csbabich

My Feedback: (2)

I'm in the process of building a Kadet Mark II - my first build in about 30 years - and am slightly baffled about the best way to join the wing halves.

When joining the wings, what is the best method to keep pressureon the glue joint?

I can't clamp along the length of the root, as the leading edge and trailing edge are sheeted, top and bottom, 3"and 1", respectively. Ican clamp in the center of the root, but I'm afraid of having a loose joint in the areas that are sheeted.

Thanks in advance for any help.

bogbeagle

Tricky one.

This is how I'd glue that joint.

I'd lay the wings on a flat surface, with their upper surfaces facing down. Then, I'd join the lower surfaces of the two panels, using strips of good quality masking tape ... pull the wing roots together, as tightly as possible. Next, I'd turn the assembly and fill the joint with glue. Now, when the panels are pulled together, to the correct dihedral angle, the tape acts like a hinge. This would allow me to exerty quite significant pressure over the whole of the glued area, whilst it is drying.

I'd need to rig things such that the two panels can be left at the correct dihedral angles ... and at the correct relative incidence angles.

Have a "dry run", with some tape and you'll be amazed at how much pressure can be exerted. Gotta use good quality tape, mind.

Mr67Stang

I would still use the clamps in the areas you can get them in. If you had more than a 1/32 inch gap in the sheeted areas, I would be suprised and look at the trueness of the root ribs before glueing. The small gap would be filled with epoxy and serve the purpose. The tape method mentioned is still advisable with the adition of your clamps. Is the rest of the center section suposed to be sheeted after the wings are joined? I would guess, yes. You can always glass the center section as well if the whole center section will be sheeted.

csbabich

My Feedback: (2)

Thanks for the replies.

Ihave read about the tape method, and I'm certain that would work, but my other concern would be introducing a "twist"in one wing half in relation to the other - i.e. different angles of incidence for each wing half.

Or am Ibeing overly concerned about this?

bogbeagle

You are very right to be concerned about "introducing a twist". You need to avoid this.

If you afix straight balsa sticks at/near each wingtip, you will be able to "eyeball" these so as to ensure that each wingtip is at the same relative incidence. These will be especially easy if your wing has a flat-bottomed section. Lots of time will be spent in setting up your bench for this job, prior to the application of glue.

How you achieve the desired outcome depends upon so many different factors. You'll make it work, somehow.

Lnewqban

No, you are not:

http://www.airfieldmodels.com/inform...nels/index.htm

csbabich

My Feedback: (2)

Yeah, the jig he has shown is kind of what I had in mind....set up a very flatsurface with devices to set the wing chords parallel to each other, the leading edges aligned, and apply a bit of inward pressure to the wing halves.

Ithink that, in addition to taping the joint, is the way to go...

Thanks for your help...

Charlie P.

Use 30 min epoxy. It does not have to be clamped (pressure squeezes the epoxy out and can weaken the joint).

csbabich

My Feedback: (2)

Yeah, I don't want to squeeze it to death, just apply enough pressure to close the seam between the 2 halves...

bchapman

I built a Kadet Mark II a few years ago after a long break (15 years) and I just followed the instructions. One of the wing panels was just laid flat on the table with wax paper over the plans. I put a few pins in the panel to keep it from moving around and then just coated both wing roots with Sig 30 min epoxy and pushed them together, blocking up the other side and making sure that it lined up with the plan underneath the wax paper. I put a straight edge along the leading and trailing edges to make sure it lined up and I took off the extra epoxy with my finger.

The joint wasn't a perfect match either because I reduced the dihedral a little from the instructions. The plane fly's great with no trim issues at all.

The Kadet Mark II is a great little airplane and everyone at the field will really like it I'm sure. You don't see many anymore what with all the ARFs. They fly much better than the ARFs as well and last much longer.

Good luck with your project!

Brian

csbabich

My Feedback: (2)

Thanks. When I decided to get back into this, Idebated ARFs, but I just couldn't bring myself to buy a semi-built airplane. Half of the fun is turning a box of sticks into a flying machine. So know I have the Kadet on the board, and an SSE, aGP RV-4, a Sig Miniplane, and a GPExtra 300Son the shelf.

But I'm somewhat of a perfectionist, so that's probably 5years worth of building for me

bchapman

I'm kind of a perfectionist too, so I know where you're coming from. Seriously though I wouldn't worry about the joint too much. When I pulled mine off the table and removed the wax paper, there was about a 1/8" gap that was filled with epoxy and I had to grind off the excess, being really careful not to touch the balsa sheeting.

Once I was done it was smooth and good to go. After you put the fiberglass cloth on that joint it's not going anywhere.

Not sure if you're up for it, but I finished mine with Sig Koverall and dope. You can't beat a painted finish in my opinion. It turned out great and you don't have to worry about the covering lifting up and fuel soaking the wood.

Let me know if you have any other questions on your build.

Brian

csbabich

My Feedback: (2)

I haven't decided if I'm going to paint or use a plastic covering. I'd like to try the plastic, since I've never done that before, and Ireally don't have a proper place to paint.

I'm not concerned about the integrity of the joint, but I do want it to match as close to perfectly as I can get it. Not onlydo I wantthis airplane to teach me to fly,I also want itto teach me to build correctly and precisely.

Ireally admire the guys on here who post pictures that show excellent craftsmanship, and I want to emulate that.

MTK

I applaud your effort to build a kit in this day of ARF. The Kadet is very lightly loaded....don't fret the wing joint. A thin paste of epoxy with microballoons works fine. Don't worry about epoxy squeeze-out. Just leave the wing alone to cure

For panel precision one to the other, you could build a simple jig from MDF. Two 2' pieces hinged in the middle will serve you fine. Establish the dihedral required and set you wing panels in there

jessiej

The Kadet Mark II is a great choice and the kit build will be far more satisfying than an ARF. I built a Mark II many years ago and it survived years of far less than expert flying. It finaly succumed to a head on mid air- with another Kadet Mark II!

jess

Lifer

My Feedback: (1)

I use 30 minute epoxy on almost all of the gluing surface. At the very front, and back of the joint I use 5 minute epoxy. The 5 minute epoxy sets up while you are holding the panels together. Once set, you now have the joint "clamped" and now have time to wipe up any of the 30 minute that squeezed out.

bogbeagle

Very sneaky, lifer.

rccrasher65

My Feedback: (35)

I've built several Sig Kadets MK2's for fellow club members, you are over thinking that step by far. If you built the wing correctly, it should line up perfectly, the dihedral was set with the first wing rib, if all ribs were sanded, stacked together as stated, there should be know problem with matching up. place first half on board flat,raise other half to match up with first, check allignment. I used straight edge on the leading edge. pin down first panel. use 30 min epoxy, don't go over board with the glue. Bring the halves together. check leading edge again for alignment. you can at this point block up the other half for support. tape the halves together till dry. place epoxy and fiberglass tape on joint, evenly on both halves and squeeze the glue out. this joint will never come apart. All mine have been perfect. no problems. I have a nice tight fitting joint, no gaps. If you have a little gap the epoxy will take care of that no problem. Sig craftsman kits are great to build and fly. only way that joint will separate is if you cut it in half. Hope this helps ,take your time and everything will be fine.