[I have a ultra stick arf with a magnum xl 46. I took it out to day for the first flights. Every thing went great , a little up elevator adjustment flew hands off. Get all done , start clean up, pull wing off and notice a burn mark on the dowel, where it goes into the ply on the plane. The hole in the ply started to elongate and burn there also. Whats up with that, and how do I fix it.[>:]

I've heard of that problem on the Ultra Stick also.......I'm building one now, and what I did was coat the wing dowels with a thin coating of epoxy......also squirted a little thin CA in the holes in the ply....

After you do the fix spoke of in the above post apply some 1/16" thick wing seat tape to the wing saddle and this will help dampen the vibration that is getting to your wing from the motor.

Another suggestion is to put some more wood behind the former. I drilled some 1/4 ply squares and epoxied them to the back side of the former that the wing dowels go in. That thin former alone doesn't supply any real support for the dowels and they chatter in the holes from engine vibration and other stresses...

I have experienced the dowel issues on other aircraft. I ended up sliding some brass tubing over the dowels and epoxy them in place.Since the holes were already enlarged it made since to go this route. Just drill/file out the holes to fit the new diameter of the wing dowels/brass and my problems went away. I am currently building a H9 p-51 150 and did this mod during the wing construction, knowing the potential for dowel problems. Hope this helps.

Mike

Hangar 9 Strikes Again!

I feel your pain Toad. I had heard of this problem before I purchased my H9 Ultra Stick 40 and at that time thought the burning was maybe just an isolated incident. Boy was I wrong!

After flying the 10 minute maiden with mine, I removed the wing just to see if I was going to have the same problem as some others with this burning issue. Guess what - there was some really nice "charring" of the wing dowels going on and after just 10 minutes of flying! Needless to say I was a little "burnt". The next day I dialed up Customer Service at Horizon and confronted them with the "defect" built in to their plane design and wanted to know if they had any fixes for the problem. To my surprise, they denied ever hearing anything about this problem and had no solutions. This did not set too well with me at all. I know that this was a problem (and had been a problem for many) and couldn't believe they were denying any knowledge of it. I love my Stick but because of this H9 is NOT on the top of my list of manufacturers to spend my $$$ on.

The good news -
There is a fix for this so don't panic. Above, there are already some suggestions from those who like you and I have had this problem. I will also add my 2 cents for what it's worth.

The whole problem is that when you put "wood to wood" together (at least in this condition) something has got to happen from all the vibration and resistance that is going on during flight. In this case, it's like creating a fire by rubbing two sticks together. Even if the connection from the wing to the fuse bulk head is good and tight and everything is good in tight - this burning can still happen.

At the suggestion(s) from others on RCU, I used brass tubing over my wing dowels to eliminate the burning. I got my brass tubing from Ace Hardware for a couple of bucks and it came in about a 2'-0" section - which is more than enough for the fix. It has a 3/8" I.D. (inner diameter) and fits quite nicely over the wing dowels which in the end will totally eliminate the charring (at least in my experience).

I first cut a 3" or so piece off of the tubing and made a "boring tool" that I could slip over the wing dowels as they were in place on the wing. You need to make teeth on one end of the tubing for cutting in to the wing wood around the dowels. I accomplished making the teeth with my Dremel. You may want to make a turning handle on the opposite end of the tool so you can turn the tool llike a drill. Once you have your boring tool made the rest is easy. Simply slip the boring tool over the first dowel, apply slight pressure while turning the tool to cut in to the wing wood around the dowel. Be careful not to cut in to the dowel. I bored in to the wing about 1/2" or so, which is ample for the final tubing to set in. You can tell by the photo that I have attached that I made a pre-measured mark on the tool so I could calibrate the depth of the cut and thus keeping the cuts the same from one dowel to the next.

I then cut two pieces of the brass tubing that I would use as "sleeves" over the dowels. The length was determined by the amount of wing dowel exposed past the LE plus the 1/2" I allowed for boring in to the wing. I test fit the brass tubing pieces that I cut and once satisfied, I removed them and mixed up some 30 minute epoxy to set them. I applied a heavy coat all around the wing dowel and in to the hole I had bored and slipped the first brass sleeve on to the dowel twisting it as I pushed it down in to the wing. This insured a good, even coverage of the epoxy between the sleeve and the dowel. I repeated this for the second wing dowel. When I was satisfied with the fit of each sleeve I then cleaned up the excess epoxy from around the sleeves and wing with alchohol and paper towel.

Once all of this cured, I then made adjustments in the receiving holes in the bulk head of the fuse so there was a nice, tight fit. I also lined my wing saddle with saddle tape to insure an even snugger fit once the wing was in place.

When all was completed I went to the field and put 'er up for a while to see if the problem was corrected. After landing and removing the wing for inspection, I found that the problem was gone. I have been flying the Ultra Stick for quite a while now (all Summer) and have had no further problems with charring. I do not take credit for this fix as it was suggested to me from others on RCU.

Hope this gives you a little piece of mind and points you in the right direction for getting you Stick back "safely" in the air.

This is the boring tool that I made.

Hope the photo above helps in making your boring tool if you decide to take this route.

I have also included this photo so you can see the fix after everything is in place on the wing.

Good luck!

I've got hundreds of flights on mine, with no burning of the dowels. I coat my dowels with a bit of CA, mostly to resist soaking up fuel. I'm not saying it can't happen - I remember seeing a large Extra model land, at a field - when we walked up to the model, you could see a little wisp of something coming from the forward hatch - the dowels were smoldering!

So next time, you might want to bring some marshmallows when you head to the field!

I used some left over pieces of Carbon Fiber arrow shafts instead of the dowels supplied and added some ply to the former. I made some inserts out of aluminum tube so the carbon shafts seat into aluminum instead of wood. Good snug fit and no problems. I had recovered my Ultra stick (.60) so I made a ply bracket to fit over the wing spars and the Carbon shafts seat in this bracket and are not just epoxied into the leading edge.

I always soak the dowels and the holes they go into with thin CA, whether the fit is loose or not. Make sure your drip the CA onto the dowel endgrain, and watch the CA get sucked into it drop after drop until it will not accept any more. The CA does tend to swell the wood a bit and help tighten the fit. Also, the dowels filled with cured CA are also less likely to be compress by being repeatedly squeezed into and vibrated inside the holes. This technique does not, however, help with a dowel-hole fit that is very loose to begin with.