBM http://troybuiltmodels.com/newsite/p...es.html#metric has 40mm CF wing tubes.

[Sukhoikid]

I know i built mine and then flew it in two weeks and the third week got a call and said ground the plane. They did send the wood dowl out right away when it was avaliable but after hearing they are still breaking with that piece in there I am getting more worried about mine. Guess time will tell I have a imac event in two weeks I might go to and I will be flying it in freestyle. luckily my free is not that rough on the plane.

[Bruce]

Martin - its only 41" long and WT is only 1.2mm which is what AW is spec'd at

[statbeast]

It certainly seems like a new tube is in order for those that have the weaker one. I don't like the idea of a wood insert.

[bodywerks]

	Quote: Originally Posted by Jim Martin
	TBM http://troybuiltmodels.com/newsite/p...es.html#metric has 40mm CF wing tubes.

Not long enough. We need about a 1220mm tube if I remember correctly - whatever 48" is. TBM and Graphtech only offer up to 1000mm. And while 1.2mm is better, we really need 1.4 to 1.5 IMO. That is the thickness of the 50mm tubes that you find on some of the other 40% ARFs. A Dalton wing tube is slightly smaller in O.D.than the AW at 1.5", but the wall thickness is darn near 1/16", or around 1.5mm. Luckily, my QB is under 38 pounds and set up for precision only, so I am a little less likely to have a failure, although my snaps are pretty wicked .
My understanding of their theory behind this repair is that the balsa dowel is there to keep the tube from being able to kink, which is what AW feels is the ultimate cause of the tube failure. That does makes sense to me, but a thicker wall would ultimately be the best solution most definitely.It looks like the tube we have is just a longer version of the 100cc carbon upgrade tube.

[bodywerks]

	Quote: Originally Posted by Bruce
	Martin - its only 41" long and WT is only 1.2mm which is what AW is spec'd at

My tube and the tube on the QB I am building for a guy is only 1mm

[bodywerks]

	Quote: Originally Posted by BOSSIER_ROB
	Adding a piece of wood inside the tube is just going to cause the stress to be on the area where the wood plug edge is.

I don't see how you can conclude that. For that to happen would require the wing to fail as well. The weakest point of the whole assembled unit is the minute gap between the root rib and the fuselage side. And most of the load is focused right around there when G's are pulled. The further out you go on the tube the lower the stresses are on it.
Also, the tensil strength of carbon fiber is in the order of about 100,000lbs/sq.in. At 1mm thickness on this tube, where the core load is only focused on about a 15mm section of the circumfrence of the tube(in a positive G mameuver, the load is focused on the bottom section of the tube, and the remaining circumfrence is just there to transfer the loads to that section), we are talking about like 2400 pounds of tensil strength! At 10 G's a 40 pound plane is probably only demanding about 800 pounds of that tensil strength. So the strength of the carbon that experiences the load is not the problem here - it is the ability of the remaining circumfrence of the tube to transfer the load properly, which is a function of shear and compression(forces that carbon fiber is not very good at handling). So what appears to be happening is the part of the carbon tube that needs to transfer the loads is failing and buckling in on itself. When this happens, the tensil-loaded carbon ceases to work, the wing folds upward, disbonds the matrix holding all the carbon together, and it shears.
So the balsa dowel is not intended to absorb G loads(heck, a kid could break it!) - it is just there in an attempt to help the shear and compression-loaded part of the tube be able to do its job without buckling.
I guess my physics 101 lecture might be a moot point, though, if what Show871 stated is true and accurate...

[Show871]

	Quote: Originally Posted by bodywerks
	I don't see how you can conclude that. For that to happen would require the wing to fail as well. The weakest point of the whole assembled unit is the minute gap between the root rib and the fuselage side. And most of the load is focused right around there when G's are pulled. The further out you go on the tube the lower the stresses are on it. Also, the tensil strength of carbon fiber is in the order of about 100,000lbs/sq.in. At 1mm thickness on this tube, where the core load is only focused on about a 15mm section of the circumfrence of the tube(in a positive G mameuver, the load is focused on the bottom section of the tube, and the remaining circumfrence is just there to transfer the loads to that section), we are talking about like 2400 pounds of tensil strength! At 10 G's a 40 pound plane is probably only demanding about 800 pounds of that tensil strength. So the strength of the carbon that experiences the load is not the problem here - it is the ability of the remaining circumfrence of the tube to transfer the load properly, which is a function of shear and compression(forces that carbon fiber is not very good at handling). So what appears to be happening is the part of the carbon tube that needs to transfer the loads is failing and buckling in on itself. When this happens, the tensil-loaded carbon ceases to work, the wing folds upward, disbonds the matrix holding all the carbon together, and it shears. So the balsa dowel is not intended to absorb G loads(heck, a kid could break it!) - it is just there in an attempt to help the shear and compression-loaded part of the tube be able to do its job without buckling. I guess my physics 101 lecture might be a moot point, though, if what Show871 stated is true and accurate...

His tube broke on the transition of the edge of the inner plug. He was flying the advanced sequence. 871

[bodywerks]

did the wing fail as well?

[Show871]

	Quote: Originally Posted by bodywerks
	did the wing fail as well?

Did not seem so, the tube snapped, and just left the wing flaping. If the wing would have broken clean off, he may have been able to knife edge it down, he is a really good IMAC pilot. Off to Moto race this morning.........but after seeing his mental anguish I would suggest second guessing the plug fix. 871

[BOSSIER_ROB]

[quote=bodywerks;562348]I don't see how you can conclude that. For that to happen would require the wing to fail as well. The weakest point of the whole assembled unit is the minute gap between the root rib and the fuselage side. And most of the load is focused right around there when G's are pulled. The further out you go on the tube the lower the stresses are on it. [quote]

That's not entirely true. Wings flex. They don't have to break to break a wingtube. They just need to flex a little more than the tube can. Placing the dowel inside the tube adds strength to the area where the dowel is but just moves the stress point further out to the end of the dowel. You are still going to allow the tube to bend, but it is going to be at the edge where the dowel stops.Take your tube and bend it slightly, then shove a woden dowel in it and bend it again. It's going to flex at the ends of the dowel way more than the center where the dowel is and now you don't have as much tube to be flexible. It's putting a greater load out toward the end of the tube. You would probably be better off without the 24"dowel. If you want to use a balsa dowel to stiffen a carbon tube, you will be better off with one that is the full length of the tube. I would find an aluminum tube until they get some new ones made with a heavier wall thickness, but that's just me and it won't be my plane that gets destroyed so it really doesn't matter to me at all. Stick a 24" balsa dowel in your tube and have at it! Good luck and if you need some heavy duty trash bags, I'll send you a few.

[ace20]

I have been calling Aeroworks on a daily basis and they have been giving me the runaround for weeks. I still haven't gotten the balsa insert that they have been promising me for weeks. Every time i call i get a different story about them not having the inserts or they have sent them out or they haven't come from China yet. I'm also glad to know that I'm not the only one who thinks this is total BS!!!