RE: One Design Build
 

Very nice work and informative thread...Keep going.

Pedro

RE: One Design Build
 

Thanks Pedro, I will.
Here the rear spars are installed, these are balsa material. They provide gluing surface for the leading and trailing edges of the aileron. The front spar is 3/8"x1/4" laid flat, the rib cap strips will get to these also.

RE: One Design Build
 

The D section balsa sheeting is pre-bent using water ammonia mixture. Once dry, it will get glued in.

RE: One Design Build
 

I added 1/8" liteply reinforcements for the control horn dowel, these are insert in the rear spar and rib before the sheeting. I used a Dremel with end cutting bit for this operation. The cutting jig was from a previous build.

RE: One Design Build
 

The 3/32" balsa sheeting installed, next come the fillers and cap strips.

RE: One Design Build
 

The cap strips and fillers are are glued in and weighted or clamped into position. I hope to cut the wings loose from the jig tonight, then finish the bottom sides.

RE: One Design Build
 

Very interesting building thread, Tony.

I once made a set of wings in a similar fashion, but with some differences. The method was described as The Laser Method in a book named Radio Control Foam Modelling by David Thomas. (Argus Books, England)

The major differences were:
A building board was used above AND below the foam blanks. The blanks were spot glued between the boards. (I used small pieces of double sided tape, this worked very well, quick and easy. It is only to stop the blanks from sliding during the cutting operation.) The upper surface cut was made similar to your method, and the top board removed, with the top blanks still attached to the board. Spar caps, wing tube etc. installed as per your method. Then the planking was installed, using the top board with rib blanks to hold everything in place and weighed down. Some double sided tape was used on the top blanks on top of the sheeting. Thereafter the lower cut was made, and the assembly turned over. The lower (now on top) board was removed, and shear web, spar caps etc. installed, followed by the sheeting, using the board to weigh down.

I am looking forward to seeing how you deal with the lower spar, shearweb and sheeting. Did you cut the blanks from a wider sheet of 1/2" foam, or were you able to purchase narrow strips? (They look about 4" wide)

Regards,
Magne

RE: One Design Build
 

Magne,
Thanks
All the wings I have built using this technique were symetrical so once I cut the bottom away, it gets turned upside down moved to the opposite jig, weighted down in place and the spars are cut same as the top side.

I bought a 4'x8' sheet of 1/2" foam board, it was $15.00 USD. I really didn't try to economize when I cut the blanks, cut them 7" high, could have got by with 5". If I worked at it I could get two wings out of one sheet, I find it better too long than short

RE: One Design Build
 

The bottom templates are screwed to the jig and ready for cutting. I note caution, check that there are no blobs of glue on the foam that will interfer with the wire travel, don't ask me how I know.

RE: One Design Build
 

The top sheeting is cut long so that it hangs over the back of the wing by a 1/4". I glued 3/16" square balsa to the sheeting and the foam, once the glue is cured, the balsa is planed and sanded to the contour on the bottom airfoil surface, the bottom sheeting will overlap and form the trailing edge.

RE: One Design Build
 

Here the wings are flipped and weighted in position, the spar slots are cut in the same manner.

RE: One Design Build
 

The shear web in the area of the wing tube socket is 1/4" balsa sheet fitted between the bottom of the socket and the the spar. The shear web is glued in with a mixture of epoxy and milled fiberglass as was the top side. Once this cures I will fit the 3/32" shear wed to the remainder of the wing bays.

RE: One Design Build
 

The 3/32" shear web is installed before sheeting the bottom side. The sheeting is glued on using Titebond.

RE: One Design Build
 

The servo mounts are installed, I used 1/4"X1/2" Spruce for the rails. The bay is fully sheeted where the servo is located, the sheeting grain runs pararell to the wing ribs. When glued to front and rear spars, it makes for a very solid mount.
The wings will get a rather large radius at the tips, here I added 3/4" scrap blocks for this purpose, the wing tips are 1" thick balsa sheet.

RE: One Design Build
 

The 3/4" filler, 1" wing tip blocks and 1/2" leading edge are glued on. I'm using Titebond white glue because it sands better I'm told. This is the first time I used the white glue. The glue line between the leading edge and the sheeting get hard and difficult to finish, so far I like it.

RE: One Design Build
 

The leading edge is carved to shape, I used a Master Airscrew plane the get close, then used a power plane to get closer, finally the sanding bar. The balsa sheet I used for the leading edge was rather hard and difficult to carve, the wing tip blocks on the other hand are nice and soft.

The radius on the wing tip is laid out with a compass.

RE: One Design Build
 

I wacked the corner off with a saw then block sanded to the line. These small details add a little weight, but this is no 3D machine so everthing will work out just fine.
I'm giving plenty of detail so if any body decides to try this method, they can see to entire process, I hope I'm not boring anybody.

RE: One Design Build
 

Tony,
You are not boring me. I really appreciate the detail you are going into building these wings. I've always used built up balsa - now you have me thinking of trying this. I've a 68" stick that has fully sheeted wings that I wrecked 2 years ago that I'd like to use as a candidate. :) Thanks.
John

RE: One Design Build
 

Same here. Loving the details! I watched the other thread that you did some time ago using the same methods. Great work! makes scratch building more appealing now.

RE: One Design Build
 

Tony,

Oh no, you are not boring anyone. You are giving priceless information. Keep on going with the details.

I have some foam-core wing kits to build in the future. I have been concerned about the sheeting process without a vacuum pump or a good flat surface that can take enough weight without bowing. With your technique, I see a totally different approach now. It would be easier for me to get a hot wire than a vacuum pump.

So, what's the glue did you use for gluing the foam pieces and balsa to the foam?

Pedro

RE: One Design Build
 

I used 3M 77 contact cement for foam to foam. The majority of the foam to wood gluing is with Polyurethane type glue, the glue that foams, I bought Elmers brand because it was cheaper than the Gorilla brand, $8 vs. $12. Wood to wood is Titebond.
The hot wire will cut through the 3M 77 cement and that's why I glue the leading and trailing edge on with it.

RE: One Design Build
 

For carving the wing tips, I lay out lines halfway between the centerline and the surface, then layout the same distance back from the tip. I do this every two inches or so and connect the marks. The 45 degree wedge formed between these two lines then gets carved away, I like to use the large Exacto 26 blade for this.

RE: One Design Build
 

The wing tip is then sanded to a smooth radius using 80 grit paper. Once complete the bottom side get the same treatment. At this point the centerline remains, this will get final sanded just prior to covering.
The poly glue is shown in the background.

RE: One Design Build
 

How is the feeling of the finished wings?

Is it pretty solid, sturdy?

Do they twist some?

RE: One Design Build
 

They are pretty much like built up wings, plenty strong to do the job. Several years ago I built foam rib wings for a 35% Hurley Extra, they did the job.