sensei

Leroy,

Don’t look at it as a scary thing, it is just something that you design to carry desired loads while doing it as light as possible, remember what I stated, make the fittings big and…

I have built a couple of three piece wings in the past with dihedral in the center sections and plug in wings. What I did was built the wing tube sockets in the center section between the spar caps setting the dihedral. Prior to that and on the bench I cut the sockets on the ends to reflect the desired dihedral and CA bonded them together; next I placed carbon tow longitudinally on the top and bottom of the tubes with epoxy resin and continued my layup by wrapping the center section tube area extending outwards from the center about 6” each direction with 3” wide strips of bidirectional carbon fiber wrapped at 45+ and 45- alternating plies, 6 plies in all in the center extending 3” each way and 3 plies going out to the full 6” each way. I then slipped the wing tubes in the sockets, slipped pre cut shrink wrap over the layup areas, heated the shrink tube with a heat gun until the shrink wrap was nice and tight consolidating the layup, I then set all aside until full cure. After that I cut the wrap with a razor blade, remove the shrink wrap, abraded and install as previously stated. This type of center section will carry the loads in your application without allot of weight.

Bob

Leroy Gardner

Bob the thing I don't quite get is the wing joining instructions addressed that issue on the joint and provided all materials to do it, so how does making the wing a 3 piece change (if it does) any strength at the joint. I may be missing something here.

Leroy

da Rock

Since Bob didn't suggest that making the wing a 3 piece would change any strength, I'd say you aren't missing something there, you're reading in something he didn't even talk about. He simply described how he built his 3 piece wings.

Has anyone in the thread said that?

Leroy Gardner

No, I'm just getting started and gathering information, I usually study the assembly manual and plans on all my builds, there may be things I want to change. This whole thing came up when I ran across an article about the wing balance point on slip tube mounted wings, it varies from design to design and I wanted to know where my wing fit in the equation of it all. I have learned a few things from it all and hope others have a better understanding as well. This stuff is good info. for those who may like to design there own wing, that's where the add on to thread comes in, thanks for bringing it up I wasn't thinking along those lines when I asked my question.


I will get started on the build as soon as the wing tubes get here and I would be happy to post pictures of what I do to accomplish a successful 3 piece wing, however it has nothing to do with aerodynamics so wonder if it fits here. Plane will be built on the completed build thread of VincentJ,s Sig 1/4 scale Spacewalker 11 build found in KIT BUILDING I'll get the URL and post it here.

Leroy
,s

da Rock

That article really shouldn't have tied a design's CG location to where the connecting hardware is in a wing. They really have nothing to do with each other. Reading that into any how to article would certainly lead anyone astray.

The fact that a models balance point "moves around" compared to other models is to be expected. Even when 2 different models have identical wings, their CG locations are going to differ unless they also share identical horizontal tails and those are exactly the same moment aft. How many different models have that.

sensei

The only real thing that causes consideration in a three piece wing with dihedral in my case is this: If there were no dihedral then the wing tube would slide straight through the center wing section and carry all the flight loads. Now with dihedral in the center section the tube sockets and center joint must be the load carrying vehicle, by adding the layups to the center section making the wing tube socket very rigid and very strong, even before adding the spar caps, ribs and any other secondary structure like the D section on the wing making it even stronger as you build. As you probably know already, I am a weight freak so I always consider weight with very high regards.

P.S. If you build up a test article as I have described, slide 30" tubes in it, support the ends and load test to destruction, you will see the light.

Bob

Leroy Gardner

I was referring to my plane and wing not his, so who is reading something else here. I know Bob pretty well and I think he will understand what I meant as that's who the statement was addressed, not someone else.

Time to move on here don't you think.

Leroy Gardner

spacewFor those that would like to see my wing build watch for it here shortly, www.rcuniverse.com/forum/kit-building-121/11510569-sig-spacewalker-ii1-4scale.html

Leroy

sensei

Cool, I will check it out.

Bob

speedracerntrixie

My Feedback: (29)

Out of curiosity, Leroy, have you considered a 2 piece wing? I'm going to assume that the original design was set up for a removable one piece wing with all associated mounting provisions. I would think it would be easier to plug the two wing halves together and then bolt the wing as a whole onto the fuse. It would make the build less complicated and you would avoid having to use the wing socket sleeves as a load bearing structure. Just a thought.

Leroy Gardner

Actually with a 8 degree dihedral that would be hard to do and not change dihedral which has a lot to do with it's flight characteristics which I do not want to change and on top of that the gear mounts directly on both sides of center section of wing which isn't getting changed either. Speedracerntrixie what I'm doing is not hard and when done I can get it in the back of a 6' truck box. This is being done or has been done with aluminum bar stock on the thread I posted in post #33 above where my build will take place also.

I think I'm done here.

Leroy

Leroy Gardner

Can't do that it's not part of my plan, characteristics would change and there are other issues to consider, go to the web site I posted in #33 and see a plane that has had it done already using aluminum bar stock and my plane will be built there also. It's a great thread with more to come, check it out.

Leroy

kaosindayton

Build it and they will fly....
Three piece wing will have most forces
from the landing impact on the center section..I don't think you need
12" of tube to get that done unless your making the tips very heavy.
If you can pick it up by the wing tips it is overbuilt for flying, but you
can use it as a simple stress test. I would think if your engaging 3 ribs on
each side of the joint that should be enough. Second pin could be just
the first rib to stop rotation. Extra tie into the spare
would be common.

Good Luck!

Leroy Gardner

That is pretty much what is going on here. Digging up info from sources other than RCU, one being a mfg. of the tube joiners and knows his business said the formula for tube insertion in wing is 1/3rd the length of wing be it 2 piece or 3 and I'm going with that, others will argue that point. I will also include an index pin toward the trailing edge. I have done this before. Tube location for my style of wing is what started this thread in the beginning, and I found the answers I was looking for.

Leroy