Hatz Biplane Association

I have all the parts finished to start building my ribs and based on what I have read here I should expect about one rib per night. I also ordered just enough wood to build the ribs so I am ready to move on to the center section. I figure that it will be a good project to build in tandem with the rib assembly. This is where I got stuck, I can't figure what type and how much to order. I have searched this forum and the archives but can't find any real answers, PoconoJohn got me close with a posted wood list but I still need some help.
Here's what I think I need:

1 4x8 1/4 plywood, for the center section bottom and all center section ribs and partial ribs and doublers.
1 4x8 1/16 plywood, for the center section skin and leading edge skin.

Here's what I don't know:

1) What type of plywood should I use for the different parts, Birch or Mahogany or other?
2) If I order a 4x8 sheet for the skin, I can only cut it one way since the center section is 4.5 feet wide. Will the grain direction be important? Can I control that when I place an order?
3) What is the best material with which to make the laminated bow?
3) Best material for the tank molding and hand holds.
4) Can I assume that if a material type is not listed then it is up to the builder?

Sorry for all the "new guy" questions but the shipping charge for 4x8 is steep and I would like to avoid screwing up too much.

Does someone have a wood material list that they used? I know that some of it is subjective but I would like to get as many 4x8 sheets ordered at one time to save on shipping.

Thanks
Ed White
HC 154

I see there are no replies yet, so here's my thoughts...and I'm new, so take this with a grain of salt.

I believe the patterns...the lines, on the gussets drawings referred to the grain, so those I complied with. I don't have the plans in front of me, but if the center section has similar markings, then I'd go with that; but I don't recall seeing grain markings on the drawing.

As far as ordering all your plywood at once to save shipping, I think you should consider storage of pieces you may not use for awhile. You don't want them warping or getting damaged, so you need a place to keep them flat and protected. I decided to order what I know I'm going to use in the immediate future, then do another big order down the road. Also, you may think you've ordered everything, but with mistakes or errors in measuring/ordering, there's the possibility you'll have to order again anyway.

I decided to make ribs first, so I ordered plywood for only that. I'm going to store the ribs and move onto the fuselage. I'll order more plywood many years from now when I hopefully build the wings and center section.

Good luck.

John

John,
Thanks for the reply. My problem is that I am not a wood person, I have no idea about what type of wood is better for each part and the merits of each choice. Its easy when the plan calls out for mahogany but when it just calls out for plywood I am stumped. I am trying to avoid ordering sheets of 4x8 plywood only to discover that it will be wrong for the application. Like you I started with the ribs and most everything is called out but I can build the center section in parallel while the ribs are gluing.
The center section has me puzzled since I need to decide on leading edge, rib and tank bottom plywood.
I ordered a few books on wood plane construction, I would assume that they will have the information that I am looking for.They should be here next week.
I gave the forum and the archives a pretty good search and I was surprised that I could only find a partial list of the wood required to build the CB1 or the Classic.
With only a few hours each night after work I hate feeling like I am wasting time, I guess after awhile I will settle down.

I have a friend building the fuselage so my responsibility is just the wings, he's not a wood person either.

I don't think you are going to find a completely clear cut answer here. Birch & Mahogany are the more commonly used plywoods. I used Birch for everything except the rib gussets where I used Mahogany (others have used Birch for the gussets). Birch is stiffer/stronger than the same thickness of Mahogany, but the penalty is slightly higher weight. Birch is also less expensive. In the grand scheme, I don't know how much more weight it would add but most of the builds/restorations I've seen seem to use Birch where plywood is called for unless the plans specified something else.

Part of the fun (???) or challenge of plans building is learning about this stuff and figuring it out. I would certainly lean towards Birch on the structural areas such as Center Section bottom, End Ribs, and Spar Doublers. For hand holds I would probably used spruce, but I haven't got there yet - what have others used?

For the laminated bow, I think the plans mention mahogany IIRC.

As an aside, Do you have any books regarding a/c construction to refer to? The EAA books by Tony Bingelis are worth buying. Also good to have is AC43-13-1b (BIG document) AC 43.13-1B - Acceptable Methods, Techniques, and Practices - Aircraft Inspection and Repair:
http://www.faa.gov/regulations_policies ... ntid/99861

Also here's a link to the MIL Spec for plywood. It won't guide you in making a choice based on the application, but it's good info to have handy.
http://www.everyspec.com/MIL-SPECS/MIL- ... 014313.PDF

Thanks Doug, the wood info is quite helpful. I have 43-13 and some books are on the way, Tonys is one of them.

I used birch throughout and agree with Doug's comments. One thing about birch... the heat and pressure used in the manufacturing process can give it a slick, hard finish that may not accept the glue very well. I scuffed the surface with sandpaper before I glued.

Jeff Moore

Hi, if you go to the builders page and go down to my pictures, 637, in the last row there is a good picture of my center section. The floor is 1/4" birch ply and the rear of the spar I used 1/8". If any questions you can e-mail me at j-jpink@bresnan.net.
Jim Pinkerton

I used all birch plywood. For the tank moldings and handholds I used spruce. Mahogany for the bow. I used 1/16" birch for all gussets. Came out real nice.
Welcome to the group, and don't worry about "new guy" questions. That's what this place is for!

Nick